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lc biology > human defence system > Flashcards

human defence system Flashcards

1
Q

define pathogen

A

an organism that causes disease

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2
Q

define immunity

A

the ability to resist disease

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3
Q

give the two parts of the human defence system that allows the body to resist infection

A

general defence system, specific defence system

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4
Q

the general defence system is non-specific, what does this mean?

A

it acts against all pathogens

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5
Q

true or false, the general defence system acts as a barrier to all pathogens which attemp to gain entry into the body

A

true

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6
Q

what does the first part of the general defence system consist of

A

skin, mucous membranes and secretions

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7
Q

what does the second part of the general defence system consist of

A

white blood cells and chemicals

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8
Q

give the function of the skin

A

provides a structural barrier to infection

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9
Q

give the function of clotting

A

prevents blood loss and prevents entery of further pathogens

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10
Q

give the funtion of lysozyme

A

an enzyme found in sweat, tears and saliva- it attacks and breaks down bacterial cell walls

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11
Q

give the function of sebaceous glands

A

found in skin- produce chemicals that are released in sebum (oil) that kills bacteria

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12
Q

give the funtion of mucous

A

traps pathogens and prevents their entry

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13
Q

give the funtion of cilia

A

tiny hairs that line the respiratory system which beat and create a current to move mucous back up the respiratory system so it can be swallowed into the stomach

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14
Q

give the funtion of acid in the general defence system

A

e.g HDl in stomach kills pathogens

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15
Q

give a function of beneficial bacteria in the general defence system

A

some can produce lactic acid which prevents the growth of pathogens

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16
Q

what does the second line of general defence consist of?

A

destruction of pathogens by white blood cells, production of a series of proteins that kill or prevent pathogens from reproducing, the inflammatory response

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17
Q

what are phagocytic white blood cells?

A

white blood cells called phagocytes that engulf and destroy any bacteria, viruses or other micro-organisms

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18
Q

explain the mechanism of phagocytes (phagocytosis)

A

cells which are damaged by micro-organisms release chemicals to attract white blood cells. some large phagocytes called macrophages move around in bodily fluids e.g lymph. they destroy and filter out pathogens by grabbing onto the pathogen with receptors, surrounding it and then digesting it

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19
Q

write a short note on defence proteins

A

these are proteins that get activiated by an infection and destroy viruses and pathogens. the set of around 20 proteins found in blood plasma is called compliment

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20
Q

what are interferons

A

are another set of defence proteins that prevent viral multiplication- limiting spread of viral infections e.g cold and flu

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21
Q

explain what happens during inflammation

A

infected cells release a chemical that causes blood capillaries to dilate and become more porous. this causes localised swelling, redness, headaches and pain. causes more white blood cells to come to the area the fight the infection. inflammation can occur over all over the body which can cause increased body temperature (fever) which affects the ability of some bacteria and viruses to reproduce

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22
Q

what’s another name for the specific defense system

A

the immune system

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23
Q

what does the immune system do

A

it attacks specific pathogens by producing antibodies or works when wbcs destroy body cells that are infected by a particular pathogen

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24
Q

where are lymphocyctes and monocytes formed

A

bone marrow

25
Q

where do lymphocytes and monocytes move to after formation

A

blood vessels and parts of the lymphatic system

26
Q

what do monocytes turn into

A

macrophages

27
Q

what can macrophages detect

A

they recognise foreign molecules called antigens present on the surface of pathogens

28
Q

explain how antigens stimulate antibodies

A

when the macrophage digests a pathogen, the antigen is displayed on the surface of the macrophage- stimulating production of antibodies

29
Q

give two ways lymphocytes fight infection

A

some attack body cells that contain antigens on their surface. others produce antibodies

30
Q

define antigen

A

a foreign molecule that stimulates the production of antibodies

31
Q

define antibody

A

protein produced by lymphocyctes in response to an antigen

32
Q

how many antibodies does a specific antigen produce

A

one

33
Q

what do antibodies do

A

prevent viruses and bacteria from entering new host cells- pathogens destroyed by phagocytes

34
Q

what happens when antibodies inactivate pathogens

A

they clump together and allow phagocytes to destroy the pathogens

35
Q

what do antibodies trigger

A

complement system- bursts pathogenic cells.

36
Q

what are memory cells

A

antibody-producing lymphocytes that remain in the body for a long time

37
Q

what do memory lymphocytes do

A

they rapidly produce large amounts of a specific antibody if a similar antigen enters the body

38
Q

how long does it take the body to produce the maximum number of antibodies on first contact

A

14 days after first contact with an antigen

39
Q

how long does it take for antibodies to be produced on subsequent contact with the same antigen

A

5 days

40
Q

how can we suffer from colds and flus more than once?

A

different forms… mutations

41
Q

define induced immunity

A

the ability to resist disease caused by specific pathogens by the production of antibodies

42
Q

give two types of induced immunity

A

active and passive

43
Q

exaplin active immunity

A

involves the production of a person’s own antibodies in response to antigens. it is long lasting as the lympocytes live for a long time in the body

44
Q

explain the two ways active immunity can occur

A

natural active immunity - pathogens enter the body in the normal way. artificial active imunity - occurs when a pathogen is medically introduced into the body

45
Q

define vaccine

A

a non-disease causing dose of a pathogen which trigger the production of antibodies without suffereing the full symptoms of the infection

46
Q

explain passive immunity

A

occurs when individuals are given antibodies that are formedby another organism- provides short term resistance

47
Q

explain the two ways passive immunity can occur

A

natural passive immunity- when a child gets antibodies from its mother. artificial passive immunity - when a person is given an injection containing antibodies made from another organism e.g anti-tetanus injection

48
Q

explain the structure of a lymphocyte

A

large round nucleus with very little cytoplasm

49
Q

name the two different types of lymphocytes and where they mature

A

B-lymphocytes (B CELLS) and T-lymphocytes ( T CELLS). B cells mature in the bone marrow, T cells mature in the thymus gland

50
Q

where do B cells go once they’ve matured in the bone marrow

A

they go to lymphatic tissue e.g spleen and lymph nodes

51
Q

what happens when a B cell comes into contact with an antigen

A

it multiples and produces large amounts of the required antibody

52
Q

how do antibodies inactivate antigen

A

they attach to them allowing the phagocytes to dispose of them or by activating the complement system to burst the cells

53
Q

where do T cells move to from the bone marrow

A

thymus gland

54
Q

do T cells produce antibodies

A

no

55
Q

explain helper T-cells

A

these recognise antigens on the surface of other WBCs especially macrophages. they stimulate the multiplication of correct B-cells which will produce the correct antibodies

56
Q

explain what killer T cells do

A

they attack and destroy abnormal body cells e.g virus/cancer infected cells. they are stimulated by chemicals produced by helper T cells. they release protein called perforin which forms pores in the membrane of the abnormal cells. this allowes water and ions to flow in and case the cell to swell and burst

57
Q

explain what supressor T cells do

A

these are stimulated to grow by specific antigens and grow slowly. they become active after the antigen has been destroyed. they inhibit B cells, other T cells and macrophages. they turn of the immune response when the infection is over

58
Q

explain what memory T cells do

A

these can survive for a long time. if the same pathogen re-enters a person’s body they quickly stimulate memory B cells to produce large amounts of the correct antibody. they also trigger the production of killer T-cells. they are responsible for lifelong immunity from infections

lc biology (25 decks)

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