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WJEC Medical Science-UNIT 6 > Immune system > Flashcards

Immune system Flashcards

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Biology 101 flashcards USMLE® Step 1 flashcards
1
Q

What are antibodies?

A

Proteins synthesised by B cells

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2
Q

What do antibodies do?

A

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

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3
Q

Why are antibodies so specific?

A

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

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4
Q

What happens when an antibody binds to an antigen?

A

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

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5
Q

What is the difference between an antigen and an antibody?

A

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.

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6
Q

Label the antibody

A

.

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7
Q

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

A

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

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8
Q

What are blood clots?

A

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.`

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9
Q

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

A

Chemicals including histamines

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10
Q

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

A

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

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11
Q

How does the mucus prevent pathogens entering the lungs?

A

traps any inhaled pathogens.

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12
Q

How does the cilia prevent pathogens enetering the lungs?

A

Beats to remove the mucus from the airways.

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13
Q

What are lysozymes?

A

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

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14
Q

Where are lysozymes found?

A

stomach acid, tears, saliva

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15
Q

What are phagocytes?

A

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

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16
Q

What are lymphocytes?

A

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

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17
Q

What is plasma?

A

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

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18
Q

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

A

The presence of antigens.

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19
Q

what is a non-self-antigen?

A

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

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20
Q

When does phagocytosis occur?

A

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

21
Q

What occurs in phagocytosis?

A

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

22
Q

What are the stages of phagocytosis?

A

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.

23
Q

How does the phagocyte become an antigen presenting cell?

A

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

24
Q

What is the complement system composed of?

A

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

25
Q

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

A

-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.

26
Q

What are the two types of specific immune repsonse?

A

cellular and humoral reponse.

27
Q

In the cellular reponse what do T cells do?

A

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

28
Q

Examples of antigen presenting cells.

A

-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.

29
Q

What do cytokines do?

A

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

30
Q

What are the stages of the cellular repsonse?

A

-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.

31
Q

What are the different T cells?

A

helper T cells, cytotoxic T cells and memory cells.

32
Q

What are Tm cells?

A

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

33
Q

What is the function of Th cells?

A

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

34
Q

What is the function of cytotoxic T cells?

A

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

35
Q

What does the humoral involves?

A

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

36
Q

How is a B cell activated?

A

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

37
Q

What do activated B cells do?

A

divide rapidly by mitosis to form a clone.

38
Q

What can daughter cells now do?

A

produce antibodies which are complementary to the specific antigen.

39
Q

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

A

plasma cells or memory cells.

40
Q

What are plasma cells?

A

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.

41
Q

What do memory cells do?

A

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.

42
Q

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

A

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.

43
Q

Similarities between the cellular and humoral reponse to a pathogen.

A

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

44
Q

Difference between the cellular and humoral reponse to a pathogen

A

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

45
Q

what does the binding of an antigen and antibody form?

A

antigen-antibody complex.

46
Q

when does agglutination occur?

A

when an antibody binds to an antigen

47
Q

What is agglutination?

A

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

48
Q

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

A

Quaternary

49
Q

What are the bonds in an antigen-binding site?

A

Disulphide

WJEC Medical Science-UNIT 6 (14 decks)

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