Chapter 28 – G.I. Hormones Flashcards
Where is gastrin produced?
G sells in antrum
Target cells of gastrin? Response?
Parietal cells and chief cells; increased HCl, intrinsic factor, pepsinogen secretion
Mechanism of action of omeprazole?
Blocks H/K ATPase of parietal cell
Where is somatostatin produced?
D cells in antrum
Secretion of somatostatin is simulated by what?
By acid in duodenum
Target cells of somatostatin? Response?
Many - the great inhibitor; inhibits gastrin, HCl release, inhibits release of insulin, glucagon, secretin, GIP, motilin, neurotensin, enteroglucagon; decreases pancreatic and biliary output
What is octreotide? What is it used for?
Somatostatin analog, can be used to decrease pancreatic fistula output
Gastric inhibitory peptide is made where?
K cells in duodenum
Secretion of GIP stimulated by what?
Amino acids, glucose, long chain fatty acids, decreased pH
Target cells of GIP? Response?
Parietal cells of stomach and data cells the pancreas, decreased HCL secretion and pepsin, increase insulin release
CCK is produced where?
Produced by I cells of duodenum and jejunum
Secretion of CCK stimulated by what?
Secretion stimulated by amino acids, fatty acid chains
Response of CCK?
Gallbladder contraction, relaxation of sphincter Oddi, increased pancreatic enzyme secretion, some increase in intestinal motility
Secretin is produced where?
S cells of duodenum
Secretion of secretin is stimulated by what? Inhibited by what?
Stimulated by fat, bile, pH less than 4; inhibited by pH greater than four, gastrin
Response to secretin?
Increased pancreatic HCO3-, increased bile flow, inhibit gastrin release (this is reversed in patients with gastrinoma), inhibit HCl release
High pancreatic duct output shows what electrolyte response?
Increased HCO3-, decreased CL-
Slow pancreatic duct output shows what electrolyte response?
Increased CL, decreased HCO3-; carbonic anhydrase in duct exchanges HCO3- for CL
Where is vasoactive intestinal peptide produced?
Produced by cells in gut and pancreas
Secretion of VIP stimulated by what?
Fat, acetylcholine
Response to VIP?
Increased intestinal secretion and motility, inhibits gastrin release
Insulin is produced where?
Beta cells of pancreas
Secretion of insulin stimulated by what? Inhibited by what?
Stimulated by glucose, glucagon’s, CCK; inhibited by somatostatin, pancreatostatin
Response to insulin?
Cellular glucose uptake; promotes protein synthesis
Where is glucagon produced?
Alpha cells of pancreas, also from alpha cells stomach, intestines
Secretion of glucagon stimulated by what? Inhibited by what?
Stimulated by decreased glucose, increased amino acids, acetylcholine, gastrin releasing peptide; inhibited by increased glucose, increased insulin, somatostatin
Response to glucagon?
Glycogenolysis, gluconeogenesis, lipolysis, ketogenesis, decreased gastric acid secretion, decreased pancreatic secretions, decreased intestinal motility, decreased stomach motility, increased LES pressure, decreased MMCs
Pancreatic polypeptide produced where?
Islet cells in pancreas
Secretion of pancreatic polypeptide stimulated by what?
Food, vagal stimulation, other GI hormones
Response to pancreatic polypeptide?
Decreased pancreatic and gallbladder secretion
Motilin is produced where?
Intestinal cells of gut
Secretion of motilin stimulated by what? Inhibited by what?
Stimulated by duodenal acid, food, vagal input, gastrin releasing peptide; inhibited by somatostatin, secretin, pancreatic polypeptide, duodenal fat
Bombesin is otherwise known as what? Response?
Gastrin releasing peptide; increased intestinal motor activity, increased pancreatic enzyme secretion, increased gastric acid secretion
Where is peptide YY produced?
Terminal ileum following fatty meal
Response to peptide YY?
Inhibits acid secretion and stomach contraction; inhibits gallbladder contraction and pancreatic secretion
Anorexia is mediated by what?
Hypothalamus
What is the recovery time for small bowel? Stomach? Large bowel?
Small bowel – 24 hours, stomach – 48 hours, large bowel - 3-5 days
