2C - Cells and The Immune System

Question 1

What does the cellular immune response include?

Answer 1

The T-Cells and other immune system cells that they interact with, e.g. phagocytes form the cellular response.

Question 2

What does the Humoral immune response include?

Answer 2

B-Cells, clonal selection and the production of monoclonal antibodies form the humoral response.

Question 3

When is the primary immune response activated?

Answer 3

When an antigen enters the body for the first time.

Question 4

Why is the primary response slow?

Answer 4

Because there aren’t many B-Cells that can make the antibody needed to bind to it.

Question 5

What is happening within the immune system while an infected person develops symptoms?

Answer 5

The body is trying to produce enough of the right antibody to overcome the infection.

Question 6

What happens in the immune system after being exposed to an antigen?
(How does a person become immune?)

Answer 6

Both T- and B- Cells produce memory cells. These memory cells remain in the body for a long time. Memory T-Cells remember the specific antigen and will recognise it a second time around. Memory B-Cells record the specific antibodies needed to bind to the antigen.

Question 7

What are “antigens”?

Answer 7

Molecules (usually proteins) that can generate an immune response when detected by the body. They are usually found on the surface of cells and are used by the immune system to identify foreign cells.

Question 8

Give examples of the types of cells that antigens allow the immune system to detect.

Answer 8

• pathogens (organisms that cause disease)
• abnormal body cells (e.g. Cancerous or pathogen infected cells, which have abnormal antigens on their surface)
• toxins
• cells from other individuals of the same species, (e.g. Organ transplants).

Question 9

What is a phagocyte?

Answer 9

A type of white blood cell

Question 10

Give an example of a phagocyte

Answer 10

A macrophage

Question 11

What is the role of a phagocyte?

Answer 11

(It’s a type of White blood cell) that carries out phagocytosis

Question 12

What is phagocytosis?

Answer 12

Engulfment of pathogens

Question 13

Where are phagocytes found?

Answer 13

They are found in the blood and tissues

Question 14

Which are the first cells to respond to an immune system trigger inside the body?

Answer 14

Phagocytes

Question 15

Describe the process of phagocytosis

Answer 15

1- A phagocyte recognises the foreign antigens on a pathogen
2- The cytoplasm of the phagocyte moves round the pathogen, engulfing it.
3- The pathogen is now contained in a phagocytic vacuole (a bubble) in the cytoplasm of the phagocyte
4- a lysosome (an organelle that contain enzymes called lysozymes) fuses with the phagocytic vacuole. The lysozymes break down the pathogen.
5- the phagocyte then presents the pathogen’s antigens- it sticks the antigens on its surface to activate other immune system cells.

Question 16

What is a lysosome?

Answer 16

An organelle that contains enzymes called LYSOZYMES

Question 17

Why does a phagocyte present the pathogen’s antigens (after phagocytosis)?

Answer 17

To activate other immune system cells

Question 18

Briefly name the four main stages in the immune response.

Answer 18

1) phagocytes engulf pathogens
2) phagocytes activate T-Cells
3) T-cells activate B-cells, which divide into Plasma Cells
4) Plasma cells make more antibodies to a specific antigen

Question 19

What is a T-cell?

Answer 19

a type of white blood cell

Question 20

What can a T cell also be called?

Answer 20

A T-lymphocyte