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Jason's GI Block > Neural/Hormonal control of GI > Flashcards

Neural/Hormonal control of GI Flashcards

1
Q

3 main ways GI prevents invasion of pathogens

A

epethelial barrier
stomach acid
largest immune system

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2
Q

microbiota of gut can be influenced by:

A

diet

nervous system

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3
Q

2 main goals of intestinal smooth muscle contractions:

A

mixing

propulsion

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4
Q

How to prevent dehydration in digestion?

A

reabsorption from lumen

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5
Q

Really bad antibiotic induced diarrhoea can be treated how?

A

faecal transplants

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6
Q

What are the local GI pace-maker cells?

A

interstitial cells of Cajal

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7
Q

What is GI endocrine system used to communicate with?

A

intestinal mucosa to brain/pancreas/gall bladder for appetite and secretion

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8
Q

What kind of nerves does the ENS have?

A

sensory
interneurons
motor

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9
Q

Where does the submucosal plexus lie? what does it control?

A

between submucosa and mucosa

control water and electrolyte secretion

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10
Q

What does ICC stand for?

A

interstitial cells of Cajal

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11
Q

95% of seretonin is made where?

A

within gut mucosa

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12
Q

what cells in the GI release histamine?

A

ECL cells

enterochromaffin cell-like cells

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13
Q

what are EE cells? what do they contain?

A

enteroendocrine cells

CCK, secretin, somatostatin, glucagon peptides

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14
Q

which cells release serotonin in the GI?

A

EC cels

enterochromaffin cells

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15
Q

Vago-Vagal reflex does what?

A

coordinate movement in upper GI

stomach secretion and movement

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16
Q

What is the intestino-intestinal reflex mediated by 3 things:

A

vagus
dorsal root ganglia/spinal cord
viscerofugal neurons

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17
Q

Does CNS have any influence on GI?

A

Yes, anticipation of food (cephalic phase of digestion)

mood such as fear and butterflies in stomach.

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18
Q

GI hormones excite what before entering the blood stream? how?

A

excite enteric and extrinsic sensory neurons via paracrine action

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19
Q

what modulates enteric neural circuits? 2 things

A

vagal

sympathetic input

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20
Q

Can the ICCs be modified?

A

Yes like the SA and AV nodes, neurons can adjust levels of excitation/inhibition

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21
Q

Appearance of food matter? example?

A

yes, changes how we experience it

red lollies are sweeter than green ones even with same amount of sugar in them

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22
Q

How does the cephalic phase of digestion operate via?

A

vagus nerve only

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23
Q

What does the cephalic phase of digestion do to the stomach?

A

salivation
gastric acid/pepsin secretion
relaxation of gastric corpus/fundus

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24
Q

acid secretion comes from which cells?

A

parietal cells

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25
Q

What 4 mediators help regulate stomach acid secretion?

A

ACh from ENS via vagus
Gastrin from G-cells
Histamine from ECL cells
Somatostatin

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26
Q

Where are G cells located predominantly?

A

antrum and duodenum

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27
Q

What does somatostatin do?

A

inhibit parietal and G cells

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28
Q

Where does somatostatin comes from? how stimulated?

A

D-cells stimulated by acid/gastrin in duodenum

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29
Q

what is Histamine in ECL cells inhibited by?

A

somatostatin from local D cells

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30
Q

peristalsis is controlled by which nerve?

A

entirely by vagus

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31
Q

If CNS is not working, can you get peristalsis?

A

yes ENS can activate secondary peristalsis

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32
Q

Lower oesophageal open or closed normally?

A

normally closed or else GORD

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33
Q

Stomach can distend how much?

A

3-4 times it’s size

34
Q

What does stomach distension activate? 3 things

A

enteric reflexes
vago-vagal reflexes
increased acid secretion

35
Q

What propels food from corpus to antrum to pylorus?

A

ICC (pacemaker cells)

36
Q

what happens to fat in the stomach?

A

separates out to fundus so it’s last to come out

37
Q

what is gastroparesis?

A

inability for pylorus to open effectively, life threatening for diabetics

38
Q

what is the order food coming out of stomach?

