Specific Cellular Defences

Question 1

What are lymphocytes?

Answer 1

Lymphocytes are white blood cells involved in the specific immune response
Lymphocytes respond to specific antigens on pathogens.

Question 2

What do lymphocytes respond to?

Answer 2

Specific antigens found on pathogen membranes

Question 3

What are antigens?

Answer 3

Antigens are molecules, often proteins located on the surface of cells that trigger a specific immune response.

Question 4

What is meant by ‘lymphocytes are complementary to antigens’?

Answer 4

This means that lymphocytes have a single type of membrane receptor that is specific for one antigen.

Question 5

What happens when a lymphocyte binds to an antigen?

Answer 5

Antigen binding results in repeated lymphocyte division white causes the formation of a clonal population of identical lymphocytes

Question 6

What are the two types of lymphocytes?

Answer 6

B lymphocytes and T lymphocytes

Question 7

What are B lymphocytes?

Answer 7

B lymphocytes are lymphocytes that produce antibodies against antigens, which leads to the specific destruction of the pathogen

Question 8

What are antibodies?

Answer 8

Antibodies are Y shaped proteins that have a receptor binding site that is specific to a particular antigen on the pathogen.

Question 9

What do antibodies do once bound to the pathogen?

Answer 9

Antibodies inactivate the pathogen, these antibodies join the inactive pathogens together which results in a antigen-antibody complex which can then be destroyed by phagocytosis.

Question 10

What happens when B lymphocytes respond to antigens on substances that are harmless?

Answer 10

The B lymphocytes would cause a hypersensitive response by activating mast cells, this would cause a release of histamine which can result in an allergic reaction.

Question 11

What are T lymphocytes?

Answer 11

T lymphocytes are a type of lymphocyte that destroys infected body cells by recognising antigens of the pathogen on the cell membrane and inducing apoptosis.

Question 12

What is apoptosis?

Answer 12

Apoptosis is programmed cell death

Question 13

How do T lymphocytes cause apoptosis?

Answer 13

T lymphocytes attach on to infected cells and release proteins, these proteins diffuse into infected cells causing production of self destructive enzymes which cause cell death.

The remains of the cell are then removed by phagocytosis.

Question 14

T lymphocytes can normally distinguish between self antigens on the body’s own cells and non self antigens on infected cells.

Answer 14

Just a fact!!

Question 15

What happens when the immune system isn’t regulated?

Answer 15

T lymphocytes will respond to self antigens, which causes autoimmune diseases.

Question 16

What happens in autoimmunity?

Answer 16

In autoimmunity, the T lymphocytes attack the body’s own cells. This causes autoimmune diseases such as type 1 diabetes and rheumatoid arthritis.

Question 17

Give 2 examples of autoimmune diseases.

Answer 17

Rheumatoid arthritis and type 1 diabetes.

Question 18

What happens on a secondary exposure to the same antigen of a pathogen?

Answer 18

Memory cells will rapidly produce specific lymphocytes that are complementary to the pathogen.

Question 19

What do memory cells cause?

Answer 19

Memory cells cause the production of specific lymphocytes that destroy the invading pathogens before an individual can show symptoms.

Question 20

Describe the secondary response in terms of antibody production + concentration

Answer 20

The antibody production is greater and more rapid than the initial response and the concentration of antibodies is greater.

Question 21

What does human immunodeficiency virus do?

Answer 21

HIV attacks and destroys T lymphocytes, resulting in a depletion of T lymphocytes, leading to the development of AIDS ( acquired immunodeficiency syndrome )

Question 22

What is typical of individuals with AIDS?

Answer 22

Individuals with AIDS have a weakened immune system and so are more vulnerable to opportunistic infections