Topic 12: Immune System and Resistance to Disease

Question 1

Types of Resitance

Answer 1

1) Innate

2) Adaptive (Immunity)

Question 2

1) Innate

Answer 2

 prevent entry of microbes into body or remove foreign material
 involves:
a) Physical Barriers – skin, mucous membranes
b) Mechanical Barriers – flow of tears, sweat, mucus; cilia beating; coughing
c) Chemical Barriers
 e.g. 1: gastric acid, lysozyme (in saliva + tears)
 e.g. 2: interferons = produced by virus infected cells – trigger mechanisms in nearby uninfected cells that prevent infection
d) Normal Flora – outcompete newcomers
e) Phagocytes – macrophages + neutrophils
f) Inflammation
g) Fever
h) Natural Killer Cells

Question 3

f) Inflammation

Answer 3

– local tissue damage ⇒ release of chemicals e.g. histamine (vasodilator) from mast cells (found in CT; similar to basophils)
 Result: vasodilation ⇒ swelling, heat, redness, pain ∴ loss of function
 attracts neutrophils (within 1 hour) and then macrophages

Question 4

g) Fever

Answer 4

• immune cells and microbe chemicals trigger release of prostaglandins in hypothalamus ⇒ ⇑ temp
   aspirin, ibuprofen, acetaminophen ⇒ ⇓ prostaglandin synthesis ∴ ⇓ fever

Question 5

2) Adaptive (Immunity)

Answer 5

 production of specific lymphocyte or antibody against recognized antigen

Question 6

o Antigen (Ag)

Answer 6

– protein/polysaccharide - recognized as foreign by immune system e.g. parts of bacteria, viruses, pollen, parasites, transplants

Question 7

o Antibody (Ab)

Answer 7

– plasma protein (γ globulin) - matches a specific Ag - produced by plasma cells

Question 8

 Immune Response

Answer 8

a) Phagocyte (e.g. macrophage) “eats” invader and displays parts of it (Ag) on its surface
b) TH binds and is activated – proliferates

Question 9

b) TH binds and is activated – proliferates

Answer 9

 releases chemicals may activate:
i. Cytotoxic T-Lymphocytes – proliferate + directly destroy: cells containing virus; cells altered by cancer; or transplanted organs
 = Cell Mediated Immunity
ii. B cells ⇒ proliferate and convert to plasma cells ⇒ antibody
 = Humoral (Antibody Mediated) Immunity
 memory B/T cells also produced = long-lived – permit rapid response on next encounter with same Ag

Question 10

 Types of Humoral Immunity

Answer 10

a) Active – lasts years

b) Passive – lasts weeks (as long as antibody present)

Question 11

a) Active – lasts years

Answer 11

 body makes antibodies, memory B cells, after:

i. exposure to disease org = natural; or
ii. injection with killed/inactivated disease org (vaccination) = artificial

Question 12

b) Passive – lasts weeks (as long as antibody present)

Answer 12

 e.g. natural: mother – fetus/baby across placenta, milk
 e.g.2: artificially produced Ab (from person, animal or monoclonal) injected for: tetanus, rabies, snake bite antivenins, Rh factor
o mops up antigen before it can trigger an immune response in person