Neurobiology and Immunology: Specific Cellular Defences Against Pathogens

Question 1

What are lymphocytes?

Answer 1

White blood cells that are involved in the specific immune response

Question 2

What do lymphocytes do?

Answer 2

Respond to specific antigens on invading pathogens

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

Lymphocytes have a single type of membrane receptor which is specific for one antigen. What does antigen binding lead to?

Answer 4

Repeated lymphocyte division, resulting in the formation of a clonal population of identical lymphocytes

Question 5

What are the two types of lymphocyte?

Answer 5

B lymphocytes and T lymphocytes

Question 6

What do B lymphocytes do?

Answer 6

Produce antibodies against antigens leading to the destruction of the pathogen

Question 7

What are antibodies?

Answer 7

Y-shaped proteins that have receptor binding sites which are specific to a particular antigen on a pathogen

Question 8

What do antibodies do?

Answer 8

Become bound to antigens, inactivating the pathogen

Question 9

What happens to the resulting antigen - antibody complex?

Answer 9

It can be destroyed by phagocytosis

Question 10

What can B lymphocytes do?

Answer 10

Respond to antigens on substances that are harmless to the body, such as pollen. This hypersensitive response is called an allergic reaction

Question 11

What do T lymphocytes do?

Answer 11

Destroy infected body cells recognising antigens of the pathogen on the cell and inducing apoptosis

Question 12

What is apoptosis?

Answer 12

Programmed cell death

Question 13

T lymphocytes attach to infected cells and release what?

Answer 13

Proteins

Question 14

What happens to the proteins released?

Answer 14

They diffuse into the infected cells, bringing about the production of self-destructive enzymes which cause cell death. The remains of the cell are then removed by phagocytosis

Question 15

What happens to the remains of the cell?

Answer 15

Removed by phagocytosis

Question 16

What can T lymphocytes normally do?

Answer 16

Distinguish between self antigens on the body’s own cells and non-self antigens on infected cells

Question 17

Failure of the regulation of the immune system leads to what?

Answer 17

T lymphocytes respond to self antigens. This causes autoimmune diseases

Question 18

What happens in autoimmunity?

Answer 18

The T lymphocytes attack the body’s own cells

Question 19

What does autoimmunity cause?

Answer 19

Autoimmune diseases such as Type 1 Diabetes and Rheumatoid Arthritis

Question 20

What happens to cloned B and T lymphocytes?

Answer 20

They survive long term as memory cells

Question 21

What happens when a secondary exposure to the same antigen occurs?

Answer 21

The memory cells rapidly give rise to a new clone of specific lymphocytes which destroy the invading pathogens before the individual shows symptoms

Question 22

What happens during the secondary response?

Answer 22

Antibody production is greater and more rapid than during the primary response

Question 23

What does HIV do?

Answer 23

Attacks and destroys T lymphocytes

Question 24

What does HIV cause?

Answer 24

The depletion of T lymphocytes which leads to the development of AIDS

Question 25

What is wrong with individuals with AIDS

Answer 25

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