antigens

Question 1

what are antigens ?

Answer 1

antigens are molecules that generate an immune response

Question 2

what are antigens complementary to ?

Answer 2

antigens are complementary to the receptors of the cells that perform an immune response i.e T helper cells

Question 3

where are antigens located ?

Answer 3

antigens are located on the surface of all cells including cells in the human body

Question 4

what are foreign antigens ?

Answer 4

antigens that belong to cells not usually found in the body

Question 5

what do foreign antigens do ?

Answer 5

stimulate the immune system

Question 6

what are 3 examples of things that have foreign antigens ?

Answer 6

-pathogens
- toxins
- cancerous cells

Question 7

what kind of response is phagocytosis ?

Answer 7

a cellular response which is non-specific

Question 8

what kind of cells are also a part of the cellular response ?

Answer 8

T-cells

Question 9

what are T-helper cells activated by ?

Answer 9

T-helper cells are activated by specific antigens that are complementary to receptors presented on an APC and not antigens detached from cells in the body fluids

Question 10

how do T- helper cells respond ?

Answer 10

by producing cytokines

Question 11

what are cytokines ?

Answer 11

chemicals that activate other cells of the immune system
- which also attract cells of the immune system which increases the immune response

Question 12

what is the humoral response to do with ?

Answer 12

antibodies

Question 13

how long do B memory cells approximately last ?

Answer 13

5 years

Question 14

explain the humoral response ?

Answer 14

B-cells are activated by cytokines and complementary antigens
- activated B-cells undergo mitosis and differentiation which is called clonal selection
- some B-cells become B plasma cells that make antibodies and some cells become B memory cells that last up to 5 years in the blood

Question 15

where are all lymphocytes made ?

Answer 15

in the bone marrow

Question 16

where do t-cells mature?

Answer 16

in the thymus

Question 17

what does APC stand for ?

Answer 17

antigen presenting cell

Question 18

what are APC ?

Answer 18

any cell that presents a non-self antigen on its cell surface membrane

Question 19

what will T-cells only respond to ?

Answer 19

T-cells will only respond to antigens which are presented on the APC and not antigens that are detached from cells and within body fluids i.e blood

Question 20

what can T-helper cells differentiate into ?

Answer 20

-some remain as T cells and activate B cells
-some stimulate macrophages to peform more phagocytosis
-some become memory cells for that shaped antigen
-some become cytotoxic T cells

Question 21

what do cytotoxic T cells do ?

Answer 21

cytotoxic T-cells destroy abnormal or infected cells by releasing a protein called perforin which embeds into cell membranes and makes a pore so that any substances can enter or leave the cell which causes cell death

Question 22

where are cytotoxic t cells most common ?

Answer 22

in viral infections because viruses infect body cells

Question 23

at is meant by active immunity ?

Answer 23

when you have been previously exposed to a pathogen so that when you get exposed again large numbers of antibodies can be produced so rapidly that the pathogen is destroyed before any symptoms occur

Question 24

What is the cell-mediated response?

Answer 24

The response involving T cells and body cells

Question 25

Example of APC

Answer 25

• Infected body cells will present viral antigen on their surf
• macrophage which has engulfed and destroyed a pathogen
• cells of a transplanted organ will have different shaped antigen on their surface compared to your self- cell antigens
• cancer cells

Question 26

First stage of the cell mediated response ?

Answer 26

• once a pathogen has been engulfed and destroyed the antigens will be presented on the cell surface membrane which is called an APC

Question 27

Second stage of the cell mediated response ?

Answer 27

Helper t cells have receptors that are complimentary to the antigens on the apc

Question 28

Third stage of the cell mediated response

Answer 28

Once attached this activates the t helper cells to divide by mitosis and replicate to make large numbers of clones

Question 29

4 th stage of the cell mediated response

Answer 29

Cloned t helper cells differentiate into different cells
- some remain as helper T cells and activate b lymphocytes
- some stimulate macrophages to perform phagocytosis
- some become memory cells for that antigen
- some become cytotoxic T cells (killer t cells )