Gastrointestinal regulatory substances Flashcards

1
Q

Source of gastrin

A

G cells (antrum of stomach, duodenum)

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2
Q

Action of gastrin

A
  • ↑ gastric H+ secretion
  • ↑ growth of gastric mucosa
  • ↑ gastric motility
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3
Q

Regulation of gastrin

A
  • ↑ by stomach distention/ alkalinization, amino acids, peptides, vagal stimulation via gastrin releasing peptide (GRP)
  • ↓ by pH
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4
Q

Source of somatostatin

A

D cells (pancreatic islets, GI mucosa)

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5
Q

Action of somatostatin

A
  • ↓ gastric and pepsinogen secretion
  • ↓ pancreatic and small intestine fluid secretion
  • ↓ gallbladder contraction
  • ↓ insulin and glucagon release
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6
Q

Regulation of somatostatin

A
  • ↑ by acid

- ↓ by vagal stimulation

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7
Q

Source of cholecystokinin

A

I cell (duodenum, jejunum)

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8
Q

Action of cholecystokinin

A
  • ↑ pancreatic secretion
  • ↑ gallbladder contraction
  • ↓ gastric emptying
  • ↑ sphincter of Oddi relaxation
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9
Q

Regulation of cholecystokinin

A

↑ by fatty acids and amino acids

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10
Q

Source of secretin

A

S cells (duodenum)

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11
Q

Action of secretin

A
  • ↑ pancreatic HCO3- secretion
  • ↓ gastric acid secretion
  • ↑ bile secretion
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12
Q

Regulation of secretin

A

↑ by acid, fatty acids in lumen of duodenum

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13
Q

Sources of glucose-dependent insulinotropic peptide

A

K cells (duodenum, jejunum)

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14
Q

Action of glucose-dependent insulinotropic peptide

A
  • Exocrine: ↓ gastric H+ secretion

- Endocrine: ↑ insulin release

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15
Q

Regulation of glucose-dependent insulinotropic peptide

A

↑ by fatty acids, amino acids and oral glucose

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16
Q

Source of motilin

A

Small intestine

17
Q

Action of motilin

A

Produces migrating motor complexes (MMCs)

18
Q

Regulation of motilin

A

↑ in fasting state

19
Q

Sources of vasoactive intestinal peptide

A

Parasympathetic ganglia in sphincters, gallbladder, and small intestine

20
Q

Action of vasoactive intestinal peptide

A
  • ↑ intestinal water and electrolyte secretion

- ↑ relaxation of intestinal smooth muscle and sphincters

21
Q

Regulation of vasoactive intestinal peptide

A
  • ↑ by distention and vagal stimulation

- ↓ by adrenergic input

22
Q

Action of nitric oxide

A

↑ smooth muscle relaxation, including lower esophageal sphincter (LES)

23
Q

Source of ghrelin

A

Stomach

24
Q

Action of ghrelin

A

↑ appetite

25
Q

Regulation of ghrelin

A
  • ↑ in fasting state

- ↓ by food

26
Q

Source of intrinsic factor

A

Parietal cells (stomach)

27
Q

Action of intrinsic factor

A

Vitamin B12 binding protein required for B12 uptake in the terminal ileum

28
Q

Source of gastric acid

A

Parietal cells (stomach)

29
Q

Action of gastric acid

A

↓ stomach pH

30
Q

Regulation of gastric acid

A
  • ↑ by histamine, ACh, gastrin

- ↓ by somatostatin, glucose-dependent insulionotropic peptide (GIP), prostaglandin, secretin

31
Q

Source of pepsin

A

Chief cells (stomach)

32
Q

Action of pepsin

A

Protein digestion

33
Q

Regulation of pepsin

A

↑ by vagal stimulation and local acid

34
Q

Source of bicarbonate

A
  • Mucosal cells (stomach, duodenum, salivary glands, pancreas)
  • Brunner glands (duodenum)
35
Q

Action of bicarbonate

A

Neutralizes acid

36
Q

Regulation of bicarbonate

A

↑ by pancreatic and biliary secretion with secretin