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Biology aqa AS > cells and the immune system > Flashcards

cells and the immune system Flashcards

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1
Q

what triggers an immune response

A

foreign antigens

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2
Q

what are antigens

A

molecules (usually proteins) found on the surface of cells, used by immune system to identify pathogens, abnormal body cells, toxins or cells from other individuals of the same species

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3
Q

what are pathogens

A

micro-organisms that cause disease

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4
Q

what are abnormal body cells

A

cells with abnormal antigens (e.g cancerous or pathogen-infected)

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5
Q

4 stages of immune response

A

1) phagocyte engulfs pathogen
2) phagocyte activates T-cells
3) T-cells activate B-cells (which divide into plasma cells)
4) plasma cells make more antibodies to specific antigen

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6
Q

phagocytes engulfing pathogens

A

1) phagocyte recognises foreign antigens a pathogen
2) cytoplasm of phagocyte moves around the pathogen and englufs it
3) pathogen is contained in phagocytic vacuole in phagocyte cytoplasm
4) lysosome fuses with phagocytic vacuole and breaks down the pathogen
5) phagocyte presents pathogens antigens on its surface to active other immune system cells (becomes antigen presenting cell)

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7
Q

what is a phagocyte

A

type of white blood cell that carries out phagocytosis, found in blood and tissues, first cells to respond to an immune trigger

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8
Q

what is phagocytosis

A

engulfment of pathogens

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9
Q

phagocytes activating T-cells

A

the receptor proteins on the T-cell surface bind to the complimentary antigens present on phagocytes

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10
Q

what are T-cells

A

type of white blood cell (t-lymphocyte)

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11
Q

types of T-cells

A

helper T-cells, cytotoxic T-cells

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12
Q

helper T-cells

A

release chemical signals that activate and stimulate phagocytes and cytotoxic T-cells, and activate B-cells

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13
Q

cytotoxic T-cells

A

kill abnormal and foreign cells

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14
Q

B-cells

A

type of white blood cell, covered with antibodies (each a different shape so bind to different antigens), secrete antigens, divides into plasma cells

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15
Q

B-cells into plasma cells

A

1) antibody on surface of B-cell meets a complimentary antigen and binds to it to form an antigen-antibody complex
2) activates the B-cell (colonial selection)
3) activated B-cell divides into plasma cells

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16
Q

plasma cells

A

secrete antibodies specific to the antigen (monoclonal antibodies) which bind to the antigens on the surface of the pathogen to form antigen-antibody complexes

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17
Q

what are antibodies

A

proteins that have variable regions, coat pathogens to make them easier to be engulfed

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18
Q

what is agglutination

A

pathogens that become clumped together (as antibodies have 2 binding sites)

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19
Q

immune responses

A

cellular or humoral

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20
Q

cellular response

A

T-cells and other immune system cells that they interact with (e.g phagocytes)

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21
Q

humoral response

A

B-cells, colonial selection and production of monoclonial antibodies

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22
Q

immune response for antigens

A

primary and secondary

23
Q

primary immune response

A

when antigen first enters body and triggers immune response, slow (as aren’t many B-cells, but eventually will come, until them symptoms are seen), afterwards B-cells produce memory cells

24
Q

what are memory cells

A

produced by B-cells, remain in body for a long time, record specific antibodies needed to bind the antigen and produce them quickly

25
Q

secondary immune response

A

if same pathogen enters body again, immune system will produce a quicker, stronger immune response (clonal selection), memory B-cells activated and divide into plasma cells that produce the right antibody, memory T-cells are activated and divided into correct T-cells, gets rid of pathogen before symptoms occur

26
Q

vaccines

A

dead or inactive forms of the pathogens that cause body to produce memory cells (become immune without symptoms)

27
Q

what do vaccines do

A

protect individuals, and create herd immunity

28
Q

what is herd immunity

A

people not vaccinated are less likely to catch the disease because there are fewer people to catch it from

29
Q

how are vaccines given

A

injected or taken orally

30
Q

disadvantage of taking orally

A

could be broken down by enzymes in the gut, or molecules of vaccine may be too large to be absorbed into the blood

31
Q

booster vaccines

A

sometimes given to ensure memory cells are produced

32
Q

antigenic variation

A

antigen changes shape (makes vaccination difficult), (e.g influenza virus = new strains that are immunologically distinct)

33
Q

immunity types

A

active or passive

34
Q

active immunity

A

when your immune system makes its own antibodies after being stimulated by an antigen
2 types - natural or artificial, requires exposure, takes a while for protection to develop, memory cells are produced, protection is long term

35
Q

natural active immunity

A

when you become an immune after catching a disease

36
Q

artificial active immunity

A

when you become immune after being given a vaccination

37
Q

passive immunity

A

immunity got from being given antibodies made by a different organism (when your immune system doesn’t produce antibodies of its own)
2 types - natural or artificial, doesn’t require exposure to antigen, protection is immediate, memory cells aren’t produced, protection is short term

38
Q

natural passive immunity

A

when a baby becomes immune due to the antibodies it receives from its mother through the placenta and in breast milk

39
Q

artificial passive immunity

A

when you become immune after being injected with antibodies from someone else (e.g tetanus can be injected with antibodies against the toxin collected from blood donations)

40
Q

what are monoclonal antibodies

A

antibodies produced from a single group of genetically identical B-cells (plasma cells), identical in structure, made to bind to anything

41
Q

example - cancer cells

A

1) cancer cells have tumour markers that are not found on normal body cells
2) monoclonal antibodies can be made that will bind to the tumour markers , and anti-cancer drugs can be attatched ti the antibodies
3) when the antibodies come in contact with cancer cells they bind to the tumor markers, so drug will only accumulate in the body where there are cancer cells
4) side effects will be lower (as they accumulate near specific cells)

42
Q

pregnancy test

A

detect the hormone human chorionic gondotropin that’s found in urine of pregnant women

43
Q

ELISA test

A

medical diagnosis that uses antibodies for things such as pathogenic infections

44
Q

ELISA test method

A

an antibody is used which has an enzyme attached to it, and the enzyme can react with a substrate to prduce a coloured product
colour change = antigen is present

45
Q

types of ELISA test

A

direct and indirect

46
Q

direct ELISA test

A

uses a single antibody that is complimentary to the antigen you’re testing for

47
Q

indirect ELISA test

A

uses 2 different antibodies

48
Q

ELISA test example

A

for HIV

49
Q

what is HIV

A

human immunodeficiency virus, causes AID’s through affecting the immune system, no cure, replicates inside host cells

50
Q

ELISA test for HIV method

A

1) HIV antigen is bound to bottom of a well in a well plate
2)sample of patients blood plasma is added to the well
3)if there are any HIV specific antibodies, they will bind to the antigen , then the well is washed out
4)secondary antibody is added to the well, which can bind to the antibody and the well is washed out to remove any un-bound secondary antibody
5)a solution that contains substrate is added to the well which will react to the with the enzyme .
if it changes colour = patient has HIV

51
Q

MMR

A

measles, mumps and rubella

52
Q

MMR scare

A

caused autism in children (insufficient testing - sample size of 12 children)

53
Q

herceptin

A

treat breast cancer - sample size of 1694

54
Q

ethical issues of vaccines

A

tested on animals, unnecessary risk for volunteers, side effects, who receives it first in an epidemic

Biology aqa AS (7 decks)

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