Innate Immunity Flashcards

1
Q

What is virulence?

A

Capacity of microbe to damage host

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2
Q

What is the definition of the immune system?

A

Cells and organs that contribute to immune defences against infectious and non-infection conditions

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3
Q

What is infectious disease?

A

When the pathogen succeeds in evading the host’s immune defences

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4
Q

What are the roles of the immune system?

A

Pathogen recognition
Containing the infection
Regulating itself
Remembering pathogens

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5
Q

What are some features of innate immunity?

A
Immediate protection 
Fast
Lack of specificity
Lack of memory
No change in intensity
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6
Q

What physical barriers are involved in the innate immune system?

A

Skin
Mucous membranes (mouth, respiratory tract, GI tract, urinary tract)
Bronchial cilia

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7
Q

What physiological barriers are part of the innate immune system?

A

Diarrhoea, vomiting, coughing, sneezing

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8
Q

What chemical barriers are involved in the innate immune system?

A
Low pH of skin, stomach, vagina
IgA (tears, saliva, mucous membrane)
Lysozyme (sebum, perspiration, urine)
Mucous 
Beta-defending (epithelium)
Gastric acid and pepsin
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9
Q

What biological barriers are part of the innate immune system?

A

Normal flora in nasopharynx, mouth/throat, skin, GI tract, vagina

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10
Q

What are the benefits of having normal flora?

A

Compete with pathogens for attachment sites and resources

Produce antimicrobial chemicals

Synthesise vitamins (K, B12, other B vitamins)

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11
Q

What normal flora are found within the vagina?

A

Lactobacillus spp

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12
Q

What are some examples of normal flora that inhabit the skin?

A
Staphylococcus aureus
Staphylococcus epidermidis
Streptococcus pyogenes
Candida albicans
Clostridium perfringens
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13
Q

What are some examples of normal flora that inhabit the nasopharynx?

A

Streptococcus pneumoniae
Neisseria meningitidis
Haemophilus species

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14
Q

When do clinical problems involving normal flora occur?

A

When normal flora are displaced from its normal location to sterile location

Or when they overgrow

Or when they are depleted by antibiotics

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15
Q

Are macrophages present in all organs?

A

Yes

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16
Q

What are the functions of macrophages?

A

Phagocytosis, antigen presentation, production of cytokines

17
Q

Where are monocytes present?

18
Q

What is the function of monocytes?

A

They are recruited at infection site and differentiate into macrophages

19
Q

Where are neutrophils present?

A

Blood (60% of blood leukocytes)

20
Q

What are neutrophils recruited by?

A

Recruited by chemokines to site of infection

21
Q

What is the function of neutrophils?

A

Ingest and destroy pyrogenic bacteria: Staphylococcus aureus and Streptococcus pyogenes

22
Q

What is the function of basophils/mast cells?

A

Early actors of inflammation, important in allergic responses

23
Q

What is the function of eosinophils?

A

Defence against multi-cellular parasites

24
Q

What is the function of natural killer cells?

A

Kill all abnormal host cells (eg virus infected or cancer cells)

25
What is the function of dendritic cells?
Present antigens to T cells
26
What is opsonisation of microbes?
Coating proteins called opsonins that bind to the microbial surfaces leading to enhanced attachment of phagocytes and clearance of microbes
27
What are some examples of opsonins?
Complement proteins (C3b and C4b) Antibodies (IgG, IgM) Acute phase proteins (CRP, MBL)
28
What is the oxygen-dependent pathway of phagocytosis?
Toxic oxygen products produced to kill the pathogens - hydrogen peroxide, hydroxyl, nitric oxide etc
29
What is involved in the oxygen-independent pathway?
Lysozyme, lactoferrin/transferrin, cationic proteins (eg cathepsin), proteolytic and hydrolytic enzymes
30
How many serum proteins are in the complement pathway?
20
31
What is the alternative pathway of the complement system initiated by?
Cell surface microbial constituents (eg endotoxins on E. Coli)
32
What are C3a and C5a involved in?
Recruitment of phagocytes
33
What are C3b-C4b involved in?
Opsonisation of pathogens
34
What is C5-C9 involved in?
Killing of pathogens | Membrane Attack Complex
35
What is the MBL pathway of the complement system initiated by?
Initiated when MBL binds to mannose containing residues of proteins found on many microbes (eg Salmonella spp. , Candida albicans)
36
What could cause a decrease in neutrophil number?
Cancer chemotherapy, certain drugs (phenytoxin), leukaemia and lymphoma
37
What could cause a decrease in neutrophil function?
Chronic granulomatous disease (no respiratory burst) | Chediak-Higashi syndrome (no phagolysosome formation)