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THE NON-SPECIFIC IMMUNE RESPONSE
Lysozyme action: An enzyme found in tears, sweat and the nose destroys bacteria by breaking down the bacterial cell walls.
Inflammation: Damaged white blood cells release histamines that cause arterioles to dilate and capillaries to become more
permeable. Blood flow to the area increases and plasma, white blood cells and antibodies leak out into tissues causing oedema
(swelling). The infected microbes can now be attacked by these intact white cells.
Phagocytosis: White blood cells engulf, digest and destroy bacteria and foreign material these include neutrophils and
macrophages. The ingested material is enclosed within a vacuole. Lysosomes containing digestive enzymes fuse with the vacuole,
the enzymes are released, and they destroy the bacteria.
Antimicrobial proteins interferon: Interferon provides non specific defence against viruses. Virus-infected cells produce
this protein; it diffuses to the surrounding cells where it prevents viruses from multiplying. It inhibits vial protein synthesis, and in this
way limits the formation of new virus particles.
PREVENTING ENTRY OF PATHOGENS
The Skin (outer layer made of keratin): This acts as a physical barrier to pathogens. Large numbers of microbes (skin flora)
live on the skin surface these prevent colonisation by other bacteria. Entry can occur through any wounds, but blooding clotting
seals the wounds and thus reduces the number of micro-organisms gaining access.
Stomach acid: Gastric juices secreted by gastric glands in the stomach walls contain hydrochloric acid, giving a pH of less than 2.
This kills most bacteria that enter with food.
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Gut flora: These harmless species of bacteria competitively exclude pathogenic bacteria, competing wit the pathogens for food
and space. The bacteria also secrete chemicals such as lactic acid that are useful in the defence against pathogens.…read more