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ATAR human bio 12 > 11. specific resistance to infection > Flashcards

11. specific resistance to infection Flashcards

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1
Q

What are lymphocytes and macrophages?

A

Cells that are involved in both non-specific and specific defence

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2
Q

Where are lymphocytes produced and what do they do?

A
  • 20-30% of WBC
  • produced in the bone marrow or lymphoid tissues
  • roam throughout the body- enter the blood or lymph from a tissue to be transported to another part of the body
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3
Q

What do macrophages do?

A
  • large, phagocytic, develop from a type of WBC
  • able to consume foreign substances and micro-organisms by phagocytosis
  • involved in specific defence by alerting immune system to presence of foreign material
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4
Q

What is the immune response?

A

a homeostatic mechanism that combats invasion of pathogens

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5
Q

What is the humoral response?

A

antibody-mediaed immunity, involving the production of antibody proteins that circulate around the body and attack invading agents

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6
Q

What is the cell-mediated response?

A

the formation of lymphocytes to destroy invading agents

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7
Q

What are specific defenses?

A

those directed towards particular pathogens

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8
Q

What is lymphoid tissue made of?

A

lymphocytes- b-cells and t-cells

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9
Q

What do b-cells and t-cells do?

A

B-cells: provide antibody mediated immunity

T-cells: provide cell-mediated immunity

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10
Q

What are antigens?

A

any substance capable of causing a specific immune response

  • large molecules (protein, carbohydrates, lipids, nucleic acids)
  • virus particle or whole micro-organism (bacterial cell, part of bacterium- flagella, cell wall, capsule)
  • toxins produced by bacteria
  • tissues transplanted from another person, blood cells of a foreign blood group
  • pollen grains, egg white
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11
Q

what are self antigens?

A

large molecules produced in a persons own body that doesnt cause an immune response

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12
Q

what are non-self antigens?

A

foreign compounds that produce an immune response

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13
Q

what are antibodies?

A

a large protein produced primarily by plasma cells, used by the immune system to neutralise pathogens

  • a specialised protein produced in response to a non-self antigen
  • immunoglobins (Ig)
  • IgA, IgD, IgE, IgG, IgM
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14
Q

What is the antigen-antibody complex?

A

antibody produced in response to an antigen, combines with that antigen to form a complex

  • antigens have specific active sites at which an antibody attached
  • specific lock-key method
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15
Q

What does the humoural response do?

A
  • involves the production and release of antibodies into the blood and lymph
  • provides resistance to viruses, bacteria and bacterial toxins before the microorganisms or substances enter the body’s cells
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16
Q

What happens in antibody mediated immunity?

A

-antigens activate B-cells
-b-cells enlarge and divide into a clone
_most become plasma cells (secrete the specific antibody capable of attaching to active antigen site)
_those that don’t remain as memory cells that spread to all body tissues to allow the response to occur more rapidly if the antigen enters the body again
- antibodies circulate in extracellular fluid and lymph to reach the site of invasion

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17
Q

What is the primary response and what occurs?

A
  • the response following the first exposure to an antigen
  • immune system responds slowly- takes several days to build up large quantities of antibodies
  • once antibody level reaches a peak, it begins to decline-primary response leaves immune system with a memory of that antigen
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18
Q

What is a secondary response and what occurs then?

A

second or subsequent exposure

  • response is faster due to activity of memory cells
  • plasma cells form very quickly-antibody levels in plasma rise rapidly
  • often quick enough so no illness results
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19
Q

how do antibodies provide resistance to infection?

A

they combine with the antigen for which they are specific to form the antigen-antibody complex, with the response varying.

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20
Q

What may occur to the response of the antigen and antibody?

A
  • it may combine with foreign enzymes or bacterial toxins
  • anctivate enzymes or toxins by inhibiting reaction with other cells or compounds
  • bind to surface of viruses and prevent from entering cells
  • coact bacteria so bacteria are easily consumed by phagocytes
  • cause agglutination-foreign cells or viruses clump together
  • dissolve organisms
  • react with soluble substances, making them insoluble and more easily consumed by phagocytes
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21
Q

What is a t-lymphocytes response to a particular antigen?

