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pcs 3 tutorials > infection and immunity > Flashcards

infection and immunity Flashcards

1
Q

what is the definition of a pathogen

A

an organism capable of causing disease in humans

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2
Q

what are the 5 taxonomic groups of pathogens

A 
bacteria
virus
fungi
protozoa
helminths
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3
Q

what are fungi subdivided into

A 
divided into 
yeasts - binary fission
mycelia - dividing by septa
AND 
superficial - skin + nail infection
systemic - immunocompromised
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4
Q

what is a protozoa

A

single celled animals which causes disease as a result of the immune response divided into
intracellular / extracellular location

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5
Q

what are helminths

A

eukaryotic parasitic worms

  • tapeworms
  • roundworms -
  • flukes
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6
Q

name 5 ways a pathogen can enter the body

A 
skin - biting or needles 
inhalation - limited anatomical barrier 
GI tract - large and exposed surface area
urogenital - via urethra 
eyes - during childbirth
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7
Q

name the 2 forms of pathogen transmission

A

vertical / horizontal transmission

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8
Q

what factors are pathogen transmission dependant on

A

stability of pathogen outside host

number of organisms to infect a new host

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9
Q

describe vertical transmission

A

mother to fetus (placenta / breastfeeding / delivery)

rubella / Hep B / HIV

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10
Q

describe horizontal transmission

A

directly - close proximity

indirectly - contaminated food / water / blood

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11
Q

describe the shape of a coccus bacteria

A

SPERICAL

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12
Q

describe the shape of a streptococci bacteria

A

LONG CHAIN

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13
Q

describe the shape of a diplococci bacteria

A

IN PAIRS

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14
Q

describe the shape of a bacillus bacteria

A

ROD SHAPED

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15
Q

describe the shape of a staphylococci bacteria

A

CLUSTERS

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16
Q

describe the shape of a vibrio bacteria

A

COMMA SHAPED

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17
Q

describe the shape of a spirochetes bacteria

A

SPIRAL SHAPED

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18
Q

what does gram positive bacteria turn purple in crystal violet stain

A

THICK peptidoglycan layer that traps the stain

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19
Q

what does gram negative bacteria NOT turn purple in crystal violet stain and what is it alternatively stained with

A

THIN lipopolysaccharide outer layer so the purple stain washes off - safranin red counterstain

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20
Q

describe the steps of gram staining bacteria

A

1 add crystal violet stain
2 add gram iodine preticipate
3 add decolouriser ( alcohol) wash
4 add red counterstain

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21
Q

what is commensal flora

A

human microorganism SYMBIOTIC but can cause infection if enters the bloodstream / immuno compromised

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22
Q

what is an opportunistic infection

A

commensal flora / pathogen taking advantage of host due to immuno-compormised / wounds / hormonal changes / pregnancy

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23
Q

what is a healthcare associated infection

A

infection related to interaction with healthcare service - catheters / feeding tubes

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24
Q

what are bacterial virulence factors

A

molecules produced by bacteria that add to their effectiveness helping them to
1 invade host
2 cause disease
3 evade host defences

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25
Q

name some bacterial virulence factors

A 
adherence factors 
capsules
endotoxins
siderophores
exotoxins 
antibiotic resistance
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26
Q

what do adherence factors do

A

use pili to adhere to cells at mucosal sites

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27
Q

what do capsules do

A

surround bacteria to protect them from phagocytosis

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28
Q

what do endotoxins do

A

on gram NEGATIVe bacteria leading to fever / inflammation / shock

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29
Q

what do siderophores do

A

iron ion binding factors to compete with host

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30
Q

what do exotoxins do

A

enzymes secreted - cytotoxins

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31
Q

what are the features of a virus

A

metabolically inert
contains DNA/RNA genome
surrounded by a capsid

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32
Q

what are the main features of the lytic cycle

A

results in destruction of the infected cell and its membrane

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33
Q

what are the main features of the lysogenic cycles

A

results in integration of pathogen nucleic acid into host genome of cell

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34
Q

describe the steps of the lytic cycle

A

1 phage attaches / penetrates host cell

2 phage DNA arcularius

3 phage DNA replicates / makes proteins

4 new phage particles are produces

5 cell lyseses and releases new phages

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35
Q

describe the steps of the lysogenic cycle

A

1 phage infects cell

2 biosynthesis of viral RNA / phage DNA incorporates into host genome

3 cell divides / prophage DNA passed to daughter cells

4 stressful cellular conditions = enters stage 3 of lytic

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36
Q

what is sense (+) in the Baltimore classification of viruses

A

used directly as mRNA to translate viral proteins

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37
Q

what is antisense (-) in the Baltimore classification of viruses

A

complimentary RNA strand has to be produced in host cell to be used as mRNA

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38
Q

what are the 4 types of cellular level viral infection

A

acute / lytic
persistent / chronic
latent / proviral
transforming

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39
Q

describe an acute / lytic cellular level viral infection

A

rapid host death

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40
Q

describe a persistent cellular level viral infection

A

long term with low levels of virus production

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41
Q

describe a latent / proviral cellular level viral infection

A

viral genome maintained within host

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42
Q

describe a transforming cellular level viral infection

A

virus produces altered cell growth

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43
Q

name 3 viruses that are linked with cancer

A

Hep B
human papilloma
epstein barrvirus

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44
Q

name the 6 components of INNATE immunity

A 
macrophages
dendritic cells 
mast cells
neutrophils
basophils
natural killer cells
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45
Q

