GI regulatory substances Flashcards Preview

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Flashcards in GI regulatory substances Deck (14):
1

Gastrin

G cells (antrum of stomach, duodenum)
- gastric H+ secretion (mainly via ECL cells)
- growth of gastric mucosa
- gastric motility

(+) stomach distention/ alkalinization, amino acids, peptides, vagal stimulation
(-) pH

2

Somatostatin

D cells (pancreatic islets, GI mucosa)
- decrease gastric acid and pepsinogen secretion
- decrease pancreatic and small intestine fluid secretion
- decrease gallbladder contraction
- decrease insulin and glucagon release

(+) acid
(-) vagal stimulation

3

Cholecystokinin

I cells (duodenum, jejunum)
- Increase pancreatic secretion (via neural muscarinic path)
- Increase gallbladder contraction
- Decrease gastric emptying
- Increase sphincter of Oddi relaxation

(+) fatty acids, amino acids

4

Secretin

S cells (duodenum)
- pancreatic HCO3– secretion
- decreased gastric acid secretion (via gastrin inhibition)
- bile secretion

(+) acid, fatty acids in lumen of duodenum

5

Glucose-dependent Insulinotropic Peptide (GIP)

K cells (duodenum, jejunum)
Exocrine: decreased gastric H+ secretion
Endocrine: increased insulin release

(+) fatty acids, amino acids, oral glucose

6

Motilin

Small intestine
- Produces migrating motor complexes (MMCs)

(+) fasting state

7

Vasoactive Intestinal Polypeptide (VIP)

Parasympathetic ganglia in sphincters, gallbladder, small intestine
- Increase intestinal water and electrolyte secretion
- Increase relaxation of intestinal smooth muscle and sphincters

(+) by distention and vagal stimulation
(-) adrenergic input

8

Nitric Oxide

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

9

Peptide YY

Colon, ileum
- decreases histamine release from enterochromaffin cells causing decreased acid

10

Intrinsic factor

Parietal cells (stomach)
- Vitamin B12–binding protein (required for B12 uptake in terminal ileum)

11

Gastric Acid

Parietal cells (stomach)
- Decreases stomach pH

(+) histamine, ACh, gastrin
(-) somatostatin, GIP, prostaglandin, secretin

12

Pepsin

Chief cells (stomach)
- Protein digestion

(+) vagal stimulation, local acid

13

HCO3-

Mucosal cells (stomach, duodenum, salivary glands, pancreas) and Brunner glands (duodenum)
- Neutralizes acid

(+) pancreatic and biliary secretion with secretin

14

Vagal NT's

ACh on parietal cells
Gastrin Releasing Peptide (GRP) on G cells