Course Objectives By the end of this course, you'll be able to Define medical terms and regions and structures of the body by analyzing medical terms Identify the anatomy, physiology, diseases, and treatments of the cardiovascular and hematologic systems Identify the anatomy, physiology, diseases, and treatments of the respiratory and endocrine systems Identify the anatomy, physiology, diseases, and treatments of the gastrointestinal, urinary, and reproductive systems

Lesson 1 Overview Medical terminology plays a vital role in the medical field. It’s the foundation for all medical professions. The easiest way to master medical terminology is to understand the way medical terms are constructed—how small parts are combined together to build a medical meaning— and that’s exactly what you’ll be learning in this lesson. This lesson provides a detailed introduction to medical terminology and will help you develop a strong basis for your professional vocabulary. The second half of this lesson covers a brief overview of the human body and body functions. You probably have a general understanding of how your body works, but do you fully comprehend how all of the intricate functions and systems of the human body work together to keep you healthy? This lesson will assist you with all the major body systems and bodily functions.    Lesson Objectives Summarize the history of medical terminology and how terms are formed Describe the relationships among the structures of the body Differentiate the positional and directional terms used to describe anatomical locations Identify the nutrients that fuel basic body functions   The Language of Medicine The medical language dates back to the fourth and fifth century B.C.E. Hippocrates was a Greek physician who lived during the fourth century B.C.E. The Hippocratic Oath, named in his honor, is taken by physicians before they begin their medical practice. He is often called the "Father of Medicine," and we've inherited much of our medical language from him. The vocabulary of medicine originates from the Greek and Latin languages, with some words derived from both. Often, our words for body organs come from Latin, yet the diseases and procedures that affect these organs come from Greek. For instance, the Latin-based word uterus refers to the organ, yet we call the removal of this organ a hysterectomy, from hyster, Greek for "womb." From another Greek word for uterus, metra, we get the word endometrium for "the inner lining of the uterus."  Latin  Primum Non Nocere. English First Do Not Harm.   Although most medical terms originate from Greek and Latin, some terms have developed under modern circumstances. You'll come across medical vocabulary words that are eponyms, terms that are named for the person who discovered the illness or procedure. For example, Parkinson's disease is named for James Parkinson, an English surgeon.  Another component to medical terminology is acronyms. An acronym is an abbreviation formed from the initial letter or letters of a word or phrase. For example, CVA is an abbreviation for cerebrovascular accident. Again, while most medical terms are of Greek and Latin origin, it's important to remember that medical terminology has continued to evolve throughout the centuries.    How Medical Terms are Formed Learning medical terminology is similar to learning a foreign language. Learning another language isn't just a matter of memorizing the vocabulary. There's a certain code to any language. Individual words, as well as groups of words, have specific meanings that depend on the order of parts. If you get the order mixed up, you'll change the meaning or make the words meaningless. If you know the meanings of the word parts and how those parts function in combination with each other, you can figure out almost any word you hear. These are the component parts—word elements—you'll be looking for when analyzing medical terms: Prefix: A unit of meaning attached to the front of a word. For example, the prefix AB- means "away from," so abnormal is "away from normal." Root: The core or foundation of the word's meaning. All medical terms have at least one root word. The root of abnormal is NORM, meaning "rule, order." Combining Vowel: A vowel (most often o) added to the end of the root, without changing the meaning. A combining vowel is placed between two roots, or between a root and a suffix that begins with a consonant, to help make the newly combined word easier to pronounce. If the suffix begins with a vowel, drop the o.  Combining Form: The root and combining vowel together, as in norm/o.  Suffix: A unit of meaning attached to the end of the word. The -AL in abnormal is a suffix meaning "pertaining to."   The hyphen after the prefix, or before the suffix, means the term isn't a complete word. We'll provide combining forms with a slash between the root and combining vowel.  AB- The hyphen shows the prefix must be attached to the beginning of a root to be part of a complete word. NORM/O The slash shows the combining vowel has been added to the root to make a combining form. -AL The hyphen shows the suffix must be attached to the end of a root to be part of a complete word.   Analyzing word parts may take some practice, but you'll notice with time the process will become easier. Let's practice analyzing a word you're familiar with. Without looking it up in the dictionary, you would probably define diagnosis as something like "the underlying cause of a patient's symptoms." Let's call that our plain English translation. And now, a more thorough analysis: Prefix/Root/Suffix + Combining Vowel = Combining Form dia- /gnos + o -sis   So we have "complete knowledge process." Compared to our plain English translation, that seems backwards. When analyzing medical vocabulary, it's important to begin at the end. Don't put the meanings in the same order as the parts of the word, or you can end up with an inaccurate description. To determine the meaning of a term, first look at the suffix, then the prefix, then the root(s). Since the combining vowel doesn't carry meaning, you don't have to add that into the definition. Thus, the term diagnosis means the "process of complete knowledge."   Prefixes and Suffixes The word prefix begins with a prefix. PRE- means "before, or in front of." The root FIX means "attach, or fasten." Thus, a prefix is attached in front of something. Not every medical term begins with a prefix, but if a prefix is there, it will always be at the beginning of the word.  We'll be providing you with lists of words to help you memorize the terms you'll need to know as a medical professional. Here's a list of common prefixes that you'll come across in your studies. Prefix | Meaning A-           without, away from AB-         away from AD-         toward AN-         without ANA-       up, apart ANTE-      before   The word suffix comes from the Latin term suffigere, "to fasten underneath." When added to a medical term, a suffix generally turns the word into a diagnosis or medical procedure. For instance, the common suffix -ITIS means "inflammation." Therefore, you can determine the tonsillitis is inflammation of the tonsils, bronchitis is inflammation of the bronchial walls of the lungs, and sinusitis is an inflammation of the sinuses. Another common suffix is -ECTOMY, which means "removal." So, a tonsillectomy is the removal of the tonsils and appendectomy is the removal of the appendix. There are some spelling rules to remember about suffixes. If the suffix begins with a consonant, you usually just add it straight to the combining form. Here is a common list of suffixes for diagnoses and medical procedures or use of instruments.  Suffix   |   Meaning  -ALGIA      pain -CYTE        cell -CYTOSIS   more than the normal number of cells -DYNIA       pain -DERMA     skin condition -DIPSIA       thirst   It's useful to separate suffixes into noun suffixes and adjective suffixes. Remember that nouns name things, and adjectives describe nouns. One of the jobs a suffix can do in a word is change the part of speech. A person suffering from psychosis (noun) will exhibit psychotic (adjective) behavior. Adjective suffixes often have the same definition. Here is a list of adjective suffixes of words that mean "pertaining to." Adjective Suffixes Each of the following means "pertaining to."  Example: cardiac, pertaining to the heart. -AC      -EAL      -NIC -AL      -IAC      -ORY -AN      -IC       -OSE -AR      -ILE      -OUS -ARY     -INE     -TIC -ATIC     -IOR   Root Words and Their Combining Forms Root Word: Just as roots are the foundation of a plant, the root word is the origin of a term. Word roots provide the overall meaning of the medical term. The word root provides information on which body system is involved in the medical term. You could look at prefixes and suffixes as limbs on a tree: cut the limbs off, and they'll die—but the roots will live. The root is the only part that can sometimes "live" by itself as a separate word. Root Word + Combining Vowel = Combining Form Combining Vowel: The combining vowel doesn't have a definition, but it's a necessary tool for the pronunciation of the medical term. Combining vowels are placed between two word roots or a word root and a suffix. Understanding when to use a combining vowel might seem complex, but we'll provide you with some simple rules to make this process easy. Root Word + Combining Vowel = Combining Form Combining Form: Combining forms are developed from word roots and combining vowels. The rule for using a combining vowel with a word root and suffix is to determine if the suffix begins with a consonant or a vowel. If the suffix starts with a vowel, you won't need to use the combining vowel. However, if the suffix starts with a consonant, you'll need to use the combining vowel, as in the term atherosclerosis (ather + sclerosis). A medical term that has two word roots often needs the combining vowel due to pronunciation issues, as in cardiogram (cardi + gram). Root Word + Combining Vowel = Combining Form Practice With Common Word Roots: Here is a list of commonly used word roots. Practice using the combining vowels. CARDIO/O       Heart           Cardiology—study of the heart DERMAT/O       Skin             Dermatitis—inflammation of the skin ELECTR/O       Electricity     Electrocardiography—process of recording electrical heart activity OSTE/O            Bone           Osteotome—instrument used to cut bone PULMON/O     Lung            Pulmonary—pertaining to the lungs

Introduction Now that we've broken down the medical language, it's time to review the main topic of the language. Medical terms are used to label diagnoses, procedures, and treatments, all of which have a direct association with the human body. It's vital to understand the language, but it's just as important to understand the subject to which these terms apply.   Structures of the Body The human body is made of different components. The structures of the human body consist of Cells Tissues Organs Systems Each component of the human body works as an active element in all of the other parts. Cells form tissue, tissue builds organs, organs make up body systems, and body systems are the essential components of the human body.   Cells A cell is the simplest of all living things, yet it's remarkably sophisticated. The most advanced computer in the world can't match the complexity of a single cell. You could devote an entire career to studying cells.  You may recall that atoms are the smallest particles of an element (such as hydrogen or oxygen), and molecules are the smallest amount of a substance (such as water). For example, one molecule of water is made up of two atoms of hydrogen and one atom of oxygen—hence the chemical shorthand H2O. When we say that cells are the smallest structures of the body, we aren't forgetting that atoms and molecules are really smaller. Although made up of molecules, which are made up of atoms, the cell is the smallest "living" unit of function in the body. All living things are made up of cells. The human body has trillions! Some of the bacteria and parasitic microorganisms that can make humans sick are plants and animals composed of just a single cell each.   Even though all cells are microscopic, they do vary in size compared to each other. The female's ovum, or egg, is a single cell that's hundreds of times bigger than a tiny red blood cell. Cells also differ in shape. The word cell may bring a block shape to mind, but some cells are round and flat, some are shaped like thread, some are shaped like bricks, and some lack a definitive shape while others are more complicated in shape. Each cell performs a different function. Cell functions include reproduction, hormone secretion, excretion, and energy production. Muscle cells contract, and nerve cells transmit electrical impulses. Cells are vital to every component of the human body. *Cells specialize, and their shapes reflect what they do. Muscle cells are long and skinny, while epithelial (skin) cells tend to be square-like and flat. Nerve cells look like roots or tentacles, and fat cells look like blobs.   There are three main cell parts: the plasma membrane, the nucleus, and the cytoplasm. Plasma Membrane: This is also known as the cell membrane.  The plasma membrane is the outer boundary of the cell and is made up of proteins and lipids. It's strong enough to keep the cell intact, yet it's thin enough to let substances in and out. Substances such as food and oxygen are allowed in, and waste products are let out. The plasma membrane keeps out harmful substances. Nucleus: In the middle of the cell is its command and control center. The nucleus is in charge of everything that goes on in the cell. The nucleus contains Nucleoplasm A nucleolus Ribosomes These are all surrounded by a nuclear membrane, a double-layered substance that has openings in it to let materials pass between it and the cytoplasm. The combining form KARY/O relates to the nucleus. Cytoplasm: Let's put this word together. The combining form for cell is CYT/O, and the suffix -PLASM means "formative, formed material." Cytoplasm is the material that form cells; it fills the space between the plasma membrane and the nucleus. In the cytoplasm there are numerous structures called organelles, which are specialized parts of cells that have important jobs in the function of the cell. The cytoplasm also contains a network of structures called the endoplasmic reticulum that connects the parts of the cell and functions in transportation and storage. There are two types of endoplasmic reticulum—rough and smooth.   You've already learned about your body consisting of innumerable cells and about the valuable role they play within the human body. It should come as no surprise that disorders at the cellular level can result in disease and illness. This is especially evident when you consider tumors. The terms tumor and neoplasm both indicate the abnormal and uncontrolled growth of cells. However, this doesn't mean that all tumors or neoplasms are signs of deadly diseases. Tumors can be benign or malignant.  Some cancers also have the tendency to send forth cells into distant sites of the body in a process called metastasis.  Benign tumors exhibit abnormal and uncontrolled cell growth, but they don't result in illness or death, and the growth is confined to one area. Sometimes they can grow to a size that causes pain or compression against nearby structures, in which case they're generally removed surgically. Examples of benign tumors include Benign breast tumor, which can be removed with surgery, with no chemotherapy or radiotherapy required Lipoma, which is a tumor of fat cells Nodule in the thyroid gland  Malignant tumors (that is, true cancers) can cause serious illness and even death. Cancerous cells don't obey the laws and restrictions that usually control cell growth. Usually, a mutation during cell division causes cells to become abnormal and develop into cancer.  Cancer cells essentially divide and multiply at the expense of normal, healthy cells. The cells may be concentrated in one place, forming a tumor. Metastasis A cancer will generally progress until it overwhelms the victim or is eradicated by medical treatment. Just as normal cells are specialized, most cancer cells can be traced back to a specific type of tissue. As an example, let's say a patient with a history of breast cancer is found to have a tumor in her lung. A pathologist can look at a biopsy sample from her lung and determine from the cells whether the patient now has a primary lung cancer or if the tumor is metastasized breast cancer.   Tissues and Membranes Tissues and membranes represent the next level of organization in the human body. A tissue is a body of cells organized to perform a certain function. You can see an example of tissue by looking at yourself. Your own skin is a tissue—epithelial tissue. Note that tissue may also contain nonliving substances produced by the cells. These substances make up the extracellular matrix, which is a complex network of proteins, fluid, and various molecules that support the cells.  There are four different tissue types: Epithelial tissue covers the inner and outer surfaces of the body. Skin is the most visible example. Connective tissue connects or supports other body structures. Muscle tissue relaxes and contracts to allow body parts to move and certain organs to function. Nerve tissue extends throughout the body to carry messages to and from the brain.   Epithelial tissue also covers organs, lines body cavities (the spaces that contain organs), and forms portions of some ducts and glands. This tissue functions to protect the body and to absorb, secrete, and excrete substances. Squamous epithelial cells form the outer layer of skin, but they serve much more than a cosmetic role. Your skin protects against invasion from bacteria and other infectious organisms. Throughout life, you collect a thin film of bacteria on your skin. If these squamous epithelial cells didn't form a tough barrier, the bacteria would penetrate the skin and invade your body.  Disorders in which this barrier is lost—such as in burns—can place an individual at great risk for infection. Columnar cells. The lining of the digestive tract, including the stomach and intestines, is also a type of epithelium consisting of columnar epithelial cells. It covers the external surface of organs just as skin covers the outside of the body.                                                                                 Columnar epithelial cells are so named because of their column-like shape. Besides the digestive tract, they also line ducts, glands, and parts of the respiratory tract. Cuboidal epithelial cells form the tissue that protects the kidney tubules and covers the ovaries and certain glands. Endocrine gland cells form a kind of epithelial tissue that secretes its products directly into the bloodstream (for example, the thyroid gland). Exocrine gland cells don't secrete into the bloodstream but rather secrete into some other compartment of the body or outside it (for example, sweat glands).   Connective tissue has a number of functions and comes in many different forms, but basically it connects or supports other body structures. It can be soft and rubbery or hard and rigid, depending on the job it has to do.  Fat, cartilage, bone, blood, and scars are all specialized forms of connective tissue. Fascia is a connective tissue that forms a membrane that surrounds muscles or organs to separate and support them. Cartilage is the rubbery, smooth material that lines the surfaces of the joints. Adipose tissue is a form of connective tissue that can also provide energy in the form of lipid molecules. Blood transports nutrients and wastes to and from cells. Lymph is interstitial fluid that has been filtered by lymph vessels.   Muscle tissue has many different functions in the body. In general, it relaxes and contracts to allow body parts to move and certain organs to function. There are three types of muscle tissue: voluntary, involuntary, and cardiac. The specific locations and roles of muscle tissue will be covered later in your program.   Nerve tissue extends throughout the body to carry messages to and from the brain. Nerve tissue makes up the brain, spinal cord, and nerves. This remarkable network of tissue coordinates the functioning of the entire body. The fundamental unit of nervous tissue is the nerve cell (or neuron). Neurons are specially designed to conduct signals from one end of the cell to another. These signals, racing along the network of nervous tissue, make it possible for you to feel pain, smell odors, see sights, hear sounds, and taste food. In your brain, these signals culminate in conscious thought and memory. Almost every part of the body is regulated in part by neurons. Even blood vessel diameter is influenced by the action of tiny nerves that course along the vessels.   *You may have heard that some lizards can regenerate a whole tail after it's broken off. Although humans can't duplicate that feat, our bodies are able to heal most wounds.  Wound healing occurs by repair of injured tissue. Note that the formation of a scab in some wounds is a normal event in the process of wound healing. As the edges of epithelium grow back together, the scab eventually disappears. A scar, however, never completely disappears. It may fade over a period of years, but the scar will always be there. Scar tissue is essentially the body's method of sealing the edges of a wound.  The scar itself is a dense mat of fibrous material that appears only after normal tissue is damaged (a normal response to injury). Scars aren't limited to the skin and can be found anywhere in the body. Since a heart attack is the death of part of the heart muscle, this dead muscle is eventually replaced by scar tissue. Cells and components of the immune system are responsible for the overall process of wound healing.  The speed and effectiveness of wound healing depends on many factors. Simple wounds heal faster and better than complex, deep, or dirty wounds. Healthy individuals heal wounds better than those individuals who have chronic diseases. The following factors can effect wound healing: Poor circulation to the wound area means that the wound isn't receiving adequate oxygen for the process of healing. Infection in the wound will prevent the cells of the immune system from functioning normally. Several drugs can interfere with the immune system. Lack of sufficient protein or vitamins in the diet will deny the body the necessary building blocks for wound repair.   Key Points The structures of the human body consist of cells, tissues, organs, and systems. Cells form tissue, tissue builds organs, organs make up body systems, and body systems are the essential components of the human body. There are three main cell parts: the plasma membrane, the cytoplasm, and the nucleus.  A tissue is a body of cells organized to perform a certain function. There are four tissue types: epithelial, connective, muscle, and nerve. The two major classifications of membranes are epithelial and connective. Two layers of connective tissue form to create connective membranes.

