T6: Specific and non specific immunity

Question 1

What are interferons

Answer 1

Proteins produced by the immune system that interfere in the lytic cycle and prevent viral reproduction

Question 2

Describe the process of inflammation

Answer 2

1. Tissue injury
2. Mast cells produce histamines which causes vasodilation
3. Fluid flows into tissues from blood vessels causing localised oedema
4. Macrophages come to site from blood, squeezing through pores in vessels - undergoing phagocytosis

Question 3

Describe the process of phagocytosis

Answer 3

1. Phagocyte (macrophage) engulfs pathogen by endocytosis into a phagososme
2. Phagosome fuses with lysosome (lysoszyme containing vesicle) to form the phagolysosome
3. Lysozyme breaks down pathogen
4. Phagocyte presents bacterial antigen becoming an APC

Question 4

Name adaptations of macrophages

Answer 4

Little cholesterol in the membrane means that thye can squeeze through pores when inflammation occurs

Contain lysozyme to break down pathogens

Question 5

Name 3 other non-specific mechanisms prevent infection

Answer 5

Gut flora outcompete harmful bacteria to prevent them from causing infection

HCl in stomach acid kills pathogens

Cilia in airways waft, preventing pathogens from entering the lungs

Question 6

What is an antibody also known as and describe its structure

Answer 6

Immunoglobins
4 polypeptide chains that are linked together by disulfide bridges
Contains pathogen antigen binding sites

Question 7

Name and describe the two mechanisms of antibody action

Answer 7

Neutralisation
When specific antibodies bind to pathogen antigens to prevent them from binding to cells to enter and reproduce

Agglutination
When antibodies bind to many pathogens, grouping them together to be easily found and destroyed by macrophages

Question 8

Describe how t-helper cells are activated

Answer 8

Phagocyte becomes an APC
APC antigen binds with complimentary CD4 receptors on t-helper cells (cytokines cause receptor to change shape - causing cell differentiation and activating T-helper cell)
T- helper divides by mitosis

Question 9

Explain the formation of active t-killer and t-memory cells

Answer 9

Infected body cells present antigen in their membrane
T-killer with complimentary CD4 receptor binds to antigen
Cytokines stimulate differentiation to active t-killer and t-memory
active T-killer release perforin which causes water to travel into infected body cell - causing cell lysis

Question 10

Explain the role of B-cells in specific immunity

Answer 10

Complimentary receptors on b-cell bind to antigen for it to become an APC

Activated t-helper with specific receptor binds to APC

Activated t-helper produces cytokines which cause differentiation of b-cell into b-memory and b-effector. Divides by mitosis

B-effector differentiate into plasma cells which secrete specific antibodies w

Question 11

Where are b-cells made

Answer 11

Bone marrow

Question 12

Where are t-cells made

Answer 12

Thymus gland

Question 13

Name the 4 types of immunity

Answer 13

Active artificial
Passive artificial
Active natural
Passive natural