Neural/Hormonal control of GI Flashcards Preview

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

Flashcards in Neural/Hormonal control of GI Deck (80):
1

3 main ways GI prevents invasion of pathogens

epethelial barrier
stomach acid
largest immune system

2

microbiota of gut can be influenced by:

diet
nervous system

3

2 main goals of intestinal smooth muscle contractions:

mixing
propulsion

4

How to prevent dehydration in digestion?

reabsorption from lumen

5

Really bad antibiotic induced diarrhoea can be treated how?

faecal transplants

6

What are the local GI pace-maker cells?

interstitial cells of Cajal

7

What is GI endocrine system used to communicate with?

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

8

What kind of nerves does the ENS have?

sensory
interneurons
motor

9

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

between submucosa and mucosa
control water and electrolyte secretion

10

What does ICC stand for?

interstitial cells of Cajal

11

95% of seretonin is made where?

within gut mucosa

12

what cells in the GI release histamine?

ECL cells
enterochromaffin cell-like cells

13

what are EE cells? what do they contain?

enteroendocrine cells
CCK, secretin, somatostatin, glucagon peptides

14

which cells release serotonin in the GI?

EC cels
enterochromaffin cells

15

Vago-Vagal reflex does what?

coordinate movement in upper GI
stomach secretion and movement

16

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

vagus
dorsal root ganglia/spinal cord
viscerofugal neurons

17

Does CNS have any influence on GI?

Yes, anticipation of food (cephalic phase of digestion)
mood such as fear and butterflies in stomach.

18

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

excite enteric and extrinsic sensory neurons via paracrine action

19

what modulates enteric neural circuits? 2 things

vagal
sympathetic input

20

Can the ICCs be modified?

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

21

Appearance of food matter? example?

yes, changes how we experience it
red lollies are sweeter than green ones even with same amount of sugar in them

22

How does the cephalic phase of digestion operate via?

vagus nerve only

23

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

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

24

acid secretion comes from which cells?

parietal cells

25

What 4 mediators help regulate stomach acid secretion?

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

26

Where are G cells located predominantly?

antrum and duodenum

27

What does somatostatin do?

inhibit parietal and G cells

28

Where does somatostatin comes from? how stimulated?

D-cells stimulated by acid/gastrin in duodenum

29

what is Histamine in ECL cells inhibited by?

somatostatin from local D cells

30

peristalsis is controlled by which nerve?

entirely by vagus

31

If CNS is not working, can you get peristalsis?

yes ENS can activate secondary peristalsis

32

Lower oesophageal open or closed normally?

normally closed or else GORD

33

Stomach can distend how much?

3-4 times it's size

34

What does stomach distension activate? 3 things

enteric reflexes
vago-vagal reflexes
increased acid secretion

35

What propels food from corpus to antrum to pylorus?

ICC (pacemaker cells)

36

what happens to fat in the stomach?

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

37

what is gastroparesis?

inability for pylorus to open effectively, life threatening for diabetics

38

what is the order food coming out of stomach?

carbs>proteins>fat at end

39

failure to neutralize acid in duodenum causes what?

peptic ulcer

40

after acid in duodenum, D-cells do what?

release somatostatin to decrease parietal activity

41

What does Brunner's Glands release?

mucus and bicarbonate

42

How are Brunner's glands activated?

via vagal afferents: vago-vagal reflex

43

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

vagovagal reflex
duodenal-pyloro-antral reflex

44

I cells secrete what?

CCK

45

What does CCK do?2 things?

helps with vagovagal reflex
regulate appetite

46

where does secretin come from? what does it release?

from S-cells
initiates bicarb secretions from pancreas

47

neutralizing acid in duodenum inactivates two things:

pepsin
somatostatin from D-cells

48

how do you uninhibit gastric emptying?

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

49

what is retropulsion?

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

50

CCK as a hormone causes what 3 main effects

gall bladder contractions
release enzymes from pancreas
satiety factor on hypothalamus

51

2 ways CCK suppresses appetite:

vagal afferents
directly on hypothalamus

52

can intestinal mucosa sense food texture?

yes, larger chunks of food detected will slow down propulsion

53

EC and EE cells are not mechanosensitive?

False. some of the are

54

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

lean: suppresses
obese: won't respond

55

Enterochromaffin cells 'taste'?

Yes, everything from bitter to umami and capsaicin

56

EC cells release what after tastant activation?

serotonin

57

what cells express components of sweet taste receptors?

L-Cells

58

glucose or artificial sweeteners activates what?

tips of villi and will absorb more carbs.

59

what is PYY?

pancreatic polypeptide Y

60

Where is PYY found? what is it for?

in L-cells for appetite and insulin secretion

61

once you pass duodenum which neural system takes over?

from vagus to enteric

62

3 motor patterns are activated once food is in duodenum:

retropulsion
segmentation: local constrict/relax
peristalsis

63

Which is slower? segmentation or peristalsis?

segmentation

64

what determines efficacy of digestion and absorption?

rate of transit

65

Fat emptying from stomach last does what?

surge of CCK to feel really full

66

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

absorption of water

67

what happens in proximal colon?

fermentation by microbiome to create short chain fatty acids

68

What is Hirschsprung's disease?

babies without ENS

69

what triggers urge to defaecate?

distension of rectum via sacral primary afferent neurons

70

irritable bowel syndrome causes what to rectum?

reduced threshold and can detect faeces in rectum

71

What moves faecal matter from colon to rectum?

mass movements

72

do you need conscious activity to relax anal sphincter?

yes for normal defecation

73

what is MMC?

migrating motor complex

74

What does MMC do?

wave of constriction in antrum propagating to ileocolonic junction

75

How many MMCs in the small intestine at once?

only one

76

MMC does what to bacteria?

clears bacteria and cellular debris from an empty lumen?

77

When does MMC occur?

in the fasted state

78

how is MMC regulated?

neurally

79

what does Ghrelin do? when released?

during fasted state
stims appetite
initiate MMC

80

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

found near G cell nerve terminals
acts in parallel to vagally release acetylcholine