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the immune system Flashcards

1
Q

what are the two ways organisms can infect you

A

via the external epithelia: skin surface, wound, insect bite

mucosal surface: airway, GI tract, reproductive tract

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2
Q

how do we defend ourselves from infection

A

barriers

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3
Q

give examples of the body’s infection barriers

A

mucus lining the nose to trap infectious material
cilia lining the lungs to sweep mucus up
defensins in the intestine (host defence peptides)

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4
Q

what is the first response to infection

A

inflammation

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5
Q

what are the steps of inflammation

A

toll like receptors recognise foreign molecules
they initiate inflammation
histamine, defensins, peptides, cytokines, chemokines are released and recruit other cells for the immune response
the immune response is triggered resulting in heat, redness, swelling and pain

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6
Q

what are toll like receptors

A

patter recognition molecules

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7
Q

what is a node

A

a point in a network of diagram at which lines or pathway intersect or branch

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8
Q

what is lymph

A

a colourless fluid containing white blood cells, which bathes the tissues and drains through the lymphatic system into the blood stream

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9
Q

what are the components of the lymphatic system

A

thymus, spleen, lymph nodes

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10
Q

what are lymph nodes

A

nodular aggregates located along lymphatic system (a communication centre for immune cells so they can coordinate a response)

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11
Q

how does lymph enter the lymph node

A

through the afferent lymph vessels

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12
Q

what is the difference between red blood cells and white blood cells

A

red blood cells carry oxygen

white blood cells are immune cells

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13
Q

list all the types of white blood cells (9)

A 
macrophage 
neutrophils 
lymphocytes - b and t cells
basophils
eosinophils 
mast cells
monocytes 
dendritic cells 
natural killer cells
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14
Q

what types of white blood cells are members of the innate immune system

A 
neutrophil
mast cells
eosinophils
dendritic cells
basophils
macrophage
monocytes
natural killer cells
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15
Q

what types of white blood cells are members of the adaptive immune system

A

lymphocytes:
b cells
t cells

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16
Q

what kind of response does the innate immune system provide

A

the same response over and over again

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17
Q

what kind of response does the adaptive immune system provide

A

an adapted immune response specific to the infection at hand

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18
Q

what is complement

A

a cascade of proteins in serum (roughly 30 proteins in blood plasma)

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19
Q

what activates complement

A

antibodies or molecules from pathogens

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20
Q

which immune response does complement amplify

A

inflammation

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21
Q

what does complement do

A

either directly kills the pathogen or attracts immune cells

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22
Q

how many bacteria can neutrophils capture

A

on or two

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23
Q

which type of white blood cell is most abundant

A

neutrophils

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24
Q

neutrophils are ………. phagocytic cells

A

active

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25
Q

how do neutrophils kill pathogens

A

they can consume them and also use NETs

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26
Q

what are NETs

A

sticky strands of DNA

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27
Q

how are neutrophils recruited

A

by inflammation in the tissues

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28
Q

what do neutrophils turn into when they die

A

snot

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29
Q

where are macrophages found

A

in all tissues

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30
Q

how many bacteria can macrophages capture

A

hundreds - they are the best phagocytic cells

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31
Q

where do macrophages develop

A

in tissues form precursors

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32
Q

how do macrophage kill pathogens

A

they consume them then kill them

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33
Q

what activates macrophages

A

inflammation in the tissues

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34
Q

are macrophages long lived or short lived

A

long lived

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35
Q

where are dendritic cells formed

A

in tissues from precursors

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36
Q

dendritic cells are active ………….. cells

A

phagocytic

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37
Q

what response can dendritic cells activate

A

the adaptive immune response

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38
Q

what do dendritic cells carry to the lymph nodes

A

proteins

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39
Q

where do dendritic cells migrate from

A

out of peripheral tissues

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40
Q

how can dendritic cells activate the adaptive immune response

A

they communicate with t cells

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41
Q

where are dendritic cells found

A

in all tissues and take bacteria back to the lymph node instead of staying in the tissue

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42
Q

what is a pathogen

A

any disease causing organism

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43
Q

does a foreign molecule have to be pathogenic to elicit an immune response

A

no

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44
Q

the first line of defence prevents pathogens form doing what

A

entering the body

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45
Q

a properly functioning immune system distinguishes ……………… from self

A

no self

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46
Q

what do immune cells do

A

produce receptor like molecules that bind specifically to molecules from foreign cells or viruses and activate defence responses

