Lymphocytes

Question 1

What are lymphocytes?

Answer 1

• a type of white blood cell that is involved in the specific immune response

Question 2

What are two types of cells

Answer 2

• B cells
• T cells

Question 3

Where are both B and T cells made?

Answer 3

• bone marrow

Question 4

Where do B - cells develop in?

Answer 4

• bone marrow

Question 5

Where do T - cells develop in?

Answer 5

• thymus

Question 6

Where do B cells invade?

Answer 6

• invade the outside of the cells

Question 7

What does each receptor do?

Answer 7

• Each receptor binds to a particular pathogen
• complementary

Question 8

What happens to the mature B and T cells?

Answer 8

• They migrate to the lymph nodes ready to be activated by a pathogen or APC

Question 9

When activated, what do B cells produce?

Answer 9

• They carry out the humoral immune system (which happens in the blood)
• which are responsible for antibody production

Question 10

When activated, what do T cells do?

Answer 10

• They differentiate to become several different cell types, including cytotoxic killer cells which carry out the cell mediated immune response. This means they recognise and destroy abnormal cells

Question 11

What are the steps of cell-mediated response?

Answer 11

• APC presents the foreign antigen to the immature T-cells
• An antigen presenting cell reaches the immature T cells in the lymph
• The APC will bind to the immature T-cells with the most complementary receptor to the foreign antigen clonal selection.
• This triggers the selected T-cell to divide rapidly by mitosis - clonal expansion
• The mature T -cells produced via clonal expansion differentiate to form 4 distinct types, T-helpers, T-regulators, T-killers and perforin
• T-killers bind to the infected body cells and destroy them by making holes in their plasma membrane
• T-helpers help to activate the humoral response by binding to complementary immature B-cell and secrete cytokines to attract phagocytes

Question 12

What are the steps of the humoral response?

Answer 12

• An APC or pathogen reaches the immature B lymphocytes
• The B-cell with the most complementary receptor to the antigen engulfs the pathogen and presents its antigens
• an activated T-helper cell binds to the antigen presenting B-cell. - Clonal selection
• The selected B-cell divides, cell divides rapidly by mitosis - clonal expansion
• The cloned cells differentiate to become either plasma or memory cells
• Plasma cells produce antibodies at a rate of 2000 molecules per second
• memory cells remain in the blood stream ready to proliferate again if you are infected with the same pathogen again.