5.4: B Lymphocytes and humoural immunity

Question 1

What Lymphocytes are involved in humoral immunity

Answer 1

B-Lymphocytes (Mature in the bone marrow and are present in bodily fluids, e.g blood plasma)

Question 2

What happens when a pathogen enters the blood stream

Answer 2

There will be one B-Cell that has a complimentary antibody. There are over 10 million B-Cells, each producing a specific antibody

Question 3

What is the humoral response

Answer 3

1. The surface antigens of an invading pathogen are taken up by a B-Cell
2. The B-Cell processes and presents the antigen on its cell surface membrane
3. Helper T cells (activated in the cellular response) attach to the processed antigens on the B-Cell thereby activating the B-Cell
4. The B-Cell is now activated to divide by mitosis to give a clone of plasma cells
5. The cloned plasma cells produce and secrete the specific antibody that fits the antigen on the pathogens surface exactly.
6. An antibody-antigen complex is formed which destroys the pathogen.
7. Some B-Cells develop into memory cells which respond to future infections of the same pathogen by dividing rapidly and developing into plasma cells which produce antibodies.

Question 4

Function of Plasma Cells

Answer 4

Plasma cells secrete antibodies into the blood plasma. These antibodies destroy the antigens and are responsible for an IMMEDIATE response. This is a primary response

Question 5

Function of Memory Cells

Answer 5

Memory cells live longer than plasma cells. These cells divide rapidly and develop into plasma cells and more memory cells. The plasma cells produce the antibodies needed to destroy the pathogen.