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47
Q

the specific binding of immune receptors to foreign molecules is a type of what

A

molecular recognition

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48
Q

is adaptive immunity found in all animals

A

no, only in vertebrates

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49
Q

is innate immunity found in all animals

A

yes

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50
Q

What does molecular recognition in innate immunity involve

A

a small set of receptor proteins that bind to molecules that belong to a group of viruses, bacteria or other pathogens. This binding activates internal defences, enabling a response to a broad range of pathogens

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51
Q

is the innate response rapid or slow

A

rapid

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52
Q

what are the innate internal defences

A

phagocytic cells
NKCs
antimicrobial proteins
inflammatory response

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53
Q

is the adaptive immunity response rapid or slow

A

slower

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54
Q

What does molecular recognition in adaptive immunity involve

A

recognition of traits specific to particular pathogens, using a vast array of receptors very very specific

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55
Q

what are the two adaptive immunity responses

A

humoral response

cell mediated response

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56
Q

what is the humoral response

A

antibodies defend against infection in body fluids (occurs in the blood ad lymph)

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57
Q

what is the cell mediated response

A

Specialized T cells destroy infected host cells

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58
Q

what is another name for the adaptive immune response

A

the acquired immune response

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59
Q

what response I developed first adaptive or innate

A

innate

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60
Q

is innate immunity found in plants

A

yes

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61
Q

how is prevention of lung infection prevented by cilia

A

the pathogens are trapped in the mucous lining and are then swept up the trachea by the cilia to be swallowed down the oesophagus

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62
Q

how do saliva, tears and mucous help prevent infection - the physical role

A

they bathe exposed epithelia and provides a washing action that inhibits colonisation of fungi and bacteria

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63
Q

how do saliva, tears and mucous help prevent infection - the chemical role

A

body secretions create a hostile environment for many pathogens
e.g. lysozyme destroys the cell walls of bacteria
e.g. ingested pathogens encounter the acidic environment of the stomach
oil and sweat gland secretions make the skin acidic preventing colony growth.

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64
Q

what do innate immune cells rely on

A

toll like receptors

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65
Q

what is a toll like receptor

A

a mammalian recognition protein

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66
Q

Upon recognition of pathogens, what do TLR do

A

they release a signal that initiate responses tuned to the invading microbe

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67
Q

TLR proteins bind to fragments of molecules characteristic of a set of pathogens. Name some examples of TLR and their functions

A

TLR3 - bind to RNA on viruses
TLR4 - binds to lipopolysaccharides found on many bacteria
TLR5 - binds to flagellin, a protein of bacterial flagella

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68
Q

what are the two main types of mammalian phagocytic cell

A

macrophages and neutrophils

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69
Q

Describe the role of neutrophils

A

they circulate in the blood
they are attracted by signals from infected tissues
they engulf and destroy the pathogens

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70
Q

Describe the role of macrophages

A

means “big eaters”
they are large phagocytic cells
they can move throughout the body or reside permanently in organs/tissues where they are likely to encounter pathogens

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71
Q

which 2 other cells have roles in the innate immune response

A

dendritic cells

eosinophils

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72
Q

describe the role of dendritic cells

A

mainly populate tissues that contact the environment e.g. skin
they stimulate adaptive immunity against pathogens that they encounter and engulf

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73
Q

describe the role of eosinophils

A

found in tissues underlying an epithelium
important in defending against multicellular invaders e.g. parasitic worms
eosinophils discharge destructive enzymes

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74
Q

natural killer cells are also involved in cellular innate defences, what do they do

A

they circulate the body and detect abnormal surface proteins characteristic of virus infected or cancerous cells

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75
Q

do natural killer cells engulf stricken cells

A

no

76
Q

how do natural killer cells kill the pathogen

A

they release chemicals that lead to cell death, inhibiting further spread of the virus or cancer

77
Q

many innate defences involve which organ system

A

the lymphatic system

78
Q

what are the components of the lymphatic system

A

Thymus, spleen, lymph, lymph nodes, bone marrow, lymph vessels

79
Q

what do macrophages that reside in the lymph nodes do

A

engulf pathogens that have entered the lymph from the interstitial fluid

80
Q

how do dendritic cells stimulate adaptive immunity

A

they reside outside the lymphatic system but migrate to the lymph nodes after interacting with pathogens. within the lymph nodes they interact with other immune cells, stimulating adaptive immunity

81
Q

pathogen recognition triggers the production and release of a variety of ……….. and ………… that attack pathogens or impede their reproduction

A

peptides

proteins

82
Q

how do antimicrobial peptides affect pathogens

A

they disrupt membrane integrity

83
Q

are antimicrobial peptides found in insects

A

yes

84
Q

are interferons and complement proteins found in insects

A

no they are unique to vertebrates

85
Q

what are interferons

A

proteins that provide innate defence by interfering with viral infections

86
Q

where are interferons excreted from

A

virus infected body cells

87
Q

what do interferons induce

A

uninfected cells to produce substances that inhibit viral replication

88
Q

interferons limit the cell to cell spread of viruses in the body helping control viral infections such as ………….

