GIT Physiology Exam Questions

## 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 decr