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Gastro Yr 2 > Immunology of the gut > Flashcards

Immunology of the gut Flashcards

1
Q

SA of the GI tract?

A

200m2

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2
Q

What is included in the antigen load of the gut?

A

resident microbiota
dietary antigens
exposure to pathogens

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3
Q

What is restrained activation?

A

Gut has to balance tolerance vs active immune response

dual immunological role

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4
Q

Features of the gut microbiota

A

10^14 gut bacteria - most densely populated ecosystem on Earth
4 major phyla of bacteria + viruses/ fungi
Provide traits that we did not have to evolve on our own (defence/ digestion of certain compounds/ contribute to intestinal architecture)

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5
Q

what is dysbiosis

A

altered microbiota composition

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6
Q

what are symbionts

A

organisms that lives with hosts (no benefit or harm to either)

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7
Q

what are commensals

A

organisms that benefits from association but no effects on host

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8
Q

what are pathobionts

A

symbionts which have the potential to cause inflammation and disease under certain conditions

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9
Q

What affects equilibrium of the gut microbiota

A 
infection/ inflammation
diet
xenobiotics
hygiene
genetics
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10
Q

what are the mucosal defence of the gut?

A

physical barriers:
(anatomical) - epithelial barrier (mucosal layer by goblet cells + tight junctions) + peristalsis

(chemical) - enzymes + acidic pH

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11
Q

how do commensal bacteria protect

A

occupy ecological niche

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12
Q

immunological barrier

A

MALT - lymphoid ass containing follicles (surrounded by HEV postcapillary venules which allow easy passage of lymphocytes)
GALT - organised or non-organised and responsible for adaptive and innate immune responses (eg. peyer’s patches)

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13
Q

what does MALT stand for

A

mucosa associated lymphoid tissue

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14
Q

what does GALT stand for

A

gut associated lymphoid tissue

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15
Q

What is non organised GALT

A

Lamina propria - immune cells of intestine found there

lymphocyte dotted between enterocytes

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16
Q

what are peyer’s patches

A

Immune sensors
Found in submucosa of small intestine - organised collection of naive T and B cells (development requires exposure to bacterial microbiota)

17
Q

What is FAE

A

Peyer’s patched covered by follicle associated epithelium (no goblet cells/ microvilli) - job is to transfer things to the patches

18
Q

what are trans-epithelial dendritic cells

A

DC which can open tight junctions - sample bacteria and bring them back to mesenteric lymph nodes

19
Q

what is the B cell adaptive response

A

B cells express IgM in peyer’s patches and on antigen presentation - switch to IgA (B cells mature to become IgA secreting cells)
- antibodies then populate lamina propria for defence

20
Q

what is lymphocyte homing

A

mesenteric lymph node

21
Q

what is the life span of enterocytes/ goblet cells

A

36 hrs

22
Q

Why do GI cells have a short turnover

A

first line of defence against GI pathogens

So any lesions will be short lived due to high turnover

23
Q

what is cholera

A

bacterial infection caused by serogroups O1 and O139

Bacteria reaches small intestine + releases cholera enterotoxin

24
Q

mechanism of cholera

A

Severe dehydration + diarrhoea (cholera toxin activated cAMP which causes release of excretion of salts and water follows)

25
Q

what is rotavirus

A

RNA virus - replicate in enterocytes
Type A is most common type from A-E
Most common cause of diarrhoea in infants worldwide

26
Q

what is norovirus

A

RNA virus
Individuals can remain infectious for up to weeks
Acute gastroenteritis
(cause for outbreaks in closed communities)

27
Q

How to treat rotavirus

A

oral rehydration therapy

28
Q

What is caused by campylobacter ‘curved bacteria’

A

food poisoning
transmission through undercooked meat/ unpasteurised milk/ untreated water
- treat with erythromycin

29
Q

what is caused by e.coli

A

diverse group of gram-neg bacteria (most harmless)

6 pathotypes cause diarrhoea

30
Q

which type of e.coli causes kidney damage

A

Shiga toxin-producing E. coli (STEC)

31
Q

how does C. Diff. cause disease

A

Taking antibiotics causes dysbiosis

C. Diff. leads to inflammation + disease due to disturbance of gut microbiota

Gastro Yr 2 (7 decks)

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