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B5- CELL RECOGNITION AND THE IMMUNE SYSTEM > 5.1- DEFENCE MECHANISMS > Flashcards

5.1- DEFENCE MECHANISMS Flashcards

1
Q

What is any infection, in effect?

A

interaction between the pathogen and the body’s various defence mechanisms

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2
Q

How can an individual die from a pathogen sometimes?

A

sometimes the pathogen overwhelms the defences

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3
Q

How can the body recover from a disease?

A

body’s defence mechanism overwhelms pathogen and individual recovers

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4
Q

How does the body overcoming a pathogen help it for next time?

A

body’s defences are better prepared for same pathogen + can kill it before it can cause any harm

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5
Q

What is the body being able to kill the pathogen before it causes harm called?

A

immunity

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6
Q

What is the main reason for why some people are unaffected by certain pathogen?

A

immunity

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7
Q

Who will rarely die from an infection?

A

fit, healthy adult

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8
Q

Who is more likely to die from an infection?

A

ill health, young and elderly usually more vulnerable

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9
Q

What does the human body have to protect itself from pathogens?

A

range of defences

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10
Q

What are the two types of defences the human body has?

A

general and immediate defences

more specific, less rapid but longer-lasting

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11
Q

Examples of general and immediate defence? (2)

A

skin forms barrier to entry of pathogens

phagocytosis

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12
Q

What do more specific, less rapid but longer-lasting response involve?

A

a type of white blood cell called a lymphocyte

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13
Q

What two forms do more specific, less rapid but longer-lasting response take?

A

cell-mediated responses

humoral responses

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14
Q

What do cell-mediated response involve?

A

T lymphocytes

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15
Q

What do humoral responses involve?

A

B lymphocytes

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16
Q

What must lymphocytes be able to do to defend the body from invasion by foreign material?

A

distinguish body’s own cells + molecules from those that are foreign

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17
Q

What are the body’s own cells + molecules called?

A

self

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18
Q

What are foreign material called?

A

non-self

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19
Q

What would lymphocytes do if they were unable to distinguish body’s own cells + molecules from those that are foreign?

A

lymphocytes would destroy organism’s own tissues

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20
Q

What does each type of cell, self or non-self have?

A

has specific molecules on its surface that identify it

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21
Q

What is most important about the molecules (cells, self + non-self)?

A

proteins

22
Q

Why are the proteins the most important (cells, self + non-self)?

A

proteins have enormous variety + a highly specific tertiary structure

23
Q

What does the variety of specific 3D structure do? (cells, self + non-self)?

A

distinguished one cell from another

24
Q

What does the protein molecule allow the immune system to identify? (4)

A

pathogen i.e. HIV

non-self material i.e. cells from other organisms of same species

toxins including those produced by certain pathogens like bacterium that causes cholera

abnormal body cells i.e. cancer cells

25
Q

As pathogens, non-self material, toxins and abnormal body cells are all potentially harmful, what is the first stage of removing the threat they pose?

A

identification

26
Q

What complications can human who have had tissue/organ transplants have?

A

immune system recognises these as non-self even though they have come from individuals of same species

27
Q

What does the immune system try and do to transplanted tissue/organ?

A

attempts to destroy the transplant

28
Q

What is done to reduce the tissue rejection?

A

donor tissues for transplant normally matched as closely as possible to those of recipient

29
Q

Where do the best matches for tissue-organ transplants come from?

A

often come from relatives that are genetically close

30
Q

What are administrated to patients after organ/tissue transplants?

A

immunosuppressant drugs

31
Q

What do immunosuppressant drugs do?

A

reduce level of immune response that still occur

32
Q

Are specific lymphocytes produced in response to an infection?

A

no

33
Q

Do all specific lymphocytes already exist?

A

yes- all 10 million different types

34
Q

Given that there are so many different types of lymphocytes, what does this mean when a pathogen enters the body? (hint: probability?)

A

high probability that when a pathogen gets into the body, one of these lymphocytes will have a protein on its surface that’s complementary to one of the proteins of the pathogen

35
Q

In other words, what happens when the lymphocyte has a protein on its surface that’s complementary to one of the proteins on the pathogen?

A

lymphocyte will ‘recognise’ the pathogen

36
Q

As there are so many different lymphocytes, what are the numbers like of each type?

A

there are very few of each type

37
Q

As there are very few of each type of lymphocyte, what happens when an infection occurs?

A

the one type already present that has the complementary proteins to those of the pathogen stimulated to divide to build up its numbers

38
Q

Why does the one type of lymphocyte already present that has a complementary protein to those of the pathogen divide and build its numbers?

A

so it has numbers to a level where it can be effective in destroying it

39
Q

What is it called when the complementary lymphocyte to the pathogen divides to destroy it?

A

clonal selection

40
Q

What does clonal selection explain?

A

why there’s a time lag between exposure to the pathogen and body’s defences bringing it under control

41
Q

About how many different lymphocytes are present at any time?

A

around 10 million

42
Q

What is each type of lymphocyte capable of?

A

capable of recognising a different chemical shape

43
Q

In the foetus, what are the lymphocytes constantly doing?

A

constantly colliding with other cells

44
Q

Why is infection in a foetus rare?

A

because it’s protected from the outside world by the mother, and in particular, the placenta

45
Q

As infection in a foetus s rare, what will the lymphocytes collide with?

A

collide almost exclusively with the body’s own material (self)

46
Q

What will some of the lymphocytes have?

A

receptors that exactly fit those of the body’s own cells

47
Q

What happens to the lymphocytes that have receptors that fit those of the body’s own cells?

A

either die or are suppressed

48
Q

What are the remaining lymphocytes like, after the lymphocytes with receptors that fit the body’s won cells are removed?

A

only remaining lymphocytes are those that might fit foreign material (non-self) and so only respond to foreign material

49
Q

What do lymphocytes produced in the bone marrow in adults initially only encounter?

A

only encounter self-antigens

50
Q

What happens to lymphocytes from the adult bone marrow that show an immune response to the self-antigens?

A

undergo programmed cell death (apoptosis) before they can differentiate into mature lymphocytes

51
Q

Will any clones of the anti-self lymphocytes appear in the blood?

A

no

52
Q

What is left as the clones of the anti-self lymphocytes do not appear in the blood?

A

leaves only those that might respond to non-self antigens

B5- CELL RECOGNITION AND THE IMMUNE SYSTEM (7 decks)

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