Digestive Physiology MCQs | MCQ Quiz | OmpathStudy Kenya

Practice 21 MCQs on Digestive Physiology MCQs with OmpathStudy. Built for Kenyan medical and health students to revise key concepts and prepare for exams.

Questions, Answers & Explanations

1. Q1. About some GIT hormones (true or false):

   • Gastrin is released as a result of stomach distension and vagal stimulation.
   • Secretin stimulates the pancreatic acinar cells to secrete enzymes.
   • Pancreozymin is itself CCK and it has a structural relationship to gastrin.
   • Secretin causes excessive gastric secretion and accelerates gastric emptying.

   Answer: Gastrin is released as a result of stomach distension and vagal stimulation.

   Explanation: Gastrin is released by stomach distension and vagal stimulation. CCK (cholecystokinin) was previously called pancreozymin and shares structural similarities with gastrin. Secretin primarily stimulates bicarbonate and water secretion from pancreatic duct cells, not enzyme secretion from acinar cells. Secretin inhibits gastric secretion and slows gastric emptying.

2. Q2. VIP causes (true or false):

   • Stimulation of the intestinal cells to secrete water and electrolytes.
   • Inhibition of gastric secretion.
   • Relaxation of the lower esophageal sphincter.
   • Peripheral vasoconstriction.
   • stimulates intestinal water and electrolyte secretion and inhibits gastric acid secretion. It causes vasodilation and doesn't significantly affect the lower esophageal sphincter.

   Answer: Stimulation of the intestinal cells to secrete water and electrolytes.

   Explanation: VIP (Vasoactive Intestinal Peptide) stimulates intestinal water and electrolyte secretion and inhibits gastric acid secretion. It causes vasodilation and doesn't significantly affect the lower esophageal sphincter.

3. Q3. Stimulation of Gastrointestinal Secretion include:

   • Chemical stimuli.
   • Tactile stimulation.
   • A and
   • Distension.
   • All are correct.

   Answer: Chemical stimuli.

   Explanation: GIT secretion is stimulated by chemical stimuli (pH, nutrients), tactile stimulation (mechanical contact), and distension.

4. Q4. The Secretin hormone:

   • Is secreted by the pancreas.
   • Is released by the pyloric mucos
   • Contracts the gall bladder wall.
   • Increases the pancreatic secretion of water and HCO3-.
   • Its primary function is to stimulate pancreatic secretion of bicarbonate and water to neutralize acidic chyme.

   Answer: Its primary function is to stimulate pancreatic secretion of bicarbonate and water to neutralize acidic chyme.

   Explanation: Secretin is released by S cells in the duodenal mucosa in response to acid. Its primary function is to stimulate pancreatic secretion of bicarbonate and water to neutralize acidic chyme.

5. Q5. Inhibition of the myenteric plexus leads to which of the following?

   • Increased secretion of secretin from the duodenum.
   • Decreased gut motility.
   • Hyperacidity in the stomach.
   • Diarrhe

   Answer: Decreased gut motility.

   Explanation: The myenteric plexus (Auerbach's plexus) primarily controls gut motility. Its inhibition decreases peristalsis.

6. Q6. Stimulation of submucosal plexus results in an increase in which of the following?

   • Motility of the gut.
   • Secretion of the gut.
   • Sphincter ton
   • Stomach pH.

   Answer: Secretion of the gut.

   Explanation: The submucosal plexus (Meissner's plexus) primarily controls glandular secretions and local blood flow.

7. Q7. About the GIT hormones affecting gastric function:

   • CCK and Secretin increase both gastric secretion and motility.
   • Gastrin secretion is stimulated by the digestive products of fat.
   • Gastrin inhibits gastric secretion and delays gastric emptying.
   • GIP and VIP inhibit gastric secretion.
   • Somatostatin is a powerful stimulator to both gastric secretion and motility.
   • and VIP both inhibit gastric secretion. CCK and secretin inhibit gastric function, while gastrin stimulates it.

   Answer: GIP and VIP inhibit gastric secretion.

   Explanation: GIP (Glucose-dependent Insulinotropic Peptide) and VIP both inhibit gastric secretion. CCK and secretin inhibit gastric function, while gastrin stimulates it.

