Immunity

Question 1

Describe the mode of action of neutrophils

Answer 1

Chemicals released by pathogens, body cells under attack and antibodies attract neutrophils to the site where pathogens are located. Once attached to a pathogen, the cell surface membrane of the neutrophil extends out and around the pathogen, engulfing it and trapping it within a phagocytic vacuole (endocytosis). The neutrophil secretes digestive enzymes that destroy the pathogen into the vacuole. Neutrophils then die

Question 2

Describe the mode of action of macrophages

Answer 2

Macrophages play an important role in initiating an immune response. They do not destroy pathogens completely, they cut the pathogens up so that they can display the antigens of the pathogens on their surface. These displayed antigens can then be recognized by lymphocytes

Question 3

What is an antigen?

Answer 3

An antigen is a marker that tells your immune system whether something in your body is harmful or not. Allow cell to cell recognition

Question 4

What are self antigens?

Answer 4

Antigens produced by the organisms own body cells. They do not stimulate an immune response

Question 5

What are non self antigens?

Answer 5

Antigens not produced by the organisms own body cells. They stimulate an immune response

Question 6

What is the role of B-lymphocytes in the primary immune response?

Answer 6

When an antigen enters the body for the first time, the small numbers of B-lymphocytes with receptors complementary to that antigen are stimulated to divide by mitosis. This is known as clonal selection. These B-lymphocytes then form 1) plasma cells that secrete lots of antibody molecules into the blood. 2) memory cells that remain circulating in the blood for a long time

Question 7

What is the role of T-lymphocytes?

Answer 7

T-lymphocytes are activated when they