Introduction There are 10 different systems that reside within the human body. Each system is responsible for performing different tasks. The human body relies on the functions of each body system to maintain good health conditions. As we go along, we'll discuss the different body systems in greater detail. However, before we can through the functions of each system, we'll need to discuss the locations of each system.   Planes of the Body To picture the relative locations of organs in the body, it's helpful to think of them as occupying imaginary planes, or sections of body space. X-ray images are often taken along these planes. There are three major types of planes: The frontal or coronal plane divides the body vertically, into anterior and posterior portions. A sagittal plane also divides the body vertically, but into right and left parts.                                                                                                                        A midsagittal plane goes through the exact median of the body, dividing it into two near-mirror images. A transverse or cross-sectional plane divides the body horizontally, into superior (upper) and inferior (lower) parts.   Quadrants and Regions The body as a whole can be divided into two major cavities. A cavity is a hollow place or space within the body or one of the body's organs. The axial portion includes the head, neck, and torso or trunk. The appendicular portion includes the appendages of the body, or extremities, better known as limbs. Axial and appendicular portions each contain specific anatomical regions of the body. The axial portion contains two major cavities, the dorsal and ventral cavities, and these are further subdivided. The dorsal cavity is subdivided into the cranial cavity (houses the brain) and the spinal cavity (vertebral canal). The spinal cavity is divided into the following sections: Cervical (neck)—contains vertebrae C-1 to C-7. Thoracic (chest)—contains vertebrae T-1 to T-12. Lumbar (loin)—contains vertebrae L-1 to L-5. Sacral (lower back)—contains fused vertebrae S-1 to S-5. Coccyx (tailbone)   The ventral cavity is subdivided into the thoracic and abdominal cavities. The abdominopelvic cavity is the largest ventral cavity and contains the stomach, intestines, kidneys, liver, gallbladder, pancreas, and spleen.   Another way of dividing the abdominal cavity is by quadrants. The midline, which divides the right and left quadrants, contains the aorta, pancreas, small intestine, bladder, and spine.  -The right upper quadrant (RUQ) contains the gallbladder, duodenum, head of pancreas, right kidney and adrenal gland, hepatic flexure of colon, part of the ascending colon, and transverse colon. -The left upper quadrant (LUQ) contains the stomach, spleen, part of the pancreas, and parts of the large and small intestines. -The right lower quadrant (RLQ) contains parts of the small and large intestines, the right ovary, the right fallopian tube, the appendix, and the right ureter. -The left lower quadrant (LLQ) contains the descending colon, sigmoid colon, left ovary and tube, left ureter, and left spermatic cord.   Key points The supine position, sometimes called the recumbent position, is on the back, face upward. When you lie on your side, either left or right, you're in the lateral recumbent position. Prone is on the belly, face down. Superior means "toward the head," and inferior means "toward the feet." Sometimes the term cephalic (pertaining to the head) is used to mean "superior," or the term caudal (pertaining to the tail) to mean "inferior." The frontal or coronal plane divides the body vertically, into anterior and posterior portions. A sagittal plane also divides the body vertically, but into right and left parts. A midsagittal plane goes through the exact median of the body, dividing it into two near-mirror images. A transverse or cross-sectional plane divides the body horizontally, into superior (upper) and inferior (lower parts).

Introduction Let's review the essential elements that the human body relies on for survival and our daily functions. Each body system has specific requirements and functions. If one of our systems fails, it will have a negative impact on all of our body systems. It's important to understand what our body needs to remain healthy.   Nutrients in the Body The food we consume contains a mixture of water, protein, carbohydrates, lipids (fats), minerals, and vitamins. This is all fuel for the body—building blocks for the chemical reactions needed to run the body. After your body digests food, it uses these building blocks to construct muscle tissue, deposit fat underneath your skin, and store carbohydrate energy. This process is called anabolism. Anabolism requires energy. Catabolism is the opposite process, in which a complex substance is broken down into its smaller components. For example, if you exercise for a sufficient amount of time, your body will begin "burning fat" (that is, breaking it down into smaller molecules to release the necessary energy required for continued exercise). Metabolism is the sum of the chemical reactions of anabolism and catabolism.   Water Water makes up more than half of the human body. Not only does water flow through our vessels as a component of blood, it fills up the space inside and between our cells. Water is required for survival. Without water, the body is at risk for serious damage. Each body system depends on fluids to operate. We need a minimal amount of water each day to continue supporting our tissues and organs. Drinking enough water isn't usually an issue. However, certain scenarios do require more water, such as the following: Vomiting and diarrhea—significant dehydration Prolonged exercise—loss of water through sweating Some crash diets—primarily water loss   Carbohydrates Carbohydrates are found in starches and sugars. They're our main source of energy. All carbohydrates are eventually broken down into or converted into glucose. This molecule serves as a ready source of energy for immediate use, or it can be stored as glycogen in the muscles and liver. Your body releases glucose from these glycogen stores during exercise or short-term starvation.   Lipids Lipids are known for their capability to store energy, but they also provide protection and communication between cells. There are different types of lipids, and each one serves a purpose. Fats and oils assist with energy storage. They're broken down and distributed when the body is in need. But in contrast to that of carbohydrates, the energy from lipids can't be used rapidly. Fat stores are designed to be used during long-term starvation. Waxes are lipids that work as a protection level. They help cells by preventing water loss within the body. Steroids are lipids that assist with the communication process between cells. Steroids are composed of cholesterol, testosterone, and estrogen.   Protein Protein is the third major nutrient. Proteins aren't designed to serve as a significant energy source. Protein is the basic building block of the body. It makes up muscles and other tissues and is found in every part of our cells. All the enzymes that drive our metabolism are proteins. Antibodies of the immune system are also proteins.  Protein is used for energy only in times of extreme stress or starvation. After carbohydrate and fat stores are consumed, the body is forced to break down protein for energy.   Use of protein for energy requires a costly sacrifice of structural proteins as well as those involved in enzyme pathways and the immune system. Dietary protein is broken down into amino acids. The body can't make all the amino acids it needs. There are nine essential amino acids that must be acquired from the diet. A food is labeled as a complete protein if it contains all nine essential amino acids. Incomplete proteins don't contain all the essential amino acids.   Minerals, Trace Elements, and Vitamins Minerals and trace elements are chemical compounds present in very small amounts in food. They don't contain calories, so they don't provide energy. But they do serve a variety of purposes in daily metabolism.  Vitamins are organic compounds that function as coenzymes, assisting enzymes in catalyzing chemical reactions. Vitamin deficiencies can result in conditions specific to the metabolic pathways involved.    Calories The calorie is a measure of energy contained in food. A kilocalorie equals 1,000 calories. We tend to use kilocalories when talking about energy content. For instance, a "600 calorie burger" actually has 0.6 kilocalories. Each individual needs a certain amount of kilocalories per day to maintain normal body function. Carbohydrates and protein both contain four kilocalories per gram (that is, a 200-gram meal of pure carbohydrates would contain 800 kilocalories). Fat contains nine kilocalories per gram.   Key Points The food we consume contains a mixture of water, protein, carbohydrates, lipids (fats), minerals, and vitamins. This is all fuel for the body. Carbohydrates are our main source of energy and are found in starches and sugars. Lipids are known for their capability to store energy, but they also provide protection and communication between cells. Protein makes up muscles and other tissues and is found in every part of our cells. All the enzymes that drive our metabolism are proteins. Minerals and trace elements are chemical compounds present in very small amounts in food; they serve a variety of purposes in daily metabolism. Vitamins are organic compounds that function as coenzymes, assisting enzymes in catalyzing chemical reactions

Lesson 2 Overview In this lesson, you’ll learn about cardiovascular and hematologic systems. The cardiovascular system is composed of the heart, blood vessels, and blood. You’ll learn the vital role of the heart in blood circulation to deliver oxygen to various body tissues and collect waste throughout the body. The hematologic system further explains the composition, formation, and distribution of blood within your body. You’ll learn the functions of various blood components. You’ll also gain knowledge of various diseases of the cardiovascular and hematologic systems along with available treatment options. While discussing treatment of these disorders, you’ll learn about the medications used to treat each disorder. Medications listed throughout this lesson are listed as the generic name, with the brand name provided in parentheses.   Lesson Objectives Describe the anatomy and physiology of the cardiovascular system Explain cardiovascular system disorders and treatments Identify the composition of blood and hematologic system in general Recognize various blood disorders and treatment options   The Cardiovascular System Introduction. Cardiovascular is made up of two words, cardiac (heart) and vasculature (vessels). The cardiovascular system plays a vital role in supplying oxygen and nutrients to the cells while removing waste. Also called the circulatory system, it consists of the heart, blood vessels, and blood. Throughout your course, there will be links to the website InnerBody.com. These links provide an interactive look at the organs discussed in your reading. Inner-Body also provides 3-D models of most organs, split-views of each anatomical structure, details about these structures' functions, and much more information that will help you in your studies.   The Heart The heart is the main organ responsible for keeping blood circulating throughout the body. The heart is made up of muscular tissue that contracts and relaxes to receive and distribute blood. In the most simplistic terms, it's the central pump that drives the circulation. While the heart collects and pumps blood, blood vessels carry blood around the body.   The heart is made up of four chambers; the top chambers are called the right atrium and left atrium, and the bottom chambers are called the right ventricle and left ventricle. Blood is distributed to all body parts and regions via arteries, and veins carry blood back to the heart. The roles of atria (plural for atrium), ventricles, arteries, and veins will be discussed later in this lesson.   Think of arteries and veins as one-way streets to transport blood, oriented in opposite directions. Blood vessels collect impure or deoxygenated blood from all parts of the body to the heart. The heart sends the deoxygenated blood to lungs to oxygenation. The heart collects pure or oxygenated blood from the lungs and then distributes it to the body. Heart rate controls the contraction and relaxation to allow inflow and outflow of the blood. Contraction of the heart pumps blood out of the heart and into the vessels, while relaxation of the heart allows blood to fill in the heart and passively move from the atria to the ventricles.   Cardiovascular Anatomy [Transcript Downloaded]   Cardiovascular Physiology The atria receive blood into the heart, and the ventricles pump blood out of the heart. The left ventricle is much larger and thicker than the right ventricle because it must send blood to the entire body instead of only to the lungs. Blood circulation consists of the following main steps: Body tissues receive oxygen from oxygen-rich blood flowing in the arteries. Veins collect waste gas, carbon dioxide, from the tissue and bring blood mixed with waste gas to the right atrium of the heart. Blood flows into the right ventricle. Blood is pumped to the lungs for oxygenation via the pulmonary artery. Oxygenation of blood takes place in the lung capillaries via exchange of oxygen into the blood and carbon dioxide into lung capillaries. (This carbon dioxide waste is exhaled out and oxygen is inhaled in during breathing.) Oxygenated blood returns back to the heart via the pulmonary vein into the left atrium. Blood flows to the left ventricle. Oxygenated blood is pumped to all body parts from the left ventricle through the aorta.   The four chambers of the heart are divided by walls called septa (singular, septum). The interatrial septum partitions the two atria, and the interventricular septum separates the ventricles. In a normal heart, there's no direct transfer of blood between the two sides of the heart—that's why you should consider the heart to be two separate pumps instead of one.   Many people get confused about arteries and veins because we've often heard that arteries carry oxygenated blood and veins carry oxygen-depleted blood. A better way to remember which vessels carry what is to remember that these are one-way vessels, and there are two major kinds of circulation. All veins carry blood toward the heart. All arteries carry blood away from the heart.  You can easily remember this by thinking "a" for away and "a" for artery. During systemic circulation, veins are carrying oxygen-depleted blood toward the heart. When the heart sends that stale blood out into pulmonary circulation, it sends it by the artery since the blood is going away from the heart to the lungs to pick up more oxygen. Once blood picks up oxygen in the lungs, it has to go back into the heart, so it goes via the veins as shown in the blood circulation image. When the oxygenated blood is back in the heart, it's returned to systemic circulation, going back out of the heart by the arteries.   The atrium and ventricle of each side are connected by an atrioventricular valve (AV). The right AV valve, which goes from the right atrium to the right ventricle , is called the tricuspid valve, named for it's three "cusps," or rounded projections. On the left side, the AV valve going from the left atrium to the left ventricle is called the bicuspid valve, but it's perhaps better known as the mitral valve. The cusps "flap" to allow blood to pass through the heart in one direction and prevent backflow into the chamber. There are also two valves guarding the exits of the ventricles. The pulmonary semilunar valve opens from the right ventricle into the pulmonary artery, which takes blood to the lungs. The aortic semilunar valve opens from the left ventricle into the aorta, which is the main artery that takes blood to the rest of the body.   The valves open in only one direction, so if blood tries to enter in a way it's not intended to, the valves will close against it. The closing of valves after cardiac contractions makes the "lub dub" heartbeat sound you hear under a stethoscope    Coronary Circulation Although the heart is filled with blood all the time, the cells of the heart must receive their own blood supply to maintain function. This blood supply comes from capillary networks. Blood gets pumped through thick arteries at anywhere from 5 to 35 liters per minute, but all tissues—even the heart—need capillary networks so that substances in the blood can diffuse across cell membranes. The process by which the heart receives its own blood supply is known as coronary circulation. The aorta is the big "pipe" that receives all the oxygenated blood that comes out of the heart, but from there it branches off into smaller vessels that go to different areas of the body.   The blood vessels that branch off the aorta to take oxygen-rich blood to feel the tissues of the heart are the coronary arteries. The veins that bring stale blood back to the right atrium to be oxygenated are the coronary veins, which join and form the coronary sinus, a trough-like structure that opens into the right atrium. The superior and inferior vena cava carry blood from the rest of the body to the right atrium.   Electrical Conduction Cardiac muscle isn't like other muscles of the body. It doesn't depend on the nervous system to send impulses to contract and relax. We typically think of a heartbeat as a single contraction of the heart muscle, but that conception isn't technically accurate. It would be more correct to think in terms of a cardiac cycle.  A single cardiac cycle consists of simultaneous contractions of both atria followed by the simultaneous contractions of both ventricles. Contraction of the ventricles (and relaxation of the atria) is called systole, whereas relaxation of the ventricles is called diastole. One way to remember this is to realize that during diastole, the ventricles dilate (relax) to receive blood. -What we call blood pressure is actually a measurement of pressure placed on arterial walls during systole and diastole. When a blood pressure reading is taken, the top number is called the systolic pressure, and the bottom number is the diastolic pressure.   The timing of each cardiac cycle must be tightly controlled to keep blood flowing smoothly through the lungs and the rest of the body. This occurs automatically, without your conscious thought. The heart itself contains its own control mechanism, such that an isolated heart (removed from the body) can continue to beat.   The main control center of the heart is a tiny bundle of nervous tissue called the sinoatrial (SA) node. This remarkable structure lies at the junction between the superior vena cava and the right atrium. The sinoatrial node is also known as the "pacemaker" of the heart because it sets the pace of the heart rate (also known as pulse rate).  Clinically, a heart rate slower than 60 bpm indicates bradycardia, and a heart rate faster than 100 bpm indicates tachycardia.   These contractions are controlled by a web of electricity-conducting fibers. The SA node is the beginning of this conducting system. The following outline explains the conduction process in simple terms: The SA node emits a signal to initiate a single cardiac cycle. This electrical signal spreads out over both of the atria, causing them to contract at the same time; this process is systole. The right atrium sends blood from the superior and inferior vena cava into the right ventricle. The left atrium sends blood from the pulmonary veins into the left ventricles. The electrical impulse from the SA node, now spread out over the atria, converges on the atrioventricular node (AV node). This node is another bundle of nervous tissue located between the atria and ventricles. The ventricles dilate to receive the blood from the atria; this process is diastole. But the ventricles can't contract until they receive the command from the conducting system. This occurs as the AV node allows the electrical impulse to proceed forward.                                                                                                                                                                                                                                                                                                            The impulse travels from the AV node to the bundle of His, which lies in the septum between the two ventricles. The bundle of His divides into two large branches, one going to the right ventricle and the other going to the left ventricle. These divide into smaller and smaller branches until they become the Purkinje fibers. The electrical impulses along these Purkinje fibers stimulate both ventricles to contract simultaneously (systole).                                                                                                                                                                                                                                                                                                                         This series of events completes a single cardiac cycle.   Key Points The heart has four chambers: the right atrium, left atrium, right ventricle, and left ventricle. Heart valves ensure that blood flows in only one direction while traveling through heart chambers. Cardiac muscle isn't like the other muscles of the body. It doesn't depend on the nervous system to send impulses to contract and relax. Pulmonary arteries deliver deoxygenated blood from the heart to the lungs, and pulmonary veins deliver oxygenated blood from the lungs back to the heart. The main function of our heart is to keep blood circulating throughout the body and supply oxygen and nutrients to the cells while removing waste.

