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Gastrointestinal DF > Intro to GI physiology > Flashcards

Intro to GI physiology Flashcards

1
Q

sympathetic innervation of GI that is different from parasympathetic

A

sympathetic can synapse on myenteric plexus or directly on motor neurons that innervate muscle or on secretory neurons that secrete

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2
Q

vago-vagal reflex tract

A

vagus sensory afferents in digestive track (nodose ganglion) send info to nucleus of tractus solitaries (NTS) synapses here then sends efferents through vagus nerve back to digestive tract

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3
Q

paracrine signaling includes what molecules and what cells release them

A

somatostatin and histamine

enteroendocrine cells

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4
Q 
somatostatin:
secreted by what cells
Stimuli
actions
where else secreted
A
  • D cells of GI mucosa
  • stimuli: decreased pH in the lumen
  • actions: decrease gastric H+ secretion and inhibits secretion of other GI hormones
  • Secreted in hypothalamus and delta cells of exocrine pancreas
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5
Q

Histamine is secreted by what cells

A

enterochromaffin-like cells in gastric glands (ECL)

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6
Q

target and action of histamine

A

parietal cells to secrete acid production

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7
Q

how do hormones get to specific receptor

A
  • enteroendocrine cells have secretary granules filled with hormone peptides that are released upon stimulation
  • secreted into portal circulation, pass through liver, and go to systemic circulation
  • bind to specific receptors on target cell
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8
Q

criteria to be a hormone

A

1) substance must be secreted in response to physiologic stimulus and carried in bloodstream to distant site
2) function must be independent of neural activity
3) must have been isolated, purified, chemically identified, and synthesized

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9
Q

Gastrin:
site of secretion
Stimuli of secretion

A
  • G cells of the antrum of stomach

- small peptides and aa, distension of the stomach, vagal stimulation via GRP

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10
Q

CCK
site of secretion
stimuli of secretion

A

site is I cells of duodenum and jejunum

small peptides and aa, fatty acids

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11
Q

secretin:
site of secretion
stimuli of secretion

A

S cells of duodenum

fatty acids in duodenum, and H+ in duodenum

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12
Q

Glucose-dependent insulinotropic peptide

A

duodenum and jejunum

oral glucose, aa, fatty acids

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13
Q

Gastrin actions

A

parietal cells secretion of gastric acid

stimulates growth of gastric mucosa

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14
Q

Zollinger-Ellison syndrome

A

increase gastrin and H+ from parietal cells

  • hypertrophy of gastric mucosa
  • duodenal ulcers
  • steatorrhea
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15
Q

steatorrhea

A

from gastrin-secreting tumors: increased H+ secretion results in acidification of intestinal lumen, so pancreatic lipase inactive so fat not absorbed so its excreted in stool

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16
Q

CCK actions

A

HCO3- pancreatic bicarb secretion potentiation (w/secretin)
Exocrine pancreas and gallbladder growth
Pancreatic enzyme secretion
Inhibits gastric emptying
contraction of gallbladder and relaxation of sphincter of oddi

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17
Q

Secretin actions

A

pancreatic and biliary HCO3- secretion
decrease gastric H+ secretion
inhibits trophic effect of gastrin on gastric mucosa

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18
Q

GIP is secreted by what cells?

A

K cells of duodenal and jejunal mucosa in response to FA,aa,glucose

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19
Q

GIP actions

A
  • increase insulin secretion from pancreatic B cells

- decrease gastric H+ secretion

20
Q

vasoactive intestinal peptide source

A

neurons of mucosa and SM

21
Q

gastrin releasing peptide source

A

neurons from gastric mucosa

22
Q

enkephalins source

A

neurons of mucosa and SM

23
Q

NPY source

A

neurons of mucosa and SM

24
Q

substance P source

A

Co-release with ACh

25
Q

Ach action

A
  • contraction of SM
  • relaxation of sphincters
  • increased salivary secretion
  • increased gastric secretion
  • increased pancreatic secretion
26
Q

Norepinephrine actions

A

relaxation of SM
contraction of sphincters
increased salivary secretion

27
Q

VIP action

A

relaxation of SM
increased intestinal secretion
increased pancreatic secretion

28
Q

Gastrin-releasing peptide (GRP) action

A

increased gastrin secretion

29
Q

enkephalins actions

A
  • contraction of SM

- increased intestinal secretion

30
Q

NPY actions

A

relaxation of SM

increased intestinal secretion

31
Q

substance P action

A

conctraction of SM

increased salivary secretion

32
Q

satiety center is located in which nucleus?

A

ventromedial nucleus

33
Q

feeding center is located where?

A

lateral nucleus

34
Q

integrative center btwn feeding and satiety

A

arcuate nucleus

35
Q

a-melanocortin (a-MSH) pathway

A
  • a-MSH released by POMC neurons
  • a-MSH binds to MCR-4 present in second order neurons
  • inhibits food intake and increases metabolism (anorexigenic)
36
Q

neuropeptide y pathway

A

hunger stimulates release NPY
NPY binds Y1R
neurons that release NPY also release AGRP which antagonizes MCR-4
=
increase feeding behavior and storage of calories (orexigenic)

37
Q

cases of obesity have been related to mutations in the ___ and ___ genes

A

POMC and MCR-4

38
Q

ghrelin

A

secreted by endocrine cells in stomach
binds to growth hormone secretagogue receptors
in hyoothalamus it stimulates neurons that release NPY

39
Q

other actions of ghrelin

A

increases appetite, gastric motility, gastric acid secretion, adipogenesis

40
Q

insulin binds

A

to receptors in satiety and hunger centers within hypothalamus

41
Q

insulin inhibits and stimulates

A

inhibits NPY

stimulates POMC

42
Q

insulin actions

A

decrease appetite and increase metabolism

43
Q

CCK elicits ___

decreases what and increases what

A 
satiety
acts on vagal-->NTS-->hypothalamus circuit
-decreases ghrelin
decreases gastric emptying 
increases gastric distension
44
Q

PYY binds

A

Y2 receptors of hypothalamus and inhibits NPY, releases inhib of POMC
potential as appetite suppressor

45
Q

Leptin is secreted by what cells

A

adipose tissue and by endocrine cells in stomach

46
Q

leptin binds to what

A

POMC and NPY, stimulates POMC inhibits NPY

47
Q

leptin increase and decrease

A

increase metab

decrease ghrelin and appetite

Gastrointestinal DF (14 decks)

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