Immune system

Question 1

What are antibodies?

Answer 1

Proteins synthesised by B cells

Question 2

What do antibodies do?

Answer 2

They react with antigens and bind with them precisely forming an antigen-antibody complex, as they are complementary shapes.

Question 3

Why are antibodies so specific?

Answer 3

Antibodies are therefore very specific, each antigen having its own individual antibody. this variety is possible because they are protein in nature, with each type of antibody aging a different tertiary structure and a different shape antigen-binding site

Question 4

What happens when an antibody binds to an antigen?

Answer 4

It causes agglutination to occur. this is when all the bacteria are clumped together. the clumps of bacteria can then be engulfed by a phagocyte easier

Question 5

What is the difference between an antigen and an antibody?

Answer 5

Antigen- triggers a immune response
Antibody- Complementary to antigen, binds to and destroys or deactivated antigens (i.e. antibodies are part of the immune response.

Question 6

Label the antibody

Answer 6

.

Question 7

Why does the skin act as a natural barrier to prevent pathogens?

Answer 7

the outer most cells are packed with keratin, which is difficult for pathogens to digest.

Question 8

What are blood clots?

Answer 8

When there is an open wound in the skin bthey are quickly blocked by blood lots which are bundles of proetins, platelets and erythrocytes that prevent pathogens from entering.`

Question 9

What do cells in the area produce when skin is damaged?

Answer 9

Chemicals including histamines

Question 10

What do chemicals such as histamines caused when they are produced due to skin dmaage?

Answer 10

vasodilation, inc blood flow to the area. This leads to more tissue fluid leaking from the capillaries causing swelling and an increase temp.

Question 11

How does the mucus prevent pathogens entering the lungs?

Answer 11

traps any inhaled pathogens.

Question 12

How does the cilia prevent pathogens enetering the lungs?

Answer 12

Beats to remove the mucus from the airways.

Question 13

What are lysozymes?

Answer 13

A group of enzymes which can digest the cell walls of bacteria, killing them and precventing disease.

Question 14

Where are lysozymes found?

Answer 14

stomach acid, tears, saliva

Question 15

What are phagocytes?

Answer 15

WBC that form part of the non-specific immune system alomng with platelets, which are involved in clotting.

Question 16

What are lymphocytes?

Answer 16

WBC that are involved in the specific immune reponse. There are 2 types, B cells and T cells.

Question 17

What is plasma?

Answer 17

The straw coloured liquid medium that transports various blood cells and components around the body.

Question 18

How are the specific and on-specific response initially activated?

Answer 18

The presence of antigens.

Question 19

what is a non-self-antigen?

Answer 19

Antigens on the surface of pathogens, and are identifies by the immune system and trigger an immune reponse.

Question 20

When does phagocytosis occur?

Answer 20

When a phagocyte encounters a non-self-antigen on the durface of a pathogen.

Question 21

What occurs in phagocytosis?

Answer 21

The phagocyte binds to the antigen and engulfs the pathogen in a vesicle.

Question 22

What are the stages of phagocytosis?

Answer 22

1.the pahgocyte encounters the non-self antigen on the surface of the pathogen.
2.the phagocyte then engulfs the pathogen by endocytosis.
3.The pathogen is then held inside specialised vesicle called a phagosome.
4.A lysome is fused to the phagosome, releasing power hydrolytic enzymes into the phagosome.
5. the enzymes digest the pathogen.
6.The phagocyte will absorb any useful materials from the digested pathogen.
7.The phagocyte will then release any waste material out of the cell by exocytosis.

Question 23

How does the phagocyte become an antigen presenting cell?

Answer 23

it will take some of the antigens from the pathogen and place them on its membrane.

Question 24

What is the complement system composed of?

Answer 24

difefrent proteins and enzymes found in the blood and on cell memebranes

Question 25

When non self- antigens are detected by the complement system what do the reactions caused lead to?

Answer 25

-stimulation of phagocytes -inflammation of affected areas to increase no. of pathogens. - Activation of a protein complex which directly kills pathogens by making holes in their cell membranes.

Question 26

What are the two types of specific immune repsonse?

Answer 26

cellular and humoral reponse.

Question 27

In the cellular reponse what do T cells do?

Answer 27

recognise non-self-antigens presneted on teh surface of otehr body cells.

Question 28

Examples of antigen presenting cells.

Answer 28

-cells that are infected by virus -a phagocyte which has just engulfed and hydrolysed a pathogen -An abnormal cell e.g. one that has become cancerous.

Question 29

What do cytokines do?

Answer 29

These cytokines help activate cytotoxic T-cells to fight the infection

Question 30

What are the stages of the cellular repsonse?

Answer 30

-Pathogens invade body cells or are taken in by phagocytes. -the phagocyte places antigens from the pathogen on its surface. -Receptors on specific T cells fit exactly with these antigens. -this activated this T cell to divide rapidly by mitosis and form a clone of genetically identical cells. it also releases chemicals to activate other cells that are specific for the antigen.

Question 31

What are the different T cells?

Answer 31

helper T cells, cytotoxic T cells and memory cells.

Question 32

What are Tm cells?

Answer 32

Enable a rapid repsonse to furture infections by the same antigen.

Question 33

What is the function of Th cells?

Answer 33

release chemical signals called cytokines which stiimulate other cells of the immune sytem.

Question 34

What is the function of cytotoxic T cells?

Answer 34

Destroy infected body cells. they produce a protein (perforin) whcih makes holes in cell memebranes.

Question 35

What does the humoral involves?

Answer 35

B cells and anti-body production. it is effective against pathogens that are circulating in the blood stream.

Question 36

How is a B cell activated?

Answer 36

When a specific B cell with a complementary antibody binds to an antigen, togetehr with the chemicals released by specific Th cells.

Question 37

What do activated B cells do?

Answer 37

divide rapidly by mitosis to form a clone.

Question 38

What can daughter cells now do?

Answer 38

produce antibodies which are complementary to the specific antigen.

Question 39

What are the 2 types of cell the B cell can develop into?

Answer 39

plasma cells or memory cells.

Question 40

What are plasma cells?

Answer 40

secrete antibodies directly. these enter the blood and bind to complementary antigens, leading to the inactivation and destruction of circulating pathogens or toxins by pahgocytosis.

Question 41

What do memory cells do?

Answer 41

If they encounter the same antigen at a later date they: divide rapidly, produce large number of memory and plasma cells. the large number of plasma cells mean that more antibodies will be produced, faster.

Question 42

Why is a secondary repsonse much more rapid than the primary one?

Answer 42

P-The antigen is taken in and needs time to activate a specifit B lymphocyte which then has to clone itself, produce plasma cells, antibodies and memory cells. S- There are already memory cells against this antigen so can quickly divide by mitosis.

Question 43

Similarities between the cellular and humoral reponse to a pathogen.

Answer 43

-Both create memory cells -Divide by mitosis -activated by T-helper cells. -Both involve lymphocytes

Question 44

Difference between the cellular and humoral reponse to a pathogen

Answer 44

-humoral produce b cells, cellular produce T-cells -humoral had antibodies, cellular doesn't -humoral in body fluid and cellular inside cells.

Question 45

what does the binding of an antigen and antibody form?

Answer 45

antigen-antibody complex.

Question 46

when does agglutination occur?

Answer 46

when an antibody binds to an antigen

Question 47

What is agglutination?

Answer 47

This is when all the bacteria are clumped together and then these can be engulfed by a phagocyte easier.

Question 48

What is the level of protein structure in an antigen binding site?

Answer 48

Quaternary

Question 49

What are the bonds in an antigen-binding site?

Answer 49

Disulphide