Introduction The heart is a complex organ vital to human life. Disorders associated with the cardiovascular system are so serious and prevalent, they're the leading cause of death in the United States. It's important to learn about these disorders so you'll know how to prevent them from happening or how to treat them if they arise.   Hypertension Most people think hypertension simply means "high blood pressure." Actually, the condition of hypertension is determined only if the patient has had elevated blood pressure readings over a significant period and under varied conditions. Hypertension is known as a "silent killer." A person with hypertension may not feel ill. However, elevated blood pressure over a long period causes progressive damage to many organs of the body.  Hypertension is a major risk factor for atherosclerosis, which is the buildup of plaque in the arteries. In turn, atherosclerosis of the renal arteries (arteries feeding blood to the kidneys) can lead to hypertension because the kidneys play a central role in blood pressure regulation. Uncontrolled hypertension leads to strokes, heart attacks (myocardial infarctions), peripheral vascular disease, chronic kidney disease, and retinal disease. Most hypertensive people have idiopathic hypertension, the cause of which is unknown.   Decades ago, hypertension was thought to be a normal and acceptable process of aging. Now, physicians know that hypertension at any age is a serious disease that needs to be treated. Normal resting blood pressure is 120/80 mmHg (120 systolic over 80 diastolic). Remember: Systolic blood pressure is a measure of the amount of pressure that blood presses against the arteries and vessels as the ventricles of the heart contract. Diastolic blood pressure is a measure of the same pressure when the heart is relaxed. Another way to think of these measures is that systolic is the "peak" pressure and diastolic is the "minimum" pressure. Blood pressure levels Normal | Systolic: less than 120 mmHg                  Diastolic: less than 80 mmHg  At risk | Systolic: 120-139 mmHg                Diastolic: 80-89 mmHg High | Systolic: 140 mmHg or higher             Diastolic: 90 mmHg or higher   Risk factors for high blood pressure include: Increased age High salt and saturated fat intake Hyperlipidemia (high level of lipids, such as fats, cholesterol, and triglycerides, in the blood) Being overweight or obese Not having an active lifestyle (also called a sedentary lifestyle) Smoking Family history of high blood pressure The best treatment for high blood pressure is changing your lifestyle. These changes include: Losing weight Drinking less or no alcohol Decreasing salt intake Exercising  Quitting smoking Eating a healthy diet   Different classes of medication are used to treat hypertension, including Diuretics  Beta blockers ACE inhibitors  ARBs CCBs Vasodilators  Each class of medication comes with its own side effects and special precautions.   Diuretics are also known as "water pills." Diuretic medications stop kidneys from reabsorbing water and electrolytes. This leads to increased loss of water and electrolytes in the form of urine. Increased water loss lowers the blood volume, which lowers the blood pressure. Medications:  Spironolactone (Aldactone) Furosemide (Lasix) Bumetanide (Bumex) Hydrochlorothiazide (Esidrix) Side effects: Hypotension (low blood pressure) Dehydration  Electrolyte deficiencies  Arrhythmias  Special precautions: Avoid taking at bedtime  May need electrolyte supplements Spironolactone, a potassium-sparing diuretic, may not require a potassium supplement   Beta blockers are beta receptor antagonists that act on the beta receptors in the heart. This causes decreased heart rate and cardiac output and lowers the blood pressure. These drugs are particularly helpful in patients with increased heart rate at rest. Note that beta blocker names end in the suffix –lol. Medications: Metoprolol (Lopressor) Atenolol (Tenormin) Metoprolol XL (Toprol XL) Carvedilol (Coreg) Labetalol (Normodyne) Propranolol (Inderal) Side effects: Hypotension Dizziness Syncope Bradycardia Fatigue Hepatic toxicity Special precautions: Don't abruptly discontinue Major drug-drug interactions occur with certain asthma medications   Angiotensin Converting Enzyme (ACE) inhibitors inhibit (that is, restrain) the conversion of Angiotensin I to Angiotensin II (a potent vasoconstrictor). ACE inhibitors decrease the fluid volume and also cause peripheral vasodilation, resulting in lower blood pressure. Most ACE inhibitor medications end with the suffix –pril. Medications: Captopril (Capoten) Lisinopril (Prinivil) Enalapril (Vasotec) Benazepril (Lotensin) Side effects: Hyperkalemia (increased blood potassium) Hypotension  Dry, persistent cough Angioedema (swelling of tongue, lips, and mouth—a serious adverse event requiring immediate treatment) Increased serum creatinine (indicator of kidney failure) Special precautions: If a cough is intolerable, may need to switch to different class of antihypertensive Monitor kidney function   Angiotensin II receptor blockers (ARBs) inhibit the binding of Angiotensin II to the Angiotensin II receptor. ARBs produce similar end results as ACE inhibitors to lower the blood pressure. Most ARB medications end with the suffix –sartan. Medications: Losartan (Cozaar) Valsartan (Diovan) Irbesartan (Avapro) Side effects: Hyperkalemia (increased blood potassium) Hypotension Dry, persistent cough Angioedema (swelling of tongue, lips, and mouth—a serious adverse event requiring immediate treatment) Increased serum creatinine (indicator of kidney failure) Special precautions: If a cough is intolerable, may need to switch to different class of antihypertensive Monitor kidney function Calcium channel blockers (CCBs) hinder the calcium ion influx (calcium is required during contraction) in the vascular smooth muscle of the heart, resulting in heart muscle relaxation—decreasing blood pressure. Most CCB medications end with the suffix –pine. Medications: Diltiazem (Cardizem) Verapamil (Calan) Amlodipine (Norvasc) Felodipine (Plendil) Side effects: Hypotension Dizziness Flushing Headache Tachycardia Exacerbation of CHF (congestive heart failure) Special precautions: Monitor for signs of peripheral or pulmonary edema Vasodilators work by directly dilating the blood vessels o produce rapid and significant reduction in blood pressure. Vasodilators are commonly used to treat dangerously high blood pressure in emergency situations due to their rapid effect on lowering blood pressure. All medications beginning with the prefix nitro– are vasodilators. Medications: Hydralazine (Apresoline) Nitroprusside (Nitropress) Nitroglycerin (Nitrostat) Isosorbide Mononitrate (Imdur) Side effects: Tachycardia Edema or fluid retention Lupus Postural hypotension Special precautions: Don't abruptly stand up Monitor for signs of swelling   Congestive Heart Failure Congestive heart failure (CHF) happens when the heart can't pump blood efficiently to deliver an adequate supply of blood to the metabolizing tissues, usually because of water and sodium retention. CHF is often confused with a "heart attack." However, it may precede or follow a heart attack. It also may be associated with other cardiovascular problems, such as high blood pressure, aortic stenosis, and coronary artery disease.   The word congestive is used to imply the edematous state commonly associated with fluid retention. CHF most commonly occurs in the elderly but could also occur in people of any age due to underlying cardiovascular problems such as coronary artery disease, pulmonary embolism, and infection. Symptoms of CHF include fatigue, increased urination at night, swelling, shortness of breath, tachycardia, and nausea/vomiting. Medications are used to help relieve these symptoms, prevent further damage, and prolong survival. Damaged heart muscle after heart failure can't be repaired. Risk factors for congestive heart failure include Increased age Infections Valve disease Arrhythmia  Trauma to heart muscle Chemotherapy and certain illicit medications Congenital heart disease Nonpharmacologic therapy for congestive heart failure may include Bed rest to decrease the cardiac load Progressive ambulation Dietary control with small, frequent meals Salt restriction   Medications used to treat congestive heart failure include the following. Digoxin (Lanoxin). Digoxin is a medication that's been proven to be very effective in treating CHF symptoms and reducing hospitalization. It's important to monitor digoxin levels closely to avoid digoxin toxicity due to its narrow therapeutic index. Diuretics. Diuretics are slowly titrated to minimize or eliminate fluid retention. Diuretics increase urination and odium excretion.  Beta Blockers. Beta blockers reduce heart rate and prevent arrhythmias to help reduce CHF symptoms. Beta blockers are known to reduce the risk of mortality and hospitalization and improve the overall clinical status of CHF patients. Sometimes beta blockers are used in conjunction with diuretics.  ACE Inhibitors and ARBs. These medications are generally used for long-term management of chronic CHF.   Hyperlipidemia  Hyperlipidemia (or high cholesterol) is the increase in circulating concentration of cholesterol, cholesterol esters, triglycerides, or phospholipids. Cholesterol is classified as steroid-based and is a primary component of the cell membrane. There are two main types of cholesterol in the blood. 1) HDL (High-Density Lipoprotein) is also known as "good cholesterol." High HDL is associated with a decreased risk of heart disease. 2) LDL (Low-Density Lipoprotein) is also known as "bad cholesterol." High LDL is associated with an increased risk of heart disease and stroke.   *Triglycerides are provided by dietary fats and hepatic conversion of carbohydrates. Triglycerides are also considered "bad" because too many also increase the risk of heart disease.   Risk factors for hyperlipidemia include A genetic defect in the receptor and/or enzyme abnormality or deficiency Obesity High fat and cholesterol dietary intake Certain medications that cause increased cholesterol Treatment for hyperlipidemia may include Dietary restrictions to avoid fatty foods Exercise Weight reduction Smoking cessation    Statins that are used to treat hyperlipidemia include Atorvastatin (Lipitor) Simvastatin (Zocor) Pravastatin (Pravachol) Rosuvastatin (Crestor) Common side effects of statins include Nausea Headache Abdominal pain Muscle pain (May be an indicator of a serious side effect of statins, called rhabdomyolysis, which is a breakdown of skeletal muscle. Routine monitoring of CK [creatine kinase] is recommended for high-risk patients.)  Liver damage (Liver function tests are recommended periodically while patients are on statins.) *Other medications used to treat hyperlipidemia include Niacin (Niaspan) Fenofibrate (Tricor) Gemfibrozil (Lopid) Ezetimibe (Zetia)   Coronary Artery Disease Coronary artery disease (CAD) is one of today's leading health problems for both men and women and effects millions of people in the United States. CAD is a condition in which plaque builds up inside the coronary arteries—also known as atherosclerosis. This narrows the arteries and limits the amount of blood and oxygen that the heart can receive. The lack of oxygen to the heart is called ischemia, and the resulting pain is called angina.  The most feared outcome associated with CAD is a myocardial infarction (MI), more commonly known as a heart attack. MI is one possible form of acute coronary syndrome (ACS), the name for a rupture of coronary arteries due to plaque buildup.  Specifically, MI occurs when a thrombus (blood clot) develops in a coronary artery that's already narrowed by atherosclerosis. The complete blockage of blood flow through the coronary artery prevents the surrounding heart muscle from receiving any blood and oxygen. One proven measure to decrease the incidence of CAD and myocardial infarction is controlling cholesterol levels.   Risk factors for coronary artery disease include Hyperlipidemia Hypertension Smoking Obesity Age Family history Sedentary lifestyle The goal of treatment is to reduce the risk of sudden death due to MI, and treat underlying conditions such as hypertension and cholesterol with therapies previously listed.   Medications commonly used to prevent MI or treat ACS are: Aspirin reduces the risk of another heart attack by keeping blood thinner. Nitroglycerin or other nitrates are used as vasodilators to prevent chest pain by increasing blood supply to the ischemic arteries. Blood thinners are used to prevent clot formation or dissolution of a clot to prevent further damage.   Dysrhythmia  Dysrhythmia is a commonly used term to define disorganized or abnormal heart rhythm. Common causes of dysrhythmias include hypertension, ACS, and heart failure. Dysrhythmias may be fatal if not treated. Medications used to treat cardiac dysrhythmia include: Amiodarone (Cordarone) Disopyramide (Norspace) Dofetilide (Tikosyn) Propafenone (Rythmol)   Key Points   Cardiovascular diseases are preventable with lifestyle modifications such as diet, exercise, and weight reduction. Beta blockers are commonly used medications to control high blood pressure and treat CHF symptoms. One way to recognize which medication is a beta blocker is to remember that these medications end with the suffix –lol. Most ACE inhibitor medications end with the suffix –pril. Most ARB medications end with the suffix –sartan. CCB medications generally end with the suffix –pine. All nitro– medications are vasodilators. Most cholesterol-lowering medications end with the suffix –statin.

Introduction The average volume of blood in the human body is approximately five to seven percent of the total body weight. Blood is essential to transport necessary elements to and from the different body systems. Think of blood like the body's gasoline; a car can't run without gasoline, just as the human body can't operate without blood.   Blood Blood is a thick and dark substance that's made up of a wide variety of particles that serve diverse functions in the body. Three main types of blood cells are Red blood cells White blood cells Platelets  Collectively, these cells are called the formed elements of blood. Blood cells are produced in the bone marrow, and the process of formation of blood cells is called hematopoiesis. The basic foundation of blood, however, is plasma. Plasma is chiefly made of water, but it also contains other particles.   Red blood cells (RBCs) are also referred to as erythrocytes. RBCs give blood its dark red color, and their main function is to deliver oxygen to the body and remove waste products. As you previously learned, oxygen molecules from the lungs cross over into the bloodstream in lungs. But that's only part of the story.   The oxygen doesn't merely dissolve into the blood plasma. Each RBC contains millions of molecules of hemoglobin, a complex protein designed to bind and release oxygen. When hemoglobin binds with oxygen, it's called oxyhemoglobin. RBCs take oxygen to body tissues, where the oxygen is released. As the tissues use oxygen, they produce the waste product carbon dioxide, which is picked up by more RBCs and brought back to the lungs for release out of the body via exhalation.  RBCs don't have nuclei, so they don't contain chromosomes and can't replicate by mitosis like other cells. Bone marrow generates red blood cells through the process of erythropoiesis. The cells are born in the bone marrow and, after maturation, are released into the bloodstream. In a typically functioning body, the spleen and liver destroy RBCs after about 120 days.   Platelets are the third and final type of blood cell. Platelets are also known as thrombocytes because they're involved in the first step of thrombosis, or blood clotting. When your arm gets cut, blood wells up in the cut because the small blood vessels have been damaged. Platelets stick to the damaged edges of the blood vessel and to each other, forming a platelet plug. This plug represents the "quick fix" patch that quickly stops blood flow until a more durable blood clot can form. Without an adequate number of platelets or properly functioning platelets, the cut would continue to bleed instead of stopping after a few minutes.   Types of Blood Cells Platelets or Thrombocytes  Normal count = 150,000—450,000 cells/microliter blood The main function is to promote blood clotting to stop bleeding Low platelet count increases the risk of uncontrolled bleeding Common disorder is thrombocytopenia  WBCs or Leukocytes  Normal count = 4,500–10,000 cells/microliter blood The main function is to produce an immune response and protect the body against foreign pathogens Increased WBC count is an indicator of infection Two main types are granulocytes and agranulocytes: (1) Granulocytes are further divided into three categories: neutrophils, eosinophils, and basophils. (2) Agranulocytes are further classified as lymphocytes and monocytes. Common disorders are leukemia and lymphoma  RBCs or Erythrocytes  Normal count = 4–6 million cells/microliter blood The main function is to transport hemoglobin that carries oxygen from the lungs to the entire body Life span is 120 days Common disorder is anemia   More than half of our blood volume is plasma, and 92 percent of that plasma is water. Plasma is a straw-colored fluid when separated from the formed elements. Besides water, plasma consists of proteins, nutrients, electrolytes, hormones, vitamins, enzymes, and waste products of metabolism. The three important proteins in plasma are fibrinogen, albumin, and globulin.  Fibrinogen: Blood-clotting protein made in the liver. Albumin: Made in the liver and is the most plentiful protein in plasma. It maintains the pressure needed to pull water from tissues back into blood vessels. Globulin: Formed both in the liver and in the lymphatic system. It can be found as two different forms in plasma. Gamma globulin helps form antibodies, and prothrombin helps blood coagulation.    Coagulation Coagulation, or blood clotting, is complex and still not entirely understood. However, it's known that the process depends on platelets. When tissue is injured, platelets and the injured tissue release thromboplastin, an enzyme that works with calcium and other factors to convert prothrombin in the plasma into thrombin. The thrombin then acts as an enzyme to convert the fibrinogen in the plasma into fibrin, which forms a mesh over the area and traps red blood cells, platelets, and plasma to form a clot. When the clot dries, it forms a scab, and the bleeding stops. Coagulation is complex process that requires the concerted action of several blood elements. If any portion of this coagulation cascade is missing, deficient, or malfunctioning, then blood clotting may be impaired. This could result in varying degrees of hemorrhage, or prolonged or absent blood clotting. Hemorrhages can range from minor bleeding—such as that after minor cuts or procedures—to spontaneous bleeding within the body, such as the cranium, chest, or abdominal cavities.  A drug or substance that promotes coagulation is a pro-coagulant, whereas a substance that inhibits coagulation is an anti-coagulant.   Blood Types A blood type is defined by genetic markers and depends on a blood protein called agglutinogen, or antigen, on the surface of the red blood cell.  There are four blood types: A, B, AB, and O. There are two types of antigen: A and B. If you have the A antigen, your blood will be type A; if you have the B antigen, your blood will be type B. If you have both A and B, then your blood will be type AB, and if you have neither of them, your blood will be type O.   Besides the A, B, AB, and O blood types, human blood is also characterized according to the presence or absence of the Rh factor—another antigen against which the body can make antibodies. Individuals with the Rh factor are called Rh positive (or RH+). Those without the Rh factor are Rh negative (or Rh–). Thus, human blood can be categorized into eight different types: Type A+ (Type A, Rh+) Type B+ Type AB+ Type O+ Type A– (Type A, Rh–) Type B– Type AB– Type O– Individuals with Type AB+ blood are universal recipients, which means that they can receive any of the four blood types. They have no antibodies against A, B, or Rh factor antigens because these antigens are present in their own blood and are considered normal.   Key Points Red blood cells are responsible for transportation of oxygen to various body organs. White blood cells are the main defense system against foreign pathogens entering our body. Platelets play a crucial role to stop bleeding by clumping at the site of bleeding. Coagulation is a complicated process that involves coordination of various blood cells and coagulation factors to stop bleeding after a trauma. The following is a list of different blood types:                                                                                                                                                                                *A– and A+                                                                                                                                                                                                                                            *B– and B+                                                                                                                                                                                                                                            *AB– and AB+                                                                                                                                                                                                                                      *O– and O+

