Pathogens cause
disease. Every
pathogen
contains antigens
White blood cells either
engulf & digest the
pathogen or release the
corresponding antibodies
that lock onto the
pathogen
After an infection, memory cells remain in the
body & they can produce the correct antibodies
corresponding to the correct pathogen
(Immunity)
A vaccine is a safe form of a virus
Viruses have side effects that differ in each person
To avoid an epidemic a high
percentage of the population
have to be vaccinated
Antimicrobials are a group of
substances that are used to kill
microorganisms or slow their growth.
They're effective against bacteria,
viruses & fungi
Antibiotics are a type of anitmicrobials that are
effective against bacteria but not viruses
It's important that a course of antibiotics is
completed otherwise bacteria can become
resistant
New drugs have to be tested to make
sure they're safe & effective
In an 'open-label' trial everybody
knows who gets the new drug
In a 'blind' trial only the doctors know who
gets the new drug
In a 'double-b;ind' trial the doctors and
patients don't know who has the new drug
(only researchers do)
The Heart
The heart is a 'double-pump'- as 1 half is pumping
oxygenated blood from the lungs to the body, the other
half is pumping deoxygenated blood from the body to
the lungs
Arteries carry blood away from the heart under high pressure
They have very thick walls to withstand pressure
Capillaries link arteries & veins
Walls are 1 cell thick to allow the transfer
of substances to & from cells
Veins collect blood and return it to the heart
Walls contain elastic, muscular tissue but are thinner
than arteries.. The blood is under low pressure & have
valves to prevent backflow of blood
Heart disease is
caused by a
build-up of fatty
substances in the
arteries
Poor diet, smoking, lack of exercise & genetics are the
main causes of heart disease
Heart rate is measured by recording
pulse rate. This is the number of
pulses as blood passes through an
artery close to skin
Blood pressure measurements record
the pressure of blood on the walls of
an artery
High blood pressure increases the chance
of strokes & heart attacks. Low blood
pressure can cause dizziness & fainting
Water Balance
Maintaining a constant internal
environment is called homeostasis
Homeostasis involves communication by the
nervous & hormonal systems
The systems involved in homeostasis are:
Receptors (detect change in the
environment), Processing centres (receive
info & determine how the body will respond), Effectors (produce a response)
If the blood plasma is too concentrated, the cells will lose water
If the blood plasma is too dilute, the cells will absorb water & burst
The kidneys respond to water concentration in the
plasma by releasing dilute or concentrated urine
ADH (Anti Diruetic hormone) keeps water
in the body. This tells the body to release
a small amount of concentrated urine
Alcohol suppresses the release of ADH, this dehydrates cells
Ecstasy increases ADH production, this drowns cells