5.4 Humoral immunity and B lymphocytes

Question 1

What does humoral immunity involve

Answer 1

Antibodies, which are soluble in blood

Question 2

What do B cells produce

Answer 2

A specific antibody to one specific antigen

Question 3

What happens when an antigen enters the blood

Answer 3

There will be one B cell that has an antibody on its surface whose shape fits exactly to the antigen, they are complementary

Question 4

What is clonal selection

Answer 4

Rapid division of B cells by mitosis which accounts for the body’s ability to respond rapidly to any of the vast number of antigens

Question 5

What can the clones as a result of clonal selection develop into

Answer 5

1. Plasma cells

2. Memory cells

Question 6

What are plasma cells

Answer 6

Cells that secrete antibodies usually into blood plasma. They are responsible for the immediate defence of the body against infection. This is the Primary immune response

Question 7

What are memory cells

Answer 7

These are responsible for the Secondary immune response. They live for decades and when they encounter the same antigen then divide rapidly and develop into plasma cells and more memory cells.

Question 8

What is the role of B cells in humoral immunity (Process)

Answer 8

1. The surface antigens of an invading pathogen are taken up by a B cell
2. The B cell processes the antigens and presents them on its surface
3. Helper T cells activated in the cellular response attach to the processed antigens on the B cell and activate the B cell
4. The B cell is now activated and divides by mitosis to give a clone of plasma cells
5. The cloned plasma cells produce and secrete the specific antibody that exactly fits the antigen on the pathogens surface
6. The antibody attaches to antigens on the pathogen and destroys them
7. Some B cells develop into memory cells.