A

the cold and influenza

89
Q

where else can interferons be excreted from and what is their function in this case

A

white blood cells

they enhance phagocytic ability of macrophages

90
Q

complement proteins circulate the body in an inactive form. how do they become activated

A

by substances on the surface of many pathogens

91
Q

what happens when complement is activated

A

a cascade of reactions that lead to lysis of invading cells

92
Q

name 2 changes that reflect a local inflammatory response

A

swelling and heat

93
Q

what is an inflammatory response

A

events triggered by signalling molecules released upon injury or infection

94
Q

describe the inflammatory response

A

activated macrophages discharge cytokines
mast cells release histamine at sites of damage
histamine triggers blood vessels to dilate and become more permeable
increase in local blood supply produces redness and increased skin temperature
activated complement proteins promote further release of histamine attracting more phagocytic cells enhanced blood flow and permeability helps deliver antimicrobial peptides and neutrophils
the result is pus

95
Q

what are cytokines

A

signalling molecules that recruit neutrophils to the site of injury

96
Q

what are mast cells

A

immune cells found in connective tissue

97
Q

what is histamine

A

a signalling molecule

98
Q

what is pus

A

a fluid rich in wbc, dead pathogens and debris from damaged tissue

99
Q

what is the hypothesis regarding fever and infection

A

increased body temperature may enhance phagocytosis and by speeding up chemical reactions, accelerate tissue repair

100
Q

what adaptations have pathogens evolved that enable them to avoid destruction by phagocytic cells

A

the outer capsule of bacteria interferes with molecular recognition and phagocytosis
some bacteria are recognised but resist breakdown after being engulfed, they can then grow inside the host cell and be hidden from the immune defences. TB is a result of this

101
Q

what does the adaptive immune response rely on

A

T cells and B cells which are types of white blood cells called lymphocytes

102
Q

like all blood cells, lymphocytes originate from where

A

the stem cells in the bone marrow

103
Q

some lymphocytes migrate from the bone marrow to where

A

the thymus (an organ in the thoracic cavity above the heart)

104
Q

the lymphocytes that migrate to the thymus mature into what

A

T cells

105
Q

the lymphocytes that remain in the bone marrow develop into what

A

B cells

106
Q

lymphocytes of a third type remain in the blood and become what

A

the natural killer cells of both the innate and adaptive immunity

107
Q

any substance that elicits and B or T cell response is called what

A

an antigen

108
Q

how does recognition occur in adaptive immunity

A

A B cell or T cell binds to an antigen via a protein called an antigen receptor. infection by a pathogen triggers activation of B and T cells with antigen receptors specific for parts of the pathogen

109
Q

a single lymphocyte produces how many types of antigen receptor

A

1 - has many of it though

110
Q

antigens are usually proteins or ………..

A

polysaccharides

111
Q

the small accessible portion of and antigen that binds to the antigen receptor is called what

A

epitope

112
Q

the antigen receptors of B and T cells have similar components but what do they do differently

A

they encounter antigens in different ways

113
Q

what shape is a B cell antigen receptor

A

Y shaped

114
Q

each B cells receptor has how many identical antigen binding sites

A

2

115
Q

what happens when a B cell antigen receptor binds to an antigen

A

it is an early step in B cell activation and leads to formation of cells that secrete the soluble form of the receptor, CALLED AN ANTIBODY, also known as immunoglobulin (Ig)

116
Q

is the antibody produced specific to the same epitope as the original B cell

A

yes

117
Q

what is different about the original B cell receptor and the produced antigen

A

they have the same y shaped structure but the antibody lacks a membrane anchor

118
Q

B cells receptors and antibodies bind to bind to antigens where

A

in the blood and the lymph

119
Q

true or false: B cell antibodies can bind to antigens on the surface of pathogens or free in body fluids

A

true

120
Q

what does the antigen receptor of a T cell consist of

A

two different polypeptide chains joined by a disulphide bridge. both polypeptides are anchored in the plasma membrane of the T cell

