Week 8 The immune system

Question 1

Cardinal features of the immune system

Answer 1

Diversity

Specificity

Self Tolerance

Memory

Question 2

Innate response

Answer 2

Surface barriers:
Skin
Mucous membranes

Internal defences
phagocytes
natural killer cells
inflammation
antimicrobial proteins
fever

Question 3

Fever

Answer 3

Widespread response to
invasion
• Abnormally high body
temperature
• Systemic response to invading
microorganisms
• Benefits
• Liver & spleen sequester Fe &
Zn less supportive of bacterial
growth
• Increases metabolic rate

Question 4

Antimicrobial proteins

Answer 4

interferons

Complement

Question 5

Adaptive Response

Answer 5

Humoral immunity:
B cells

Cellular immunity:
T cells

Question 6

Humoural immune response

Answer 6

Antibody mediated immunity

• Protection from the
‘humours’ ie: bodily fluids

Question 7

Antigens and Antigenic determinants

Answer 7

Antigen

• Foreign protein/particle
• Elicits immune response

Antigenic Determinants

• Small region of antigen that the antibody recognises
• Can have lots of the same epitopes on one bacterium
• Can have lots of different epitopes on one bacterium

Question 8

Antibody classes

Answer 8

IgG – most abundant (75-85%)
IgM – first type released in primary
response
IgA – in bodily secretions
IgE – causes histamine release
(↑ allergy)
IgD – activates B cells

Question 9

Clonal selection of B cell

Answer 9

When exposed to a
foreign antigen, B
cells are stimulated
to become either:
• PLASMA Cells
• Actively secrete
antibodies
• MEMORY Cells
• Remember the specific antigen to prepare the
body for the next
exposure

Question 10

Antigen-Presenting Cells (APCs)

Answer 10

Types

• Dendritic cells
• Macrophages
• B Lymphocytes

Functions

• Capture/process antigens for T lymphocytes
• Signalling for proliferation/differentiation of lymphocytes

Question 11

Effector T cells

Answer 11

• Made in bone marrow
• Mature in thymus
• Antigen-receptor interactions on cell surface

3 Types of T Cells:

• Helper T cells - with APC
• Cytotoxic T cells - with abnormal/virus infected cells
• Regulatory T cells

Question 12

Human immunodeficiency virus

Answer 12

• Causes AIDS (acquired immunodeficiency syndrome)

- Virus infects and destroys helper T cells

Question 13

Cytotoxic T cell Defence Proteins

Answer 13

Perforins
- Drill holes into abnormal (target) cell

Granzymes

• Digestive enzymes
• Enter via holes

Question 14

Immunodeficiencies

Answer 14

Failure of Self-Tolerance Autoimmunity

• Biggest challenge to selectively block autoimmune without blocking responses necessary to combat infection

Question 15

Regulatory T Cells

Answer 15

Dampen the immune response
Two basic mechanisms of action:
• Direct contact
• Releasing inhibitory cytokines

Question 16

Hypersensitivities

Answer 16

Fights perceived threat otherwise harmless eg. pollen, animal dander (allergies).

Not deadly, just miserable distinguished by

• Time course
• involve Ab or T cells