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Gastrointestinal > Benefits & Mischiefs from Normal Microbiota 1 > Flashcards

Benefits & Mischiefs from Normal Microbiota 1 Flashcards

1
Q

Which type of bacteria is predominant in the gut?

A

gram negative bacteria

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2
Q

Are the bacteria in the gut predominantly aerobes or anaerobes?

A

anaerobes

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3
Q

In which part of the gut is most of the microbiota?

A

The colon

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4
Q

What are the most common aerobic microbiota in the gut?

A

staphylococcus, streptococcus, lactobacillus, enterobacteriaciae

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5
Q

What are the most common anaerobic microbiota in the gut?

A

bacteriodes, streptococcus, bifidobacterium, clostridium

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6
Q

What are the four main phyla in the gut?

A

Mostly bacteriodetes, firmicutes with some actinobacteria and few proteobacteria

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7
Q

What do the genes of the microbiota contribute to?

A

metabolic activity, development, immune system function and protection against pathogens

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8
Q

What factors influence gut microbiota?

A

mode of delivery (vaginal vs caesarian), age, diet, antibiotics, genetics, environment, chronic inflammation

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9
Q

Which phyla of bacteria is most prominent in the microbiota in the first few years of life?

A

fermicutes

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10
Q

At what age will there be sufficient microbiota to utilise plant base products?

A

a few months

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11
Q

At what age is the microbiota the same that it will be throughout the rest of life/

A

2.5 years

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12
Q

What diet changes affect microbiota?

A

changing from a high fat/low fibre diet to a low fat/high fibre diet

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13
Q

What will happen to the microbiota on an animal based diet?

A

There will be an increase in bile tolerant bacteria such as bacteroides

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14
Q

What will happen to the microbiota on an iron free diet?

A

There will be an increase in bifidobacterium and clostridium and a decrease in bacteroides

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15
Q

What happens to microbiota after antibiotic treatment?

A

It goes back to normal

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16
Q

Which antibiotic may effect the microbiota so that it doesn’t go back to normal after treatment is stopped?

A

vancomycin

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17
Q

What role does microbiota have in providing nutrition?

A

Directly supplying nutrients as well as altering metabolic machinery by inducing changes in genes and maintaining enterocyte differentiation

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18
Q

How do microbiota help with the metabolism of carbohydrates?

A

They break lactose and cellulose down into short chain fatty acids

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19
Q

Which vitamins are absorbed with the help of microbiota?

A

vitamin B2, vitamin K, biotin, folate

20
Q

How do microbiota help break down bile acids?

A

By dehydroxylation which then allows reabsorption back into the liver

21
Q

Which amino acids particularly need the help of microbiota?

A

lysine and threonine are broken down to urea

22
Q

Why is important that bacteria degrades host glycans (such as mucin)?

A

Because it induces synthesis

23
Q

What are some functions of short chain fatty acids as a product of metabolism by bacteria?

A

they maintain entrocyte differentiation and alter host genes to maintain angiogenesis

24
Q

What are the main short chain fatty acids?

A

acetate, propionate and butyrate

25
Q

How is butyrate an energy source?

A

it is absorbed by the colon and is an energy source for colonic epithelial cells

26
Q

How is acetate and propionate an energy source?

A

They are transported to the liver where they are substrates for gluconeogenesis and lipogenesis

27
Q

What enzyme is inhibited by short chain fatty acids?

A

histone deacetylase

28
Q

Which antibody is most common in the gut MALT?

A

IgA

29
Q

What are Peyer’s patches and isolated lymphoid follicles (ILFs)?

A

aggregates of lymphoid tissue in the small and large intestine - they are the site of induction of T and B cell activation

30
Q

What is the immune function of enterocytes?

A

secretes cytokines, chemokines ant anti-microbial peptides

31
Q

What is the immune function of goblet cells?

A

Secrete mucins, lysozyme and lactoferin

32
Q

What is the immune function of paneth cells?

A

secrete defensins

33
Q

What are IELs?

A

intra epithelial lymphocytes - these are non conventional lymphocytes

34
Q

What are the innate defences of the gut?

A

peristalsis, acid, mucus, enterocyte barrier, antimicrobial factors, cytokines and chemokines, innate leukocytes

35
Q

What are ILCs?

A

Innate lymphoid cells - including LTis, IELs, NK cells, MAIT cells, invariant NKT cells and macrophages

36
Q

What are LTis?

A

lymphoid tissue inducer cells - stimulate recruitment of dendritic cells, T and B cells to Peyer’s patches and isolate lymphoid follicles

37
Q

What is the function of IL-22?

A

enhances antimicrobial defence, epithelial repair and barrier integrity

38
Q

What cells produce IL-22?

A

NK cells and IELs and MAIT cells

39
Q

What are MAIT cells?

A

mucosal associated invariant T cells - unknown function

40
Q

Why are macrophages in the gut harder to stimulate?

A

Because they have lower amounts of TLRs and PRRs

41
Q

What is an M cell?

A

The cell located directly over the site of organised lymphoid aggregates to deliver antigens directly to these cells

42
Q

What are the features of M cells?

A

a folded luminal surface (no villi) and a thick glycocalyx (no mucus)

43
Q

What are the two ways that dendritic cells sample antigens from the mucosa?

A

directly or indirectly via goblet cells and M cells

44
Q

Under normal conditions what type of T cell differentiation do dendritic cells produce?

A

Treg and Th2

45
Q

Under inflammatory conditions what type of T cell differentiation do dendritic cells produce?

A

Th1 and Th17

46
Q

How do B and T cells find their way back to the gut?

A

because they are induced to express mucosal addressin alpha4beta7 which binds to the mucosal endothelial integrin MAdCAM1

47
Q

What is the role of IELs?

A

eliminated damaged enterocytes

Gastrointestinal (40 decks)

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