B5-094 GI Physiology I Flashcards

1
Q

major spinchters of the GI tract

5

A
  • upper esophageal
  • lower esophageal
  • pyloric
  • ileocecal
  • internal and external anal spinchters
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2
Q

from I cells in duodenum and jejunum and neurons in ileum and colon

A

CCK

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3
Q

increases enzyme secretion from pancreas

A

CCK

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4
Q

increases gallbladder contraction

A

CCK

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5
Q

released from K cells in duodenum and jejunum

A

GIP

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6
Q
  • decreases fluid absorption in pancreas (exocrine)
  • increases insulin release from pancreas (endocrine)
A

GIP

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7
Q

released from G cells in the antrum of stomach

A

gastrin

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8
Q

increases H+ secretion via the parietal cells in the body of the stomach

A

gastrin

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9
Q

released from vagal nerve endings

A

GRP

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10
Q

increases gastrin release from the G cells in antrum of stomach

A

GRP

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11
Q

released from endocrine cells in the upper GI tract

A

motilin

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12
Q

increases smooth muscle contraction of esophageal spinchters, stomach, duodenum

A

motilin

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13
Q

released from S cells in small intestine

A

secretin

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14
Q

increases HCO3- and fluid secretions by pancreatic ducts

A

secretin

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15
Q

decreases gastric acid secretion in stomach

A

secretin

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16
Q

released by D cells of stomach and duodenum, pancreatic islet cells

A

somatostatin

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17
Q

inhibits gastrin release

A

somtatostatin

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18
Q
  • increases fluid absorption, decreases secretion
  • increases smooth muscle contraction in small intestine
A

somatostatin

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19
Q

decreases pancreatic secretions

A

somatostatin

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20
Q

decreases bile flow from liver

A

somatostatin

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21
Q

released from L cells in ileum and large intestine

A

GLP-1

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22
Q

reduces gastric empyting, gastric acid secretion, and gastric motility

A

GLP-1

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23
Q

released from ENS neurons

A

VIP

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24
Q

increases smooth muscle relaxation and secretion in small intestine

A

VIP

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25
Q

increases secretions from pancreas

A

VIP

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26
Q

produced in antrum, duodenum, and jejunum

A

gastrin

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27
Q

produced in duodenum, jejunum, and ileum

2

A

CCK
secretin

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28
Q

produced in duodenum and jejunum

2

A

GIP
motilin

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29
Q

what pattern of motility moves material orally and aborally?

A

isolated contraction

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30
Q

what pattern of GI motility mixes material?

A

segmentation

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31
Q

what pattern of GI motility requires coordinated contraction and relaxation to move the material aborally?

A

peristalsis

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32
Q

describe the peristaltic reflex

A
  1. distension is sensed by intrinsic afferent neurons
  2. stimulate interneurons to contract proximal to bolus through excitatory neurons
  3. intrinsic afferent neurons inhibit the segment distal to the bolus causing relaxation
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33
Q

stimulate muscles of the enteric nervous system to contract

A

Ach

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34
Q

stimulates muscles of the enteric nervous system to relax

2

A

VIP
NO

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35
Q

describe movement of food through the pharynx and upper esophagus during swallowing

A
  1. tongue pushes food to back of mouth
  2. soft palate blocks nasal passage
  3. epiglottis covers the glottis
  4. bolus descends into esophagus
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36
Q

generally describe the vagovagal reflex

A

afferent (sensory) -> hindbrain -> efferent (motor)

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37
Q

function to coordinate chewing, salivation, swallowing

control digestive processes in oral cavity

A

mechanoreceptors

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38
Q

decreasing […] pressure helps to move the food bolus down the esophagus during primary peristalsis

A

luminal pressure

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39
Q

mechanosensory control of the esophagus regulates

3

A
  • peristalsis
  • spinchter tone
  • gastric compensation
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40
Q

allows for the expansion of the stomach by food, without changing intraluminal pressure

