Immune Response

Question 1

What are antigens?

Answer 1

Proteins on the surface of cells that stimulate an immune response when detected

Question 2

What are pathogens?

Answer 2

Orgamisms that cause disease

Question 3

What are abnormal body cells?

Answer 3

Cancerous or pathogen-infected cells that have abnormal antigens on their surface

Question 4

What are toxins?

Answer 4

Poisons produced by pathogens

Question 5

What happens if you receive cells that have foreign antigens?

Answer 5

Immune response is triggered. Immunosuppressants taken to avoid rejection of transplanted organs

Question 6

What are the main stages of the immune response?

Answer 6

1) Specific phagocytosis
2) T-cells
3) B-cells
4) Antibody production

Question 7

Phagocytosis

Answer 7

• Phagocyte recognises foreign antigens on pathogen
• Engulfs pathogen into phagosome
• Lysosomes fuse with phagosome
• Lysozymes hydrolyse pathogen

Question 8

T-cells process (cellular response)

Answer 8

Receptor proteins on its surface that bind to complementary antigens presented to it by phagocytes, activating the T-cell. Th cells release chemical signals that activate B-cells which secrete antibodies. Tc cells kill pathogens

Question 9

B-cells process (humoural response)

Answer 9

Th cell with binds to antigen, forming an antigen-antibody complex. This activates specific B-cell to divide by mitosis into plasma cells (clonal selection) which release antibodies

Question 10

Antibody production

Answer 10

Plasma cells secrete many antibodies specific to the antigen (monoclonal antibodies). Antibodies bind to the antigens on the surface of the pathogen to form antigen-antibody complexes. Some antibodies are used to produce memory cells

Question 11

Antibody structure

Answer 11

Proteins with a highly specific tertiary structure. Its variable regions, which form the antigen binding sites, are complementary to one specific antigen. All antibodies have the same constant regions

Question 12

Primary immune response

Answer 12

The first immune response to a pathogen/antigen. Response is slow as there are no memory T-cells to recognise the specific antigen memory or B-cells to record the specific antibodies needed

Question 13

Secondary immune response

Answer 13

Second immune response to a pathogen/antigen. Response is quicker and stronger as clonal selection happens faster where memory B-cells are activated and divide into plasma cells that produce the right antibody and memory T-cells are activated and divide into T-killer cells