A
  • t-lymphocytes occupy different areas of lymphoid tissue-thousands of types, each only respond to a particular antigen
  • antigen enters the body
  • specific t-cell becomes sensitised- only occurs after a b-cell encounters the antigen, presenting the complex to the nearest lymph node
  • sensitised t-cells enlarge and divide, giving rise to a clone- some will be memory cells, the others will divide further into the other types
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22
Q

What are memory cells?

A

remain in the lymphoid tissue and are able to re-recognise invading antigens, initiate faster response to subsequent infections

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23
Q

What are killer cells?

A

-cytotoxic, migrate to site of infection, attach to invading cells and secrete a substance that will destroy antigens

24
Q

What are helper cells?

A

humoural and cellular immunity, secrete substances that:

  • cause lymphocytes at the infection site to become sensitised, intensifying response
  • attract macrophages to the place of infection so macrophages destroy antigens by phagocytosis
  • intensify phagocytic activity of macrophages
25
Q

What are suppressor cells?

A

act when immune activity becomes excessive or infection has been dealt with successfully, release substances that inhibit t and b-cell activity, slowing immune response

26
Q

What is the antibody mediated immunity process?

A

Works against bacteria, toxins and viruses before they enter cells, as well as against RBC of a different blood group

  1. foreign antigen reaches lymphoid tissue
  2. b-lymphocytes undergo rapid cell division
  3. most develop into plasma cells, which produce antibodies and release them into blood and lymph
  4. Antibodies combine with specific antigen to inactivate or destroy it
  5. some form memory cells
27
Q

what is the cell-mediated immunity process?

A

works against transplanted tissues and organs, cancer cells and infected cells

  1. foreign antigen reaches lymphoid tissue
  2. t-lymphocytes are stimulated to undergo rapid cell division
  3. most new t-cells develop into killer t-cells or helper t-cells, which migrate to the site of infection
  4. killer t-cells destroy the antigen, helper t-cells promote phagocytosis by macrophages
  5. sensitised t-cells form memory cells
28
Q

what is immunity?

A

the resistence to infection by invading micro-organisms

29
Q

What is natural immunity?

A

occurs without human intervention

30
Q

What is passive immunity?

A

when a person is given antibodies by someone else

  • body plays no part in production
  • antibodies from mother passed to baby in breast milk
  • artificially through antibodies injected to combat a particular infection- antibodies given to establish immediate immunity
  • short lived, lasting only until antibodies are broken down and excreted
31
Q

What is active immunity?

A

results when the body is exposed to a foreign antigen and manufactures antibodies in response to an antigen

  • prolonged because ‘memory’ of antigen persists
  • subsequent infection dealt with quicker because appropriate antibodies can be produced quickly before disease symptoms are produced
  • can result from actual disease attack (natural active immunity), or injections of antigens associated with disease (artificial active immunity)
32
Q

What is immunisation?

A

programming the immune system so the body responds rapidly to infecting micro-organisms (can be done through natural active immunity or vaccination)

33
Q

What is a vaccination?

A

the artificial introduction of antigens of pathogenic organisms so the ability to produce appropriate antibodies is aquired

34
Q

What is a vaccine?

A

the antigen preparation used in artificial immunisation

35
Q

what are the types of vaccines?

A
  • living attenuated micro-organisms (a reduced ability to produce disease symptoms so disease is not contracted but antibodies are created) eg. polio, TB, rubella, measles, mumps, yellow fever
  • dead microorganisms usually not as prolonged immunity eg. cholera, typhoid, whooping cough
  • contains filtrates of bacterial cultures containing toxins (sued when bacteria cause symptoms by liberating toxins) that are inactivated to become toxoids eg. diptheria and tetanus
  • sub-unit vaccines- a fragment of the organism is used to provoke immune response eg. hpv, hepatitis b
36
Q

what are risks with vaccines?

A

they are effective but may cause
nervous system damage (can cause death)
cholera vaccine only useful for a short period of time

37
Q

What are effective methods to modify a pathogen?

A
  • slightly change the DNA so the pathogen is less virulent
  • can also insert DNA sequences from the pathogen into harmless bacterial cells, chosen DNA sequence producing antigens that are characteristic of the pathogen
  • recombinant DNA method
38
Q

what are the types of vaccine delivery method?

