B Lymphocytes And Humoral Immunity

Question 1

What does humoral immunity involve?

Answer 1

This involves antibodies.

Question 2

What are antibodies soluble in?

Answer 2

Blood and tissue fluid.

Question 3

Are there lots of types of B cell?

Answer 3

Yes there are many different types of B cells.

Question 4

What does each B cell start to produce?

Answer 4

It starts to produce a specific antibody that responds to one specific antigen.

Question 5

Where can antigens be found?

Answer 5

Pathogens
Foreign cells
Toxins
Damaged cells
Abnormal cell

Question 6

What happens when an antigen enters the blood?

Answer 6

There will be one B cell that has an antibody on its surface which will have the exact shape to fit the antigen.

Question 7

What is meant be complementary?

Answer 7

This is when the antigen and antibody have shapes that allow them to exactly fit into each other.

Question 8

How does the antigen enter the B cell?

Answer 8

By endocytosis.

Question 9

What happens when the antigen enters the B cell?

Answer 9

It gets presented on its surface (processes).

Question 10

What binds to the processed antigens?

Answer 10

T helper cells bind to the processed antigens which stimulates the B cell to divide by mitosis.

Question 11

What happens when the B cell divides by mitosis?

Answer 11

It produces identical clones that produce the same antibody that is specific to the foreign antigen.

Question 12

What is clonal selection?

Answer 12

This is where the one type of lymphocyte that has the complementary protein replicates to create enough cells to destroy the pathogen.

Question 13

What is clonal sélection responsible for?

Answer 13

This is responsible for the body’s ability to respond rapidly to any of a vast number of antigens.

Question 14

Why is there a time lag between exposure to the pathogen and the body’s defences bringing it under control?

Answer 14

This is because clonal selection does not happen straight away- the right type of cell must be found first.

Question 15

Do pathogens only have one antigen on their surface?

Answer 15

No, they have many different proteins in their surface which act as antigens.

Question 16

What does each toxin also act as?

Answer 16

An antigen.

Question 17

Why do many different B cells make clones?

Answer 17

They all produce their own type of antibody.

Question 18

Why are these antibodies referred to as monoclonal antibodies?

Answer 18

This is because each clone produces one specific antibody.

Question 19

In each clone, what do the cells produced develop into?

Answer 19

Plasma cells or memory cells.

Question 20

What do plasma cells secrete?

Answer 20

They secrete antibodies into the blood plasma.

Question 21

How long do plasma cells survive for?

Answer 21

A few days but they make lots of antibodies.

Question 22

What are the plasma cells responsible for?

Answer 22

They are responsible for the immediate defence of the body against infection.

Question 23

What do the antibodies produced by plasma cells lead to?

Answer 23

They lead to the destruction of the antigen.

Question 24

What is the production of antibodies and memory cells known as?

Answer 24

The primary immune response.

Question 25

What are memory cells responsible for?

Answer 25

The secondary immune response.

Question 26

How long do memory cells live for?

Answer 26

Considerably longer than plasma cells- for decades.

Question 27

What do memory cells not do?

Answer 27

They don’t produce antibodies directly.

Question 28

What do memory cells do?

Answer 28

They circulate in the blood and tissue fluid.

Question 29

What happens when meme pet cells encounter the same pathogen at a later date?

Answer 29

They divide rapidly and develop into more plasma and memory cells.

Question 30

What type of immunity do memory cells provide?

Answer 30

Long-term immunity.

Question 31

What ensures them at the new infection can be destroyed before it can cause any harm?

Answer 31

Thanks to the memory cells, a large quantity of antibodies can be secretes faster than in the primary immune response.

Question 32

What is a monoclonal antibody?

Answer 32

This is an antibody that is produced by a single clone of cells.

Question 33

Summarise humoral immunity.

Answer 33

The surface antigens of an invading pathogen are taken up by a B cell.
Helper T cells attach to the processed antigens in the B cell which stimulates the B cell to divide by mitosis to create a clone of plasma cells.
The cloned plasma cells produce and secrete a specific antibody that exactly fits the antigen on the pathogen’s surface.
The antibody attaches to antigens on the pathogen and destroys them.
Some B cells develop into memory cells.