describe the function of a macrophage

A

key sentinel cell in peripheral tissue

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46
Q

describe the mechanism of a macrophage response

A

1 sense pathogen with PATTERN RECOGNISING RECEPTORS

2 communicate detection of pathogen with INFLAMMATORY CYTOKINES (IL1 /6/12 and TNF alpha)

3 macrophages perform phagocytosis

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47
Q

what is the effect of IL 1 and TNF alpha release

A

capillary dilation

increase endothelial wall permeability

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48
Q

what is the function of a dendritic cell

A

similar to macrophage in peripheral tissue

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49
Q

where to dendritic cells migrate to from the infection site

A

lymphatic vessels

present peptide complexes to TCR (t cell receptor) on T native T cells

50
Q

where are mast cells found

A

connective tissue

51
Q

what does mast cell activation entail

A

release of HISTAMINES / PROSTAGLANDINS leading to vasodilation

52
Q

where are neutrophils found

A

the blood

53
Q

when can neutrophils enter an infection site

A

when vessels have increased permeability

54
Q

what do neutrophils perform efficiently

A

phagocytosis

55
Q

what to basophils protect against

A

protozoa / helminths

56
Q

where are natural killer cells found

A

blood

peripheral tissue

57
Q

what does PAMP stand for

A

pathogen associated molecular patterns

58
Q

what are PAMPs

A

component of pathogen which allows recognition from host components

59
Q

what recognises PAMPs

A

PRR - pattern recognition receptors

60
Q

name a PRR

A

TLR

toll-like receptors which are expressed by B cells / macrophages / NK cells and dendritic cells

61
Q

What is the function of a TLR

A

SIGNALLING

10 receptors with variable specificity

62
Q

what function do macrophage receptors perform

A

phagocytosis
targets bacteria
targets mannose receptors with ligand activation

63
Q

where are TLR 4 / 5 located in the body

A 
plasma membrane (extracellular)
endosome
64
Q

what is the cascade activated by these TLRs when bacteria / fungi are detected

A

1 transcriptional factor activation

2 TNF alpha / IL 1 / 6 expressed

3 co-stimulatory receptor ligands expressed B7 1 and 2

65
Q

where are TLR 3 / 7 /8 / 9 located

A

intracellular in endosomal compartment

66
Q

what is the cascade activated by these TLRs when viruses are detected

A

signalling production of cytokines

67
Q

what are the 3 locations of entry and un-coating for bacteria

A

plasma membrane
within endosome
at nuclear membrane

68
Q

what are the 3 key soluble components of innate immunity

A

antimicrobial peptides
compliment proteins
cytokines

69
Q

describe the overall steps of the compliment system

A

1 alternative / classical / lectin pathway

2 terminal pathway

3 C5a formation and membrane attack complex

70
Q

describe the classical pathway

A

1 IgM / IgG binds to pathogen

2 this is recognised by 1st component of compliment C1 and follows a cascade to form C3b

71
Q

describe the lectin pathway

A

1 mannose residue on pathogen is recognised by mannan binding lectin

2 C3b is produced via production cascade

72
Q

describe the alternative pathway

A

1 auto-activation of C3 that occurs on the surface of the pathogen

73
Q

when is the alternative pathway the most important

A

early infection

74
Q

what function does C3b serve (steps)

A

1 covalently binds to pathogen surface

2 flags pathogen to phagocytes that have a C3b receptor

3 OPSONISATION

4 terminal pathway activation = C5a formation

75
Q

what is OPSONISATION

A

pathogen is chemically modified to be more attractive to phagocytes / NK cells

76
Q

what is the function of C5a (generalised)

A

strong chemoattractant and is involved in the recruitment of inflammatory cells such as neutrophils, eosinophils, monocytes, and T lymphocytes, in activation of phagocytic cells and release of granule-based enzymes and generation of oxidants

77
Q

what are the steps of opsonisation

A

overall = C3b fixation to pathogens (particularly bacteria)

1 CR1 / 3 receptors recognise C3b fixation

2 phagocytosis (++ efficiency)