A

compensation

requires vagal innervation

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41
Q

compenstation of the stomach requires […] innervation

A

vagal

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42
Q

bolus […] impacts the rate of gastric empyting

A

composition

oleate>acid>saline

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43
Q

describe the mechanical actions of the stomach on its contents

A
  1. propulsion: bolus pushed toward closed pylorus
  2. grinding: antrum chruns the trapped material
  3. retropulsion: bolus pushed back into the proximal stomach
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44
Q

[…] innervation is required for gastric empyting

A

vagal

45
Q

migrating motor complexes (MMCs) are activated by […] and regulated by […]

A

motilin
food/energy content

46
Q

Phase I MMC

A

quiescent
stomach is digesting and churning

47
Q

Phase II MMC

A

small, irregular contractions
as motilin is secreted in duodenum

48
Q

Phase III MMC

A

5 minutes of strong, regular contractions
migrated down small intestine into colon

49
Q

the phases of MMCs repeat until

A

food has left duodenum

no more motilin being secreted

50
Q

what reflexes power the propulsions of the colon?

2

A

gastrocolic
duodenocolic

51
Q

what reflex relaxes the internal anal spinchter?

A

rectoanal reflex

52
Q

reflexes of defecation

3

A
  • gastrocolic
  • duodenocolic
  • rectoanal
53
Q

describe the pressure changes occuring in rectal distension

A
  1. if passive distension of the rectum is sufficiently large, it triggers active contraction of the rectal smooth muscles
  2. passive rectal distension also triggers relaxation of the internal anal spinchter
  3. if defecation is not desired, the skeletal muscle of the external anal spinchter contracts by voluntary reflex
54
Q

describe the difference between a resting and stimulated parietal cell

A
  1. Resting: tubulovesicles
  2. Active: tubulovesicles fuse to form canaliculi, creating far more surface area to secrete H+
55
Q

H+ is produced by what enzyme in the parietal cell?

A

carbonic anhydrase

56
Q

to maintain the hydrogen, […] is pumped out into the interstitial lumen and […] is pumped in

A

HCO3- out
Cl- in

57
Q
  • enters lumen via CTFR
  • combines with H+ to make gastric acid
A

Cl-

58
Q

describe the process of acid secretion by parietal cells

A
  1. H/K/ATPase pumps H+ out to lumen, and K+ into cell
  2. K+ is recyled
  3. H+ and HCO3- are produced by carbonic anhydrase
  4. HCO3- pumped out of cell into interstitial space (alkaline tide)
59
Q

describe the process of chloride secretion by parietal cells

A
  1. Cl- enters through HCO3- exchanger, Na/K/Cl cotransporter, and single anion transporter
  2. pushed out into lumen via CFTR
  3. combines with H+ to make HCl
60
Q

describe direct stimulation of parietal cells

A

Ach, gastrin, and histamin stimulate the parietal cells, causing increased H+ in lumen

61
Q

3 acid secretagogues

A

Ach
gastrin
histamine

62
Q

describe the indirect stimulation of parietal cells

A
  1. Ach and gastrin stimulate ECL cell to release histamine
  2. histamine acts on parietal cell to stimulate H+ release
63
Q

gastrin receptors

A

CCK2

64
Q

histamine receptors

A

H2

65
Q

Ach receptors

A

M3

66
Q

Gaq-DAG/Ca++/PKC

A

gastrin and ACh

67
Q

Gas-AC/cAMP/PKA

A

Histamine

68
Q

Gai-inhibits adenylate cyclase

A

somatostatin and prostaglandins

69
Q

circadian pattern of gastric secretion

A

less in morning
more at night

70
Q

which phase accounts for 30% of gastric secretions?

A

cephalic

71
Q

cephalic secretion is stimulated by

A

sight
smell
taste
thought of food
swallowing

72
Q

in what phase of gastric secretion do sensory signals activate the dorsal motor nucleus and vagus nerve?