Introduction Blood diseases can be associated with a number of different diagnoses. Blood disorders can indicate medical problems that either reside within another body system or are strictly connected to the blood cells. Some blood disorders due to bone marrow disease can be severe. This is because they affect blood cell formation and impact various blood cell functions throughout the body.   Red Blood Cell Disorders Anemia is defined as low red blood cell (RBC) or hemoglobin concentration. Anemia is one of the major RBC disorders. Anemia can be caused by blood loss, destruction of RBCs, or inadequate blood cell production. Blood loss, or hemorrhage, can occur after trauma (such as a car accident) or surgery. Ulcers or tumors in the gastrointestinal tract can bleed as well.  The symptoms of anemia can happen because of a lack of adequate RBCs available to carry oxygen to the body's tissues. People with anemia are often pale and weak. They complain of low energy levels. They may also experience shortness of breath. The acute treatment of anemia is a correction of the underlying problem and transfusion of red blood cells. Sickle cell anemia (SCA) is a genetic disorder that's caused by abnormal hemoglobin production. Abnormal hemoglobin molecules are unable to carry appropriate amounts of oxygen and also make a rigid polymer that can occlude small blood vessels. The occlusion of blood vessels causes extreme pain, requiring hospitalization and treatment with pain relievers, such as acetaminophen (Tylenol), Ibuprofen (Advil), morphine, or fentanyl. There's no definitive treatment option for SCA. Patients require frequent blood transfusions and also need treatment of severe pain during an SCA crisis. Some patients may require long-term treatment of pain associated with SCA.   Microcytic anemia is characterized by the formation of tiny RBCs. The main causes of microcytic anemia are iron deficiency and lead poisoning. Iron deficiency refers to the improper intake of iron or chronic diseases leading to iron deficiency. Mild forms of iron deficiency anemia can be treated by increasing the iron-rich food in your diet. With microcytic anemia, the body forms very large RBCs. The main cause of microcytic anemia is a vitamin B12 and folic acid deficiency. This deficiency could be due to an inappropriate amount of vitamin B12 and folic acid in the diet or the result of another health condition or genetic disorder.   Anemia can be caused by certain chronic diseases, such as renal or kidney disease, cancer, and HIV. Kidney or renal disease can result in decreased production of erythropoietin, leading to anemia. Erythropoietin is a hormone produced in the kidneys that stimulates RBC production. Erythropoietin-stimulating factors are available in injectable forms to increase RBC production in these patients. Treatment of the underlying disease also reverses the anemia once the body starts producing normal amounts of erythropoietin. Common medications for the treatment of anemia due to chronic diseases are Epoetin alpha (Epogen, Procrit) and Darbepoetin alpha (Aranesp). The most common side effects of these medications are hypertension and thrombosis. Patients at increased risk of thrombosis due to other factors need to be watched closely for these side effects. For some patients, risks will need to be evaluated against benefits.   Hemolytic anemia is a result of decreased RBC survival time due to excessive hemolysis or destruction of RBCs. Excessive destruction of RBCs releases too much of the bile pigment bilirubin for the liver to handle. Jaundice, the yellowing of the skin, is a sign of hemolytic anemia. Treatment is generally focused on handling underlying disorders. Steroids and immune-suppressants are sometimes used to manage this type of anemia.   Aplastic anemia is caused by a condition of the bone marrow known as aplasia. In aplasia, the bone marrow cells fail to develop. The body doesn't produce enough leukocytes to help fight infections or enough platelets to help clot the blood. This very serious condition is often treated with blood transfusions.   White Blood Cell Disorders Infections are the most common cause of an increased WBC count. They're treated with antibiotics based on the source of infection. Another common WBC disorder is cancer. Cancer is treated with chemotherapy and radiation. Chemotherapy medications can also affect WBC count. These medications can cause neutropenia (decreased neutrophil count). Severe neutropenia increases the risk of infections because neutrophils are the main cells to defend against foreign pathogens.   Leukemia is a disorder in which the bone marrow produces an extreme abundance of WBCs. Leukemia is a type of cancer. It's caused by the production of WBCs going unchecked, which can destroy other blood cells. Some forms of leukemia afflict young children, but other forms are more common in adults.   There are two main types of leukemia. Acute (sudden onset) leukemia is a characterized by large numbers of undeveloped WBCs. Chronic (gradual development) leukemia has fully matured WBCs present. The subtypes of leukemia include Acute myelogenous (or myelocytic) leukemia (AML) Acute lymphocytic leukemia (ALL) Chronic myelogenous (myelocytic) leukemia (CML) Chronic lymphocytic leukemia (CLL) Leukemia is treated with a combination of chemotherapy medications. The combination depends on the type of leukemia. When the patient goes into remission, a period in which the signs of disease are absent, a bone marrow transplant may be performed. You'll learn about chemotherapy medications in a different lesson of your course.   Lymphoma is another WBC disease. It's caused by cancerous tumor cells developing in the lymphatic system. There are two types of lymphoma: Hodgkin's lymphoma Non-Hodgkin's lymphoma Non-Hodgkin's lymphoma is more common than Hodgkin's lymphoma. The Reed-Sternberg cell is what separates Hodgkin's and Non-Hodgkin's lymphoma. If a doctor sees the Reed-Sternberg cell under a microscope, the lymphoma is classified as Hodgkin's. Lymphoma is treated with a combination of chemotherapy medications.   Neutropenia is a condition in which the neutrophil count is decreased. Neutropenia is usually a side effect of medications such as chemotherapy medications, heparin, and antibiotics, but can also be the result of some genetic disorders. Dangerously low levels of neutrophils pose an extremely high risk of contracting various bacterial and fungal infections. Treatment is the discontinuation of offending medications causing neutropenia. There are medications called granulocyte colony stimulating factors (gCSF) available that stimulate the production of neutrophils. Two common gCSF medications are Filgrastim (Neupogen) Pegfilgrastim (Neulasta)  Patients with severe neutropenia are generally treated with a course of prophylactic antibiotics.   Platelet Disorders Hemophilia is a genetically inherited disease. It's generally characterized by a deficiency of certain clotting factors (factor VII and factor IX), which prevents the blood from clotting. These clotting factors are essential components of the coagulation pathway. Deficiencies of any of these clotting factors prevent blood from clotting, resulting in bleeding episodes. This means that a person with hemophilia may continue to bleed after getting a cut because the blood won't clot. Hemophilia is treated by infusing factors that are available as injectable medications. Hemophilic patients may lose a lot of blood, which means many patients require frequent blood transfusions.   Thrombocytopenia is defined as an abnormally low level of platelets in the blood. It's a general condition that stems from an underlying disease. Low levels of platelets can be due to Chronic liver disease, causing the spleen to enlarge and destroy platelets Antibodies to platelets in some individuals Diseases of the bone marrow, resulting in adequate production of platelets Certain medications (such as Heparin) Because platelets are involved in the initial steps of blood clotting, thrombocytopenia creates a risk for prolonged bleeding. In idiopathic thrombocytopenic purpura (ITP), a body's own antibodies destroy blood platelets. Spontaneous hemorrhages will appear in the skin, mucous membranes of the mouth, and internal organs.  Treatment involves treating the underlying disease or discontinuing offending medications.   Arterial clots are blood clots that occur inside the arteries. Atherosclerosis results from the adherence of cholesterol, RBCs, platelets, fibrin, and other substances to an injured arterial wall that can result in a heart attack or stroke. Venous clots are clots that occur in veins, usually in deep veins within the legs. Venous clots are generally characterized as deep vein thrombosis (DVT). If a venous clot breaks off and travels through the bloodstream, it's called embolus. Leg DTVs often travel to the lungs, causing pulmonary embolism (PE). PE is usually painful and fatal. A clot that develops in the heart can travel to the brain, causing a stroke. Common cause of developing DVT are Trauma to blood vessels Clotting factor deficiencies Prosthetic heart valves Pregnancy Atrial fibrillation (A-fib), which means irregular heart rhythm Prolonged immobility  Orthopedic surgery Certain cancers Estrogen use   Antiplatelet medications disrupt platelet aggregation to help prevent a clot from forming. Oral Medications Aspirin (Ecotrin) Dipyridamole (Persantine)  Clopidogrel (Plavix) Ticlopidine (Ticlid) Prasugrel (Effient) Intravenous Medications Abciximab (Reopro) Eptifibatide (Integrilin) One of the major side effects of antiplatelet medications is an increased risk of bleeding.   Anticoagulant medications disrupt the clotting pathway to slow or stop the clotting process. These medications don't  Require routine lab tests to adjust dosage and measure effectiveness Have many drug-drug interactions Have many drug-herbal interactions One disadvantage is that a reversal agent to control bleeding may not be easily accessible.  All anticoagulants increase the risk of bleeding, and patients are instructed to take these medications exactly as prescribed. Patients are also instructed to watch for any signs and symptoms of bleeding.   Key Points Common medications related to blood disorders are shown below. Generic name: Warfarin | Brand name: Coumadin | Prevents and treats DVT,  PE, and stroke Generic name: Heparin | Brand name: Heparin | Prevents and treats DVT, PE, and stroke Generic name: Darbepoetin alfa | Brand name: Aranesp | Treats anemia from chronic kidney disease (CKD) Generic name: Filgrastim | Brand name: Neupogen | Treats neutropenia due to cancer or chemotherapy Generic name: Clopidogrel | Brand name: Plavix | Prevents myocardial infarction (MI) and stroke Generic name: Eptifibatide | Brand name: Integrilin | Prevents acute coronary syndrome (ACS) and percutaneous coronary intervention (PCI) Generic name: Enoxaparin |Brand name: Lovenox | Prevents and treats DVT, PE, and stroke Generic name: Rivaroxaban | Brand name: Xarelto | Prevents and treats DVT, PE, and stroke

Lesson 3 Overview In this lesson, you’ll learn the basic principles of the respiratory and endocrine systems. The respiratory system is mainly responsible for maintaining appropriate breathing to ensure the body receives a sufficient supply of oxygen and removes carbon dioxide. The endocrine system is mainly responsible for secreting chemicals called hormones that carry signals from the central nervous system to control various processes throughout the body. You’ll also gain knowledge of various diseases of the respiratory and endocrine systems along with available treatment options. While discussing treatment of these disorders, you’ll learn about the medications used to treat each disorder. Medications listed throughout this lesson are listed as generic names with brand names provided in parentheses.   Lesson Objectives Describe the anatomy and physiology of the respiratory system Explain various diseases and treatments of the respiratory system Identify the components and functions of the endocrine system Recognize common endocrine system disorders and treatment options

Introduction As you learned in the previous lesson, the respiratory system, also known as the pulmonary system, is intimately related to the cardiovascular system. The lungs supply oxygen to the blood and get rid of the carbon dioxide waste that the blood brings back to the heart. Without a properly functioning respiratory system, the cardiovascular system can't fulfill its own duties. You may hear people refer to cardiopulmonary disease, or you may have heard of cardiopulmonary resuscitation (CPR). The respiratory and cardiovascular systems are so interdependent that they're sometimes considered one.   Respiration The main function of the respiratory system is to supply oxygen to the body's cells and remove carbon dioxide. This requires coordination among all the organs of the respiratory and cardiovascular systems. Respiration actually occurs on two separate levels, external and internal. External respiration is the type of respiration that you're already familiar with. When you breathe in, oxygen is brought into the lungs for the blood to pick up. When you breathe out, you blow out carbon dioxide that has moved from the blood to the lungs.    Internal respiration, or cellular respiration, is parallel to the process involved in external respiration, but conducted at the cellular level.  After blood passing through the lungs picks up oxygen, the heart pumps the blood to the rest of the body. The oxygen passes through the capillary walls and into the interstitial space, where the cells absorb the oxygen. The cells release carbon dioxide as a byproduct of metabolism. This carbon dioxide waste is picked up by the bloodstream and carried to the lungs for expiration.    Anatomy and Physiology  The respiratory system is comprised of the nose, pharynx, trachea, bronchi, lungs, and diaphragm.  All of these organs work in coordination to maintain appropriate breathing to supply needed oxygen to the body and remove carbon dioxide via exhalation.  Breathing can be done via the nose or mouth. Nose: The nose has two main jobs. First, it provides our bodies with warm, filtered, and moistened oxygen. Second, it holds the olfactory nerve that enables us to smell. Although you can breathe through either your nose or mouth, the nose has features that are designed specifically for the act of inspiration, or the movement of air into the lungs. The main advantage to breathing through the nose is that this passageway warms, moistens, and filters the air before it reaches the lungs. The external nares (or nostrils) are lined with mucous membranes and short, coarse hairs, or cilia, that filter out foreign particles such as dust. Another filter system is provided by the mucus, which also traps foreign particles. The mucus also provides another benefit: it kills some germs and stops the growth of others.  Larynx: The larynx is located between the pharynx and trachea. It's also called the voice box because it houses the vocal chords. Vocal chords are tough bands of ligamentous tissue that vibrate to produce speech. The size and tightness of the vocal chords determine the sound of your voice. The space between the vocal chords is the glottis. The epiglottis, a leaf-shaped flap on top of the larynx, is responsible for sealing off the airway to the lungs when you swallow food or water.  Bronchi: The branches of the bronchi (singular: bronchus) lead to the right and left lungs. After entering the lungs, the bronchi continue branching to smaller and smaller airways. The smallest ones are called bronchioles. The bronchioles open out into balloon-like pouches called alveoli (plural). Each alveolus (singular) expands and contracts with each inhalation or exhalation of air. Capillary beds contain the smallest blood vessels of the lungs, and they lie next to the thin tissue membranes of the alveoli. Here, oxygen from the alveoli combines with hemoglobin, a protein in the red blood cells, and is carried to all parts of the body. At the same time, carbon dioxide is transferred to the alveoli to be discarded by the body when you breathe out. Recall this transfer of the gases from the blood into lung spaces from the discussion of the cardiovascular system in the previous lesson. Diaphragm: The diaphragm sits at the bottom of the lungs. Each breathe is initiated by the coordinated movement of the diaphragm, internal intercostal muscles, and external intercostal muscles. Pharynx: The pharynx, or throat, is a multipurpose tube leading from the back of the nose and mouth. down to the trachea (windpipe) and to the esophagus. It allows air to reach your lungs and food to reach your stomach. Trachea: The larynx leads to the trachea. The trachea is a long, hollow, smooth muscle tube that runs down the chest in front of the esophagus. The trachea separates the upper respiratory system (above the neck) from the lower respiratory system (below the neck). Those who are severely ill, undergoing surgery, or in an emergency situation can receive continuous, artificial ventilation by having a mechanical ventilator connected directly to the trachea—either through the mouth or by puncturing the skin in the neck area. The ventilator then pushes and pulls air in and out of the lungs to continue supplying oxygen and removing carbon dioxide. The trachea branches off into two main bronchi, and then the bronchi branch off to several bronchioles. Lungs: Although the body consists of several paired structures that are identical, the lungs aren't exactly alike. The right lung is divided into three lobes, and the left lung is divided into two lobes. The left lung also has a notch in it to accommodate the heart, and the right lung accommodates the liver. Lungs are balloon-like organs that inflate and deflate to continue normal breathing. The lungs and the heart are protected by the chest wall.   Key Points The upper respiratory system includes the nose, pharynx, larynx, and trachea. The lower respiratory system includes bronchi, bronchioles, and lungs. Breathing is a coordinated effort of various respiratory system organs to receive oxygen and eliminate carbon dioxide. The cardiovascular system works in coordination with the respiratory system to receive oxygen into the blood and remove carbon dioxide out of the blood. Artificial breathing is done by a mechanical ventilator in emergency situations when a person is unable to breathe on his or her own.

