Human Body

Anatomy is the science that studies body structures and the relationships among them. Physiology is the science that studies body functions or how the body parts work.Anatomical position, the person stands erect, facing the observer, with the head level and the eyes facing forward. The feet are flat on the floor and directed forward, and the arms are hanging at the sides, with the palms facing forward. Prone position is when the body is lying face down.Supine position is when the body is lying face up.Major regions the head, neck, trunk, upper limbs and lower limbs.Directional terms are words that describe the position of one body part relative to another, and they are used to locate various body structures.Body planes are imaginary flat surfaces that are used to divide the body or organs to visualize interior structures. Sagittal plane is a vertical plane that divides the body or an organ into right and left sides. Frontal or coronal plane divides the body or organ into anterior and posterior parts.Transverse plane divides the body or an organ into superior and inferior parts. Body cavities are spaces in the body that help protect, separate and support internal organs.Body membranes line cavities and the internal spaces of organs and tubes that open to the outside.Mucous membranes line the tubes of the digestive, respiratory, urinary, and reproductive systems. They are composed of an epithelium overlying a loose fibrous connective tissue layer. The epithelium contains goblet cells that secrete mucus that protects the body from invasion by bacteria and viruses. More mucus is secreted when a person has a cold and has to blow their nose.Serous membranes, which line the thoracic and abdominal cavities and cover the organs they contain, are also composed of epithelium and loose fibrous connective tissue. They secrete a watery fluid that keeps the membranes lubricated, thus reducing friction and allowing the organs or viscera to slide some during movements, such as when the lungs inflate and deflate during breathing. Serous membranes support the internal organs and compartmentalize the large thoracic and abdominal cavities. This helps hinder the spread of any infection.pericardium covers the heartThe peritoneum lines the abdominal cavity and covers its organs, Peritonitis is a life-threatening infection of the peritoneum that may occur if an inflamed appendix bursts before it is removed, or if the digestive tract is perforated for any other reason.The pleurae (pleura for singular) line the thoracic cavity and cover the lungsthe.Synovial membranes line freely movable joint cavities, and are composed only of loose connective tissue. They secrete synovial fluid that lubricates the cartilage at the ends of the bones so that they can move smoothly in the joint cavity.The meninges are membranes within the dorsal cavity that are composed of only connective tissue and serve as a protective covering for the brain and spinal cordHomeostasis is a condition of equilibrium in the body’s internal environment produced by the interplay of all the body’s regulatory processes.Body fluids, watery solutions containing dissolved chemicals that are found inside cells as well as surrounding them. The fluid inside of cells is called intracellular fluid, while the fluid outside the body cells is called extracellular fluid can be classified as interstitial fluid, blood plasma, lymph, cerebrospinal fluid, synovial fluid, aqueous humor and vitreous bodyFeedback system is a cycle of events in which the status of a body condHuman body careition is monitored, evaluated, changed, remonitored, reevaluated and so on.Each monitored variable, such as body temperature, blood pressure, or blood glucose level, is called a controlled condition. Any disruption that changes a controlled condition is called a stimulus.Receptor is a body structure such as a nerve ending or sensory receptor that monitors changes in a controlled condition and sends input, Control center sets the range of values within which a controlled condition should be maintained, evaluates the input it receives, and generates output commands, Negative feedback system reverses a change in a controlled conditionPositive feedback system strengthens or reinforces a change in one of the body’s controlled conditions.Effector is a body structure, such as a muscle or gland that receives output from the control center and produces a response or effect that changes the controlled condition. Disorder is any abnormality of structure or function.Disease is a more specific term for an illness characterized by a recognizable set of signs and symptoms. Diseases alter body structures and functions in characteristic ways. Symptoms, which are subjective changes in body functions that are not apparent to the observer, such as a headache, nausea, and anxiety. Signs of a disease on the other hand, are objective changes that a clinician can observe and measure. Signs can be either anatomical, such as swelling or a rash, or physiological, such as fever, high blood pressure, or paralysis.Diagnosis of disease is the science and skill of distinguishing one disorder or disease from another. Topic 2. Body Tissues Tissue is a group of similar cells that work together to carry out a specific function. Body tissues can be classified into four basic types according to their function and structure: Epithelial tissue, connective tissue, muscular tissue and nervous tissue.Epithelial tissue or epithelium consists of tightly packed cells that form a continuous layer. Because the cells are closely packed, and are held tightly together by many cell junctions, there is little intercellular space between adjacent plasma membranes.Epithelial tissue has many different functions in the body; the most important are protection, filtration, secretion, absorption and excretion.Epithelial tissue can be divided into two types: covering and lining epithelium, that forms the outer covering of the skin and some internal organs, as well as the inner ining of blood vessels, ducts, and body cavities, and the interior of the respiratory, digestive, urinary, and reproductive systems Glandular epithelium, that makes us the secreting portion of glands such as the thyroid gland, adrenal glands, and sweat glandsCovering and lining epithelium are classified by two characteristics: the shapes of the cells (squamous, cuboidal, or columnar) and the number of layers of cells (simple, stratified and pseudostratified). Simple epithelium has a single layer of cells that function in diffusion, osmosis, filtration, secretion, and absorption.Exocrine glandsSecrete their products into ducts that empty onto the surface of a covering and lining epithelium such as skin or the lumen of a hollow organ. The secretions of exocrine glans include mucus, sweat, oil, earwax, saliva, and digestive enzymes. Examples of exocrine glands include sudoriferous (sweat) glands, which produce sweat to help lower body temperature, and salivary glands, which secrete saliva. Some glands in the body, such as the pancreas, ovaries, and testes, are considered mixed glands because they contain both endocrine and exocrine tissue.Endocrine glandsSecrete substances called hormones into the interstitial fluid, where they then diffuse into the bloodstream, without flowing through a duct. Hormones regulate many metabolic and physiological activities to maintain homeostasis. The pituitary, thyroid, and adrenal glands are examples of endocrine glands.Epithelial tissue can be divided into two types: covering and lining epithelium, that forms the outer covering of the skin and some internal organs, as well as the inner