CH11

Question 1

First line of defence

Answer 1

Physical
Act as an obstacle to pathogen
Skin & Mucous layer
Cilia - filter inhaled air

Chemical
Destroy pathogen
Tears & sebum - contains lysozyme

Question 2

Mechanism of inflammation

Answer 2

Damaged tissue releases histamine
Histamine causes blood capillary to dilate so more blood flow to the infected area
Histamine increases permeability of blood capillary to phagocytes
Phagocytes and clotting factor accumulate in infected area
Blood clotting mechanism is triggered
Phagocytes carry out phagocytosis

Question 3

Mechanism of Phagocytosis

Answer 3

Phagocytes are attracted to chemical released by pathogen
Phagocytes moves towards pathogen by extending its pseudopodium and engulf the pathogen
Engulf pathogen form phagosome
Phagosome fuses with lysosome to form phagolysosome
Pathogen is destroyed by lysozyme in the phagosome
remains of undigested microorganism is expelled out of phagocytes

Question 4

Third line of defence

Answer 4

Specific defence mechanism
Involves antibodies produced by lymphocytes
Action of antibody is specific
Antibody is not produced instantaneously as lymphocytes must recognize the antigen before producing antibody

2 types of lymphocytes
T lymphocytes attack cells infected by pathogen.
T Lymphocytes stimulate b lymphocytes to produce memory cells
Memory cells will be stimulated to produce antibody immediately when attacked by the same pathogen before

Question 5

3 Action of antibody on antigen

Answer 5

Lysis; combine causes bacteria to be broken down and decomposes
Opsonisation; combine & act as marker for phagocytes to recognize and destroy
Precipitation; react with dissolved antigens to form insoluble complex which is easily destroyed by phagocytes

Question 6

Action of antibody on toxin

Answer 6

Neutralisation; bind + neutralise bacterial toxins

Question 7

Action on antibody on pathogen

Answer 7

Agglutination; coagulate pathogen & make them an easy target to be trapped and destroyed by phagocytes

Question 8

Active Natural Immunity

Answer 8

Acquired when someone recovers from an infection
Lymphocytes produce antibody
Permanent immunity against the diseases
Memory cells rapidly produce antibody when individual is attacked by the same pathogen

Question 9

Active artificial immunity

Answer 9

Acquired through vaccine injection
Vaccine contain weakened pathogen
Body produced own antibody
Long lasting
Vaccine injection given before infection
Has side effects
for prevention

Question 10

Passive Natural immunity

Answer 10

Acquired through mothers milk
antibody produced by mother
Immunity is temporary
No side effects
Mothers milk contain antibody
Non immediate protection
Booster dose must be given to boost level of antibody above level of immunity

Question 11

Passive artificial immunity

Answer 11

Acquired through antiserum injection
Antiserum contains specific antibody from external source
Antibody is obtained from antiserum
Immediate immunity//protection
Temporary immunity
Booster dose is only given if antibody level drops below immunity level and the person is still infected