L21 - the immune system Flashcards

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1
Q

what is the job of the immune system

A

repair damaged tissues
respond to infection
slow cancer growth

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2
Q

what is humoral immunity

A

secretion of protective substances eg antibodies into body fluids

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3
Q

what is cellular immunity

A

cellular response to infection (phagocytes etc)

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4
Q

list the physical barriers that prevent pathogen entry

A

skin
mucous
mucous membranes (cilia)
scabs

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5
Q

List chemical barriers that prevent pathogen entry

A

mucus
stomach acid
lysozymes in tears/saliva

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6
Q

briefly describe innate immunity

A

non specific
rapid
responds to infections (non self) & altered self (cancer)
can be humoral/cellular

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7
Q

what does the innate immune system promote

A

inflammation

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8
Q

briefly describe adaptive immunity

A

specific
slower than innate
humoral or cellular
has memory

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9
Q

list the cells involved in the innate immune system

A
  1. macrophages

2. neutrophils

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10
Q

describe features of macrophages

A

large
highly phagocytic
non specific (eat anything)
can produce new lysosomes

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11
Q

describe features of neutrophils

A

respond to infection
quicker than macrophages
die after disposing of target

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12
Q

what are the cells of the adaptive immune system

A

lymphocytes ( B&T cells )

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13
Q

what is the specific name for macrophages in the:

  1. liver
  2. bone
  3. kidney
  4. brain
A
  1. kupffer cells
  2. osteoclasts
  3. mesangial cells
  4. microglia
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14
Q

what does the adaptive immune system recognise?

A

antigens

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15
Q

where are lymphocytes found

A

circulating blood and lymph

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16
Q

where are lymphocytes activated?

A

in 2ndary lymphoid organs (mainly lymph nodes)

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17
Q

where are b cells produced

A

bone marrow

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18
Q

where are t cells produced

A

bone marrow

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19
Q

where do B cells mature

A

in bone marrow

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20
Q

where do T cells mature

A

in thymus

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21
Q

what is the general function of B cells

A

secrete antibodies specific to target antigen (humoral)

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22
Q

what is the general function of T cells

A

activated to induce direct cell mediated response by:
recruiting other cells
attacking themselves

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23
Q

how do T cells recognise antigens?

A

T cell receptors (TCR)

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24
Q

how many types of T cell are there

A

4

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25
Q

name the types of T cells

A
  1. helper T cells
  2. cytotoxic T cells (killer)
  3. regulatory T cells
  4. memory T cells
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26
Q

function of helper T cells

A

activate B cell response

activate the other 3 T cell types

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27
Q

function of cytotoxic T cells

A

specifically kill infected cells

28
Q

function of regulatory T cells

A

help modulate responses

29
Q

function of memory T cells

A

remember antigen for rapid future response

30
Q

how are B cells activated

A

by the antigen aided by T helper cells

31
Q

function of antibodies

A
  1. neutralise pathogen

2. facilitate uptake by phagocytes (opsonization)

32
Q

what is opsonization

A

the action of B cell antibodies coating an antigen to facilitate its uptake by phagocytes

33
Q

name the two types of B cells

A
  1. plasma cells

2. memory cells

34
Q

what are plasma cells

A

activated B cells secreting antibodies

35
Q

what are memory B cells

A

B cells that remember the antigen

36
Q

what is an antigen

A

a substance that activates the immune system and may (or may not) be harmful
can be protein/lipid/carbohydrate
can induce T and/or B response

37
Q

what are antibodies

A

glycoproteins (immunoglobulins) that interact with specific antigens

38
Q

how many varieties of antibodies

A

5x10^3

39
Q

characteristics of antibodies

A
  1. 2x heavy chain
  2. 2x light chain
  3. specific antigen binding regions
  4. FC region
40
Q

what is the FC region

A

region of antibody involved in specific macrophage signalling

41
Q

how are there so many combinations of antibodies

A

at the DNA level the light chain variable region can be spliced and recombined in many ways

42
Q

characteristics of the T cell receptor

A

has a & B chain

10^8 types - due to recombination

43
Q

how are T cells activated

A

if the antigen on an antigen presenting cell (of immune response) fits the T receptor

44
Q

explain the process of T cell activation

A
  1. if antigen on APC fits T receptor clonal expansion occurs
  2. in clonal expansion many TH, CT and MT are produced
  3. TH aid B cell activation
45
Q

explain process of B cell activation

A
  1. B cells bind to antigen when aided by TH cell
  2. clonal expansion of that specific B cell
  3. many plasma and memory B cells produced
46
Q

what are antigen presenting cells? and what part of the immune response are they

A

innate

they are cells that engulf pathogens and express the pathogens antigen on their surface

47
Q

what type of cells can be APCs

A

macrophages
dendritic cells
b lymphocytes

48
Q

explain how APCs activate the adaptive immune response

A
  1. antigen taken up by phagocytosis into APC
  2. APC presents antigen on its surface
  3. APC migrates to lymphoid tissue and presents antigen to T cells
  4. if T cell has the specific receptor for antigen - immune response triggered
49
Q

give some characteristics of dendritic cells

A

APC’s
reside in tissues but can circulate
specific names based on location(langerhans in skin)
can migrate to lymph nodes

50
Q

what is a primary lymphoid tissue

A

where lymphocytes acquire ability for immune response (born and matured)
(bone marrow & thymus)

51
Q

what is a secondary lymphoid tissue

A

sites of lymphocyte activation

52
Q

list 3 secondary lymphoid tissues

A

lymph nodes
spleen
mucosa associated lymphoid tissue (MALT)

53
Q

function of lymph nodes

A

screen lymph

54
Q

function of spleen

A

screens blood born antigens

removes aged/defective blood cells

55
Q

function of MALT

A

screens mucosa

56
Q

how are T cells matured in thymus

A
  1. receptor added to T cell
  2. ensured that T cell not responsive to self antigen
  3. enters circulation
57
Q

what is found in lymph nodes

A

phagocytic cells for non specific filtering

lymphocytes to interact with new found antigens

58
Q

where are mature and immature T cells found in thymus

A

mature - medulla

immature - cortex

59
Q

how does adult thymus differ to infant thymus

A

degeneration in adult as all needed T cells have been produced

60
Q

where are b cells activated

A

follicles of lymph nodes

61
Q

what is in the mantle zone of lymph nodes mainly composed of

A

resting B cells

62
Q

where in the lymph nodes are T cells mainly located

A

para cortex

63
Q

where is MALT

A

mucosa of many epithelial cells

tonsil
ileum

64
Q

characteristics of MALT

A

can be aggregations or scattered lymphocytes

65
Q

how do macrophages recognise bacteria

A

they have receptors that bind antibodies bound to the bacterial surface