The specific immune system.

Question 1

What do antigens do?

Answer 1

Trigger an immune response, which involves the production of polypeptides called antibodies.

Question 2

What are antibodies?

Answer 2

Y-shaped glycoproteins called immunoglobulins, which bind to a specific antigen on the pathogen or toxin that has trigged the immune response.

Question 3

What are antibodies made up of?

Answer 3

• Two identical long polypeptide chains called the heavy chains and two much shorter identical chains called the light chains.

Question 4

What are the chains in the antibodies held together by?

Answer 4

Disulphide bridges.

Question 5

What is formed when an antibody binds to an antigen?

Answer 5

an antigen-antibody complex

Question 6

What does an antibody contain which allows it ti bind to two separate antigens?

Answer 6

A hinge region.

Question 7

How do antibodies defend the body?

Answer 7

1- The antibody of the antigen - antibody complex acts as an opsonin so the complex is easily engulfed and digested by phagocytes.
2- Most pathogens can no longer effectively invade tbs host cells once they are part of an antigen-antibody complex.
3- Antibodies act as agglutinins causing pathogens carrying antigen-antibody complexes to clump together. This helps prevent them spreading through the body and makes it easier for phagocytes to engulf a number of pathogens at the same time.

Question 8

What is the name of white blood cells?

Answer 8

lymphocytes

Question 9

Where do B and T lymphocytes mature?

Answer 9

B lymphocytes - Bone marrow
T lymphocytes - Thymus gland

Question 10

What do T helper cells do?

Answer 10

• They produce interleukins, which are a type of cytokine. This stimulates the activity of B cells, which increases antibody production, stimulates production of other types of T cells and attracts and stimulates macrophages to ingest pathogens with antigen-antibody complexes.

Question 11

What do T killer cells do?

Answer 11

Destroy the pathogen carrying the antigen. They produce a chemical called perforin, which kills the pathogen by making holes in the cell membrane so it’s freely permeable.

Question 12

What do T memory cells do?

Answer 12

• These are part of the immunological memory.
• If they meet an antigen a second time, they divide rapidly to form a huge number of clones of T killer cells that destroy the pathogen.

Question 13

What do T regulator cells do?

Answer 13

These cells suppress the immune system, acting to control and regulate it.
They stop the immune response once a pathogen has been eliminated, and make sure the body recognises self antigens and does not set up an autoimmune response.

Question 14

What are the main types of B lymphocytes?

Answer 14

• Plasma cells
• B effector cells
• B memory cells

Question 15

What do plasma cells do?

Answer 15

These produce antibodies to a particular antigen and release them into the circulation.

Question 16

What do B effector cells do?

Answer 16

These divide to form the plasma cell clones.

Question 17

What do B memory cells do?

Answer 17

These provide the immunological memory. They are programmed to remember a specific antigen and enable the body to make a very rapid response when a pathogen carrying that antigen is encountered again.