121
Q

what does the antigen receptor of a B cell consist of

A

two identical non variable light chains and tow identical fixed heavy chains that link together by disulphide bridges. the heavy chains are anchored in the plasma membrane of the B cell

122
Q

what is the difference in the binding of B and T cell receptors to an epitope

A

the B cells bind to epitopes of intact antigen protruding from pathogens or circulating free in body fluids
the T cells bind only to fragments of antigens that are displayed or presented on the surface of host cells

123
Q

what is a major histocompatibility complex (MHC) molecule

A

a host protein that displays an antigen fragment on the cell surface

124
Q

what is essential for antigen recognition by T cells

A

MHC molecules

125
Q

how does antigen recognition by T cells work

A

pathogen infects an animal cell
inside the cell an antigen fragment of the pathogen binds with an MHC molecule
the MHC molecule with the antigen fragment bound is brought to the cell surface where it is displayed
the combination of MHC molecule and antigen fragment is recognised by the T cell
the interaction triggers an adaptive immune response

126
Q

What part of the MHC antigen fragment complex is the T cell receptor specific for

A

the antigen fragment

127
Q

what are the four major characteristics of adaptive immunity

A
  1. the large stock of lymphocytes and receptors enables detection of antigens never before encountered
  2. adaptive immunity normally has self tolerance (doesn’t react with the animals own cells)
  3. cell proliferation triggered by activation increases the no. T and B cells specific for an antigen
  4. There is a stronger and more rapid response to an antigen encountered previously due to immunological memory
128
Q

assembly of a functional immunoglobin (antibody gene) requires what

A

rearrangement of DNA

129
Q

which enzyme joins to the immunoglobin gene during formation of a functional antibody

A

recombinase

130
Q

what happens during the recombination event

A

a long stretch of DNA is eliminated, leaving behind only the DNA to be transcribed and translated into the functional gene of the antigen receptor

131
Q

how does recombinase act randomly

A

it connects any part one of the V (variable) gene segments to any one of the J (joining) gene segments

132
Q

after DNA arrangement what is the next step in generation of diverse B and T cells

A

the rearranged genes are transcribed and translated. The resulting chains then join together forming an antigen receptor

133
Q

why are B and T cells so highly specific

A

due to DNA arrangement and mutations introduced during the recombinant stage. depends which parts are treated as introns/exons as to what is included

134
Q

some immature lymphocytes produce receptors specific for epitopes on the organisms own molecules . what would happen if these were not eliminated or inactivated

A

the immune system could not distinguish between self and non self and would attack body proteins, cells and tissues

135
Q

what is tested when lymphocytes are maturing in either the bone marrow or the thymus

A

they are tested for self reactivity

136
Q

what are the two ways that self reactivity can be eliminated

A

B/T cells with receptors for the body’s own molecules undergo apoptosis or are just rendered non functional

137
Q

as the body normally lacks mature lymphocytes that can react against its own molecules the immune system is said to be what

A

self tolerant

138
Q

where is the first place that an antigen is presented

A

to a steady stream of lymphocytes in the lymph node until a match is made

139
Q

a successful match between an antigen receptor and an epitope initiates what

A

events that activate the lymphocyte bearing the receptor

140
Q

Once B/T cell is activated what happens

A

it undergoes multiple cell divisions

141
Q

what is produced when the b/T cells proliferate

A

lots of clones of the original cells

142
Q

some of the cloned cells become what

A

effector cells

143
Q

what is an effector cell

A

short lived cells that take effect immediately against antigens and pathogens

144
Q

what are the effector cell forms of B cells

A

plasma cells which secrete antibodies

145
Q

what are the effector cell forms of T cells

A

helper T cells and cytotoxic T cells

146
Q

other than effector cells what else can the clone cells become

A

memory cells

147
Q

what are memory cells

A

long lived cells that can give rise to effector cells If the same antigen is ever encountered again

148
Q

what is clonal selection

A

the process by which an antigen selectively binds to and activates only those lymphocytes bearing receptors specific to the antigen. The lymphocytes proliferate into a clone of effector cells and memory cells for that antigen
ANTIGEN SELECTS LYMPHOOCYTE THEN DIVIDES TO PPRODUCE CLONES

149
Q

what does immunological memory provide

A

long term protection provided by a prior infection e.g. chicken pox

150
Q

prior exposure to an antigen alters which 3 aspects of the immune response

A

speed, strength and duration

151
Q

the effector cells formed by clones of lymphocytes after initial exposure to an antigen produce what kind of immune response

A

primary immune response

152
Q

if the same antigen is encountered again what kind of immune response is produced

