Download AbsiteGIHormones - Open Source Surgery

1/19/2013
Gastrin
Absite: GI Hormones
http://opensourcesurgery.com
• Produced: in G cells in the antrum
• Stimulated by: Amino acids, Vagal Input, Calcium, Alcohol, Antral Distention, normal or high pH, histamine
• Inhibited by: Low pH in duodenum, Somatostatin, Secretin, CCK, VIP, Gastrointestinal inhibitory peptide
• Acts on: Parietal and chief cells to increase
– Acid/H+ release(Parietal), blocked by PPI at H/K ATPASE in parietal cell.
– Intrinsic factor(Parietal) binds B12 absorbed at TI,
– Pepsinogen secretion(Chief)
Somatostatin
Produced by: D‐cells in the antrum
Stimulated by: Acid in the stomach
Inhibitor: Many, known as the great inhibitor
Acts to decrease the action of most of the other GI Hormones, decrease motility, decrease blood flow to GI Tract
• Octreotide: Somatostatin Analogue, Decreases Pancreatic Fistula output. Also used in variceal
bleeding.
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CCK
• Produced by I Cells of the Duodenum
• Stimulated by: Amino Acids and Fatty Acids
• Acts on: Gallbladder causing contraction, relaxation of sphincter of Oddi, Increases pancreatic enzyme secretion, decreases gastric emptying.
• CCK given when checking ejection fraction in HIDA scans.
Gastric Inhibitory Peptide
• Produced by K cells in duodenum
• Stimulated by Amino acids, glucose, long chain fatty acids, decreased pH
• Acts on parietal cells, and Beta Cells of the pancreas. Decreases HCl+ Pepsin, Increases insulin.
Secretin
• Produced by S cells of the Duodenum
• Stimulated by: Low pH and Fatty Acids in Duodenum
• Inhibited by: High pH, gastrin
• Acts to: Increase pancreatic HCO3 Release, increased bile flow, inhibits gastrin release, inhibits HCL release.
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Motilin
• Produced by M cells in Duodenum
• Stimulated by: Duodenal acid, food, vagus
input, gastrin‐releasing Peptide
• Inhibited by: Somatostatin, Secretin, Pancreatic Polypeptide, duodenal fat
• Causes increased small bowel motility
• Erythromycin acts here
Insulin
• Insulin
– Released by Beta cells of pancreas
– Stimulated by glucose, glucagons, cck
– Causes: Glucose uptake, protein synthesis
– Reglan acts as antagonist on D2 Receptors
Glucagon
• Glucagon
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Alpha Cells of Pancreas
Increased Glycogenolysis, and gluconeogenesis
Breaks down fats and proteins
Relaxes Sphincter of Oddi – used to power flush stones out of the common duct in lap chole.
Vasoactive intestinal peptid
• Produced in GI tract and Pancreas
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Secretion stimulated by fat, acetylcholine
Causes increase in water secretion and motility
Inhibits gastrin release
Relaxation of GI smooth muscle
– Over production in VIPoma leads to watery diarrhea.
Pancreatic Polypeptide
• Secreted by the islet cells of the pancrease
• Stimulated by: Food, Vagal Stimulation
• Acts to: Decrease pancreatic endocrine and exocrine function
Bombesin(aka gastrin releasing peptide)
• Released from post‐synaptic fibers of vagus
nerve
• Increases gastrin/gastric acid secretion, intestinal motility, pancreatic secretion
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Peptide YY
• Released from Terminal Ileum
• Inhibits gastric motility
• Increases water and electrolyte absorption in the colon
• Decreases Pancreatic secretion
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