3 intracellular killing

78
Q

what happens if there is a C3 component deficiency within the body

A

more susceptible to bacterial infection

79
Q

what is C5a anaphylatoxin

A

a chemotactic agent (chemoattractant)

80
Q

describe the steps of C5a anaphylatoxin mechanism

A

1 attracts neutrophils / macrophages

2 enhances neutrophil phagocytosis ability

3 VASODILATION / increased permeability

4 degranulation of mast cells / basophils / muscle contraction

5 INFLAMMATION

81
Q

describe the process of degranulation

A

release of antimicrobial cytotoxic or other molecules from secretory vesicles called granules

82
Q

describe the process of forming the membrane attack complex

A

C5b

C5b7

MAC - cell lysis and membrane lesions

83
Q

what is the function of the MAC

A

creates pores in the pathogen surface membrane allowing lysozymes to enter and destroy the protective cover - particularly effective against gram negative bacteria

84
Q

what facilitates the changing of membrane phospholipids into prostaglandins

A

IL-IB

TNF alpha

85
Q

what is the function of prostaglandins

A
  • inflammation
  • reduced pain threshold
  • fever
86
Q

what is the outcome of IL-6 conc. increase

A

fever

hepatocyte inflammation

87
Q

what is the outcome of TNF alpha conc. increase

A

increased vascular permeability
fever
shock

88
Q

what is the outcome of IL-1/3 conc. increase

A

fever
IL-6 production
lymphocyte activation

89
Q

what is the outcome of CXCL 8 conc. increase

A

basophil / neutrophil recruitment

90
Q

what is the outcome of IL-12 conc. increase

A

activates natural killer cells

91
Q

when is adaptive immunity initiated

A

when the innate immunity becomes overwhelmed

92
Q

describe the clonal selection hypothesis

A

1 many individual different lymphocytes

2 pathogen binds to unique receptor + activates it

3 mytotic expansion - daughter cells express same receptor

4 body gives rise to effector cells that eliminates pathogen

93
Q

where is the lymphocyte initially activated

A

draining lymph node

94
Q

what cell brings the pathogen component to the lyphocyte

A

dendritic cell

95
Q

where are t cell receptors find

A

trans-membrane NOT SECRETED

96
Q

what is the function of processing and presenting pathogen antigens

A

recognising infected host cells

97
Q

describe the steps involved in antigen processing / presentation

A

1 pathogen invades host cell

2 protein from pathogen binds to MHC

3 presented on cell surface of infected cells

4 recognised by TCR on T cell surface

98
Q

what does MHC stand for

A

major histocom patibility complex

99
Q

where are MHC class 1 found

A

all nucleated cells

100
Q

where are MHC class 2 found

A

exclusive to

  • b cells
  • macrophages
  • dendritic cells
101
Q

what are CD8+ cells and what is their function

A

killer T cells

directly kills infected cells

102
Q

what are CD4+ cells and what is their function

A

helper T cells

provides assistance to other immune system cells by secreting cytokine activating macrophages / B cells

103
Q

what are immunoglobulins a secreted form of

A

B-cell antigen receptor

104
Q

what are immunoglobulins made up of

A

glycoproteins

4x chains 2x heavy 2x light

105
Q

how many antigen binding regions are there on an immunoglobulin

A

2

106
Q

what is somatic rearrangement

A

multiple encoding domains which randomly rearrange DNA / imprecise chain joining to allow immunoglobulin diversity

107
Q

what immunoglobulin are all others rearranged forms of

A

IgM

108
Q

describe the process of class switching

A

modification of the heavy chain of an immunoglobulin to produce different classes (types) from IgM

109
Q

what function do IgM perform

A

neutralisation
compliment system activation
epithelium transport

110
Q

what function does IgD perform

A

basophil sensitisation

111
Q

what function does IgA perform

A

neutralisation
oponization
compliment system activation
extravascular diffusion

112
Q

what function does IgE perform

A

mast cell sensitisation

extravascular diffusion

113
Q

basophil / mast cell function

A

release of inflammation / allergic response chemicals

114
Q

neutrophil function

A

ingest / destroy pathogens

115
Q

eosinophils function

A

destroy pathogens (particularly antibody coated ones)

116
Q

monocyte / macrophage function

A

antigen presentation / ingest pathogens

117
Q

lymphocyte / plasma cell function

A

specific response to pathogens / antibody production

118
Q

dendritic cell function

A

recognise pathogens and activate other immune cells by antigen presentation in lymph nodes

119
Q

name the cellular components - innate immunity

A 
macrophage
natural killer cells
dendritic cells 
neutrophils
eosinophil 
basophil 
T cell
Natural killer T cell
120
Q

name the cellular components - adaptive immunity

A

B cell
T cell - CD4+ / 8+
Natural killer T cell
Antibodies

pcs 3 tutorials (1 decks)

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