A

cephalic

73
Q

during the cephalic stage, parietal cells are stimulated […]

direct/indirectly

A

both direct and indirect

74
Q

what two things begin the gastic phase of secretion?

A
  • distension of stomach by food
  • digestion of protein
75
Q

distension of food by the stomach in the gastric secretion phase tiggers what two reflexes?

A

local ENS
vagovagal

releases ACh and GRP

76
Q

peptides and amino acids activate G cells to produce

A

gastrin

77
Q

produced by D cells

A

somatostatin

78
Q

inhibits G cell production of GRP and directly inhibits acid secretion by parietal cells

A

somatostatin

79
Q

D cells respond to luminal acid by producing

A

somatostatin

inhibits G cell GRP production

80
Q

G cells secretion of gastrin simulates D cells to

A

secrete somatostatin to inhibit acid secretion

81
Q

the intestinal phase of gastric secretion occurs when

A

food moves into duodenum

82
Q

cephalic phase is mediated by the […] nerve

A

vagus

83
Q

which phase of gastric secretion:

  1. local nervous secretory reflexes
  2. vagal reflexes
  3. gastrin-histamin stimulation
A

gastric

84
Q

which phase of gastric secretion:

  1. nervous mechanisms
  2. hormonal mechanisms
A

intestinal

85
Q

enteric hormones that inhibit gastric H+ secretion

8

A
  1. CCK
  2. secretin
  3. VIP
  4. GIP
  5. neurotensin
  6. peptide YY
  7. somatostatin
  8. GLP-1
86
Q

secreted by chief cells in response to mechanicoreceptor activation and nutrients in lumen of stomach

A

pepsinogen

87
Q

above the pH of 3, pepsinogen is

A

inactive

88
Q

pH must be lower than […] to prevent the inactivation of pepsin

A

3.5

89
Q

liquid leaving the gastric gland is very acidic and under high pressure allowing vertical tunneling into lumen

A

viscous fingering

hypothesis of how H+ moves from gastric gland to lumen

90
Q

primary symptom of patients following truncal vagotomy

A

delayed gastric emptying

91
Q

functions to activate MMCs through ENS

A

motilin

92
Q

loss of vagovagal reflex reduces pyloric […]

A

relaxation

93
Q

following truncal vagotomy, the MMCs of the ENS are sufficient to maintain motility of

A

small intestine

94
Q

defecation is controlled by […] nerves

A

spinal

95
Q

vasovagal reflex secretes […] from distal vagal nerve endings to stimulate gastrin release

A

GRP

96
Q

increases smooth muscle contraction rate

A

motilin

97
Q

inhibit gastric acid secretion

3

A

CCK
secretin
somatostatin

98
Q

what muscle relaxes during defecation to enable the passage of fecal matter past the anal spinchters?

what muscle contracts?

A

relaxes: puborectalis

contracts: adominal muscles

99
Q

a carbohydrate and lipid rich meal would […] gallbladder contractions

increase/decrease

A

increase

100
Q

what cells produce somatostatin?

A

D cells

101
Q

a meal high in calories and fat results in a […] of MMC intiation

A

longer delay

102
Q

acts on ECL cells to stimulate it to produces histamine in the oxyntic mucosa

A

gastrin

103
Q

chief cells produce

A

pepsinogen

104
Q

weak stimulator of chief cells to produce pepsinogen

A

gastrin

105
Q

the tone of the LES will […] following a meal

increase/decrease

A

increase

106
Q

gastrin can act in a paracrine fashion to get D cells to produce

A

somatostatin

107
Q

a somatostatinoma would result in […] due to decreased gastric acid production

A

hypochlorhydria

108
Q

the stomach undergoes fast emptying for a […] diet versus and […]

A

liquid; solid

109
Q

an incompetent LES can cause

A

GERD/heartburn

gastric contents enter esophagus