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immune system Flashcards

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1
Q

what is a vaccination?

A

a medical procedure that involves administering a weakened or dead form of a pathogen in a person, to trigger the production of antibodies

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2
Q

how do vaccines work?

A

dead/weakened viral preparations have antigens to stimulate the immune system to recognize and eliminate the particular pathogen, so if it reenters, the body can detect and eliminate it. they cause memory cells to be created

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3
Q

when does herd immunity occur

A

when large proportion of the population has been vaccinated which makes it difficult for pathogens to spread. those who aren’t immunized are protected as its unlikely to contract the disease as the levels of it are low

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4
Q

how does active immunity work?

A

the body makes its own antibodies in response to pathogen exposure
- vaccination provides active immunity (booster vaccinations are needed)

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5
Q

features of active immunity?

A
  • long term
  • takes a long time to develop immunity
  • body produces antibodies in response to pathogen exposure
  • produces memory cells
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6
Q

how does passive immunity work?

A

develops due to antibodies which come form another animal

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7
Q

features of passive immunity

A
  • short term
  • develops immunity fast
  • body develops immunity due to antibodies which came from another animal
  • doesn’t produce memory cells so antibodies get used up
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8
Q

Why it is easier to develop vaccines for some diseases and not others

A

some viruses are able to undergo rapid modifications. these modifications allow viruses to easily evade the immune system and most of the vaccines fail to work against these viruses

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9
Q

What is a pathogen

A

A microorganism that causes a disease

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10
Q

1st line fo defence
Physical:

A
  • skin
  • cilia
  • mucus
  • nasal hair
  • friendly bacteria
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11
Q

1st line of defence
Chemical:

A
  • mucus
  • tears, lysosomes
  • stomach acid, HCL
  • platelets
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12
Q

Process of phagocytosis

A
  1. Phagocyte is attracted to the pathogen by chemotaxis
  2. Pathogen attaches to phagocyte by antibody and surface receptors
  3. Pathogen engulfed by an infolding of the phagocyte membrane
  4. Lysosomes release sets lysines into phagosomes
  5. Harmless end products of digestion are absorbed
  6. Phagocyte displays the antigens form the pathogen on its cell surface membrane and becomes an antigen presenting cell (APC)
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13
Q

What is a macrophage

A

Phagocyte ell that releases lytic enzymes to break down pathogenic cell

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14
Q

What is a cytotoxic T cell

A

Cells that destroys pathogenic cells by releasing chemical into the invaded cells

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15
Q

What is a Helper T cell

A

Cell that stimulates and recruits more cells to assist in the immune response

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16
Q

What are b lymphocytes

A

Are responsible for humorous immunity (the humours = body fluids). They produce antibodies

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17
Q

What are t lymphocytes

A

Are responsible for cell mediated (requires cells) immunity

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18
Q

Cell maturation of b lymphocytes and t lymphocytes

A

Both cells begin life as stem cells in the bone marrow
- T cells mature in the thymus
- B cells mature in the bone marrow

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19
Q

What are antigens

A

part of an organism/ substance thats recognized as foreign by the immune system, which stimulates an immune response.
They are often proteins or glycoproteins on the cell surface membrane

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20
Q

Features of cell mediated immunity

A
  • cell mediated response can only be initiated by APc’s
  • cell mediated responses are specific to the antigens presented
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21
Q

Examples of APC’s:

A
  • phagocytes that have engulfed, invading microorganisms
  • cells which ave been infected by a virus
  • cancer cells
  • cells transplanted from anther organism

Any of these can trigger an immune response

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22
Q

Process of cell-mediated immunity

A
  1. Phagocyte ingest pathogens by phagocytosis
  2. Pathogens is digests and the cell becomes an APC
  3. T helper cells attracted to phagocyte by chemicals
  4. T helper cell binds to antigen on surface of phagocyte
  5. T helper cell undergoes clonal expansion
  6. Clones activate cytotoxic T cells
  7. Cytotoxic T cells bind to antigens and secrete performing
  8. Perforin makes holes in the pathogen membrane and kills the cell
  9. Some T cells remain as memory cells
23
Q

B lymphocytes activation process

A
  1. T helper cells active specific B cells
  2. Once activated the B cells undergo clonal expansion and differentiate to form either plasma cells or memory cells
24
Q

What a plasma cells

A

produce antibodies which are complementary to the antigens on the pathogen

25
Q

What are memory cells

A

Memory cells remain circulating the blood for periods of time.
The next time the same pathogen invades they turn into plasma cells and produce more antibodies, more quickly (secondary response is faster and stronger)

26
Q

Process of monoclonal antibody production

A
  1. Mouse is exposed to antigens which antibody is required
  2. B cells in the mouse produce a mixture of antibodies
  3. This is extracted from the spleen of the mouse
  4. B cells are mixed when cells that divide readily outside the body e.g. tumour cells
  5. Detergents is added to break the plasma membranes in the cells so they fuse and form hybridoma cells
  6. Hybridoma cells are separated each one is cultured to form a clone
  7. Any clone producing the required antibody is grown on a large scale & the antibodies are extracted
27
Q

What can Monoclonal antibodies used:

A
  • to target cells
  • for molecule detection, e.g. pregnancy testing used to detect the hormones hCG
28
Q

How can moloclonal antibodies be used to target cells?