A

carbs>proteins>fat at end

39
Q

failure to neutralize acid in duodenum causes what?

A

peptic ulcer

40
Q

after acid in duodenum, D-cells do what?

A

release somatostatin to decrease parietal activity

41
Q

What does Brunner’s Glands release?

A

mucus and bicarbonate

42
Q

How are Brunner’s glands activated?

A

via vagal afferents: vago-vagal reflex

43
Q

two things inhibit gastric emptying once acid is detected in the duodenum, they are?

A

vagovagal reflex

duodenal-pyloro-antral reflex

44
Q

I cells secrete what?

A

CCK

45
Q

What does CCK do?2 things?

A

helps with vagovagal reflex

regulate appetite

46
Q

where does secretin come from? what does it release?

A

from S-cells

initiates bicarb secretions from pancreas

47
Q

neutralizing acid in duodenum inactivates two things:

A

pepsin

somatostatin from D-cells

48
Q

how do you uninhibit gastric emptying?

A

once secretin is released it terminated acid stimulated inhibition of gastric emptying

49
Q

what is retropulsion?

A

used by duodenum to push pancreatic juices up towards pyloris to get better mixing and neutralize pH

50
Q

CCK as a hormone causes what 3 main effects

A

gall bladder contractions
release enzymes from pancreas
satiety factor on hypothalamus

51
Q

2 ways CCK suppresses appetite:

A

vagal afferents

directly on hypothalamus

52
Q

can intestinal mucosa sense food texture?

A

yes, larger chunks of food detected will slow down propulsion

53
Q

EC and EE cells are not mechanosensitive?

A

False. some of the are

54
Q

What does fat and protein do to appetite in lean and obese people?

A

lean: suppresses
obese: won’t respond

55
Q

Enterochromaffin cells ‘taste’?

A

Yes, everything from bitter to umami and capsaicin

56
Q

EC cells release what after tastant activation?

A

serotonin

57
Q

what cells express components of sweet taste receptors?

A

L-Cells

58
Q

glucose or artificial sweeteners activates what?

A

tips of villi and will absorb more carbs.

59
Q

what is PYY?

A

pancreatic polypeptide Y

60
Q

Where is PYY found? what is it for?

A

in L-cells for appetite and insulin secretion

61
Q

once you pass duodenum which neural system takes over?

A

from vagus to enteric

62
Q

3 motor patterns are activated once food is in duodenum:

A

retropulsion
segmentation: local constrict/relax
peristalsis

63
Q

Which is slower? segmentation or peristalsis?

A

segmentation

64
Q

what determines efficacy of digestion and absorption?

A

rate of transit

65
Q

Fat emptying from stomach last does what?

A

surge of CCK to feel really full

66
Q

what makes contents more viscous as you pass from jejunum to colon?

A

absorption of water

67
Q

what happens in proximal colon?

A

fermentation by microbiome to create short chain fatty acids

68
Q

What is Hirschsprung’s disease?

A

babies without ENS

69
Q

what triggers urge to defaecate?

A

distension of rectum via sacral primary afferent neurons

70
Q

irritable bowel syndrome causes what to rectum?

A

reduced threshold and can detect faeces in rectum

71
Q

What moves faecal matter from colon to rectum?

A

mass movements

72
Q

do you need conscious activity to relax anal sphincter?

A

yes for normal defecation

73
Q

what is MMC?

A

migrating motor complex

74
Q

What does MMC do?

A

wave of constriction in antrum propagating to ileocolonic junction

75
Q

How many MMCs in the small intestine at once?

A

only one

76
Q

MMC does what to bacteria?

A

clears bacteria and cellular debris from an empty lumen?

77
Q

When does MMC occur?

A

in the fasted state

78
Q

how is MMC regulated?

A

neurally

79
Q

what does Ghrelin do? when released?

A

during fasted state
stims appetite
initiate MMC

80
Q

What does gastrin releasing peptide do? where is it found?

A

found near G cell nerve terminals

acts in parallel to vagally release acetylcholine

Jason's GI Block (32 decks)

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