Unit 3: Neurobiology and Immunology - Key Area 6: Specific Cellular Defences Against Pathogens

Question 1

What is the specific immune response brought about by?

Answer 1

White blood cells called lymphocytes.

Question 2

Where are lymphocytes produced?

Answer 2

From stem cells in the bone marrow.

Question 3

What are the two types of lymphocytes?

Answer 3

B and T lymphocytes

Question 4

What are T lymphocytes?

Answer 4

Lymphocytes that pass into the thymus where they develop into T lymphocytes.

Question 5

What are B lymphocytes?

Answer 5

Lymphocytes that remain in the bone marrow an become B lymphocytes.

Question 6

What do lymphocytes respond to?

Answer 6

Specific antigens on invading pathogens.

Question 7

What is an antigen?

Answer 7

A molecule (often a protein) found on the surface of cells.

Question 8

What are the 2 types of antigen?

Answer 8

Self antigens (belong to the body’s own cells) and foreign antigens (do not belong to the body’s own cells).

Question 9

What do foreign antigens do?

Answer 9

Trigger a specific immune response.

Question 10

What do lymphocytes have in terms of antigens?

Answer 10

Lymphocytes have a single type of antigen receptor which is specific for one antigen.

Question 11

After foreign antigen binding what does the lymphocyte do?

Answer 11

The lymphocyte divides repeatedly, resulting in the formation of a clonal population of identical lymphocytes.

Question 12

What do B lymphocytes do?

Answer 12

Produce antibodies against antigens and this leads to destruction of a pathogen.

Question 13

What are antibodies?

Answer 13

Y-shaped protein with receptor binding sites that are specific to a particular antigen on a pathogen.

Question 14

What do antibodies do?

Answer 14

Antibodies bind to their specific antigens which are on the surface/membrane of the pathogen. The resulting antigen-antibody complex can then be destroyed by a phagocyte.

Question 15

What does an allergic reaction happen?

Answer 15

When B lymphocytes respond to antigens on substances that are harmless to the body, e.g. pollen. This hypersensitive response is called an allergic reaction.

Question 16

What are examples of allergic reactions?

Answer 16

Hayfever and peanuts.

Question 17

Which type of lymphocytes produce antibodies?

Answer 17

B lymphocytes

Question 18

What do T lymphocytes do?

Answer 18

Destroy infected body cells by recognising antigens on the pathogen on the cell surface.

Question 19

How do T lymphocytes destroy infected body cells?

Answer 19

They attach onto the infected cells and release proteins. These proteins diffuse into the infected cells causing production of self-destructive toxic chemicals which cause cell death.

Question 20

How are remaining cells of destruction of infected cells by a T lymphocyte removed?

Answer 20

By phagocytes

Question 21

What is apoptosis and what is an example of this?

Answer 21

Programmed cell death, like T lymphocytes.

Question 22

What can T lymphocytes normally distinguish between?

Answer 22

Self antigens on the body’s own cells and non-self antigens on infected cells.

Question 23

What does failure of the regulation of the immune system lead to?

Answer 23

T lymphocytes responding to self antigens.

Question 24

What happens when T lymphocytes respond to self antigens?

Answer 24

T lymphocytes attack the body’s own cells causing autoimmune disease such as type 1 diabeties and rheumatoid arthritis.

Question 25

What are disease caused by the failure of the regulation of the immune system where T lymphocytes attack the body’s own cells?

Answer 25

Type 1 diabetes and rheumatoid arthritis.

Question 26

What do some B and T lymphocytes produced in the response to antigens do?

Answer 26

Survive long term as memory cells.

Question 27

How do memory cells work?

Answer 27

When the body is exposed to the same antigen for a second time the memory cells quickly give rise to a new clone of specific lymphocytes, which destroy the invading pathogens before an individual shows symptoms.

Question 28

How does secondary response due to memory cells usually prevent diseases?

Answer 28

Antibody production is rapid and more effective than during the primary response.

Question 29

What does HIV stand for?

Answer 29

The human immunodeficiency virus.

Question 30

How does HIV work?

Answer 30

The HIV attacks and destroys T lymphocytes causing depletionof T lymphocytes which leads to the development of AIDS.

Question 31

What does AIDS stand for?

Answer 31

Acquired Immune Deficiency Syndrome

Question 32

What are the characteristics of someone with AIDS?

Answer 32

They have a weakened immune system and so are vulnerable to opportunistic infections.

Question 33

What does autoimmunity mean?

Answer 33

When the T lymphocytes attack the own body’s cells.

Question 34

Why does someone not experience symptoms if exposed to an antigen a second time?

Answer 34

The response of antibodies is more rapid and effective.

Question 35

Why are people with AIDS more likely to get ill from opportunistic infections?

Answer 35

They have a weakened immune system