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