human defence system

is a disease - causing microorganism

bacterium, fungus, virus

contaminated food and drink, infected wounds, droplets breathed in

the general defence system and the specific defence system

involves barriers and non-specific cell responses. it does not fight particular pathogens

structural barrier

prevents entry of pathogens

contains the enzyme lysozyme

kill pathogens

found of the skin and in the large intestine (colon)

stop harmful microorganisms growing

natural moisturiser (oil) produced by the sebaceous glands in skin

stops the skin cracking (opening)

hydrochloric acid in stomach, lactic acid in vagina

kills pathogens

in the breathing, digestive and reproductive system

traps pathogens

high temperature

denatures enzymes in the pathogen, destroying it

(called phagocytes/macrophages)

engulf pathogens by phagocytosis

clot blood when skin is cut

stops pathogens entering the body

chemical produced body cells

causes inflammation - blood vessels dilate so it is easier for white blood cells to get to the area of infection

chemical that body cells produce when they are infected by a virus

stops viral replication and so stop virus spreading

found in blood plasma

makes holes in the pathogens and burst them

distinguishes between different pathogens and responds to each particular one