Microbiota 1 Flashcards Preview

Jason's GI Block > Microbiota 1 > Flashcards

Flashcards in Microbiota 1 Deck (64):
1

how many commensals in/on us?

1-2kg

2

microbiome provides us with extra source of?

genes

3

humans and microbiota are known as:

mutualists

4

how many bacteria in microbiota?

10^14

5

how many species of bacteria on us?

1000

6

majority of bacteria use oxygen?

99.9% are anaerobes

7

Gram what in
Throat and skin
Gut
Vaginal?

Throat/ skin: +ve
gut: -ve
vaginal: +ve

8

4 main bacteria phyla from most to least

1. bacteroides
2. firmicutes (clostridia, mollicutes)
3. actinobacteria
4. proteobacteria (E.coli)

9

each body site has low or high diversity of microbiota?

high

10

twins have the same microbiota?

share <50% of bacterial species

11

microbiota unstable in host?

stable but influenced by determinants

12

4 things microbiota contribute to:

metabolism (cellulose)
development
immunity
protection

13

6 factors that influence gut microbiota?

mode of delivery
age (more diversity with age)
diet (breast milk)
antibiotics
genetics/environment (rural vs. city)
chronic inflammation

14

vaginal birth associated with rapid acquisition of?

Firmicutes Bifidobacteria

15

animal based diets do what to microbiota?

decrease plant metabolizing bacteria, more bile-tolerant bacteria

16

what does iron do to mice microbiota?

more bacteroides
less bifidobacteria

17

does microbiota of mice treated with amoxicillin/metronidazole and bismuth recover?

yes

18

which antibiotic do you not recover your diversity of microbiota?

vancomysin

19

microbiota provides how much calories?

10% of calories from plant CHO

20

microbiota in nutrition does 2 things to help us

1. change our genes for CHO/lipid metabolism
2. maintain enterocyte differentiation/function

21

microbiota taxa varied by site, what remained stable?

metabolic pathways eg. 16S rRNA

22

what vitamins do microbiota make for us?

vitamin B12, K
biotin
folate

23

what happens to bile acid in the gut?

microbiota break it down to desoxycholic acid to reabsorb back into liver

24

what happens to amino acids in gut?

nitrogen recycling from lysine and threonine

25

what does bacterial degradation of host glycans do?

elicits synthesis of new glycans by host

26

how does microbiota maintain enterocyte differentiation

from production of short chain fatty acids from fibre

27

is angiogenesis affected by microbiota?

yes

28

describe the metabolism path of dietary fibre:

broken into monosaccharides>fermented into SCFAs>absorbed by colon>reaches liver>substrates for gluconeogenesis/lipgenesis

29

how do the colonic epithelial cells get their energy?

from fermented and absorbed SCFAs

30

SCFAs do more than just be energy source, explain:

control colonic gene expression via HDAC inhibition and GPCR signal regulation

31

mucosal immune systemis closely associated with?

intestinal microbiota

32

what is MALT?

mucosa-associated lymphoid tissue

33

SI covers how many square metres? so what?

400m2, big antigenic challenge, which is why it has the largest collection of lymphoid tissue

34

2 big things the MALT must be able to do

protection from pathogens (IgA)
tolerance to normal microbiota/food

35

what is ILFs? where are they found?

isolated lymphoid follicles in large/small intestine

36

where are Peyers patches? what happens there?

small intestine
induction of T, B Cells

37

enterocytes secrete what cytokines?

TGF-B, chemokines, anti-microbial peptides

38

what is lactoferrin? where does it come from on the small intestine?

on villus
from Goblet cells
inhibits bacteria growth

39

Paneth cells do what?

secrete defensins

40

what immune cells are in the lamina propria of the small intestine?

Intraepithelial lymphocytes (IEL)

41

2 kinds of Intraepithelial lymphocytes in the villus?

nonconventional lymphocytes
innate lymphocytes

42

what two cells in the small intestine play a role in tolerance?

enterocytes
IEL (intraepithelial lymphocytes)

43

3 innate defences of gut?

peristaltic (flushing) action
acid
mucous layer to hold commensals at 'arms length'

44

Describe the 3 innate defensive roles of enterocytes

1. barrier: integrity is critical tight junctions
2. antimicrobial factors
3. cytokines/chemokines

45

What is a mechanism for controlled antigen access?

M Cells/ dendritic cells

46

innate leucocytes include:

lymphocytes
macrophages

47

What are ILCs? what do they do?

innate lymphoid cells
secrete cytokines

48

what does IL-17, IL-22 do?

recruits and activates neutrophils

49

What does lymphoid tissue inducer cells do?

stim DC, T, B cells, PPs, ILFs

50

what cytokine does IELs secrete?

IL-22

51

what does IL-22 do?3 things

enhances antimicrobe defence
epithelial repair
barrier integrity

52

What are MAIT cells? what do they do?

mucosal associated invariant T cells
rapid response to bacterial antigen

53

what do invariant NKT cells do?

secrete pro-inflamm cytokines like IL-22

54

M cell stands for? where is it?

microfold cell
directly over the lymphoid aggregates (PPs, ILFs isolated lymphoid follicles)

55

villi on M cells?

Nope
folded luminal surface

56

M-cell secrete mucous? why?

does not
microbial access easier

57

DCs are located directly below the M-cell, how do they sample? 2 ways:

directly (tentacle into lumen)
indirectly (via goblet/M-cells

58

TGF-B stands for?

transforming growth factor

59

tell me what DCs do in:
1. steady state
2. inflamm state

1. induce Tregs/TGF-B
2. induce Th1/Th17

60

DCs bias what immunoglobulin from B-cells?

Isotype switching to IgA

61

inducing mucosal addressin a4B7 on T/B cells does what?

1. allows to bind to MAdCAM1 on mucosal surfaces
2. also gives chemokine receptors specific for lamina propria

62

a4B7 activated T/Bcells are found where?

distributed through all mucosal surfaces

63

IELs do what to enterocytes?

may eliminate damaged ones

64

what happens in MALT?

stimulation
suppression
of immune cells