Introduction Respiratory system diseases are divided into upper and lower respiratory system disorders. Upper respiratory system disorders are diseases specific to the upper part of the respiratory system, such as the nose and throat. The most common upper respiratory diseases are cold and flu. Lower respiratory system disorders are more severe than upper respiratory system diseases. They often require hospitalization, chronic use of medications, and lifestyle improvements. The most common lower respiratory system disorders are asthma, COPD, bronchitis, and pneumonia.   Common Cold The chances are good that you've had a cold. The common cold is an extremely common viral disease.  The common cold is more common and lasts longer in children. It's also highly contagious. The best way to prevent the common cold is thorough handwashing and avoiding contact with sick people. The common cold usually starts with a scratchy throat, followed by a runny nose. On days 3 and 4, chest congestion starts due to the buildup of mucus in the upper respiratory tract, leading to a cough. On days 6 and 7, patients generally start feeling better. The common cold doesn't require antibiotics because it isn't a bacterial infection. Patients are treated with medications for symptom management.   The symptoms of the common cold include Scratchy or sore throat Nasal congestion, sneezing, sniffing, or runny nose Chest congestion Cough (productive or nonproductive) Body aches Tiredness Fever (most common in children)   Decongestants Decongestants are used to dry excessive mucus and open up the nasal passageway. Most decongestant medications are available OTC without prescription. Side effects of these medications include dryness of mouth and wakefulness, so it's recommended to drink plenty of water and avoid taking these medications in the evening or at bedtime. Some commonly used decongestant medications are Pseudoephedrine (Sudafed) Phenylephrine (Sudafed PE) Oxymetazoline (Afrin)—nasal drops First-Generation Antihistamines  Antihistamines are commonly used to treat symptoms such as runny nose, sneezing, and sore throat. Antihistamines are classified as first generation and second generation.  First-generation antihistamines target more general receptors in the central nervous system and have more side effects than second-generation antihistamines.  Some examples of first-generation antihistamines are  Diphenhydramine (Benadryl) Hydroxyzine (Atarax, Vistaril) Brompheniramine (Bromax) Chlorpheniramine (Chlortrimeton)  Azelastine (Astelin)—nasal spray  Second-Generation Antihistamines Antihistamines are commonly used to treat symptoms such as runny nose, sneezing, and sore threat. Antihistamines are classified as first-generation and second generation.  Second-generation antihistamines are known to cause fewer side effects of dizziness, drowsiness, and dry mouth. Also, these medications are taken only once or twice daily, compared to taking multiple doses of first-generation antihistamines. Some examples of second-generation antihistamines are  Fexofenadine (Allegra) Loratadine (Claritin) Desloratadine (Clarinex)—disintegrating tablet Cetirizine (Zyrtec)  Cough Medications One symptom of the common cold is a cough, which usually starts on day 3 or 4. Coughing is the body's way of trying to eliminate mucus that's been building up in the upper respiratory tract. Cough suppressant medications act on the central nervous system to suppress the urge to cough, and expectorants help bring out the mucus.  Some examples of commonly used cough medications are Dextromethorphan (Delsym)—cough suppressant Guaifenesin (Robitussin)—expectorant Benzonatate (Tessalon) Hydrocodone-homatropine (Hycodan) Promethazine/dextromethorphan (Phenergan)  Pain and Fever Medications Pain and fever medications are used to treat symptoms of body pain, lethargy, and fever. Some examples of commonly used medications for pain and fever are Acetaminophen (Tylenol) Ibuprofen (Motrin) Naproxen (Aleve) Aspirin is also a pain and fever reducer but not commonly recommended due to the risk of bleeding and developing gastric ulcers. Aspirin isn't recommended for children due to the risk of a rare but dangerous disease called Reye's syndrome. Other Treatments Other treatments for cold symptoms are Plenty of fluids to help treat the side effects of cold medications and loosen mucus Rest until symptoms resolve and the cold virus runs its course (five to seven days) Vitamin C and zinc to boost the immune system and help prevent frequent cold infections Eucalyptus and other herbal medications to help relieve cold symptoms   Influenza Influenza, commonly known as the flu, is also a viral infection that's caused by the influenza virus. As with the common cold, antibiotics are ineffective in treating flu. The best option is to prevent the flu by thorough handwashing and immunization. The flu is very common and is sometimes considered a mild disease. However, the flu shouldn't be ignored. It can cause life-threatening complications if not treated. The flu is treated in the same way as the common cold. The difference between a cold and the flu is that the flu is usually a more severe form of a cold. The flu generally has more severe symptoms, such as fever and dehydration. If untreated, the flu can possibly lead to pneumonia and hospitalization.    Seasonal flu vaccines are extremely important for high-risk people. High-risk people include The elderly Children Pregnant women People with chronic diseases People with compromised immune systems Healthy adults living with high-risk people Healthy adults caring for high-risk people   Treatment for symptoms of the flu is the same as the treatment of cold symptoms. Decongestants, antihistamines, cough, and pain and fever medications (previously described with cold treatments) are all used to provide symptomatic relief for the flu. However, the flu must run its course. Some antivirals are available to treat the flu. While antibiotics can cure bacterial infections, there's no cure for viruses. Antibiotics are more effective than antivirals, but not against viral infections. Antivirals can only shorten the length of an illness or reduce the severity of symptoms. To be effective, antivirals must be taken within 36 to 48 hours of the start of symptoms. Patients don't usually seek treatment until they've had symptoms for 48 hours.  Two examples of commonly used antiviral medications to treat the flu are Oseltamivir (Tamiflu) Zanamivir (Relenza) inhaler   Asthma and COPD There are beta-2 receptors in the lungs similar to beta receptors in the heart.  You've already learned that beta blocker medications work on beta receptors in the heart to treat hypertension and other cardiovascular disorders. Beta-2 receptor agonists (meaning these medications enhance the effect of beta-2 receptors) act similarly in the lungs to cause smooth muscle relaxation. There are two kinds of beta-agonist inhalers—short acting and long acting.  Short-acting Short-acting beta-agonist inhalers are used to provide quick relief.  Some examples of short-acting inhalers are Albuterol HFA Levalbuterol (Xopenex) Pirbuterol (Maxair) While not an inhalant, epinephrine (adrenaline) functions very similarly to a short-acting inhaler. Epinephrine is used as an anti-anaphylactic to treat airway obstruction brought on by severe allergic reaction. People who are allergic to such things as nuts, bee stings, or latex will often carry an epinephrine auto-injector for emergency situations.  Long-acting Long-acting beta-agonist inhalers have a slower onset of action but provide relief for a longer period and are used as maintenance therapy in combination with steroid inhalers. Steroid medications simply produce an anti-inflammatory effect in the lungs.  Some examples of long-acting inhalers are Salmeterol/fluticasone (Advair) Formoterol/budesonide (Symbicart) Vilanterol/fluticasone (Breo Ellipta)  The first drug listed in the combination of inhalers is the long-acting beta-agonist, and the second drug is the steroid. These medications are usually given on a scheduled basis (that is, every 12 hours).    Other medications for asthma and COPD include Anticholinergic Medications Anticholinergic medications are also used to prevent constriction of the smooth muscle surrounding airways. These medications are mainly used as a long-term therapy of COPD, but ipratropium may also be used for immediate relief of asthma symptoms. These medications are also available as inhalers. Examples of anticholinergic medications are Ipratropium bromide (Atrovent) Tiotropium (Spiriva) Side effects of these medications are dry mouth, nausea, and a metallic taste in the mouth. Inhaled Corticosteroids Corticosteroid medications make up another class of medications that are commonly used as maintenance therapy to help reduce airway obstruction by decreasing inflammation. It takes two to three weeks for these medications to exert some effect, and it may take from six to eight weeks for maximum symptom relief.  Some examples of steroid inhalers are  Budesonide (Pulmicort) Fluticasone (Flovent) Mometasone (Asmanex) Side effects of the steroid inhalers include a sore throat, a bad taste in the mouth, and thrush (a fungal infection). Patients are instructed to rinse their mouths after each dose of the steroid inhaler. Oral/Injectable Corticosteroids  Some examples of oral/injectable corticosteroids are Prednisone (Deltasone) Prednisolone (Omnipred) Dexamethasone (Maxidex) Methylprednisolone (Medrol) Leukotriene Modifiers Leukotriene modifiers work by producing bronchodilation to improve allergy or asthma symptoms. Examples of leukotriene modifiers are Montelukast (Singulair) Zafirlukast (Accolate) Both of these medications are available as oral agents and aren't as effective as other treatment options for controlling asthma and allergy symptoms.   Bronchitis Bronchitis is the acute or chronic inflammation and/or infection of the mucous membranes of the bronchial passages of the respiratory tract. The main symptom of acute bronchitis is a cough lasting for more than five to seven days. Acute bronchitis is generally self-limiting, and treatment is targeted for symptom relief. On the other hand, chronic bronchitis patients with a productive cough that persists for several months may need further evaluation to possibly diagnose asthma or COPD. Bronchitis is primarily caused by a viral infection and rarely needs antibiotic therapy. Due to increasing trends of antibiotic resistance, many healthcare organizations are taking steps to ensure antibiotics aren't prescribed regularly for acute bronchitis. Patients commonly use acetaminophen, ibuprofen, and naproxen to treat pain and reduce inflammation. Patients can use guaifenesin and dextromethorphan to relieve coughing.   Pneumonia Pneumonia is usually a bacterial infection but can sometimes be viral. Pneumonia symptoms are differentiated from acute bronchitis by the presence of a fever and a sever productive cough. Pneumonia is further classified as community-acquired pneumonia (CAP) or healthcare-associated pneumonia (HCAP). It's important to identify which type of microorganism is likely to be responsible for the infection. Certain microorganisms that exist in healthcare settings can cause a more severe form of disease and are likely to resist first-line antibiotics.   Treatment of pneumonia often requires antibiotics. The type of antibiotic depends on various factors, including the type of organism causing the infection, age, severity, diagnosis of CAP or HCAP, resistant patterns, and comorbidities.  Some commonly used antibiotics for pneumonia are Cephalexin (Keflex) Cefdinir (Omnicef) Amoxicillin/clavulanate (Augmentin) Azithromycin (Zithromax) Moxifloxacin (Avelox) Ciprofloxacin (Cipro) Minocycline (Minocin) Piperacillin/tazobactam (Zosyn) Ampicillin/sulbactam (Unasyn) Vancomycin (Vancocin) Linezolid (Zyvox)   Key Points Inhalers are commonly used medications to treat asthma and COPD. Influenza or flu is a viral infection that can be prevented with good hand hygiene and vaccination. The common cold is also a viral infection that doesn't require antibiotic treatment. Second-generation antihistamines provide the benefit of fewer side effects of dizziness, drowsiness, and dry mouth compared to first-generation antihistamines. Cough medications are cough suppressants such as dextromethorphan or expectorants such as guaifenesin.  Most cold and cough medications are available as combination products over the counter.

Introduction The endocrine system is composed of the thyroid glands, parathyroid glands, pituitary glands, adrenal glands, pancreas, gonads, and pineal glands. Unlike other body systems, the endocrine system glands aren't connected to one another.   Location of the Endocrine Glands The endocrine system is composed of ductless glands scattered throughout the body. The function of these glands is to produce substances called hormones. The word hormone comes from the Greek word meaning "impulse" or "to urge on." One of the jobs of hormones is to stimulate "target" cells to react in specific ways. For example, the hormone prolactin "urges" the mammary glands to secrete milk, and insulin "urges" blood cells to take on glucose. Hormones act as messengers to ensure the proper development and operation of many organs, control the metabolic rate of all cells, and regulate the homeostasis of body fluids. After producing hormones, the glands release them into the bloodstream.   Functions The endocrine glands are regulated by two systems: positive feedback and negative feedback. Positive feedback is demonstrated by our example of prolactin stimulating the mammary glands. This system is activated by a stimulus, such as a baby sucking, providing a cue for the release of a hormone. Negative feedback is a system by which the endocrine system keeps other systems in balance. Think of it as the thermostat for your body. In a building, a thermostat is set to a certain temperature. If it detects that the temperature has dropped lower than the set point, it turns on the heat to warm it back up to the set temperature. If it detects that the air is warmer than desired, it turns off the heat to allow the temperature to fall again. This is called negative feedback because the reaction is opposite to the stimulus. If there's too much stimulus, the gland stops or slows production; if there's too little stimulus, the gland increases production. Many hormones function under this type of negative feedback control.   Some hormones are also controlled directly by the nervous system. This allows the central nervous system to control bodily functions through the endocrine glands.  A familiar example of this is adrenaline, a hormone released by the adrenal glands. It's released in response to outside stimuli, such as being startled by a noise or perceiving danger. This hormone is responsible for our "fight or flight" reaction. It gives us a boost of energy to act quickly. Adrenaline is a part of a feedback loop. An increase in stimuli causes an increase in production of adrenaline. When the stimuli decrease, the body stops producing adrenaline.    Each endocrine gland produces its own hormones that have specific functions in the human body. You'll learn more about these next, but here is a brief overview: Thyroid Thyroid Gland.  Thyroxine and triiodothyronine regulate metabolism in body cells. Calcitonin stimulates the passage of calcium from the blood into the bones. Pancreas Insulin regulates the transport of glucose to the body's cells. Glucagon increases blood sugar by causing conversion of glycogen to glucose. Adrenal Cortex. Cortisol (glucocorticoid) regulates the quantities of sugars, fats, and proteins in cells. Aldosterone (mineralocorticoid) regulates the amount of salt in the body. Estrogen and testosterone (gonadocorticoids) maintain secondary sex characteristics.  Medulla. Epinephrine (adrenaline, norepinephrine) mimics the sympathetic nervous system's response. Parathyroid Parathyroid hormones regulate calcium in the blood. Pituitary (Anterior) Anterior Lobe. Luteinizing hormone (LH) promotes ovulation. Prolactin (PRL) promotes growth of breast tissue and milk secretion. Growth hormone (GH; somatotropin) increases bone and tissue growth. Melanocyte-stimulating hormone (MSH) Increases pigmentation of the skin. Gonadotropins (Follicle-stimulating hormone or FSH) stimulates growth of eggs and ovarian hormone secretion.  Adrenocorticotropic hormone (ACTH) stimulates secretion of hormones from the adrenal cortex, especially cortisol. Thyroid-stimulating hormone (TSH) stimulates production of thyroxine and growth of the thyroid gland. Pituitary (Posterior) Posterior Lobe. Antidiuretic hormone (ADH; vasopressin) stimulates reabsorption of water by kidney tubules.  Oxytocin stimulates contraction of the uterus during labor and childbirth. Testes Testosterone promotes growth and maintenance of secondary sex characteristics in the male. Ovaries Estradiol develops and maintains secondary sex characteristics in the female. Progesterone prepares and maintains the uterus in pregnancy.   Endocrine Glands The largest of the endocrine glands is the thyroid gland. This gland, popularly called the "Adam's apple" in men, is located in the front and sides of the neck. The bowtie-shaped thyroid gland has two lobes, one on either side of the trachea. Thyroid hormones play an essential role in body metabolism. There are three thyroid hormones: Thyroxine (T4) Triiodothyronine (T3) Calcitonin    T4 and T3 are the major thyroid hormones. When T4 and T3 are in the bloodstream, the body's cells are able to consume oxygen at an increased rate. The increased oxygen level allows the cells to use carbohydrates and break down proteins. In other words, T4 and T3 help give the body the energy needed for maintenance and growth. They're also important for bone growth, especially in children. The T3 and T4 abbreviations come from the number of iodine atoms in one molecule of each hormone. Thyroxine has four iodine atoms, while triiodothyronine has three. Calcitonin (also called thyrocalcitonin) is the third thyroid hormone. It's important in calcium metabolism. Calcium is one of the electrolytes necessary for the proper function of every human cell. Calcium is particularly important to the health of bones and teeth and to the function of muscles. Calcitonin prevents calcium loss in the bones, lowering the amount of calcium in the bloodstream. It also plays a part in knowing when you've had enough to eat or drink.   The parathyroid glands are located next to the thyroid gland. They're embedded in the connective tissue that holds the thyroid in place. The main function of these glands is to regulate calcium levels by exerting the opposite effect from calcitonin. Parathyroid hormone (PTH) increases the level of calcium in the blood. Each affect of PTH is balanced by an opposite effect from calcitonin. This system allows the body to maintain healthy levels of calcium.   The two adrenal glands are sometimes called suprarenal glands because they're located on top of the kidneys. The adrenal glands are composed of an outer adrenal cortex and an inner adrenal medulla. The adrenal cortex helps regulate your body's metabolism and stress responses by releasing three different types of steroid hormones, or corticosteroids. Cortisol (glucocorticoid) Aldosterone (mineralocorticoid) Estrogen and testosterone (gonadocorticoids) The adrenal medulla develops from nervous tissue. It's sometimes discussed in relation to the central nervous system. The adrenal medulla is nicknamed "the emergency gland" because it secretes two types of catecholamine—hormones that help the nervous system handle any type of alarm or danger to the body. Epinephrine, or adrenaline Norepinephrine, or noradrenaline   The most important glucocorticoids are cortisone (or hydrocortisone) and cortisol. Glucocorticoids have an anti-immunity or anti-allergy effect. They're given to patients to stop the body's natural defense to allergens or irritants. Cortisol is the principle steroid. Some of its main functions include Regulation of carbohydrate, protein, and fat metabolism throughout the body Stimulation of gluconeogenesis in the liver (conversion of amino and fatty acids to glucose) Increase of blood sugar concentration   Aldosterone regulates the balance of electrolyte (mineral) salts in blood and body fluids. It triggers the kidney tubules to reabsorb sodium and excrete potassium. The adrenal glands produce small amounts of androgens (male sex hormones, testosterone) and even smaller amounts of the female sex hormone estrogen. These steroids are weak and have little effect on the male body since the testes already produce so much testosterone, but adrenal androgens stimulate the sex drive in females.   The presence of epinephrine, or adrenaline, in the bloodstream causes an increase in heart rate, blood pressure, and cardiac output. It also causes dilation of the bronchial tubules to increase oxygen intake, which explains why a shot of epinephrine can control a severe asthma attack and treat anaphylactic shock from a severe allergic reaction. Adrenaline elevates the blood-sugar level, too. All of these physiological effects combine to give the body an extra spurt of energy and strength.   Norepinephrine, or noradrenaline, reinforces many of the effects of epinephrine. It dilates vessels to the brain, muscles, and heart and constricts blood vessels leading to organs nonessential in an emergency reaction (such as the skin). This explains why superficial wounds don't bleed as profusely when adrenaline is flowing, and why there's a sensation of blood draining from your face when you're upset, angry, or scared. Norepinephrine also acts as a neurotransmitter, thus heightening the ability to think quickly and clearly during an emergency.   The pancreas is an organ located behind the stomach that serves as an accessory organ of digestion. It secretes pancreatic juice, which contains enzymes responsible for the digestion of protein, carbohydrates, and fats. Scattered along its surface, like tiny islands in the ocean, are clusters of microscopic cells called pancreatic islets, or the islets of Langerhans. These cells have a specialized function: to secrete insulin and glucagon, two hormones that play an important role in keeping balanced levels of blood sugar in our body. Insulin Insulin helps push glucose from blood into our cells, causing decreased levels of blood sugar. Carbohydrates, proteins, and lipids are organic compounds used for energy in your body. Insulin affects the way your body uses these compounds. Insulin allows body cells to take up glucose for energy.  Glucagon Glucose is stored in the liver as glycogen. Glucagon speeds up the conversion of glycogen stored in the liver into glucose, thus increasing the blood sugar level.   Key Points The adrenal glands are composed of two different layers, called an outer adrenal cortex and an inner adrenal medulla. Both layers produce completely different hormones.  Insulin and glucagon have opposite functions in your body. While insulin pushes glucose into the cells, glucagon breaks down glucose stores in the liver to release glucose into your blood. The pituitary gland is also called the "master gland" due to its function in controlling hormone secretions from other glands. The pituitary gland, on the other hand, is stimulated by the hypothalamus.  The adrenal cortex releases cortisol, aldosterone, and sex hormones that play an important role in regulating a wide variety of processes such as metabolism of organic compounds, maintenance of electrolyte balance, and secondary sex characteristics. The adrenal medulla releases hormones called epinephrine and norepinephrine that trigger your body's "fight or flight" response.

