GIT Physiology Exam Questions Section A: Multiple Choice Questions 1. How is the HCO3- content of saliva altered in the presence of food? a) Food stimulates the
GIT Physiology Exam Questions Section A: Multiple Choice Questions 1. How is the HCO3- content of saliva altered in the presence of food? a) Food stimulates the parasympathetic nervous system to reduce HCO3- secretion into the saliva. b) Food stimulates the sympathetic nervous system to increase HCO3- secretion into saliva. c) Food stimulates the parasympathetic nervous system to increase HCO3- secretion into the saliva. d) Food inhibits parasympathetic input, which in turn reduces HCO3- secretion into the saliva. Answer: c) Food stimulates the parasympathetic nervous system to increase HCO3- secretion into the saliva. Explanation: The parasympathetic nervous system , activated during eating, stimulates salivary glands to secrete saliva with increased bicarbonate (HCO3-) to neutralize acids and aid digestion. 2. What type of cells produce somatostatin in the stomach and duodenum? a) D cells b) Acinar cells c) I cells d) S cells Answer: a) D cells Explanation: D cells , located in the stomach and duodenum, produce somatostatin , which inhibits the release of other gastrointestinal hormones and regulates gastric acid secretion . 3. What enzyme is involved in the combination of water and carbon dioxide during carbonic acid production in the pancreas ? a) Carbonic dehydratase b) Carbonic reductase c) Carbonic anhydrase d) Carbonic hydratase Answer: c) Carbonic anhydrase Explanation: Carbonic anhydrase catalyzes the reaction between water and carbon dioxide to form carbonic acid , which dissociates into bicarbonate (HCO3-) in the pancreas . 4. Which peptide hormone released by the stomach wall stimulates appetite ? a) Insulin b) Ghrelin c) Leptin d) Somatostatin Answer: b) Ghrelin Explanation: Ghrelin , produced by the stomach wall , is known as the " hunger hormone " and stimulates appetite , particularly before meals. 5. In which section of the gastric pits are mucus-secreting cells found? a) Approximately halfway down the gastric pit b) The neck of the gastric pit c) Along the entire length of the gastric pits d) Acinar cells Answer: b) The neck of the gastric pit Explanation: Mucus-secreting cells are primarily located in the neck region of gastric pits , where they produce mucus to protect the gastric mucosa . 6. Which of the following is not part of the exocrine pancreas ? a) Acinar tissue b) Duct tissue c) Islets of Langerhans d) Digestive enzymes Answer: c) Islets of Langerhans Explanation: The Islets of Langerhans are part of the endocrine pancreas , responsible for hormone production (e.g., insulin , glucagon ). 7. What effect does somatostatin have on pancreatic exocrine secretion ? a) Inhibits all gastric secretions, resulting in an overall increase in exocrine secretion b) Increases bicarbonate secretion, which stimulates an overall reduction in exocrine secretion c) Acts to increase histamine secretion from the stomach, promoting an overall increase in pancreatic exocrine secretions d) Inhibits CCK-stimulated enzyme secretion to cause an overall reduction in pancreatic exocrine secretion Answer: d) Inhibits CCK-stimulated enzyme secretion to cause an overall reduction in pancreatic exocrine secretion 8. What is the role of bicarbonate secreted by the pancreas ? a) Reduce pH of the small intestine b) Neutralize stomach acid c) Decrease activity of digestive enzymes d) Break down the mucous layer Answer: b) Neutralize stomach acid 9. What happens to the sodium concentration of saliva during ductal modification ? a) Sodium concentration increases b) Sodium concentration decreases c) Sodium concentration does not change d) Sodium is not present in the saliva at this stage Answer: b) Sodium concentration decreases Explanation: During ductal modification , salivary ducts reabsorb sodium , reducing its concentration in saliva. 