A
  • cancer cells contain specific antigens called tumour markers
  • anti-cancer drugs can be attached to the complementary antibodies

This allows for more specific targeting of cancer cells and fewer side effects from the drugs

29
Q

What does ELISA stand for and what is it

A

Enzyme linked immunosorbent assay
ELISA is a technique used to detect (assay) specific molecules (e.g. proteins & carbs) in samples

30
Q

Features of the ELISA method

A

Immunological technique: uses antibodies
Quantitative
Very sensitive
Used in medicine and scientific research

31
Q

Basic steps of ELISA

A
  1. Antigens are bound onto plastic surface (sorbent)
  2. Antigen of interest is recognised by a specific antibody (immuno)
  3. This antibody is recognised by a second antibody (immuno) which has an enzyme attached (enzyme-linked)
  4. Substrate is hydrolysed by the enzyme to produce a product usually coloured

Amount of coloured product= quantitative measure of antigen present

32
Q

What is a direct assay

A

Enzyme attached a primary antibody

33
Q

What is an indirect assay

A

Enzyme attached to the secondary antibody

34
Q

Why do you to do the first wash in ELISA

A

want the antigens to be fixed in place

35
Q

Why do you want to do the second wash in ELISA

A

so there are no floating primary antibody that the secondary one can bind to

36
Q

Why do you have to do the last wash in ELISA

A

to remove any floating secondary antibody so the substrate won’t bind, which could give a false positive

37
Q

Uses of ELISA:

A
  • disease detection in people, animals and plants (e.g. HIV in humans)
  • detection of allergens in food e.g. peanuts
  • detection of illegal drugs in humans
  • detection of hormones e.g. pregnancy testing kit
38
Q

what is HIV?

A

human immuno-deficiency virus
its a retrovirus

39
Q

what does hiv infect?

A

t helper cells (host cells)

40
Q

what does HIV contain

A

RNA, not DNA

41
Q

how is viral DNA made

A

by the host cell from the RNA using the viral enzyme reverse transcriptase

42
Q

how is viral DNA incorporated into host DNA?

A

via viral enzyme integrase in the nucleus

43
Q

how does a membrane enveloped virus benefit HIV

A

allows the cell to fuse with other cells more easily, as it gives it seamless entry

44
Q

process of HIV entering the body?

A

1.virus binds to receptor of plasma membrane on helper T cells
2. virus envelope fuses with plasma membrane allowing the viral RNA and enzymes to enter the cell
3. virus reverse transcriptase copies viral RNA into viral DNA
4. Integrase inserts viral DNA into host DNA
5. translation of virus envelope proteins
6. transport of virus envelope protein’s
7. virus envelope proteins are incorporated into the cell membrane
8. virus particle budding becomes wrapped in plasma membrane forming the virus, and is released

45
Q

how are t lymphocytes killed by HIV

A
  • killed when the HIV virus exits the t cell via budding
  • infected helper cells are destroyed by cytotoxic t cells
46
Q

what happens due to loss of t helper cells

A

loss of activation of both t and b cells so the effectiveness of the specific immune response is reduced

47
Q

what is AIDS

A

the collection of diseases that result from the destruction of t helper cells

48
Q

Structure of an antibody

A
  • 4 polypeptide chains he’ll together by disulphide bridges
  • each antigen can bind to two antibody binding sites at a time
49
Q

Different regions on an antibody

A
  • generic constant region - binds to lymphocytes
  • variable region - its complementary to a specific antigen and forms the antigen binding site
  • hinge region - allows the antibody to flexi in order to bind to more than one antigen at a time
50
Q

What is agglutination?

A
  • antibodies cause pathogens to stick together
  • makes it easier for phagocytes to engulf them
51
Q

What is neutralisation with an antibody

A
  • pathogens cause illness by producing toxins
  • some antibodies work by neutralising these toxins by binding to them
52
Q

what are antibodies affect on viruses

A

antibodies can bind to viruses and stop them attaching to their host cell

53
Q

What’s a polyclonal antibody

A

A diverse antigen binding site. They can only recognise a particular antigen but can recognise different variations of it

Biology (10 decks)

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