Introduction Endocrine glands can develop tumors and inflammations, causing them to be hyperactive (overactive) or hypoactive (underactive). Endocrine glands also have the potential to develop serious pathological conditions caused by an excessive or inadequate production of hormones. Imagine the dire consequences if your master gland is overworked or stops working altogether. Abnormalities in hormone levels can cause a number of physical problems, ranging from fatigue to physical disfigurement to diabetes and even death. Hypersecretion is often corrected with surgery, and hyposecretion may be treated with hormone supplements.    Hyperthyroidism Hyperthyroidism is a thyroid gland disorder that causes the release of too much thyroid hormone. Hyperthyroidism most commonly results from a syndrome called thyrotoxicosis, or Graves' disease. Tremors or shakiness Palpitations Weakness Weight loss Insomnia (unable to fall asleep or stay asleep) Increased heart rate Sweating Protrusion of eyeballs Radioactive iodine is a commonly used treatment for hyperthyroidism. Thyroid cells are the only cells that absorb iodine, so there's no ill effect of the radioactive iodine on other cells of the body. Once thyroid cells absorb radioactive iodine, they're either damaged or killed. The body then eliminates the iodine by excretion. Surgical removal of the enlarged gland with or without iodine is another treatment option for hyperthyroidism. The surgery is called a thyroidectomy. Patients often require thyroid replacement therapy after surgery. Medications to treat hyperthyroidism include Methimazole (Tapazole) Propylthiouracil (PTU)   Hypothyroidism is a thyroid gland disorder that causes the release of too little thyroid hormone. Underproduction of thyroxine or thyroid hormone slows down the body's metabolism.                                                                                                                                                                                        Hypothyroidism will often cause an increased level of TSH because the pituitary gland continues to release TSH due to a low level of thyroid hormone in the blood. (Remember the negative feedback system.) Hypothyroidism is a chronic disease that occurs more commonly in women. Mental and physical sluggishness Obesity Enlargement of the tongue Swelling of the lips and nose Sensitivity to cold Muscle weakness The treatment for hypothyroidism is thyroid hormone replacement. Levothyroxine (Levoxyl, Synthroid, Levothroid)  Thyroid (Armour Thyroid)   Goiters A goiter is a disease characterized by enlargement of the thyroid gland, causing swelling of the neck. A goiter can be cause by either hypothyroidism or hyperthyroidism. It often occurs in a particular geographical area, such as Haiti, because of insufficient dietary intake of iodine. Most patients with a goiter are asymptomatic (show no symptoms) with the exception of airway obstruction, difficulty swallowing, and a hoarse voice due to the enlarged gland. Treatment for goiters involves surgical removal—the patient will need thyroid replacement therapy after surgery—and radioactive iodine.   Cushing's Syndrome Cushing's Syndrome is an adrenal gland disorder caused by a hyperactive adrenal gland. In most cases, hyperactivity is the result of too much ACTH secretion by the pituitary gland. Weight gain Susceptibility to bruises Hypertension Diabetes Weakness Mitotane (Lysodren) Cyproheptadine (Periactin) Ketoconazole (Nizoral) Surgical removal of tumor of the pituitary or adrenal gland   Addison's Disease Addison's disease is due to abnormally low levels of hormones secreted by the adrenal glands. This disease may result from steroid abuse or from an autoimmune disease. Electrolyte imbalance Weight loss Hypoglycemia (low blood sugar) Muscle weakness and pain Hypotension Treatment is generally the replacement of the adrenal hormones. The following two medications can be used for this purpose:  Hydrocortisone (Solu-Cortef) Fludrocortisone (Florinef)   Diabetes Diabetes develops from a deficiency or decreased production of insulin by the pancreas. Since insulin controls glucose levels in the blood, diabetes results in an increased glucose level. There are three types of diabetes: Type 1, Type 2, and gestational diabetes. Diabetes is diagnosed by measuring fasting blood sugar levels. Normal fasting blood sugar level in healthy individuals should be less than 100 mg/dL. A test that measures average blood sugar levels over a two- to three-month period is called hemoglobin A1c (HbA1c or A1c). A normal A1c level for healthy individuals is 4 to 6.2 percent. Symptoms of diabetes include: Feeling very thirsty all the time Frequent urination Extreme fatigue or tiredness Weight loss Blurred vision Tingling pain or numbness in hands or feet Cuts or bruises that are slow to heal Type 1 Average time of onset is childhood, specifically 10 years of age or earlier Sudden onset Mainly caused by the destruction of insulin-producing cells of the pancreas due to genetic or environmental factors Accounts for less than 10 percent of all diabetes Type 2 Average time of onset is adulthood Progressive disease Mainly caused by decreased insulin secretion or development of insulin resistance Accounts for more than 90 percent of all diabetes Gestational Occurs during pregnancy If uncontrolled or untreated, may cause birth defects   Diabetes leads to many chronic complications that can result in frequent hospital admissions and decreased quality of life. Some of the major complications of uncontrolled diabetes are Heart disease Hypertension Stroke Nerve damage (diabetic neuropathy) Blindness (diabetic retinopathy)  Foot ulcers or wounds that don't heal Infections of resistant organisms Amputations (removal of part of a limb) Kidney failure   Listed below are some of the lifestyle modifications that can prevent diabetes and avoid chronic complications of the disease: Balanced diet Decreased consumption of sugars Exercise Maintaining healthy weight   Type 1 diabetes is treated with insulin injections. There are many oral medication options to treat type 2 diabetes. These medications are often used in combinations to treat progressive cases of the disease. Insulin injections may be required in combination with oral medications if oral agents alone fail to keep a desirable glucose level in type 2 diabetes patients. Metformin (Glucophage) Metformin is the first line of treatment for type 2 diabetes after lifestyle modifications fail to keep blood glucose levels in check. Metformin works by increasing glucose uptake in muscles and inhibiting glucose release from the liver. It also increases our body's sensitivity to insulin. Metformin causes side effects in the kidneys, so it generally isn't the drug of choice for patients with poor kidney function. Metformin doesn't cause hypoglycemia, contrary to most other oral diabetes medications. Sulfonylureas  These medications increase insulin release from the pancreas and also make your body cells more sensitive to insulin: Glipizide (Glucotrol, Glucotrol XL) Glyburide (DiaBeta, Micronase) Glimepiride (Amaryl) A major side effect of these medications is hypoglycemia (sudden decrease in blood sugars). Other Oral Medications Pioglitazone (Actos) Rosiglitazone (Avandia) Repaglinide (Prandin) Nateglinide (Starlix) Sitagliptin (Januvia)   Insulin is the primary treatment option for type 1 diabetes. Insulin is administered via the subcutaneous route (injection under the skin). Insulin can cause severe hypoglycemia, so regular monitoring of blood glucose levels while taking insulin is highly important. Insulin is available in short-acting, intermediate-acting, and long-acting forms. Some of the commercially available insulins are a mixture of short-acting and intermediate-acting insulins. Short-Acting Work immediately (5–30 minutes) Typically used with meals to control increased glucose level with food Examples: Humulin R, Novolin R, Humalog, Novolog Intermediate-Acting Work within 2–4 hours Typically used to control glucose levels throughout the day between meals Examples: Humulin N, Novolin N, Humalog 70/30 Long-Acting Work within 6–10 hours Typically used to control glucose levels throughout the day between meals Examples: Lantus, Levemir The following is a list of important information regarding insulins: Insulins must be stored in a refrigerator. Insulins are administered via injection under the skin or into the veins. Once opened or removed from the refrigerator, an insulin vial is good for 28 days at room temperature. Only administer insulin via an insulin needle. Insulin is measured in units, not mgs or mLs (for example, 40 units).   Hypoglycemia Hypoglycemia is defined as dangerously low levels of blood glucose. As mentioned previously, most diabetes medications, including insulin, can cause hypoglycemia. Nervousness Sweaty palms Dizziness Weakness Tachycardia Coma (if untreated) Juice consumption Glucose tablet intake Glucagon injection Dextrose 50% injection   Key Points Know the following key points regarding insulins: They must be refrigerated. They're administered via injection under the skin. Once removed from a refrigerator, a vial is good for 28 days at room temperature. Insulins should be administered only via insulin needle. Insulins are measured in units, not mgs or mLs (example: 40 units).

Lesson 4 Overview In this lesson, you’ll learn the basic principles of the gastrointestinal, urinary, and reproductive systems. The gastrointestinal system is mainly responsible for the absorption and digestion of the food that you eat. It also helps with distribution of the nutrients to various organs as well as elimination of byproducts in the form of stool. The urinary system maintains an appropriate water and electrolyte balance and eliminates waste in the form of urine. The reproductive system is responsible for maintaining normal levels of various reproductive hormones to keep all the reproduction-related processes functioning. You’ll also gain knowledge of various diseases of the gastrointestinal, urinary, and reproductive systems and the available treatment options. While discussing treatment of these disorders, you’ll learn about the medications used to treat each disorder. Medications named throughout this lesson are listed as the generic name with the brand name provided in parentheses.   Lesson Objectives Describe the gastrointestinal system and its disorders and treatment options Describe the urinary system and its disorders and treatment options Describe the reproductive system and its disorders and treatment options   Introduction Every time you enjoy your favorite meal or snack, your gastrointestinal (GI) system is hard at work. Your GI system processes the nutrients and minerals that are important for your survival. It also disposes of unnecessary waste. You'll learn about the GI system's anatomy, physiology, common diseases, and their treatments.   The Digestion Process The GI system is also sometimes referred to as the digestive system and comprises two related sets of organs: the GI tract and the accessory organs.  The GI tract is a long, continuous tube that stretches from the mouth to the anus. In between are the pharynx, esophagus, stomach, small intestine, large intestine, and rectum. Food passes straight through this tract in a line. The accessory organs are the salivary glands, liver, and pancreas, which all help the mechanical and chemical digestion of food as it passes through the gastrointestinal tract.   The process of digestion involves four major functions: Ingestion is the process of putting food in the mouth, chewing, and swallowing. Digestion is the process of physically and chemically breaking chunks and large molecules of food into small molecules that will pass through cell membranes. Digestive enzymes are substances that break down complex nutrients:                                                                                                  - Proteins into simpler amino acids                                                                                                                                                                                                  - Sugars into simple sugars, such as glucose                                                                                                                                                                                  - Fats into fatty acids and triglycerides  Absorption is the process of transferring digested food from intestinal membranes into the blood circulation, which takes most nutrients straight to the liver for further processing and/or storage. Elimination is the process of passing undigested and unabsorbed food out of the body in the form of stool.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         Major Organs of the GI System Mouth. Your mouth's job is to ingest food and prepare it for digestion. The mouth is also referred to as the oral cavity or the buccal cavity, formed from the term "bucca," meaning "cheeks." Once you take food in through your mouth, your teeth, tongue, and saliva work together to chew, process, and swallow the food.   Pharynx The back of the mouth is called the throat or pharynx. The pharynx is the common channel through which air, food, and liquids must pass through to either go to larynx (voice box), the trachea (windpipe), or the esophagus (food pipe). Swallowing is a complex action that requires coordination of the tongue, soft palate (the roof of your mouth), and the muscles of the pharynx. The epiglottis is a flap of cartilage that fold down to cover the larynx during swallowing to prevent food from entering the larynx, and therefore the lungs.    Esophagus The esophagus is 10- to 12-inch long tube that extends from the pharynx to the stomach. Once food passes from the pharynx to enter the esophagus, muscle movements called peristalsis move the food down into the stomach. Sometimes, food can irritate your esophagus and cause the esophagus muscles to contract and expel food. The lower esophageal sphincter maintains enough pressure to prevent stomach content from refluxing back into the esophagus.     Stomach The esophagus empties food straight into the stomach. The stomach has three parts: The fundus is the broad portion near the esophagus. The body is the central portion. The pylorus (or antrum) is the lower, narrow section that joins with the small intestine. When empty, the stomach resembles the size and shape of a large eggplant. It's about 12 inches long with the widest part measuring about six inches around. On the outside of the stomach is a mucosa, a membrane that lines various cavities in the body and surrounds internal organs, composed of layers of epithelial cells surrounding a layer of loose connective tissue. The stomach's mucosa folds into structures called rugae, or a series of ridges. As the stomach fills up, the rugae unfold so the stomach can stretch and smooth out. You've probably seen (or felt) just how much a full stomach can expand. It can hold more than one quart at one time. Overeating can make the stomach push against the diaphragm, causing discomfort that takes a while to wear off. Food stays in the stomach for about three hours. The three layers of muscle (longitudinal, oblique, and circular) in the stomach allow it to contort and twist to mechanically break food apart. As the food is churned about, two sphincters prevent the food from spilling out from either end of the stomach. As previously stated, the lower esophageal sphincter prevents food from refluxing into the esophagus. The pyloric sphincter prevents food from proceeding into the small intestine before the gastric process of digestion is complete. While the stomach churns the food, thousands of tiny glands in the mucous membranes of the stomach's lining secrete gastric juices, including pepsin and hydrochloric acid (HCI). These enzymes mix in with the churned food to form a soupy mixture called chyme.  The pepsin breaks down proteins, and hydrochloric acid maintains an acidic environment in the stomach that kills bacteria. Peristalsis of the stomach muscles forces the chyme to continue down the digestive tract, through the pyloric sphincter, and into the small intestine.   Small Intestine The small intestine (or small bowel) has a deceiving name; it's actually about 20 feet long! But its diameter, at approximately 1 inch, is much smaller than that of the large intestine (which averages 2 1/2 inches in width). Food passes through three parts of the small intestine in the following order. The duodenum is the top part of the small intestine that extends from the stomach. It's about 12 inches long and curves around the head of the pancreas. Besides receiving food from the stomach, the pancreatic duct and the common bile duct from the liver both open into the duodenum to empty digestive juices. The jejunum is the middle part of the small intestine. It's about 8 feet long and is covered in villi—projections that help to absorb nutrients. The ileum is the final section of the small intestine. It's 10 to 12 feet long, and it absorbs the nutrients that aren't absorbed in the jejunum.   Pancreas The pancreas is a gland located behind the stomach, nestled in the curve of the duodenum. As you've already learned in the previous lesson, the beta cells of the pancreas secrete insulin directly into the bloodstream. As an accessory organ to the digestive system, it secretes the most important digestive juice, called pancreatic juice. Pancreatic juice is rich in enzymes that digest all three major kinds of food: carbohydrates, proteins, and fats. The main enzymes are trypsin, lipase, and amylase. Trypsin breaks down protein, whereas lipase breaks down fat. Amylase, also secreted by the salivary glands, breaks down carbohydrates. The pancreas also secretes sodium bicarbonate (a base) to neutralize the gastric acid.   Liver The liver, the largest gland in the body, is also one of the most complex organs. It weighs about 3.5 pounds and is somewhat triangular. It performs over 500 jobs and produces more than 1,000 essential enzymes. The liver's important jobs are to Store blood and filter out toxic elements Convert sugars into glycogen (starch), which it stores Maintain a normal blood sugar level Maintain a normal sex hormone level in the blood Break down fats and temporarily store fatty acids Store vitamins B12, A, D, E, and K Destroy old RBCs, storing useful components and sending others to the kidneys for disposal in urine Produce fibrinogen and prothrombin, proteins that facilitate blood clotting As the main "supply center" of glucose in the body, the liver has a lot of freedom in how it delegates nutritional duties. It can convert excess fats and proteins into sugar for immediate use or sugars and starches into fat and ship them off to storage in other parts of the body. The blood vessels that take blood to the liver from the intestine comprise what's called the hepatic portal system. The liver is the only organ in the body that can actually regenerate if it's damaged. The liver only needs one-quarter of its cells to completely regenerate.   Large Intestine The large intestine (or large bowel), at five feet long, is larger in diameter than the small intestine. The chief function of the large intestine is to receive waste material from the small intestine, absorb water and sodium from the waste material before it passes out of the body, and incubate bacteria that produce essential vitamins. The large intestine forms a three-sided frame around the small intestine. At the joint of the small and large intestines, there's a pouch called the cecum. The ileocecal valve (a sphincter-like structure) regulates the passage of material from the ileum of the small intestine to the cecum of the large intestine. When material enters the large intestine, most of the digestible nutrients have already been absorbed by the small intestine. The chyme has become fecal matter, which may take one to three days to move from the ileocecal valve to the rectum, the terminal portion of the large intestine. The portion of the large intestine between the cecum and the rectum is called the colon. The ascending colon, transverse colon, descending colon, and sigmoid colon are named for the shapes of various sections of the colon. The ascending colon "climbs" straight up from the cecum to the liver; the transverse colon goes "across" the abdomen; the descending colon goes "down" along the flank; and the sigmoid colon, which makes an S shape, empties into the rectum. At either end of the rectum are anal sphincters. The internal sphincter will relax automatically when the rectum fills with feces, stimulating the desire to defecate. The external sphincter, or anus, is controlled voluntarily.   GI Disorders Gastrointestinal inflammation is a common disease that can occur from ingesting food toxins, sustaining injury, or developing an infection from bacteria such as H. pylori. An increased amount of acid from certain drugs (steroids, aspirin, Motrin) can also irritate the stomach. H. pylori. can induce gastric or stomach ulcers as well. Treatment is targeted to remove the offending agent with pain relievers, anti-inflammatory medications, and antibiotics.   Flatulence is commonly called gas. Gas causes abdominal pain and discomfort. A decrease in GI motility and certain foods and drugs can cause accumulation of gas bubbles in the GI tract. Treatment includes using simethicone (Mylicon, Gas-X, Phazyme).   Inflammatory bowel disease (IBD) is the chronic inflammation of the GI tract. Two common types of diseases associated with IBD are called ulcerative colitis and Crohn's disease, which can affect any part of the GI tract. Common symptoms of IBD include Diarrhea Constipation Abdominal pain Weight loss Commonly used medications to treat IBD are Sulfasalazine (Azulfidine)  Methylprednisolone (Solu-Medrol) Cyclosporine (Sandimmune)  Infliximab (Remicade) Mesalamine (Rowasa) Metronidazole (Flagyl)   Pancreatitis is an inflammation of the pancreas. Most cases are caused by alcohol ingestion or gallstones.  Symptoms of this condition include Severe upper abdominal pain Nausea Loss of appetite Treatment for acute pancreatitis requires hospital admission for intravenous (IV) fluids, antibiotics, and medication to relieve pain and inflammation. In the case of gallstone pancreatitis, the gallbladder may be surgically removed.   Cirrhosis is chronic liver failure often caused by alcoholism combined with malnutrition. However, infections and poisons can also cause deterioration of the liver. Cirrhosis takes a long time to develop, but its symptoms appear abruptly. Liver damage can also happen due to untreated viral infections of the liver, such as hepatitis. Common symptoms of liver disease include Abdominal pain Vomiting of blood Jaundice (the yellowing of skin due to buildup of a protein called bilirubin in the blood) Swelling Ascites (fluid accumulation in the peritoneal cavity) Acetaminophen (Tylenol) is a common OTC drug used widely to treat pain and inflammation. An overdose of Tylenol can cause severe liver damage requiring hospitalization and an antidote called acetylcysteine.    Diarrhea is defined as watery, loose, and frequent stools with or without abdominal pain. Diarrhea can result from various illnesses such as colon cancer, inflammatory bowel syndrome, AIDS, and diabetes. Food toxins can also result in acute diarrhea. Certain medications such as antibiotics, antihypertensive medications, and antacids can also cause diarrhea. Patients are instructed to keep themselves hydrated with electrolyte-containing solutions to prevent dehydration from continuous diarrhea. Diarrhea due to food poisoning isn't treated with anti-diarrheal drugs, as diarrhea can help remove the toxin from the body.   Constipation is defined as the difficult or infrequent passing of stools. Patients suffering from constipation have stools that are hard or firm and thus difficult to pass. Constipation can be associated with other medical conditions such as diabetes, thyroid disorders, inflammatory bowel disease, and pregnancy. Constipation can also be induced by certain medications such as antacids, iron, diuretics, and opiates. You can prevent constipation by drinking plenty of fluids, eating a fiber-rich diet, and exercising regularly.   Nausea is defined as an uneasiness or discomfort of the stomach with the urge to vomit. Increased salivation commonly occurs with nausea, and nausea may precede vomiting. Vomiting, also called emesis, is the act of throwing up the contents of one's stomach through the mouth. Nausea and vomiting can be caused by motion sickness, migraines, stomach inflammation or infection, and food poisoning. Nausea and vomiting are also common side effects of many drugs. Chemotherapy medications often cause a severe form of nausea and vomiting. Nausea or emesis may also be triggered by motion. All methods of travel have a tendency to cause motion sickness. Morning sickness is nausea and vomiting that occur very commonly during the first trimester of pregnancy. Motion sickness can be prevented by taking anti-nausea or anti-emetic medications before traveling. Patients undergoing chemotherapy administration are usually given antiemetic and anti-nausea medications prophylactically.   Gastro-esophageal reflux disease (GERD) is a chronic but treatable disease that results from stomach acid backing up into the esophagus. Common risk factors for GERD include pregnancy, obesity, smoking, and surgery. Common symptoms of GERD are Heartburn Coughing Chest pain Difficult breathing Regurgitation GERD can be prevented with such lifestyle modifications as Weight loss Exercise Smoking cessation Consumption of smaller meals Staying upright for two to three hours after meals Avoiding chocolate, alcohol, and caffeine   A peptic ulcer is an open lesion or wound in the mucosal lining of the GI tract including the esophagus, stomach, and intestine. Peptic ulcers can be caused by cigarettes, alcohol, NSAIDs, aspirin, steroids, and H. pylori. The most frequent and severe complication of peptic ulcer disease (PUD) is GI bleeding. PUD may also occur due to complications of untreated, chronic GERD. Treatment usually involves lifestyle modifications such as avoiding alcohol, cigarettes, and drugs that are known to cause peptic ulcer disease. Refer to the Medications to Treat GERD table. The medications used to treat both GERD and PUD are the same. However, they may be used in different combinations and strengths for each disease. PUD may require combining antacids with antibiotics.   Key Points Two common types of diseases associated with IBD are ulcerative colitis and Crohn's disease. Nausea and vomiting can be caused by motion sickness, migraines, stomach inflammation or infection, and food poisoning. The pancreas secretes juice that's rich in enzymes and helps to digest all three major kinds of food: carbohydrates, proteins, and fats. The main enzymes are trypsin, lipase, and amylase. Three main parts of the small intestine are the duodenum, the jejunum, and the ileum. The ascending colon, transverse colon, descending colon, and sigmoid colon describe the shapes of various sections of the colon. The liver is the only organ in your body that can regenerate itself from only 1/4 of its cells. The small intestine is about 20 feet long, which is much longer than the large intestine at 5 feet long. The diameter of the small intestine is much smaller, approximately 1 inch wide, when compared to the large intestine, which averages 2 1/2 inches wide.

