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emma gi > GI Motility, Stomach Physio > Flashcards

GI Motility, Stomach Physio Flashcards

1
Q

7 sphincters

A
  • UES
  • LES
  • pyloric
  • oddi
  • ileocecal
  • internal anal
  • external anal
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2
Q

parasympathetic NS acts thru _________ to stim enteric NS activity

A

dorsal motor nucleus of vagus nerve

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3
Q

ACh

A 
excitatory 
smc contraction
intestinal secretions
enteric hormone release
blood vessel dilation
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4
Q

NE

A

inhibitory
extrinsic sympathetic neurons
opposite effect of ACh

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5
Q

myenteric plexus

A

between longitudinal and circular layers of m. in tunica musclularis

exerts control over digestive tract motility

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6
Q

submucous plexus

A

buried in submucosa

principal role = senses envious w/i lumen (regulates blood flow and epithelial cell function)

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7
Q

equivalent of Z-lines in smc

A

dense bodies, points of attachment for myofilaments

single-unit muscle cells contract as a single unit bc electrically linked by gap junctions

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8
Q

interstitial cells of cajal

A

intestinal wall, between longitudinal and circular layers of muscular externa

transmission of info from enteric neurons to smc

PACEMAKER cells, have capacity to generate basic electrical rhythm (slow wave activity)

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9
Q

esophageal achalasia

A

motor disorder characterized by complete loss of contraction and relaxation of m. used to move contents down esophagus

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10
Q

paraesophageal hernia

A

stomach protrudes thru diaphragm into chest alongside esophagus

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11
Q

negative regulators of esophageal smc (relax)

A

VIP (vasoactive intestinal polypeptide)

Nitric oxide

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12
Q

positive regulators of esophageal smc (contraction)

A

ACh

Substance P

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13
Q

ileocecal valve

A
  • joining point between lg and small intestines

- controls flow and retains contents of colon (gut microbiota)

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14
Q

primary movements in colon

A

haustral contractions and mass movements, mostly in ascending and transverse colon

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15
Q

haustral contactions

A

colon

slow, about every 30 mins, last approx 1 in

stim by stretch

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16
Q

mass movements

A

colon

slow, powerful contractions

move over colon 3-4x daily, typically after meals

stim by GASTRIN release when stomach receives food

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17
Q

stomach functions

A
  • reservoir
  • food mixing
  • kneeding of food
  • metered emptying in response to duodenal feedback
  • vomit
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18
Q

stomach secretions

A 
H+ 
Pepsinogens/pepsin
Mucus
Intrinsic factor
Water
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19
Q

converts pepsinogen –> pepsin

A

H+

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20
Q

kills microbes, denatures protein

secreted prod of stomach

A

H+

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21
Q

enterochromaffin-like cell

A

histamine secretion

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22
Q

parietal cells

A

acid, intrinsic factor secretion

23
Q

chief cells

A

pepsinogen secretion

gastric lipase secretion

24
Q

cell surface pH of gastric mucosal barrier

A

~7

25
Q

pH of gastric juice

A

1-2

26
Q

agents that disrupt gastric mucosal barrier

A 
weak acids (aspirin)
alcohols (EtOH)
NSAIDs (indomethacin)
detergents (bile salt/acids)
inflammation (H. pylori)
27
Q

most common cause of gastritis and peptic ulcer disease

A

H. pylori infection

28
Q

breakage of gastric mucosal barrier allows back diffusion of

A

H+ (damages tissue)

29
Q

____ strongly increases vascular permeability

A

HISTAMINE

30
Q

gastrin hormone MOA

A

endocrine, secretion

31
Q

gastrin releasing peptide MOA

A

neurocrine, action potential

32
Q

histamine MOA

A

paracrine, diffusion

33
Q

gastric mucosa cells produce _____ hormones

A

peptide

34
Q

Gastrin

A

prod by G cells, Antrum of stomach,

target parietal cell in stomach

stim acid secretion
stim pepsinogen secretion

35
Q

Somatostatin

A

prod by D cells

inhibits gastrin release

36
Q

cell source of gastrin releasing peptide

A

vagal nerve endings

*neurocrine not hormone

37
Q

CCK

A

source: duodenum and jejunum
target: pancreas and gallbladder

inc enzyme secretion, contraction

38
Q

secretin

A

source: duodenum
target: pancreas and gallbladder

inc HCO3- and fluid secretion by pancreatic and bile ducts

39
Q

gastrin releasing peptide

target/action

A

target: antrum

inc gastrin release

40
Q

somatostatin

A

source: stomach and duodenum
target: stomach, pancreas, liver

dec gastrin release, dec endocrine and exocrine secretions, dec bile flow

41
Q

gastrin inhibitory peptide

A

source: duodenum and jejunum
target: pancreas
action: dec fluid absorption

42
Q

site of B12 absorption

A

distal ileum

43
Q

cephalic phase

A

everything short of having food enter stomach

44
Q

2 paths by which vagus nerve exerts its effects

A

direct stim by ACh

indirect through gastrin

45
Q

gastric phase

A
  1. dissension of stomach –> activates stretch receptors and inc in pH –> chemoreceptors in mucosa

=mucin, lots of acid, pepsinogen are secreted.

  1. enteric NS + gastrin release –> smc contraction
46
Q

bulk of protein digestion occurs in the

A

SI

47
Q

resting pH of sotmach

A

1-2

48
Q

stimulated pH of stomach

A

> /=3

49
Q

H2 receptor blockers and PPIs reduce ___ secretion but have no effect on ___ production/action

A

H2 receptor blockers and PPIs reduce [H+] secretion but have no effect on [GASTRIN] production/action

50
Q

majority of chyme entering SI is ____mm

A

<1mm

51
Q

CCK and GIP are activated by the presence of

A

lipids and carbs

52
Q

secretin is activated by

A

dec pH

53
Q

intestinal phase

A

digestive prod and H+ move into SI

–> release of CCK, GIP, secretin (inhibit H+, pepsinogen, and stomach mixing, slow passage of chyme to SI which may be filled/overactive)

54
Q

duodenal stretch and chemoreceptors action on myenteric plexus

A

inhibition

emma gi (18 decks)

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