Flashcards in Chapter 28: GI Hormones Deck (43):
Produced by G cells in stomach antrum
What stimulates secretion of gastrin?
Amino acids, vagal input (acetylcholine), calcium ETOH, antral distention, pH > 3.0
What inhibits secretion of gastrin?
Inhibited by pH
Gastrin target cells
Parietal cells and chief cells
Gastrin elicited response
Increased HCl, intrinsic factor, and pepsinogen secretion
Blocks H/K ATPase of parietal cell (final pathway for H+ release)
Mainly produced by D cells in stomach antrum
What stimulates secretion of somatostatin?
Secretion stimulated by acid in duodenum
Somatostatin target cells
Many, is the great inhibitor
Somatostatin elicited response
Inhibits gastrin and HCl release, inhibits release of insulin, glucagon, secretin, and motion; decreased pancreatic and biliary output
Can be used to decreased pancreatic fistula output
Octreotide (somatostain analogue)
Produced by I cells of duodenum
What stimulates secretion of CCK?
Amino acids and fatty acid chains
CCK elicited response
Gallbladder contraction, relaxation of sphincter of Oddi, increased pancreatic enzyme secreiton
Produced by S cells of duodenum
What stimulates secretin secretion?
Stimulated by fat, bill, pH
What inhibits secretin secretion?
Inhibited by pH > 4.0, gastrin
Secretin elicited response
Increased pancreatic HCO3- release, inhibits gastrin release (this is reversed in patients with gastrinoma), and inhibits HCl release
- High pancreatic duct output: increased HCO3-, decreased Cl-
- Slow pancreatic duct output: increased Cl-, decreased HCO3- (carbonic anhydrase in duct exchanges HCO3- for Cl-)
Produced by cells in gut and pancreas
Vasoactive intestinal peptide
What stimulates secretion of vasoactive intestinal peptide?
Secretion stimulated by fat, acetylcholine
Vasoactive intestinal peptide elicited response
Increased intestinal secretion (water and electrolytes) and motlity
Mainly released by alpha cells of pancreas
What stimulates secretion of glucagon?
Decreased glucose, increased amino acids, acetylcholine
What inhibits secretion of glucagon?
Inhibited by increased glucose, increased insulin, somatostatin
Glucagon elicited response
Glycogenolysis, gluconeogensis, lipolysis, ketogenesis, decreased gastric acid secretion, decreased gastrointestinal motility, relaxes sphincter of Oddi
Released by beta cells of the pancreas
What stimulated secretion of insulin?
Glucose, glucagons, CCK
What inhibits secretion of insulin?
Insulin elicited response
Cellular glucose uptake, promotes protein synthesis
Secreted by islet cells in pancreas
What stimulates secretion of pancreatic polypeptide?
Food, vagal stimulation, other GI hormones
Pancreatic polypeptide elicited response
Decreased pancreatic and gallbladder secretion
Released by intestinal cells of gut
What stimulates release of Motilin?
Duodenal acid, food, vagus input
What inhibits release of motion?
Somatostatin, secretin, pancreatic polypeptide, duodenal fat
Motilin elicited response
Increased intestinal motility (small bowel; phase III peristalsis) -> erythromycin acts on this receptor
Where does erythromycin act to increase peristalsis?
Increase intestinal motor activity, increase pancreatic enzyme secretion, increase gastric acid secretion
Bombesin (gastrin-releasing peptide)
Released from terminal ileum following a fatty meal -> inhibits acid secretion and stomach contraction; inhibits gallbladder contraction and pancreatic secretion
What mediates anorexia?
Small bowel recovery