Introduction Everything we eat or drink must be either used or eliminated. Waste elimination occurs as a natural process of our daily lives. Most of us take it for granted, but without proper excretion, waste products would build up to toxic levels within our bodies.   Function Recall the role that the intestines in the GI system and the lungs in the respiratory system play to eliminate waste from your body. The urinary system plays an important role in maintaining the appropriate balance of water and electrolytes, and also eliminates wastes in the form of urine. Your very survival depends on a stable internal environment of body fluids, temperature, blood pressure, and countless other factors. The term body fluid  refers not only to the water that makes up 60 percent of the human body's weight, but also the substances dissolved in the water—most importantly, the electrolytes. Fluid both fills and surrounds each cell. About two-thirds of all body fluid is within cells in the intracellular compartment; the remaining must keep a correct electrolyte balance in these fluids for the proper function of muscle and nerve cells. The processes of the urinary system can be broken down into three parts. Filtration—removing toxic wastes and excess substances from the blood Formation of urine—converting wastes and excess waste substances into urine Micturition—excreting urine from the body, also called urination or voiding   The urinary system functions as the body's main waste disposal, flushing away the "garbage" that results from the metabolic processes in every cell of the body. It also helps to maintain the proper pH (acid-base) balance of the blood. Failure of the urinary system to do its job is fatal to the body. If the nitrogenous (nitrogen-containing) wastes of protein metabolism build up in the bloodstream, a toxic condition called uremia will result. The kidneys, the most important organs of the urinary system, also have an endocrine function because they secrete substances that influence the function of other body parts. For example, they secrete the enzyme renin, which plays an important role in regulating blood pressure; the hormone erythropoietin, which stimulates the maturation of red blood cells in the bone marrow; and vitamin D, which makes it possible for the intestines and the bones to absorb calcium.   Organs of the Urinary System The organs of the urinary system include two kidneys, two ureters, the urinary bladder, and the urethra. Because the male urinary system shares some common anatomy with the male reproductive or genital system, these systems are sometimes studied together as the urogenital or genitourinary (GU) system. The branch of medicine concerned with the male genital tract and the urinary tracts of both genders is urology.   Your kidneys look like a pair of reddish-brown kidney beans, each about the size of a computer mouse. The kidneys lie in the posterior aspect of the upper abdomen. The right kidney is just below the liver, and the left kidney is just below the spleen. The left kidney is a little higher than the right one. They are located beneath a layer of muscle and a cushion of fat just under your ribs, not in the peritoneum (membrane lining the abdominal cavity).   The kidneys are complex organs made up of several microscopic parts. The word renal is used in terms relating to the kidneys because the combining form ren/o means "kidney." The renal cortex is the outer layer, and the renal medulla is the inner portion. The heart pumps over 20 percent of its blood flow straight to the kidneys because a high rate of blood flow through the kidneys is essential for the formation of urine. This high flow rate exerts high pressure on the narrow renal capillaries, forcing the blood to filter through nephrons.   Clean blood leaves the kidney via the renal vein. Meanwhile, the waste material that's now urine is funneled through the renal pelvis into the ureter. The ureter is a 10- to 12-inch duct that uses peristalsis (muscle contractions) to move urine along to the urinary bladder.   The urinary bladder  is a reservoir made of muscular walls lined with a loose mucous membrane that wrinkles into folds called rugae when it's empty. These folds enable the bladder to expand when full, similar to stomach folds. The bladder lining has a smooth, close-to-the-muscle section called the vesical trigone. The term trigone means triangular area," and the three corner of the vesical trigone are where the two ureters enter and the urethra exits. As a storage reservoir, the bladder has its limits—about 1 1/2 pints. When the bladder expands enough to stimulate the nerves that initiate the emptying reflex, the internal urethral sphincter is automatically released. Urine then passes into the urethra.    The urethra is the tube leading from the bladder to the surface that carries urine out from your body via urination. The adult male's urethra is approximately seven inches long; it passes through the penis and also conveys semen. The female's urethra is much shorter—1 1/2 inches in length—and opens between the clitoris and the vagina. The external urethral sphincter, at the end of the urethra, is the last valve holding the urine back. This sphincter is under voluntary control after the age of two or three. The opening through which urine leaves the body is the urinary meatus. (A meatus is an opening or a passage.)   The prostate is a gland of the male reproductive system that's slightly larger than the size of a walnut. It's located between the urinary bladder and the penis.  The urethra, from the urinary bladder to penis, runs through the center of the prostate. The prostate gland secretes a milky fluid that's discharged into the urethra at the time of ejaculation that nourishes and protects sperm.     Control of Urinary Secretion The selective reabsorption or secretion of materials in the urine is regulated by chemical and nervous system control. The two main systems of chemical control are the antidiuretic hormone (ADH) system and the renin-aldosterone (RA) system.  ADH is secreted by the hypothalamus in response to high sodium concentrations in the blood, which is called hypernatremia. To lower the salt concentration, ADH works on the tubules to promote reabsorption of water. This excess water enters the bloodstream and dilutes the sodium, thus bringing the sodium concentration back to normal. The name "antidiuretic hormone" implies that this hormone counteracts the effects of diuretics. Since ADH allows reabsorption of water, it reduces the amount of water in the urinary filtrate; on the other hand, diuretics increase the water volume in the urinary filtrate. Diuretics allow the kidneys to eliminate more water volume from the bloodstream. Common substances such as alcohol and caffeine are diuretics. The RA system works in a different way. The kidneys can detect when blood pressure is too low. In response, the kidneys produce a hormone called renin, which stimulates the adrenal glands to produce aldosterone. This substance promotes the reabsorption of sodium and water from the tubules into the bloodstream, which raises blood pressure. The kidneys also produce another hormone called erythropoietin (erythr/o refers to red blood cells). This hormone stimulates the bone marrow to produce red blood cells. Chronically diseased kidneys don't produce enough erythropoietin, which ultimately results in anemia.     Diseases and Treatments Common symptoms of urinary system disorders include Retention (unable to empty the bladder) Incontinence (unable to control the urination) Dysuria (pain on urination) Oliguria (no urine formation) Frequency Urgency Common diseases of the urinary system include Benign prostate hyperplasia (BPH) in men Urinary incontinence Infections Renal failure   Benign prostate hyperplasia (BPH) is defined as the enlargement of the prostate gland and is the most common urinary system disorder in men. Even though enlargement of the prostate occurs throughout a man's life, it usually doesn't become problematic until old age. Enlargement or inflammation of the prostate causes the urethra to constrict, resulting in difficult urination, inability to empty the bladder, and frequent urination due to weakness of the bladder muscles. Along with surgical removal of the prostate, there are many drugs that can be used to treat BPH. Some of the common drugs used for BPH treatment include Tamsulosin (Flomax) Dutasteride (Avodart) Finasteride (Proscar) Terazosin (Hytrin) Doxazosin (Cardura)   The bladder stores and expels urine with the coordinated response from the nervous system and urinary system muscle contractions. Incontinence results from either uncontrolled contraction or overactivity of the bladder muscles. The frequent urge to void can lead to leakage during the night. Other conditions such as urinary tract infection, prostate gland inflammation, and obstruction of the urinary system can also cause incontinence. Certain medications can lead to weaker bladder muscle control as well. Some of the medications that are commonly used to treat uncontrolled or overactive bladder include Tolterodine (Detrol) Oxybutynin (Ditropan) Solifenacin (Vesicare) Trospium (Santura)   Infections may occur in any of the urinary system organs. Urinary tract infections (UTIs) are more prevalent in women than men due to a smaller urethra. UTIs are also more common in sexually active women. Intercourse can cause the GI tract bacteria to move around the surface of the vagina. From there, bacteria can move up to the urethra, uterus, bladder, and even kidneys causing urethritis, ureteritis, cystitis, and pyelonephritis, respectively. UTIs also occur very frequently in elderly people who are bed-bound and/or have catheters in place to remove urine from the bladder.   There are many antibiotics available to treat frequent UTIs. Foods that create an acidic environment in the bladder can also help alleviate minor UTIs. Cranberry juice or tablets are commonly used in young women to prevent reoccurring, mild UTIs. Severe UTIs can lead to hospitalization and intravenous antibiotics. Some of the commonly used antibiotics to treat UTI include Sulfamethoxazole and trimethoprim (Bactrim, Septra) Ciprofloxacin (Cipro) Amoxicillin/Clavulanate (Augmentin) Cefaclor (Ceclor) Piperacillin/tazobactam (Zosyn) A medication called phenazopyridine (AZO, Pyridium) is also available OTC to treat pain associated with UTI.   Renal failure is defined as decreased or total lack of kidney function. Acute renal failure is the quick onset of decline in kidney function due to dehydration, prolonged hospitalization, severe illness, trauma, or drugs. Acute renal failure is generally reversible with hydration and removal of offending medications or treatment of an offending disease. On the other hand, chronic renal failure signifies a progressive decline in renal function. Chronic renal failure (CRF) can be the result of age, uncontrolled hypertension, uncontrolled diabetes, and genetic or environmental factors.   Renal failure causes your body to build up waste due to the kidneys' inability to remove nitrogenous waste. During renal failure, certain drugs aren't excreted from the body quickly and may require dose or frequency adjustments to avoid accumulation of those drugs in the body. Patients with mild renal failure may live their life normally but are instructed to avoid certain foods and may have to limit the consumption of fluids. Patients with chronic and severe renal failure may require mechanical means of filtering wastes from the blood. Mechanical filtration of your blood using different machines is called dialysis.  Some of the mechanical filtrations commonly used in renal failure patients are hemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD). During HD, patients are hooked to a machine that acts as a filter as blood is run through it. HD generally takes two to three hours, and patients with complete renal failure may require HD two to three times a week. CAPD is the continuous method of dialyzing blood with a dialysis solution infused in the peritoneal cavity. The peritoneum membrane acts as a filter as wastes are drawn into the dialysis solution.   Key Points The urinary system plays a very important role in maintaining fluid, electrolytes, and other essential elements in your body and helps eliminate waste. Many drugs are excreted via the kidneys, which means a decrease in renal function can affect drug levels in your body. Close monitoring and dose adjustment may be essential in patients with compromised renal function. UTIs are the most common urinary system disorder and may require antibiotics, hydration, symptom relief medications, and hospitalization for severe cases. End stage renal failure requires mechanical forms of filtration to remove waste and toxic chemicals from your blood. Two common types of mechanical filtration methods are continuous ambulatory peritoneal dialysis (CAPD) and hemodialysis (HD). BPH is a common prostate gland disorder in elderly men. Medications including tamsulosin, dutasteride, finasteride, and terazosin (Hytrin) are used to treat BPH. Severe forms of BPH may require surgical removal of the gland.

