Flashcards in Gastrointestinal regulatory substances Deck (36)
1
Source of gastrin
G cells (antrum of stomach, duodenum)
2
Action of gastrin
- ↑ gastric H+ secretion
- ↑ growth of gastric mucosa
- ↑ gastric motility
3
Regulation of gastrin
- ↑ by stomach distention/ alkalinization, amino acids, peptides, vagal stimulation via gastrin releasing peptide (GRP)
- ↓ by pH
4
Source of somatostatin
D cells (pancreatic islets, GI mucosa)
5
Action of somatostatin
- ↓ gastric and pepsinogen secretion
- ↓ pancreatic and small intestine fluid secretion
- ↓ gallbladder contraction
- ↓ insulin and glucagon release
6
Regulation of somatostatin
- ↑ by acid
- ↓ by vagal stimulation
7
Source of cholecystokinin
I cell (duodenum, jejunum)
8
Action of cholecystokinin
- ↑ pancreatic secretion
- ↑ gallbladder contraction
- ↓ gastric emptying
- ↑ sphincter of Oddi relaxation
9
Regulation of cholecystokinin
↑ by fatty acids and amino acids
10
Source of secretin
S cells (duodenum)
11
Action of secretin
- ↑ pancreatic HCO3- secretion
- ↓ gastric acid secretion
- ↑ bile secretion
12
Regulation of secretin
↑ by acid, fatty acids in lumen of duodenum
13
Sources of glucose-dependent insulinotropic peptide
K cells (duodenum, jejunum)
14
Action of glucose-dependent insulinotropic peptide
- Exocrine: ↓ gastric H+ secretion
- Endocrine: ↑ insulin release
15
Regulation of glucose-dependent insulinotropic peptide
↑ by fatty acids, amino acids and oral glucose
16
Source of motilin
Small intestine
17
Action of motilin
Produces migrating motor complexes (MMCs)
18
Regulation of motilin
↑ in fasting state
19
Sources of vasoactive intestinal peptide
Parasympathetic ganglia in sphincters, gallbladder, and small intestine
20
Action of vasoactive intestinal peptide
- ↑ intestinal water and electrolyte secretion
- ↑ relaxation of intestinal smooth muscle and sphincters
21
Regulation of vasoactive intestinal peptide
- ↑ by distention and vagal stimulation
- ↓ by adrenergic input
22
Action of nitric oxide
↑ smooth muscle relaxation, including lower esophageal sphincter (LES)
23
Source of ghrelin
Stomach
24
Action of ghrelin
↑ appetite
25
Regulation of ghrelin
- ↑ in fasting state
- ↓ by food
26
Source of intrinsic factor
Parietal cells (stomach)
27
Action of intrinsic factor
Vitamin B12 binding protein required for B12 uptake in the terminal ileum
28
Source of gastric acid
Parietal cells (stomach)
29
Action of gastric acid
↓ stomach pH
30
Regulation of gastric acid
- ↑ by histamine, ACh, gastrin
- ↓ by somatostatin, glucose-dependent insulionotropic peptide (GIP), prostaglandin, secretin
31
Source of pepsin
Chief cells (stomach)
32
Action of pepsin
Protein digestion
33
Regulation of pepsin
↑ by vagal stimulation and local acid
34
Source of bicarbonate
- Mucosal cells (stomach, duodenum, salivary glands, pancreas)
- Brunner glands (duodenum)
35
Action of bicarbonate
Neutralizes acid
36