CELLS 4 (immune system)

Question 1

Where are lymphocytes made?

Answer 1

Bone marrow

Question 2

Where do T cells mature?

Answer 2

Thymus

Question 3

What type of response are T cells associated with?

Answer 3

Cell-mediated responses

Question 4

How are T cells activated?

Answer 4

• Bind to a host APC
• Divide by mitosis
• differentiate into T Helper, T Killer Cells and T memory.

Question 5

What is the role of a T Helper cell?

Answer 5

T Helper cells coordinate all specific cell responses
(notably with use of cytokines which is a cell signalling chemical)

Question 6

What do cytokines do?

Answer 6

The release of cytokines is stimulated by T Helper cells
- Stimulate the activation of B cells by binding to an antigen that’s on a pathogen.
- Stimulate phagocytosis
- Stimulate the division of T Killer cells once an infected cell has been identified to speed up the immune response to clone the T Killer = many specific/complementary receptors.

Question 7

Explain how T Killer cells target a foreign cell.

Answer 7

• A fragment of the pathogen is displayed on the cell surface = Antigen presenting cell.
• T Killer cell with complementary receptor binds to the foreign cells antigen.
• Cytokines stimulates cell division of the specific T Killer cell, forming clones
• Specific T Killer cell receptors bind to the specific antigen
• Forms pores in the foreign cell membrane
• Injects enzymes that cause lysis.

Question 8

Do lymphocytes have antibodies on the surface of cells?

Answer 8

B cells have antibodies on the surface whereas T cells only have receptor proteins.

Question 9

What is lysis?

Answer 9

Lysis is the breaking open of bacterial cells and occurs when T killer cells inject enzymes through cell membrane pores.

Question 10

What types of T cells are there?

Answer 10

• Cytotoxic T-cells (T-Killer)
• T Helper
• T memory