A
  • injection through syringe
  • polio vaccine given via sweet drupe or lumps of sugar
  • fine spray into the nostril
  • skin patches (abled to be self administered so useful in developing countries)
  • vaccines in foods
  • engineering of non-food plants to produce vaccines
39
Q

What is herd immunity?

A

the resisitance of spread of contagious disease that results if a sufficiently high proportion of individuals are immune to the disease

  • depends on a large number of individuals being vaccinated
  • large number of immune individuals results in less of a chance of disease transmission
  • extra vaccinations are available when travelling overseas
40
Q

What are problems with herd immunity?

A
  • as risk of disease decreases, people become complacent and decide risk of side effects from vaccine is higher than risk of getting disease
  • declining vaccination rates lead to serious outbreaks
  • objection to vaccination on religious grounds also leads to outbreaks
  • childhood vaccination is not compulsory in Australia
  • when new vaccines are introduced, extent and length of protection is never known
  • misunderstandings about vaccine risks lead to parents not vaccinating their kid
41
Q

What are risks of vaccinations?

A

allergic reaction - not necessarily from vaccination but the medium in which it was cultured

  • can be impossible to completely isolate one virus from others within an animal tissue hat is being used as a culture medium
  • Chemicals are used as preservatives which can affect nervous system
42
Q

What are vaccines trialled?

A
  • tested for safety and effectiveness
  • clinal trials and then in much larger populations
  • all manufactured to safety guidelines
  • evaluated by TGA before advertised
  • most are produced in developed countries for use in developing countries
  • most are tested on animals before humans
43
Q

What are some ethical concerns with vaccines?

A
  • how vaccine was manufactured, how it was tested and associated risks
    -manufactures require host tissues as viruses can only reproduce in living cells
    >influenza cultured in chicken embryos
    >japanese encephalitis virus grown in brains of mice
    -use of human tissue- source is up for ethical consideration
44
Q

What influences a persons participation in vaccinations?

A
  • economic/social/cultural background
  • Economic circumstances of the individual may prevent them
  • emerging nations may not have the resources to immunise everyone
  • low income level means low parental education rate
  • religious beliefs in places where traditional medicine is superior
  • internet can misinform
45
Q

What are antibiotics?

A

drugs that are used to fight infections of microorganisms, particularly bacteria

46
Q

What is penicilin

A
  • first to be discovered, widely used
  • prevents synthesis of the walls of bacterial cells
  • inhibits bacterial reproduction
  • effectiveness is reduced over time as bacteria have developed a resistance to it
47
Q

What is streptomycin?

A

produced by an actinomycete that lives in the soil

  • bacteria that produce branching filaments like mould threads
  • interferes with bacterial protein synthesis
48
Q

what are cephalosporin?

A
  • derived from a fungus, interfere with syntheses of cell wall, less likely to result in allergic reactions
  • only on prescription as only effective for certain types of bacterial infection and must be a well considered decision
49
Q

what are bactericidal antibiotics?

A

kill bacteria by changing the structure of the cell wall or cell membrane, or by disrupting the action of essential enzymes

50
Q

What are bacteriostatic antibiotics?

A

stop bacteria from reproducing , usually by disrupting protein synthesis

51
Q

what are broad-spectrum antibiotics?

A

effective in fighting a wide range of different types of bacteria

52
Q

What are narrow-spectrum antibiotics?

A

effective only against a very specific type of bacteria

53
Q

How is resistance to antibiotics hastened?

A

by the overuse of antibiotics in medicine and agriculture, used to prevent infection rather than treat existing conditions

54
Q

How can you prevent the misuse and overprescription of antibiotics?

A
  • develop a new class of antibiotics to which bacteria have no resistance
  • revive old antibiotics by using them in combination with other substances
  • genetically engineer bacteria to disable antibiotic-resistant genes
55
Q

what are antiviral drugs?

A

used specifically for treating viral infections

56
Q

How does a virus replicate to make it difficult to find drugs which treat infections?

A
  • host cells produce new virus particles
  • any drug interfering with virus replication is likely to be toxic to the host
  • if viral proteins are different enough to human proteins, then drugs should have few side effects
  • antivirals inhibit development of a virus.

ATAR human bio 12 (19 decks)

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