B Lymphocytes

Question 1

What is humour?

Answer 1

Body fluids.

Question 2

Why is humoural immunity called what it is?

Answer 2

It involves antibodies, antibodies are soluble in the blood and tissue fluid of the body.

Question 3

How are B cells unique?

Answer 3

• Each B cells produces a specific antibody antibody that responds to one specific anti gen.

Question 4

How B cells respond to respond to antigens?

Answer 4

• When an antigen enters the blood, or tissue fluid, a B cell with a complementary antibody on it’s surface will attach to the complementary antigen, forming an antigen-antibody complex.
• The antigen enters the B cell via endocytosis and gets presented on its surface.
• T Helper cells bind to the processed antigens and stimulate the B cell to divide by mitosis to form a clone of identical B cells, which produce the antibody that is specific to the foreign antigen ( clonal selection ).

Question 5

What is clonal selection?

Answer 5

B cell is stimulated by T helper cells to divide by mitosis, to form identical B cells, which produce the antibody which is specific to the foreign antigen.

Question 6

What are monoclonal antibodies?

Answer 6

Plasma cells that secrete antibodies specific to the anti gen, these are monoclonal antibodies.

Question 7

What are the two types of cells that the clones can develop into?

Answer 7

• Plasma Cells

* Memory Cells

Question 8

What do plasma cells do?

Answer 8

• Plasma cells secrete antibodies into blood plasma, these cells only survive for a short time, the produced anti bodies bind to the anti-gens to form antigen-antibody complexes.
• The antibodies produced lead to the destruction of the anti gen.
• These plasma cells are identical to the B cell.

Question 9

What is agglutination?

Answer 9

• Antibodies have two binding sites.

* They can therefore bind to two pathogens at the same time, resulting in pathogens being clumped together.

Question 10

How do antibodies lead to the destruction of antigens?

Answer 10

• Antibodies bind to two pathogens at the same time, the pathogens are then clumped together.
• Phagocytes then bind to the antibodies and phagocytose many pathogens at once.
• This leads to the destruction of pathogens carrying the anti gen in the body.

Question 11

What is the primary immune response?

Answer 11

The production of antibodies and memory cells.

• When an antigen enters the body for the first time and activates its immune system, this is the primary response.

Question 12

What are memory cells’ purpose?

Answer 12

• Memory cells are responsible for the secondary immune response, they live longer than plasma cells.
• They do not produce antibodies, but circulate in the blood and tissue fluid, when they encounter the same antigen at a later date, they divide rapidly and develop into plasma cells and more memory cells, plasma ccells then produce antibodies required to destroy the pathogen.
• Memory cells therefore can provide long term immunity against the original infection.

Question 13

How does the secondary immune response differ to the primary immune response?

Answer 13

• An increased quantity of antibodies is secreted at a faster rate than in the primary immune response, allows the infection is to be destroyed before it can cause any harm.
• Clonal selection happens faster, memory B cells are activated and divide into plasma cells that produce the right antibody to the antigen, memory T cells are activated and divide into the correct type of T cells to kill the cells carrying the antigen

Question 14

Why is the primary response slow?

Answer 14

There are not many B cells that can make the antibody needed to bind to it.