Non specific immunity

Question 1

Mucous membranes

Answer 1

lack keratin layer so is moist - favourable
mucus - traps microbes, cilia moves them
Line airways providing easier route into the body as it lacks

Question 2

Gut flora

Answer 2

Bacteria ie E.coli are found in intestines
Ideal conditions: warm,moist,plentiful food supply, host benefits too
Bacteria aid digestion and competitively exclude pathogenic bacteria competing with pathogens for food
Bacteria secrete chemicals ie lactic acid to defend

Question 3

Blood clotting

Answer 3

Platelet sticky to form platelet plug
thromboplastin released causing a cascade of chemical changes - vit k and calcium ions needed
prothrombin--> thrombin
Fibrinogen --> insoluble fibrin
mesh of fibrin strands to trap RBC

Question 4

Lysozyme

Answer 4

Attacks bacteria
Occurs in tears, saliva, nasal secretion
Kills bacteria by break down of their cell walls

Question 5

Describe inflammation

Answer 5

Attacks bacteria
Occurs in injuries, cuts and grazes
Damaged WBC in connective tissue below skin release chemicals like Histamine
Cause arterioles in the area to dilate increasing blood flow in capillaries increasing permeability of capillaries and cells in capillary walls separate so vessels leaks
Plasma fluid, WBc antibodies leak from blood into tissue causing oedema
Microbes attacked by WBC

Question 6

Describe phagocytosis

Answer 6

Attacks bacteria - attracted by chemicals realised by bacteria
Occurs in site of infection
Bacterium on surgace with antigens are engulfed by neutrophil and macrophages
Enclosed in vacuole and lysosmomes fuse releasing enzymes destroying foreign material

Question 7

Describe action to prevent spread of infection

Answer 7

Attacks bacteria
Occurs in site of infection
Tissue fluid drains into lymphatic vessels
Lymph flows along and passed through lymph nodes and returns to blood by thoracic and lymphatic ducts
Any pathogens present activate macrophages and lymphocytes killed microbes

Question 8

Describe interferon

Answer 8

attacks viruses
occurs in microbe infected cells
diffuses to surrounding cells where it prevents microbes from multiplying
inhibits microbial protein synthesis limiting formation of new microbes

Question 9

Describe skin preventing entry of pathogens

Answer 9

Entry occurs through wounds but blood clots seal it reducing access
Large numbers of microbes live on skin - harmless and prevent colonisation by other bacteria
Keratin layer prevents entry - tough protein

Question 10

Stomach acid

Answer 10

HCL with a pH of 2 kills bacteria that enter via food

Optimum pH for pepsin(digestive enzymes)