10. Which cell releases cholecystokinin (CCK) ? a) I cells b) N cells c) K cells d) Enterochromaffin cells Answer: a) I cells 11. What is the role of bicarbonate in the composition of gastric mucus ? a) To maintain the viscosity of the mucus b) To negatively regulate mucus production c) To increase the pH of the mucus d) To negatively regulate acid production Answer: c) To increase the pH of the mucus 12. What effect does sympathetic nervous system stimulation have on the blood flow to the salivary glands ? a) Sympathetic stimulation releases noradrenaline, which acts at adrenergic receptors to increase the blood flow b) Sympathetic stimulation releases acetylcholine to increase blood flow c) Sympathetic stimulation releases noradrenaline , which acts at adrenergic receptors to decrease the blood flow d) Sympathetic stimulation releases acetylcholine to decrease blood flow Answer: c) Sympathetic stimulation releases noradrenaline, which acts at adrenergic receptors to decrease the blood flow 13. Where in the GI tract does most absorption of water and electrolytes occur? a) Stomach b) Small intestine c) Large intestine d) Kidney Answer: c) Large intestine 14. Which salivary enzyme helps to produce bradykinin ? a) Amylase b) Kallikrein c) Lipase d) Lysozyme Answer: b) Kallikrein 15. Which peptide hormone released by cells in the ileum and colon suppresses appetite ? a) Insulin b) Leptin c) Ghrelin d) PYY (Peptide Tyrosine Tyrosine) Answer: d) PYY (Peptide Tyrosine Tyrosine) 16. Where is leptin released from? a) Pancreas b) Adipocytes c) Stomach wall d) Cells of the ileum and colon Answer: b) Adipocytes 17. What is the main method used to increase stomach acid production ? a) Direct stimulation via the vagus nerve b) The hormone gastrin c) Histamine release from ECL cells d) All 3 of the above are equally involved Answer: d) All 3 of the above are equally involved 18. Which of the following is not directly involved in the urge to defecate ? a) Relaxation of internal anal sphincter b) Contraction of rectal muscles c) An increase in pressure of the bladder on the rectum d) Initial contraction of the external anal sphincter Answer: c) An increase in pressure of the bladder on the rectum 19. Which of the following is correct regarding the effect of NSAIDs on the stomach epithelium ? a) NSAIDs block the synthesis of bicarbonate b) NSAIDs act at ECL cells to increase production of histamine c) NSAIDs directly damage the gastric epithelium d) NSAIDs block the synthesis of prostaglandins , reducing gastric mucus production and leaving the epithelium exposed to acidic contents . Answer: d) NSAIDs block the synthesis of prostaglandins, reducing gastric mucus production and leaving the epithelium exposed to acidic contents. 20. All the following statements concerning pancreatic secretion are true except: a) Sympathetic stimulation inhibits pancreatic HCO3- secretion b) The cephalic phase accounts for about 20% of secretion after a meal c) Pancreatic HCO3- depresses further release of secretin d) Contains enzymes which digest polysaccharides to monosaccharides Answer: d) Contains enzymes which digest polysaccharides to monosaccharides Explanation: Pancreatic amylase digests polysaccharides to disaccharides , not monosaccharides . 21. The following stimulate pancreatic secretion rich in enzymes and poor in HCO3- except: a) Cholecystokinin b) Gastrin c) Secretin d) Vagal stimulation Answer: c) Secretin Explanation: Secretin primarily stimulates bicarbonate-rich secretion . 22. Chymotrypsinogen in pancreatic juice is activated by: a) Enterokinase b) Alkaline pH c) Trypsin d) Bile salts Answer: c) Trypsin 23. The following statements about succus entericus are true except: a) It contains digestive enzymes b) Its secretion depends on the amount of chyme in the small intestine c) It is secreted by intestinal glands d) It is released mainly by vagal stimulation Answer: d) It is released mainly by vagal stimulation 24. Vitamin D is absorbed from the small intestine as the absorption of: a) Water-soluble vitamins b) Glycerol c) Cholesterol d) Short-chain fatty acids Answer: c) Cholesterol 25. The major site of absorption of Vitamin B12 is: a) Duod