1. Immune System

Question 1

foreign antigens e.g. pathogens, abnormal body cells, toxins, cells from other individuals of same species =

Answer 1

trigger immune response

Question 2

pathogens

Answer 2

cause disease

Question 3

antigens are

Answer 3

proteins that are presented on cell surface membrane of cells

Question 4

4 main stages in immune response

Answer 4

1. phagocytes engulf pathogens
2. phagocytes activate T-cells
3. T-cells activate B-cells which divide into plasma cells
4. plasma cells make more antibodies to a specific antigen

Question 5

1. phagocytes (WBC) engulf pathogens

Answer 5

1. recognises foreign antigens on pathogen
2. phagocyte englufs pathogen
3. lyspsome fuses with phagocytic vacuole and lysozomes (enzyme) break down pathogen
4. presents pathogens antigens on surface (Activate other immune cells)

Question 6

2. T-Cells (WBC activated by phagocyte)

Answer 6

receptor proteins than bind to complimentary antigens presented by phagocytes = activated
helper T-cells release chemical signals that activate/stimulate phagocytes and; cytotoxic tcells (kill abnormal/foreign cells)
activate Bcells

Question 7

3. B-cells which divide into plasma cells (WBC activated by T cells)

Answer 7

antibody on membrane which binds to specific antigen
antibody meets complimentary shaped antigen and binds (antigen-antibody complex)
this combined with substance released from helper T-cell activates B cell
divides into plasma cells (clonal selection

Question 8

4. plasma cells (clones of b cells)

Answer 8

secrete antibodies specific to antigen (monoclonal antibodies)
bind to antigen on pathogen = antigen-antibody complex
antibody has 2 binding sites can bind to 2 pathogens at same time
pathogens clump together (agglutination)
phagocytes bind to antibodies and phagocytose many pathogens at once = destruction of pathogen in body

Question 9

antibodies

Answer 9

proteins
specificity depends on variable region which form antigen binding sites
variable region has unique tertiary structure thats complimentary to 1 specific antigen.
all antibodies have same constant regions

Question 10

cellular response

Answer 10

t-cells and other cells they interact with e.g. phagocytes

Question 11

humoral response

Answer 11

b-cells, clonal selection and production of monoclonal antibodies

Question 12

primary immune response

Answer 12

1. antigen enters body for first time
2. slow. arent many b cells to bind.
3. infected person experiences symptons whilst not enough antibodies to overcome infection
4. after exposure to antigen t and b cells produce memory cells which remain in body
5. memory t cells remember specific antigen
6. memory b cells record specific antibody
   7 person now immune can respond quickly to infection

Question 13

secondary immune response

Answer 13

1. same pathogen. quicker stronger immune response
2. clonal selection faster. memory b cells activated and divide into plasma cells memory t cells activated divide into correct type of t cells to kill cell carrying antigen
3. gets rid of pathogen before you show symptoms = immune

Question 14

t cells and b cells are also called

Answer 14

t and b lymphocytes