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GI Physiology: Test Questions on Hormonal and Neural Functions, Exams of Biology

North Carolina State University (NCSU)Biology

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

2024/2025

Available from 06/03/2025

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PHY 503: GI PRINCIPLES, HORMONAL FUNCTIONS, NEURAL

FUNCTIONS: TEST QUESTIONS WITH ACCURATE ANSWERS

What is GLIP and what does it do? -- Answer ✔✔ 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 ✔✔ 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 ✔✔ gastrin and CCK

What hormones are part of the secretin family? -- Answer ✔✔ secretin, GLIP, and

glucagon-like peptide 1 (GLP-1)

What are the 6 sphincters of the GI tract? -- Answer ✔✔ upper esophageal, lower

esophageal, pyloric, ileocecal, internal anal, external anal

What are the 4 layers of the GI tract? -- Answer ✔✔ serosa, muscularis, submucosa,

mucosa

What is somatostatin and what does it do? -- Answer ✔✔ 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 ✔✔ 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

Partial preview of the text

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PHY 503: GI PRINCIPLES, HORMONAL FUNCTIONS, NEURAL

FUNCTIONS: TEST QUESTIONS WITH ACCURATE ANSWERS

What is GLIP and what does it do? -- Answer ✔✔ 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 ✔✔ 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 ✔✔ gastrin and CCK What hormones are part of the secretin family? -- Answer ✔✔ secretin, GLIP, and glucagon-like peptide 1 (GLP-1) What are the 6 sphincters of the GI tract? -- Answer ✔✔ upper esophageal, lower esophageal, pyloric, ileocecal, internal anal, external anal What are the 4 layers of the GI tract? -- Answer ✔✔ serosa, muscularis, submucosa, mucosa What is somatostatin and what does it do? -- Answer ✔✔ 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 ✔✔ 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 ✔✔ promotes relaxation of GI smooth muscle and stimulation of fluid/electrolyte secretion in the intestine What does gastrin-releasing peptide (GRP) do? -- Answer ✔✔ triggers release of gastrin from G cells What do enkephalins do? -- Answer ✔✔ block pain transmission by binding to opioid receptors, and trigger increased smooth muscle tone which reduces GI motility What are enteroendocrine cells? -- Answer ✔✔ endocrine and neurocrine cells that physically connect to enteric neurons Why can SSRIs cause GI side effects? -- Answer ✔✔ because 95% of the body's serotonin is found in the gut What are the two main nerve plexuses in the enteric NS? -- Answer ✔✔ myenteric and submucosal What is the myenteric (Auerbach's) plexus? -- Answer ✔✔ 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 ✔✔ 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 ✔✔ 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 ✔✔ 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 ✔✔ interleukins, CCL3, leukotrienes, and platelet-activating factor What is the serosa? -- Answer ✔✔ the outermost connective tissue layer that is covered with squamous epithelium What is the muscularis externa? -- Answer ✔✔ contains two smooth muscle layers (inner circular and longitudinal) with enteric neurons between the layers What is the submucosa? -- Answer ✔✔ an epithelial cell layer and underlying loose connective tissue called the lamina propria What is contained in the lamina propria of the submucosa? -- Answer ✔✔ capillaries, enteric neurons, and immune cells, plus a thin layer of smooth muscle called the muscularis mucosae What is the mesentery? -- Answer ✔✔ 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 ✔✔ 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 ✔✔ amylase and lipase What is colipase? -- Answer ✔✔ 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 ✔✔ it is an enzyme that specifically digests phospholipids; secreted as prophospholipase

What is chymotrypsin? -- Answer ✔✔ 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 ✔✔ small neutral amino acids, which leave room for the bulky aromatic side chains to enter the active site What is trypsin? -- Answer ✔✔ 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 ✔✔ 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 ✔✔ activating trypsinogen to trypsin What are the 4 criteria that conclusively determine that a substance acts as hormone? -- Answer ✔✔ 1) physiological effect in one part of the body must alter activity in another part of the body

effect of the substance must persist after extrinsic denervation
eliminating the source tissue must prevent the response in the target tissue
the substance must be isolated from source tissue and shown to produce the correct response when injected into the bloodstream at the proper dose What do gastrin and CCK have in common? -- Answer ✔✔ common amino acid sequence at the C-terminus, and can act on each other's receptors due to the strong sequence identity (but are more potent when they act on their own receptors) What is the importance of the sulfated status of tyrosine at position 7 of CCK? -- Answer ✔✔ it can shift a substance from more gastrin-like activity to more CCK-like activity Where is little gastrin secreted from and in response to what? -- Answer ✔✔ antral G cells; in response to both luminal and basolateral stimuli

What is ChiRhoStim and what effect should it have on gastrin? -- Answer ✔✔ 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 ✔✔ 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 ✔✔ any increase in serum gastrin >100 pg/mL above baseline after ChiRhoStim injection What are the triggers for CCK release? -- Answer ✔✔ 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 ✔✔ 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 ✔✔ because it triggers HCO3- secretion AND inhibits further acid secretion from the stomach Besides HCO3- secretion, what else does secretin do? -- Answer ✔✔ promotes exocrine pancreas growth and stimulates pepsin secretion

GI Physiology: Test Questions on Hormonal and Neural Functions, Exams of Biology

Related documents

Partial preview of the text

Download GI Physiology: Test Questions on Hormonal and Neural Functions and more Exams Biology in PDF only on Docsity!

PHY 503: GI PRINCIPLES, HORMONAL FUNCTIONS, NEURAL

FUNCTIONS: TEST QUESTIONS WITH ACCURATE ANSWERS