immune responses

Question 1

How do antigens trigger an immune response

Answer 1

Antigens (usually proteins) found on the cs m can be used to identify pathogens, abnormal body cells etc

Question 2

What is phagocytosis

Answer 2

Phagocyte recognises foreign antigens on pathogen, cytoplasm wraps around pathogen, engulfing it (now contained in a phagocytic vacuole) lysosome containing lysozymes fuses w phagocyte and breaks down pathogen, phagocyte become APC.

Question 3

Role of Th cells

Answer 3

Stimulate phagocytes and cytotoxic T cells, which kill abnormal and foreign cells, also activate B cells which activate antibodies

Question 4

What are B cells

Answer 4

Antibodies on surface that bind w antigens to form AA complex, each antibody is specific and complimentary to a different shaped antigen. AA complex activates B cell (clonal selection) to divide into plasma cells

Question 5

Plasma cells

Answer 5

B cell clones, secrete monoclonal antibodies (specific). Antibodies have two binding sites so can bind to two pathogens, causes agglutination. Phagocytes bind to many antibodies and phagocytose many pathogens at once.

Question 6

Primary immune response

Answer 6

When antigen enters body for first time, individual experiences symptoms of the disease as there are few b cells that can produce specific antibodies. T and B cells both then produce memory cells which remain in the body for a long time – person is now immune

Question 7

Immunity

Answer 7

Immune system has the ability to respond quickly to a second infection with memory cells, can rapidly produce more antibodies

Question 8

Secondary immune response

Answer 8

Clonal selection happens faster, memory b cells activated and divide into plasma cells that produce specific antigen. Memory t cells activated and divide into correct type of t cell to kill the cell carrying the antigen. Response often gets rid of pathogen before individual shows symptoms