Non-specific animal defences to pathogens Flashcards

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1
Q

what is quicker, specific or non-specific immune responses?

A

non-specific

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2
Q

what are the barriers your body has to pathogens?

A
  • skin
  • mucous membranes
  • lysozymes
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3
Q

how does the skin act as a barrier to pathogens?

A

it has healthy microorganisms which out compete the pathogens for space on the skin surface

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4
Q

how does the skin prevent growth of pathogen?

A

it produces sebum which prevents growth

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5
Q

how do mucous membranes act as a barrier to pathogens?

A

they secrete a sticky mucus which traps microorganisms and contains lysozymes which destroy the cell walls of bacteria and fungi

the mucus also contains phagocytes which remove pathogens

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6
Q

how is a wound sealed in the skin?

A

a blood clot is formed

when platelets come into contact with collagen in the skin they start to secrete:

  • thromboplastin
  • serotonin
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7
Q

what does thromboplastin do?

A

triggers blood clot formation

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8
Q

what does serotonin do?

A

makes smooth muscle in blood vessel walls contract and reduce the blood flow in the area

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9
Q

what happens when the blood clot dries?

A

it forms a scab which keeps pathogens out

epidermal cells grow and seal the wound
collagen deposited and eventually the scab falls off and leaves a healed wound

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10
Q

what is an inflammatory response?

A

localised response to pathogens which causes inflammation

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11
Q

what are mast cells and what doe they release?

A

cells which when activated release chemicals called histamines and cytokines

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12
Q

how do histamines stop pathogens reproducing?

A

they cause the blood vessels to dilate which increases the temperature and prevents pathogens from reproducing

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13
Q

how do cytokines get rid of pathogens?

A

they attract white blood cells which destroy pathogens by phagocytosis

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14
Q

why is a fever useful?

A
  • a fever raises the temperature so that it is higher than 37C which stops most pathogens from reproducing
  • the specific immune system works faster at higher temperatures
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15
Q

what are the two types of phagocyte?

A
  • neutrophils

- macrophages

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16
Q

what do phagocytes do?

A

they are specialised white blood cells which engulf and destroy pathogens

17
Q

what are the stages of phagocytosis?

A
  1. pathogen releases chemicals which attract phagocytes
  2. phagocyte recognises the non-self antigens on the pathogen
  3. the phagocyte engulfs the pathogen and encloses it in a phagosome
  4. the phagosome combines with a lysosome to form a phagolysosome
  5. enzymes from the lysosome digest and destroy the pathogen
18
Q

what does a macrophage do which is different to a neutrophil?

A

it combines the antigens from the pathogen surface membrane and forms the MHC (major histocompatability complex)
the MHC moves the antigens to it’s own surface membrane and it becomes an APC (antigen presenting cell)

19
Q

what are cytokines?

A

a chemical used for cell signalling

they can also increase body temp and stimulate the immune response

20
Q

what are opsonins?

A

chemicals which bind to pathogens and tag them which makes it easier to be recognised by phagocytes