Gastrointestinal regulatory substances Flashcards
(36 cards)
Source of gastrin
G cells (antrum of stomach, duodenum)
Action of gastrin
- ↑ gastric H+ secretion
- ↑ growth of gastric mucosa
- ↑ gastric motility
Regulation of gastrin
- ↑ by stomach distention/ alkalinization, amino acids, peptides, vagal stimulation via gastrin releasing peptide (GRP)
- ↓ by pH
Source of somatostatin
D cells (pancreatic islets, GI mucosa)
Action of somatostatin
- ↓ gastric and pepsinogen secretion
- ↓ pancreatic and small intestine fluid secretion
- ↓ gallbladder contraction
- ↓ insulin and glucagon release
Regulation of somatostatin
- ↑ by acid
- ↓ by vagal stimulation
Source of cholecystokinin
I cell (duodenum, jejunum)
Action of cholecystokinin
- ↑ pancreatic secretion
- ↑ gallbladder contraction
- ↓ gastric emptying
- ↑ sphincter of Oddi relaxation
Regulation of cholecystokinin
↑ by fatty acids and amino acids
Source of secretin
S cells (duodenum)
Action of secretin
- ↑ pancreatic HCO3- secretion
- ↓ gastric acid secretion
- ↑ bile secretion
Regulation of secretin
↑ by acid, fatty acids in lumen of duodenum
Sources of glucose-dependent insulinotropic peptide
K cells (duodenum, jejunum)
Action of glucose-dependent insulinotropic peptide
- Exocrine: ↓ gastric H+ secretion
- Endocrine: ↑ insulin release
Regulation of glucose-dependent insulinotropic peptide
↑ by fatty acids, amino acids and oral glucose
Source of motilin
Small intestine
Action of motilin
Produces migrating motor complexes (MMCs)
Regulation of motilin
↑ in fasting state
Sources of vasoactive intestinal peptide
Parasympathetic ganglia in sphincters, gallbladder, and small intestine
Action of vasoactive intestinal peptide
- ↑ intestinal water and electrolyte secretion
- ↑ relaxation of intestinal smooth muscle and sphincters
Regulation of vasoactive intestinal peptide
- ↑ by distention and vagal stimulation
- ↓ by adrenergic input
Action of nitric oxide
↑ smooth muscle relaxation, including lower esophageal sphincter (LES)
Source of ghrelin
Stomach
Action of ghrelin
↑ appetite