A

secondary immune response

153
Q

which immune response is faster, of greater magnitude and prolonged

A

secondary immune response

154
Q

what does the secondary immune response rely on

A

the reservoir of T and B memory cells

155
Q

what about the memory cells makes them well adapted for immunological memory

A

they are long lived (can live for many decades)

156
Q

what do the memory cells do if they encounter the antigen

A

they form clones generating an enhanced immune defence

157
Q

can humoral and cell mediated immunity include both primary and secondary immune responses

A

yes

158
Q

what type of cell activates both the humoral and cell mediated response

A

helper T cell

159
Q

what must happen before a helper T cell can activate either a humoral or cell mediated response

A

a foreign molecule must be present that can bind specifically to the antigen receptor of the helper T cell
the antigen must be displayed on the surface of an antigen presenting cell e.g. dendritic cell, macrophage or B cell

160
Q

how many classes of MHC cell do body cells have

A

1

161
Q

how many classes of MHC cell do antigen presenting cells have

A

2

162
Q

run through the process of helper T cells activating adaptive immunity

A

helper T cell antigen receptors bind to the antigen fragment and the class 2 MHC molecule displaying the fragment on the antigen presenting cell
CD4 (attached to helper T) binds to the MHC molecule keeping the cells joined
cells interact when cytokines are exchanged (dendritic cell produces cytokines triggering the helper T cell to do the same)
proliferation results in clones that secrete more cytokines, activating B cells (humoral - secretion antibody) and Cytotoxic T cells (cell mediated - infected cell attack)

163
Q

is secretion of antibodies a humoral or cell mediated response

A

humoral

164
Q

what is involved in B cell activation

A

helper t cells and proteins on the surface of pathogens

165
Q

what stimulates proliferation of B cells

A

antigen and cytokines

166
Q

how are macrophages and dendritic cells different to B cells

A

B cells only presents the antigen that it is specific to

167
Q

what happens when an antigen binds to the B cell receptor

A

the B cells take in a few of the foreign molecules

168
Q

A class 2 MHC protein of the B cell presents an antigen fragment to what

A

a helper T cell

169
Q

Cell-cell contact is critical to ….. cell activation

A

B

170
Q

what does B cell activation lead to

A

humoral response - plasma cells (effectors) stop expressing the antigen receptor and instead secrete antibodies

171
Q

do antibodies directly kill pathogens

A

no - they interfere with pathogen activity or mark them for deactivation or destruction

172
Q

what is opsonization

A

antibodies bound to antigens do not block infection but instead present a structure that promotes phagocytosis

173
Q

what does phagocytosis enable macrophage and dendritic cells to do

A

present antigens to and stimulate helper T cells which then stimulates the B cells whose antibodies contribute to phagocytosis

174
Q

what are the 5 types of Immunoglobulin produced by B cells

A

IgA (breastmilk, saliva, tears, blood and airways),
IgM, (blood and lymph)
IgD, (not well understood, lining of abdomen and chest)
IgE (lungs, skin, mucous. common allergies, hay fever), IgG (in blood cross placenta to fetus)
MADGE

175
Q

what is a cytotoxic T cell

A

a T lymphocyte that kills cancer cells, cells that are infected, or cells that are damaged in other ways

176
Q

how do cytotoxic T cells kill infected host

A

inject proteins (perforin and granzyme) into the cell that induce cell death (apoptosis)

177
Q

what activates a cytotoxic T cell

A

helper T cell or antigen presenting cell

178
Q

what is active immunity

A

the defences that arise when a pathogen infection prompts an immune response

179
Q

what is passive immunity

A

the short-term immunity which results from the introduction of antibodies from another person or animal. mother and fetus

180
Q

what is a large factor responsible for immune rejection

A

differences in MHC cells (different in everyone except twins)

181
Q

what is agglutination

A

when an antibody binds to more than one antigen at a time

182
Q

what is an autoimmune disease

A

when the immune system is active against particular molecules of the body e.g. lupus, arthritis, multiple sclerosis

183
Q

what is an immunodeficiency disease

A

a disorder in which an immune system response to antigens is defective or absent e.g. AIDS

184
Q

what is antigenic variation

A

mechanism by which a pathogen alters its surface proteins in order to evade a host immune response. why flu vaccine need renewed

185
Q

what is latency

A

in latency the production of most viral proteins and free viruses ceases so they don’t trigger an adaptive immune response. the viruses wait until the environment is more favourable for their survival before reactivating

186
Q

which pathogen causes AIDs

A

HIV

A (17 decks)

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