AS Biology: parts of immunity

There are three types of white blood cells

Phagocytes - they are non specific

T-lymphocytes/ T-cells - part of the cell mediated responce

B-lymphocytes/ B-cells - part of the humoural responce

The stages of phagocytosis

1) Chemoattractants attract the phagocyte to the pathogen.

2) The phagocyte engulfs the pathogen.

3) The phagocyte traps the pathogen in a vesicle.

4) Lysosomes fuse with the vesicle.

5) The lysosome puts lysosomial enzymes on the pathogen.

6) The pathogen is digested.

This is the cell mediated responce:

1) The infected cell displayes the pathogens antibodies on it's cell.

2) A t-cell with a receptor that is complementary to the antibody binds.

3) The t-cell then divides by mitosis.

These t-cells then do these things

• Make a protien which makes holes in the infected cell's cell surface membrane
• Make memory cells
• Stimulate the production of b-cells.

This is part of the humoral responce

1) A b-cell with a complementary antigen to the pathogens antibody bind to form an antigen-antibody complex

2) B-cells then divide by mitosis

3) They then become plasma cells which release antibodies that destroy pathigens + their toxins