B2: Pathogens
Harmful micro-organisms that cause disease.. Include bacteria and viruses
B2:Disease
Define set of symptons caused by genetics, micro-organisms or social
B2:Bacteria
Single celled micro-organism, some invade body and cause disease. 0.0005mm, no nucleus but DNA in a loose mass in cytoplasm. Reproduce rapidly in warm moist conditions, dividing in to 2 copies.
B2:Viruses
Single celled micro-organism, need host cell for reproduction. Hijack cell's mechanisms to make proteins and DNA , make copies of themselves. Cause damage to cells. 0.001mm, has a nucleus where DNA is kept.
B2:Immune system
Body's internal defence. Uses white blood cells-produced in bone marrow.
B2:Body's external defences
Skin, saliva, tears, acid in stomach
B2:Antigen
Chemicals on surfaces of pathogens- Harmful substance stimulates antibody production in body (trigger immune responses)
B2:Lymphocyte
White blood cell produces ANTIBODIES or ANTITOXINS.-recognise and destroy invading micro-organisms
B2:Antitoxin
Produced by lymphocytes to link with a toxin produced by bacteria and neutralise it.
B2:Antibodies
Produced by lymphocytes that fit on to site of specific microbe to destroy it. Shape important as specific to one antigen.Locking on to an antigen leads to: 1. WBC divides produce many copies. 2. each wbc produces antibody molecules to lock on to inavadin
B2:Different types on antibody
-destroy invading microorganism
-enable white blood cells to recognise microorganism as being foreign
-cause microorganism to clump together so easier for phagocytes to engulf
B2:Phagocyte
White blood cell that engulfs then ingests harmful microbes. Microbe destroyed by powerful digestive enzymes released from cytoplasm of WBC.
B2:Platets
Substances in the blood that make it clot.
B2:Homeostasis
Maintaining constant internal environment- controlled by hormones and germs. Communication of nervous and hormonal systems. For body to function: temperature, pH and sugar, water and salt levels must be kept values within narrow range.
B2:Memory cells
Remain in bloodstream after initial infection clears up.-Produce large numbers antibodies very quickly if microorganism enters body again.
B2:Vaccine
Contains innactive form of a pathogen so you don't get ill from that disease after receiving it. Babies have course of vaccinations in first year of life. some pathogens don't change so same vaccinations used. other pathogens change a lot so vaccinations
B2:Epidemic
Disease spreads rapidly through a population. Prevented if high percentage of population is vaccinated- leads to 'HERD IMMUNITY'
B2:Antimicrobials
Group of substances used to kill microorganisms or inhibit their growth-without seriously damaging body cells. Effective against bacteria, viruses and fungi.
B2:Antibiotics
Type of antimicrobial effective against bacteria-NOT VIRUSES.
B2:Resistance to antimicrobials
Over time bacteria and fungi can develop resistance to them. they survive the antimicrobial, then pass on resistance which spreads through microorganism population.
Bacteria can also get resistant through mutations.
B2:Laboratory tests
Test on human cells, and sometimes animals, to measure effects of new drug and see if harmful
B2:Clinical trials
If drug seems sage, tested on human volunteers- both healthy (test safety) and ill (test safety and effectiveness)
B2:Placebo
Group of volunteers in test receive fake drug- test to see if psychological reasons make patient feel better
B2:'Open-label' trial
Both researchers and patients know which drug patient receives
B2:'Blind' study
Patient doesn't know what drug receiving but doctor does
B2:'Double-blind' study
Neither researcher nor patient knows which drug is being given
B2:Circulatory system
Transport system in body made up of heart, blood vessels and blood- carries oxygen and food molecules
B2:Double pump
One half of heart pumps oxygenated blood from lungs to body, other half pumps deoxygenated blood from body to lungs
B2:Arteries
Take blood away from heart under high pressure-walls thick, elastic and muscular to with-stand pressure
B2:Capillaries
Link the arteries and veins- walls only one-cell thick to allow transfer of substances to and from cells
B2:Veins
Collect blood from body and return it to the heart- walls contain elastic muscular tissue but thinner than arteries.
B2:Coronary arteries
Run over surface of heart as it's own blood supply and provide it with nutrients and oxygen needed to contract, and remove waste products.
B2:Coronary Heart Disease (CHD)
Caused by build up of fatty substances in coronary arteries-causes heart attack.
B2:Lifestyle choices and CHD
Correlation between CHD and; 1.Smoking, 2. Poor diet (high saturated fat+salt), 3. Drugs misuse, 4. Stress. Regular exercise strengthens heart muscle and helps prevent CHD
B2:Systems in Homeostasis
1.RECEPTORS- Detect change in environment
2.PROCESSING CENTRES-receive info and determine body response
3.EFFECTORS-Produce response
B2:Kidneys
Respond to blood plasma changes by changing urine concentration excreted. Hep balance levels of water, urea, salts and other chemicals in blood.
B2:ADH
Released by PITUITARY GLAND as response to blood plasma concentration changes. ADH secretion controlled by negative feedback.
B2:Effects of alcohol
Causes kidneys to produce large volume dilute urine and body becomes dehydrated. Supresses ADH release, so less water absorbed by kidneys.
B2:Effects of ecstasy
Causes kidneys to produce small volumes of concentrated urine. Body's cells swell with water. Ecstasy increases ADH production, more water reabsorbed by kidneys.