Defence-Immune System 1

Question 1

Define specific defences.

Answer 1

They are adaptive mechanisms that protect against specific targets.

Question 2

What are lymphoid tissues?

Answer 2

Essential parts of the defence system e.g. Thymus, bone marrow, spleen, lymph nodes.

Question 3

Define lymph.

Answer 3

Lymph consists of fluids that accumulate outside of the bloodstream in the lymphatic system.

Question 4

Define lymphatic system.

Answer 4

A branching system of tiny capillaries connecting larger vessels.

Question 5

Name the two main types of white blood cell.

Answer 5

Phagocytes and lymphocytes.

Question 6

What is the function of phagocytes?

Answer 6

To engulf and digest foreign materials.

Question 7

Describe lymphocytes.

Answer 7

Most abundant white blood cell consisting of two types: T cells and B cells.

Question 8

What is the function of T cells?

Answer 8

They migrate from the circulation to the thymus where they mature.

Question 9

What is the function of B cells?

Answer 9

Circulate and also collect in lymph vessels, and make antibodies.

Question 10

What is the function of platelets?

Answer 10

Initiate blood clotting.

Question 11

What are T cell receptors?

Answer 11

Cell surface receptors that bind nonself substances on the surface of other cells.

Question 12

What is major histocompatibility complex (MHC) proteins?

Answer 12

Exposed outside cells of mammals - these proteins help to distinguish self from nonself.

Question 13

What are cytokines?

Answer 13

Soluble signal proteins released by T cells. They bind and alter the behaviour of their target cells.

Question 14

What three defences do complement proteins provide?

Answer 14

• Attach to microbes helping phagocytes recognise and destroy them
• Activate inflammation response and attract phagocytes to infected site
• They lyse invading cells.

Question 15

Define interferons.

Answer 15

They are produced by cells that are infected by a virus. They increase neighbouring cell resistance to the same or other viruses.

Question 16

Name the different types of phagocyte.

Answer 16

• Neutrophils
• Monocytes/macrophages
• Eosinophils
• Dendritic cells
• Natural killer cells.

Question 17

What is the function of neutrophils?

Answer 17

Attack pathogens in infected tissue.

Question 18

What is the function of monocytes?

Answer 18

They mature into macrophages. They live longer and consume more pathogens than neutrophils.

Question 19

What is the function of eosinophils?

Answer 19

They kill parasites such as worms that have been coated with antibodies.

Question 20

What is the function of dendritic cells?

Answer 20

Have highly folded plasma membranes that can capture invading pathogens.

Question 21

What is the function of natural killer cells?

Answer 21

They are a class of nonphagocytic white blood cells. They can initiate the lysis of virus-infected cells and some tumour cells.

Question 22

What is the inflammatory response?

Answer 22

It is used when dealing with infection or tissue damage.

Question 23

What are basophils?

Answer 23

Mast cells and white blood cells which produce histamine, which triggers inflammation.

Question 24

Define antigens.

Answer 24

Organisms/molecules that are specifically recognised by T cell receptors and antibodies.

Question 25

Define the humoral immune response.

Answer 25

Involves antibodies that recognise antigenic determinants by shape and composition.

Question 26

Define the cellular immune response.

Answer 26

Is able to detect antigens that reside within cells.

Question 27

Define nonspecific/innate defences.

Answer 27

They are inherited mechanisms that protect the body from many different pathogens.