Gi Hormones

Front 1

Gastrin

(Source, Action, Regulation, Notes)

Back 1

1. G cells (antrum of stomach)
2. ↑ gastric H+ secretion, ↑ growth of gastric mucosa, ↑ gastric motility
3. ↑ by stomach distension, amino acids, peptides, vagal stimulation, ↓ by stomach pH < 1.5
4. ↑↑ in Z-E, phenylalanine/tryptophan are potent stimulators

Front 2

Cholecystokinin (CCK)

(Source, Action, Regulation, Notes)

Back 2

1. I cells (duodenum, jejunum)
2. ↑ pancreatic secretion, ↑ gallbladder contraction, ↓ gastric emptying
3. ↑ by fatty acids, amino acids
4. In cholelithiasis, pain worsens after fatty food ingestion due to ↑ CCK

Front 3

Secretin

(Source, Action, Regulation, Notes)

Back 3

1. S cells (duodenum)
2. ↑ pancreatic HCO3- secretion, ↑ bile secretion, ↓ gastric acid secretion
3. ↑ by acid, fatty acids in lumen of duodenum
4. ↑ HCO3- neutralizes gastric acid in duodenum, allowing ancreatic enzymes to function

Front 4

Somatostatin

(Source, Action, Regulation, Notes)

Back 4

1. D cells (pancreatic islets, GI mucosa)
2. ↓ gastric acid and pepsinogen secretion, ↓ pancreatic and small intestine fluid secretion, ↓ gallbladder contraction, ↓ insulin and glucagon release
3. ↓ by vagal stimulation, ↑ by acid
4. Inhibitory hormone, antigrowth hormone effects (digestion and absorption of substances needed for growth), used to treat VIPoma and carcinoid tumors

Front 5

Glucose-dependent insulinotropic peptide (GIP)

(Source, Action, Regulation, Notes)

Back 5

1. K cells (duodenum, jejunum)
2. Exocrine: ↓ gastric H+ secretion
Endocrine: ↑ insulin release
3. ↑ by fatty acids, amino acids, oral glucose
4. An oral glucose load is used more rapidly than the equivalent used by IV

Front 6

Vasoactive intestinal polypeptide (VIP)

(Source, Action, Regulation, Notes)

Back 6

1. Parasympathetic ganglia in sphincters, gallbladder, small intestine
2. ↑ intestinal water and electrolyte secretion, ↑ relaxation of intestinal smooth muscle and sphincters
3. ↑ by distention and vagal stimulation, ↓ by adrenergic input
4. VIPoma = non-a, non-B islet cell pancreatic tumor that secretes VIP. Copious diarrhea

Front 7

Nitric Oxide

(Action, Notes)

Back 7

1. ↑ smooth muscle relaxation, including LES
2. Loss of NO secretion is implicated in ↑ LES tone of achalasia

Front 8

Motilin

(Source, Action, Regulation)

Back 8

1. Small Intestine
2. Produces migrating motor complexes (MMCs)
3. ↑ in fasting state

Front 9

Ghrelin

(Source, Action, Regulation)

Back 9

1. P/D1 cells (stomach)
2. ↑ growth hormone, ACTH, cortisol, and prolactin secretion
3. ↑ before meals, ↓ after meals
4. Regulates hunger, meal initiation. Lost following gastric surgery. Assoc w/ hyperplasia in Prader-Willi

Front 10

Intrinsic Factor

(Source, Action, Notes)

Back 10

1. Parietal cells (stomach)
2. Vit B12 binding protein (req for B12 uptake in terminal ileum)
3. Autoimmune destruction of parietal cells >> chronic gastritis and pernicious anemia.

Front 11

Gastric Acid

(Source, Action, Regulation, Notes)

Back 11

1. Parietal cells (stomach)
2. ↓ stomach pH
3. ↑ by histamine, ACh, gastrin, ↓ by somatostatin, GIP, prostaglandin, secretin
4. Gastrinoma: gastrin-secreting tumor that causes continuous high levels of acid secretion and ulcers

Front 12

Pepsin

(Source, Action, Regulation, Notes)

Back 12

1. Chief cells (stomach)
2. Protein digestion
3. ↑ by vagal stimulation, local acid
4. Inactive pepsinogen >> pepsin by H+

Front 13

HCO3-

(Source, Action, Regulation, Notes)

Back 13

1. Mucosal cells (stomach, duod, salivary glands, pancreas) and Brunner's glands (duod)
2. Neutralizes acid
3. ↑ pancreatic and biliary secretion with secretion
4. HCO3- is trapped in mucus that covers the gastric epithelium