Introduction The reproductive system is the only body system that's completely unique to either males or females. Both reproductive systems depend on each other for the procreation process.   Reproductive Characteristics The reproductive organs of both sexes are designed to allow fertilization of the germ or "seed" cells called gametes. The female gametes are called ova, plural for ovum or egg. The male gametes are called spermatozoa, or sperm. Gametes are produced in organs called gonads, specifically the ovaries and testes, which are the essential reproductive organs.  The reproductive system has primary and secondary sex characteristics. Primary sex characteristics are directly related to the growth and function of the reproductive organs themselves. Secondary sex characteristics refer to those "masculine" and "feminine" body features, such as beard growth and breast development. The hormones that develop all these characteristics also cause the sex drive, leading men and women to reproduce. The complex human organism constantly grows and changes. Humans grow from embryo, fetus, infancy, and childhood to adolescence, young adulthood, middle age (40–65), and old age (after 65). Amazingly, it all begins with fertilization.   Fertilization is the fusing of ovum and sperm. Ova and sperm cells differ from other body cells in that they carry only half the usual number of chromosomes. When fertilization occurs, and the gametes from the male combine with the gametes from the female, the hereditary material for a new individual is complete. At this point, the male has contributed his reproductive component. The female system has only just begun. It provides nourishment to the developing life for the approximately 40-week gestation period inside the female's uterus. Once the baby is born, the female reproductive system lactates. This lactation provides milk, the perfect nutrition for the child's early growth.  The development of both males and females is essentially identical except for the development of the reproductive organs. Early in the gestation period, the fetal reproductive organs are said to be undifferentiated, meaning the fetus is neither male nor female, and the basic structures have the potential to become either sex. Differentiation begins at two months of fetal age. The fetus will then take on either male or female reproductive characteristics.    The Male Reproductive System Let's look at the male reproductive system and its organs. The penis and scrotum are called external genitalia. They're located on the outside of the body. The remaining male reproductive organs are all inside the body. Internal genitalia include the testes, duct system, and accessory glands. The male urinary system and the male reproductive system are intertwined. The specialty area of medicine that treats male urinary and reproductive disorders is called urology.   The penis is the male sex organ composed of three parts: A shaft A tip called the glans A cuff of skin called the prepuce (or foreskin) Sexual arousal causes two important reflex actions of the penis: erection and ejaculation. Erection of the penis is made possible by this organ's porous tissue. Arteries bring blood into the penis. This pressure squeezes against the veins, preventing the blood from going back out again. The penis becomes engorged with blood, causing the erectile tissue of the penis to become firm. Ejaculation of semen occurs when sexual arousal reaches a peak, known as orgasm.   A skin-covered sac called the scrotum contains two testes (or testicles), which produce millions of sperm cells each day. This organ is located in a vulnerable position, not encased in the safety of the pelvic cavity. There is a good reason for its location. The body's internal temperature is too hot for spermatogenesis, or the creation of spermatozoa. The scrotum provides a cooler environment. It does this by adjusting position relative to the body to maintain the ideal temperature.   The teste originally develop within the abdominal cavity of the male embryo. A couple of months before birth, they descend into the scrotum through a passageway called the inguinal canal. The inguinal canal shrinks shortly after birth. This leaves just enough room for the spermatic cord to pass through, but not enough for the testes to return to the abdomen. Each testis has about 250 lobules. They hold the seminiferous tubules, threadlike coils where the sperm-manufacturing cells are located.   Leydig cells in the testes produce a class of hormones called androgens. These hormones are produced in response to the luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which are both secreted by the pituitary gland. The most important androgen produced by these cells is testosterone, the male sex hormone. At age 12 or 13 is the typical period of sexual maturation known as puberty. At this age, testosterone stimulates the development of secondary sexual characteristics, such as a deep voice, broad chest, and growth of facial hair. A male begins producing sperm at puberty. He continues to produce sperm and testosterone throughout his lifetime.    Once the sperm is produced, it's secreted from the seminiferous tubules into the epididymis, a 16-foot-long tube coiled tightly into a two-inch space along the length of the testicle. A single sperm looks like a microscopic tadpole. Its oblong head region contains genetic material. The tail, called a flagellum, enables the sperm to "swim" through the female reproductive tract. Each ejaculation of semen contains approximately one teaspoon's worth of fluid, which contains 300 million sperm.   The duct system includes four parts: Epididymis Vas deferens Urethra Ejaculatory ducts The main function of these ducts is to transport sperm from the testes to the urethra for ejaculation as semen. The epididymis performs two functions: Storing sperm produced in the seminiferous tubules Continuing to develop the sperm   When sperm enter the epididymis, they're not fully developed. They're unable to swim or fertilize an egg. They mature while they move through the body of the epididymis. Once matured, they can perform their functions. The matured sperm is stored in the tail end of the epididymis. The epididymis leads to the two-foot-long vas deferens, also called ductus deferens. The vas deferens is a firm, hollow tube that carries sperm straight through the spermatic cord. The spermatic cord is a sheath of connective tissue that also encases the blood vessels and nerves on their way to and from the testes. The vas deferens enters the pelvis and crosses over and behind the urinary bladder, where it meets the accessory gland, the seminal vesicle.   As the vas deferens emerges from the seminal vesicle, it joins with the ejaculatory duct in the prostate. The converged ducts pass through the Cowper's glands, and then join the urethra, the tube leading from the bladder to the outside of the body. From there, the semen (sperm mixed with the seminal fluids) passes out of the body through the urethral orifice or meatus. As you know, the urethra also expels urine from the body, but during ejaculation, the sphincter to the bladder stays closed to keep urine in.   The seminal fluids contained in semen are secreted by the accessory sex glands. Seminal fluid consists of proteins, minerals, fructose, enzymes, mucus, and citric acid. The main accessory glands of the male reproductive system include seminal vesicles, prostate gland, and Cowper's glands. A large percentage of seminal fluid comes from two seminal vesicles, small glands located at the base of the bladder. The fluid picked up within the seminal vesicles makes up about 65 percent of the fluid in semen. These thick, yellowish, sugar-rich secretions provide energy for the sperm's long trip through the female reproductive system to reach ovum.   Another part of seminal fluid comes from the prostate gland, a doughnut-shaped structure located just beneath the bladder and surrounding the beginning of the urethra. The prostate closes the urethra during ejaculation, preventing the passage of urine while semen is being ejaculated. This gland's thin, milky, alkaline secretions help the sperm move along and stay healthy in the acidic environments of the urethra and the vagina. Furthermore, the prostate's musculature helps push the sperm forward during ejaculation. Finally, a small but important amount of fluid comes from the pea-shaped bulbourethral glands, also called Cowper's glands, located just below the prostate. Their alkaline secretions empty into the urethra to lubricate it so the sperm will have an easy passage.   Male Reproductive System Disorders Erectile dysfunction (ED), also referred to broadly as impotence, is an ability to achieve or maintain an erection for sexual intercourse. The cause for this condition may be physical (disease, injury, or side effects of certain drugs) or psychological (depression, stress, or fear of sexual failure). Diseases that may cause erectile dysfunction include hypertension, diabetes, nerve disease, and abnormal hormone production. Certain medications, such as beta blockers and antidepressants, are also known to cause ED. Impotence is actually any male condition that interferes with reproduction. Besides ED, other forms of it include ejaculation problems, low sperm count, or lack of sexual desire. Sperm production may be inhibited by chemotherapy.   Treatment is usually selected based on the cause of the erectile dysfunction. Many psychological measures are available to treat ED. Healthy lifestyle choices such as smoking cessation, decrease in alcohol consumption, and weight reduction help treat ED. Some commonly used medications to treat the condition are Sildenafil citrate (Viagra) Vardenafil (Levitra) Tadalafil (Cialis) Avanafil (Stendra) While sildenafil and vardenafil are taken 30–60 minutes prior to sexual activity and their effects last for up to 4 hours, tadalafil is longer-acting, lasting for up to 36 hours. Avanafil is faster-acting, usually taken 15 to 30 minutes before sexual activity. All of these medications can cause hypotension (sudden decrease in blood pressure). Patients taking blood pressure medications are recommended to avoid taking these medications. ED medications are contraindicated—meaning advised against due to a conflict with another medication—in patients taking nitrates such as nitroglycerin; taking both can result in hypotension.   Priapism is a disorder in which an erection persists for more than four hours without stimulation. This is a very painful condition and is considered a medical emergency. The condition can be caused by certain medications, such as the drugs given for erectile dysfunction. It can also be caused by the use of some recreational drugs, such as cocaine. Untreated, this condition can cause damage to blood vessels in the penis, blood clotting, and ischemia (restriction of blood supply), which can lead to gangrene. Priapism generally requires emergency room admission, with treatments requiring aspiration of blood from the penis, medications such as phenylephrine, and surgical interventions when necessary.   The Female Reproductive System The ovum is considered the largest cell in the female body. A female is born with all of the ova she will ever have—about one million immature sex cells. However, only about 400,000 of those will develop as the female matures, and of those, only 350 to 500 will ripen and be released during the fertility period between puberty and menopause. Usually, only one ovum a month leaves the ovary and travels down the fallopian tube, where it may meet up with a sperm. This process is called ovulation. *At times, more than one ovum may be released, especially when using certain fertility treatments; the fertilization of two ova will result in fraternal or dizygotic twins. If one ovum is fertilized and then splits to form two embryos, it will result in identical twins.    Since sperm live for about 48 hours after ejaculation and the ovum lives for only 24 hours after ovulation, intercourse has to occur the day before, the day of, or the day after ovulation for fertilization to occur. An unfertilized ovum will simply disintegrate. A fertilized ovum will become an embryo and move down to the uterus to implant itself there for the nine-month job of becoming a fully developed baby.   The medical specialty that treats the female reproductive system actually has two components called obstetrics and gynecology. The obstetric component deals with pregnancy and childbirth, whereas the gynecologic component deals with diseases and illnesses affecting the female reproductive tract.  The female reproductive organs include the ovaries, fallopian tubes, uterus, vagina, and accessory glands.   Unlike the male's, the female's reproductive system functions cyclically. Males have a relatively constant hormone level and are always producing sperm. Female hormone levels and ovulation patterns follow a monthly menstrual cycle. Every month, the uterus gets itself ready for pregnancy. Menstruation occurs when pregnancy doesn't happen. Menstruation is the process of discarding old tissues so that fresh ones can be prepared for the next potential embryo.   The ovaries are located on each side of the uterus. They're shaped like large almonds. Ovaries contain thousands of tiny sacs called Graafian follicles. Each Graafian follicle contains an ovum in varying stages of maturation. After the onset of puberty, once a month, a Graafian follicle ruptures and a mature ovum leaves the ovary for the journey down the fallopian tube. This process is called ovulation.  Then, a very important physiological event happens. The ruptured follicle transforms into a yellow, glandular structure called the corpus luteum, literally meaning "yellow body." The corpus luteum secretes the female hormone progesterone, which plays a major part in the menstrual cycle. Progesterone stimulates the uterus to prepare for pregnancy. During pregnancy, it causes many changes in the body to provide the proper environment for a fetus.   When pregnancy doesn't occur, the corpus luteum stops producing progesterone and decays, forming a mass of scar tissue. Without the supply of progesterone, the uterus can't maintain its lining, so it sloughs it off and menstruation results. Beginning at puberty, the ovaries start secreting the female sex hormone estrogen, which causes the reproductive organs and the secondary sex characteristics that shape a woman's figure to develop. The secretion of estrogen causes the female's first menstrual cycle, or menarche. Similar to the male system, the pituitary hormones FSH and LH stimulate the production of female hormones at puberty, and they continue to influence ova formation and ovulation. High levels of progesterone and estrogen in the bloodstream during pregnancy cause the pituitary to shut off its production of FSH and LH, which stops the ovulation process. Birth control pills contain enough estrogen and/or progesterone to trick the pituitary into stopping ovulation.   Even though they're called oviducts, the fallopian tubes aren't actually attached to the ovaries; they open into the peritoneal cavity (the abdomen). Each fallopian tube curves around to the edge of the ovary. Its fingerlike fringed edges, called fimbriae, catch the released ovum. This section of the fallopian tubes is called the infundibulum.  Peristalsis of the fallopian tube, combined with the sweeping movement of hairs called cilia, moves the ovum toward the next portion of the fallopian tube called the ampulla.   If intercourse has taken place in the past day or two and no contraceptive has been used, chances are good that a sperm will fertilize the ovum. If the ovum is fertilized, it will continue on through the isthmus (the section of fallopian tubes that enters the uterus), exit into the uterus through the intramural oviduct, and attach itself to the uterine wall. If the ovum wasn't fertilized during its journey through the fallopian tube, it will disintegrate, and the uterus will get the message that fertilization hasn't taken place, initiating the menstrual period.   About the size and shape of a pear, the uterus is mostly muscle—one of the strongest muscles in the human body. The uterus does the important and delicate job of holding, nurturing, and growing the fetus and laboring during childbirth to deliver the baby. The thin, skin-like outer layer of uterine tissue is called the perimetrium. The middle layer is the muscular part, called the myometrium. The inner lining of the uterus, the endometrium, is a mucous membrane with a rich supply of blood vessels. This layer has two parts: (1) the basal endometrium stays in place all the time, and (2) the functional endometrium develops to prepare for pregnancy, then sloughs away at the end of the menstruation cycle. The rounded, upper portion of the uterus where the fallopian tubes enter is the fundus, and the large center part is called the corpus, or body. The cervix is the rounded bulb at the bottom that protrudes into the innermost portion of the vagina.   The vagina is a muscular yet elastic tube lined with mucous membrane in folds called rugae. It's a passage for the entry of sperm and the exit of menstrual fluid and babies. The vagina opens between the anus and the urethra. Bartholin's glands, also called greater vestibular glands, secrete mucus-like fluid from duct orifices on either side of the vagina. They're analogous to the bulbourethral or Cowper's glands in the male. A number of smaller vestibular glands secrete mucus near the opening of the urethra.   The breasts are also glands of the reproductive system, attached by connective tissue to the muscles of the chest. Female breast sized is determined by the amount of adipose tissue (fat) that surrounds the actual mammary glands (milk-secreting glands). This fat amount has absolutely nothing to do with the quantity of milk produced by a nursing mother.   The milk-producing mammary gland is actually a modified sweat gland, but it doesn't work full-time like the sweat gland. The mammary gland starts secreting milk three days after parturition (childbirth). During this time, the suckling child will ingest colostrum, a thin, yellow fluid containing protein and lactose (milk sugar) but little fat. Release of the hormone prolactin from the pituitary stimulates the production of milk, and the hormone oxytocin releases the milk from the glands. The milk-secreting tissue is made up of 15 to 20 lobes that converge at the nipple. These lobes are composed of many different smaller lobes, which in turn are made of many milk-secreting cells in grapelike clusters. There's one lactiferous duct per lobe, and each duct empties through the nipple. Thus, there are 15 to 20 pores from which milk leaves the breast. The medical name for the nipple is the mammary papilla, and the pigmented area surrounding the nipple is the areola.   The menstrual cycle is designed to prepare an egg for fertilization with sperm. The process of an ovary ejecting a mature egg into the fallopian tube is known as ovulation, which generally occurs once every 28 days, although the length of this cycle varies among females. The menstrual cycle repeats itself about 13 times per year for 30 or 40 years in most women. There are four phases of the menstrual cycle: Even though the menstrual phase is technically the last phase of the cycle, we count it as the beginning because it's the only phase that's measurable without special equipment. The first day of a woman's period counts as the first day of her menstrual cycle. During this time, the uterus sheds the functional endometrium because there was no fertilized ovum to implant. The normal time range for this phase is 3–7 days. During the follicular or proliferative stage, a Graafian follicle grows an ovum to maturity, and estrogen signals the basal endometrium to start growing a new functional endometrium. The cervix starts to produce less-acidic mucus that will actually assist the sperm in their journey to the fallopian tubes. This phase lasts 6–12 days. The ovulation phase lasts one or two days and typically occurs midway through the cycle. When the ovum has nearly matured, the estrogen level is high enough to trigger the pituitary gland to release luteinizing hormone (LH). This causes the ovary to release the ovum. As you know, the ovum then enters the fallopian tube and awaits fertilization by sperm. If fertilized, the ovum will immediately begin to develop, still moving through the fallopian tube. It will take about three days to implant into the endometrium.  The luteal phase, or secretory phase, is dominated by the corpus luteum, the "yellow body" created when the ovum left the ovary. The corpus luteum produces hormones to make the endometrium receptive to implantation and early pregnancy. During this phase, a woman's body temperature increases. After ovulation, the hormones FSH and LH sustain the corpus luteum. If the egg is fertilized, the resultant embryo will produce the hormone human chorionic gonadotropin (HCG), which can support the corpus luteum instead of LH. If the LH is too low and there's no embryo to produce HCG, the corpus luteum stops producing hormones to prepare the body for pregnancy. This will be the signal for the endometrium to slough off, starting the cycle all over again. This final phase lasts about two weeks.   Pregnancy starts when a sperm cell reaches the egg and penetrates the epithelial, or outside, layer of the egg and enters it. When the sperm makes it to the center and combines its nucleus with the egg's nucleus, a fertilized egg cell called a zygote is created. As soon as the zygote divides itself into two cells, it's called an embryo. Cell division continues at a rapid pace; by the time the embryo implants itself on the uterine wall a few days later, it's a cluster of 16 cells. Four weeks later, it has a brain and spinal cord. After the second month, the embryo is referred to as a fetus.   Many hormones are present during pregnancy. Particularly important is human chorionic gonadotropin (HCG). This is the hormone that's produced by the embryo and sustains the corpus luteum in place of LH. It's also the identifying hormone in urine tests for pregnancy. This hormone signals the corpus luteum to grow larger and produce the massive quantities of estrogen and progesterone needed for the uterus to grow.   Most people consider menopause, which is the cessation of menstruation, to be climacteric or "the change of life." This condition is a normal consequence of aging. In healthy women, the menstrual cycle will continue repeating until menopause, with some interruptions if pregnancies occur. Menopause usually occurs between the ages of 45 to 55, but it can occur earlier or later. Menopause that occurs before age 35 is considered "premature." If it occurs after age 58, it's considered "delayed."  The cause of menopause is the cessation of the production of eggs and hormones by the ovaries. Without these hormones, the endometrium never receives a signal to start preparing for pregnancy, so there's nothing to slough off at the end of the cycle. Therefore, the menstrual period ends. Once these events have occurred, the woman can no longer bear children.   Menopause, however, isn't an instantaneous event; it occurs gradually over a few years. The woman's menses become less and less frequent because the ovaries release ova erratically. When they do release them, the cycle continues as usual. If another egg isn't matured after the start of menses, the next period will be skipped. Eventually, the ovaries stop producing progesterone and estrogen, and the cycle ceases altogether.  Menopause results in dryness and atrophy of the reproductive organs. Many women experience hot flashes, fatigue, headaches, depression, anxiety, or irritability.    Female Reproductive System Disorders Endometriosis is a condition where the endometrium (the innermost layer of the uterus) grows out of the uterus. The exact cause of endometriosis is unknown. Some women may have this condition without any symptoms, while others may experience symptoms such as pain during menstruation or during sexual intercourse. Endometriosis may also interfere with fertility. In younger women who wish to have children, hormone therapy is given as a treatment. Depending on the severity of the condition, the offending tissues may be removed in surgery and a complete hysterectomy performed to prevent a reoccurrence. Some medications that are also useful to treat endometriosis include Danazol (Danocrine) Nafarelin (Synarel) Lupron Depot   Bacteria, viruses, and parasites can cause infection that may ascend from the vagina and cervix, through the uterus and fallopian tubes, all the way to the ovaries. Pelvic inflammatory disease (PID) is characterized by inflammation of the cervix (cervicitis), uterus (endometritis), fallopian tubes (salpingitis), ovaries (oophoritis), and sometimes the connective tissue of the uterus (parametritis). Abdominal pain, fever, and vaginal discharge of pus are all symptoms of PID. The most common cause of PID is gonorrhea, a bacterial infection that's discussed later. The Trichomonas parasite and a fungus named Candida albicans are common causes of vaginitis. Infection with Trichomonas results in a foul-smelling, whitish-yellowish discharge, or leukorrhea, which in turn causes itching, burning, and soreness in the vaginal area. Candidiasis, more commonly known as a "yeast" infection, causes a clumpy discharge and intense itching, termed pruritus vulvae. Any itching is referred to as pruritus, in medical terms.   Ironically, antibiotics used to combat an infection elsewhere in the body can also lead to vaginitis by killing the harmless microorganisms that live there and keep the harmful population low. Antibiotic-resistant fungi and viruses can then thrive.   Male and Female Reproductive System Disorders Human immunodeficiency virus (HIV) is a viral disease that's sexually transmitted. You'll learn more about HIV and its treatments in a later discussion of immune system disorders. Some commonly used HIV drugs include Zidovudine (Retrovir) Didanosine (Videx) Stavudine (Zerit) Abacavir (Ziagen) Tenofovir (Viread) Saquinavir (Invirase) Indinavir (Crixivan) Efavirenz (Sustiva) Lopinavir + Ritonavir (Kaletra)   Gonorrhea is caused by the bacterium Neisseria gonorrhoeae . Men receive more symptoms, such as dysuria (painful urination) and discharge of pus from the penis. Although women may also have dysuria and vaginal discharge, the symptoms are typically milder than those in men. Gonorrhea can cause pelvic inflammatory disease (PID) and infertility in women if left untreated. Gonorrhea can be diagnosed with tests that detect the bacterial genes in a urethral or cervical swab sample.   Infertility is defined as difficulty in conceiving a child. This is a unique medical condition that involves a couple rather than a single individual.  There are many causes of female and male infertility. A woman can be infertile because of an ovulation disorder, endometriosis, tubal disease, uterus abnormalities, chronic infection, or hormone irregularities. A man can be infertile because of low sperm count, a defect in sperm transport, testicular dysfunction, or hormonal irregularities. Infertility treatment is tailored to the causing factor. Common medications that are used to treat infertility include Clomiphene (Clomid) Human chorionic gonadotropin (Pregnyl) Letrozole (Femara) Hormone replacement therapy with estrogen, progestin, and testosterone   Key Points Male gonads are called testes, and female gonads are called ovaries. Testes produce testosterone and sperm. Ovaries produce estrogen, progesterone, and ova, or eggs. Secretion of sex hormones is controlled by hormones released from the pituitary gland. Sex hormones determine the secondary sex characteristics specific to the male and female body. The glands of the male and female reproductive system produce secretions and hormones to facilitate the fertilization of the egg and sperm. Once fertilization takes place, an embryo travels to the uterus and implants there to grow into a baby. Unlike the male reproductive system, the female reproductive system is more complex and plays an extensive role in growing, nourishing, and delivering a baby. The main disorders of the male reproductive system include prostate disease, erectile dysfunction, priapism, infections, and STDs. The main disorders of the female reproductive system include endometriosis, infections, PID, STDs, and menstrual cycle dysfunctions.