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Biology- Ms Pedrosa > Immune system - P1 > Flashcards

Immune system - P1 Flashcards

1
Q

define antigen

A
  • Molecules which recognised as non-self/foreign by the immune system,
    stimulate an immune response and lead to the production of antibodies
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2
Q

why is antigen specificity important

A
  • Pathogens (disease causing organisms)
  • Cells from other organisms of the same species
  • Abnormal body cells
  • Toxins released from bacteria
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3
Q

define pathogen

A

disease causing microorganisms

triggering an immune response

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4
Q

describe phagocytosis

A
  1. phagocyte attracted to bacteria by chemicals/recognise antigen on pathogen as foreign
  2. phagocyte engulfs/ ingest pathogen
  3. pathogen in vacuole/vesicle
  4. lysosome fuses with vesicle/ vacuole + releases lysozymes (hydrolytic enzymes)
  5. pathogen digested
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5
Q

describe the cellular response - t lymphocytes

A
  1. T lymphocytes recognises antigen presenting cells after phagocytosis (foreign antigen)
  2. Specific T helper cell with receptor complementary to specific antigen binds to it, becoming activated and dividing rapidly by mitosis to form clones which:
    a) Stimulate B cells for the humoral response
    b) Stimulate cytotoxic T cells to kill infected cells by producing perforin
    c) Stimulate phagocytes to engulf pathogens by phagocytosis
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6
Q

examples of a specific response

A

humoural

cell-mediated

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7
Q

what are antibodies

A

quaternary strucutred proteins
secreted by B-cells
bind to specific antigen to form antigen-antibody complex

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8
Q

describe + explain how structure of antibody relates to its function

A

primary structure - sequence of amino acids in polypeptide chain
determines folds in secondary structure
determines tertiary structure + placement of ionic, hydrogen + disulfide bonds
quaternary structure- 4 polypeptide chains
2 heavy chains, 2 light chain
specific shaped variable region - different in each antibody - forms complex with complementary antigen
allows antigen-antibody complex to form

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9
Q

how do antibodies work to destroy pathogens

A

binds to 2 pathogens at a time, at variable region
forming antigen- antibody complex
enables antibodies to clump together - agglutination
phagocyte binds to antibody + phagocytoses many pathogens at same time

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10
Q

what does the hinge region enable

A

antibody can bind to antigen/pathogen at different distances apart

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11
Q

why will an antibody bind to a specific antigen

A
  1. antibodies’ variable region has specific sequence of amino acids
  2. so shape of binding site
  3. is complementary to only the antigen
  4. forming an antigen-antibody complex
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12
Q

describe the humoral response

A
  1. clonal selection
    a) specific b-cell binds to antigen presenting cell, stimulated by t-cells
    b) divides rapidly by mitosis to form clones
  2. some b-cells divide into plasma cells
  3. some b-cells divide into memory cells
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13
Q

what do plasma cells do

A

secrete large amounts of specific antibody

for primary response

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14
Q

what are memory cells for

A

secondary response

so specific antibody can be produced quickly

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15
Q

what is the primary response

A

when the pathogen enters for the first time

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16
Q

describe the primary response

A

antibodies produced slowly + in lower concentration
not many b-cells to make required antibody
t-cells need to activate b-cells to make antibodies
so symptoms occur

17
Q

describe the secondary response

A

produces antibodies at higher rate + conc
b + t memory cells present
so b cells undergo mitosis quicker/clonal selection

18
Q

how does antigen variability create difficulties for effective vaccines

A

new vaccines against disease need to be developed more frequently
vaccines may not be developed or hard to develop against disease
may experience disease more than once

19
Q

explain effect of antigen variability on disease

A
  • Change in antigen shape (due to a genetic mutation)
  • Not recognised by B memory cell → no plasma cells / antibodies
  • Not immune
  • Must re-undergo primary immune response → slower / releases lower concentration of antibodies
  • Disease symptoms felt
20
Q

Explain the effect of antigen variability on disease prevention (vaccines)

A
  • Change in antigen shape (due to a genetic mutation)
  • Existing antibodies with a specific shape unable to bind to changed antigens / form antigen-antibody complex
  • Immune system i.e. memory cells won’t recognise different antigens (strain)
21
Q

what is a vaccine

A

injection of antigens
from attenuated pathogens
stimulating formation of memory cells
can lead to symptoms

22
Q

Explain how the use of vaccines can provide protection for individuals against disease

A
  • Normal immune response but the important part is that memory cells are produced
  • On reinfection / secondary exposure to the same antigen, the secondary response therefore produces antibodies faster and at a higher concentration
  • Leading to the destruction of a pathogen/antigen (e.g. agglutination and phagocytosis) before it can cause harm / symptoms = immunity
23
Q

Explain how the use of vaccines can provide protection for populations against disease (herd immunity)

A
  • Large proportion but not 100% of population vaccinated against a disease – herd immunity
  • Makes it more difficult for the pathogen to spread through the population because…
  • More people are immune so fewer people in the population carry the pathogen / are infected
  • Fewer susceptible so less likely that a susceptible / non-vaccinated individual will come into contact with an infected person and pass on the disease
24
Q

difference between active + passive immunity ; exposure to antigen

A

active - exposure

passive - no exposure

25
Q

difference between active + passive immunity ; memory cells

A

active - memory cells made

passive - no memory cells

26
Q

difference between active + passive immunity ; antibodies

A

active - antibodies produced/secreted by b/plasma cells

passive - antibody introduced through another organism

27
Q

difference between active + passive immunity ; time

A

active - slow

passive - fast

28
Q

difference between active + passive immunity ; immunity time

A

active - long term immunity - antibody can be produced in re-exposure to antigen
passive - short term - antibody broken down

29
Q

Explain the effect of antigen variability on disease prevention (vaccines)

A
  • Change in antigen shape (due to a genetic mutation)
  • Existing antibodies with a specific shape unable to bind to changed antigens / form antigen-antibody complex
  • Immune system i.e. memory cells won’t recognise different antigens (strain)
30
Q

ethical issues of use of vaccines

A

tested on animals
tested on humans
side effects
expensive

31
Q

Evaluate methodology relating to the use of vaccinations

A
  • A successful vaccination programme:
  • Produce suitable vaccine
  • Effective – make memory cells
  • No major side effects → side effects discourage individuals from being vaccinated
  • Low cost / economically viable
  • Easily produced / transported / stored / administered
  • Provides herd immunity

Biology- Ms Pedrosa (12 decks)

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