Stages Of Immune Response

Question 1

1) phagocytes engulf pathogens

Answer 1

Phagocytes recognise the antigen of the pathogen. The cytoplasm of phagocyte moves to the pathogen, engulfing it. May be easier in presence of opsonins. Molecules in the blood that attach to foreign antigens to aid phagocytosis. The pathogen is now contained in phagosome. A lysosome fuses with phagosome and break down the pathogen. Phagocyte becomes an antigen presenting cell by placing the antigen on the surface to activate other immune system cells

Question 2

2) phagocytes activate T lymphocytes

Answer 2

T lymphocytes are a type of white blood cell. Their surface is covered with receptors which bind to antigens. Each lymphocyte has a different receptor. When the receptor on the surface meets a complimentary antigen it binds to it. This activates the lymphocytes and bind to different antigen. T lymphocytes go under clonal expansion. It divides to produce clones of itself.

Question 3

3) t lymphocytes activate b lymphocytes which divide into plasma cells

Answer 3

Another type of white blood cell. Covered in antibodies which bind to antigen which is complimentary to the antibodies and vice versa.

Question 4

4) plasma cells make more antibodies to a specific antigen

Answer 4

B lymphocyte secrete complimentary antibodies in the blood for next time if the antigen enters. This creates an antigen-antibody complexes.