



Study with the several resources on Docsity
Earn points by helping other students or get them with a premium plan
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Community
Ask the community for help and clear up your study doubts
Discover the best universities in your country according to Docsity users
Free resources
Download our free guides on studying techniques, anxiety management strategies, and thesis advice from Docsity tutors
This resource offers test questions and answers on gastrointestinal (GI) physiology, hormonal and neural functions. It covers hormones like GLIP, motilin, gastrin, and CCK, plus sphincter and GI tract layer functions. It explores the enteric nervous system, including myenteric and submucosal plexuses, mast cells, and digestive enzymes. Designed to test GI function understanding, it's valuable for students and professionals. It also covers the enteric nervous system's reflex arc, substances synthesized post-mast cell activation, gastrin and CCK's roles in acid secretion and mucosal growth, and gastrinoma effects. Ideal for exam prep and GI physiology study.
Typology: Exams
1 / 7
This page cannot be seen from the preview
Don't miss anything!
What is GLIP and what does it do? -- Answer โโ substance secreted by duodenal/proximal jejunal K cells in response to glucose ingestion (before food gets to the SI), and it stimulates insulin release and inhibits acid secretion What is motilin and what does it do? -- Answer โโ hormone released from duodenal/proximal jejunal M cells during fasting, and it increases gastric emptying during the time in between meals (interdigestive period) What hormones are part of the gastrin family? -- Answer โโ gastrin and CCK What hormones are part of the secretin family? -- Answer โโ secretin, GLIP, and glucagon-like peptide 1 (GLP-1) What are the 6 sphincters of the GI tract? -- Answer โโ upper esophageal, lower esophageal, pyloric, ileocecal, internal anal, external anal What are the 4 layers of the GI tract? -- Answer โโ serosa, muscularis, submucosa, mucosa What is somatostatin and what does it do? -- Answer โโ peptide hormone secreted from gastric/duodenal D cells and pancreatic delta cells that directly inhibits acid secretion and mediates acid-induced inhibition of gastrin release; it is inhibited by ACh What is histamine and what does it do? -- Answer โโ stimulator of parietal cells that is released from ECL cells in the corpus, acting as a paracrine on neighboring parietal cells to stimulate acid release
What does vasoactive intestinal peptide (VIP) do? -- Answer โโ promotes relaxation of GI smooth muscle and stimulation of fluid/electrolyte secretion in the intestine What does gastrin-releasing peptide (GRP) do? -- Answer โโ triggers release of gastrin from G cells What do enkephalins do? -- Answer โโ block pain transmission by binding to opioid receptors, and trigger increased smooth muscle tone which reduces GI motility What are enteroendocrine cells? -- Answer โโ endocrine and neurocrine cells that physically connect to enteric neurons Why can SSRIs cause GI side effects? -- Answer โโ because 95% of the body's serotonin is found in the gut What are the two main nerve plexuses in the enteric NS? -- Answer โโ myenteric and submucosal What is the myenteric (Auerbach's) plexus? -- Answer โโ plexus located between the circular and longitudinal muscles from the proximal esophagus to the rectum that contains primarily motor neurons involved in GI motility What is the submucosal (Meissner's) plexus? -- Answer โโ the plexus located in the submucosa of the SI and colon that contains primarily sensory neurons involved in local control of secretion/absorption and in modulating contractions of the muscularis mucosae How is the enteric NS organized? -- Answer โโ cell bodies of the ENS reside in the nerve plexuses; interneurons and motor neurons contain a single axon and depolarize quickly, with projections pointing either towards the mouth or towards the anus What is the function of ascending cholinergic motor neurons during peristalsis? -- Answer โโ provide muscle contractions that propel intraluminal GI contents distally before the anus (contracting behind the food bolus to push it further along the GI tract)
Which substances are synthesized after mast cell activation? -- Answer โโ interleukins, CCL3, leukotrienes, and platelet-activating factor What is the serosa? -- Answer โโ the outermost connective tissue layer that is covered with squamous epithelium What is the muscularis externa? -- Answer โโ contains two smooth muscle layers (inner circular and longitudinal) with enteric neurons between the layers What is the submucosa? -- Answer โโ an epithelial cell layer and underlying loose connective tissue called the lamina propria What is contained in the lamina propria of the submucosa? -- Answer โโ capillaries, enteric neurons, and immune cells, plus a thin layer of smooth muscle called the muscularis mucosae What is the mesentery? -- Answer โโ layer of peritoneum that surrounds the intestine and is made up of membranous tissue containing blood vessels that exchange O2 and nutrients for CO2 and waste from the intestines What does churning in the stomach do? -- Answer โโ reduces the size of food particles to 2 mm or less in diameter so that they can pass through the pyloric sphincter to the SI Which two pancreatic enzymes are secreted in the active form? -- Answer โโ amylase and lipase What is colipase? -- Answer โโ cofactor for lipase that stabilizes the structure of lipase and prevents it from being washed away by bile salts; secreted as procolipase What is phospholipase? -- Answer โโ it is an enzyme that specifically digests phospholipids; secreted as prophospholipase
What is chymotrypsin? -- Answer โโ preferentially cleaves peptide bonds at aromatic amino acids (i.e. Trp, Tyr, Phe); secreted as chymotrypsinogen and cleaved by trypsin to be activated What lines the active site of chymotrypsin and why? -- Answer โโ small neutral amino acids, which leave room for the bulky aromatic side chains to enter the active site What is trypsin? -- Answer โโ preferentially cleaves at Lys and Arg residues, and is responsible for activating all other pancreatic zymogens; secreted as trypsinogen and is autocatalytic What is at the base of the active site pocket of trypsin and why? -- Answer โโ an acidic amino acid (aspartate), which provides a negative charge to attract a basic amino acid side chain like Lys or Arg What is enterokinase responsible for? -- Answer โโ activating trypsinogen to trypsin What are the 4 criteria that conclusively determine that a substance acts as hormone? -- Answer โโ 1) physiological effect in one part of the body must alter activity in another part of the body
What is ChiRhoStim and what effect should it have on gastrin? -- Answer โโ a synthetic secretin, which stimulates HCO3- secretion into the duodenal lumen and has an inhibitory effect on acid secretion, so it should reduce serum gastrin in a healthy individual since the two hormones have opposite effects What happens to gastrinoma patients after injection with ChiRhoStim? -- Answer โโ gastrin levels increase because the gastrinoma is not subject to the negative feedback mechanisms by which secretin normally inhibits gastric release from G cells How is Zollinger-Ellison syndrome diagnosed? -- Answer โโ any increase in serum gastrin >100 pg/mL above baseline after ChiRhoStim injection What are the triggers for CCK release? -- Answer โโ main triggers are fatty acids and monoglycerides in the duodenum, but peptides, amino acids, and gastric acid in the duodenum can augment What is secretin and what does it do? -- Answer โโ hormone released from duodenal S cells when gastric acid enters the duodenum, and it triggers the release of pancreatic and bile HCO3- in direct proportion to the amount of acid needing to be neutralized in order to protect the intestinal mucosa Why is secretin referred to as "nature's antacid"? -- Answer โโ because it triggers HCO3- secretion AND inhibits further acid secretion from the stomach Besides HCO3- secretion, what else does secretin do? -- Answer โโ promotes exocrine pancreas growth and stimulates pepsin secretion