8. Q8. Cholecystokinin:

   • Release is stimulated by protein hydrolysates in the lumen of the small intestin
   • Is released from gastric mucosal cells.
   • Release is stimulated by distension of the colon.
   • A and C are correct.

   Answer: Release is stimulated by protein hydrolysates in the lumen of the small intestin

   Explanation: CCK is released from I cells in the duodenal mucosa in response to protein hydrolysates and fats in the small intestine.

9. Q9. The major factor that stimulates the release of Secretin into the blood stream is:

   • An acid pH of the chyme entering the duodenum.
   • The parasympathetic stimuli.
   • Peptones in the gastric chyme that enter the duodenum.
   • A stomach full of digested contents.

   Answer: An acid pH of the chyme entering the duodenum.

   Explanation: Secretin is specifically released in response to acidic chyme (pH < 4.5) entering the duodenum.

10. Q10. It is known that gastrin:

    • It is a large protein molecule, somewhat similar in size to pepsin.
    • Is not secreted by empty stomach when peristaltic movements may be quite forceful.
    • Reaches the secretory cells of the fundus of the stomach through the blood and not through the lumen.
    • Promotes the secretion of pepsin, but not that of HCl.

    Answer: Reaches the secretory cells of the fundus of the stomach through the blood and not through the lumen.

    Explanation: Gastrin is released from G cells in the antrum and reaches parietal cells in the fundus via the bloodstream (endocrine action). It stimulates both acid and pepsinogen secretion.

11. Q11. It is known that secretin:

    • It is a large protein hormone synthesized by the pancreas, together with pancreozymin.
    • Is a small polypeptide synthesized by the intestinal mucos
    • Neutralizes directly the acid chyme that passes through the pylorus.
    • Has an optimal activity at a pH equal to 8.4.
    • It stimulates bicarbonate secretion to neutralize acid.

    Answer: Is a small polypeptide synthesized by the intestinal mucos

    Explanation: Secretin is a small polypeptide hormone synthesized by S cells in the duodenal mucosa. It stimulates bicarbonate secretion to neutralize acid.

12. Q12. Concerning the gastrin hormone:

    • It is secreted at the pyloric antrum and reaches the fundus through the gastric lumen.
    • It promotes the secretion of pepsin, but not HCl.
    • Its secretion stimulated by secretin and GIP.
    • It is structurally similar to CCK.
    • It has +ve feedback relation with gastric acidity.

    Answer: It is structurally similar to CCK.

    Explanation: Gastrin and CCK belong to the same hormone family and share structural similarities. Gastrin travels through blood and has negative feedback with acid.

13. Q13. About Cholecystokinin-pancreozymin (CCK), all the following are true except:

    • It is GIT hormone secreted by the duodenal mucosa in response to presence of fat or protein digestive products.
    • It causes contraction of the gall bladder wall being a natural cholagogu
    • It produces a pancreatic secretion rich in enzymes.
    • It potentiates the action of secretin on the pancreas.
    • It inhibits both gastric and intestinal motility.

    Answer: It produces a pancreatic secretion rich in enzymes.

    Explanation: CCK inhibits gastric motility but stimulates small intestinal motility.

14. Q14. The GIT hormones are characterized by all the following except:

    • They are secreted by APUD system and are divided into 2 families on the basis of their structural similarity.
    • They are secreted in response to specific physiological stimuli during digestion.
    • Their effects are abolished by cutting the nervous connections of GIT.
    • They affect areas in GIT that may be far away from the sites of their releas
    • I.V injection of their extracts produces similar effects to those produced by the stimuli that release them.

    Answer: Their effects are abolished by cutting the nervous connections of GIT.

    Explanation: GIT hormones work through the bloodstream (endocrine action) and their effects are not abolished by cutting nerve connections.

15. Q15. About the GRP, all the followings are true except:

    • It inhibits the intestinal motility (through liberating gastrin).
    • It increases the gastric secretion (through liberating gastrin).
    • It increases the pancreatic secretion (through liberating gastrin).
    • It is found in the hypothalamus (in addition to GIT).
    • It is the neurotransmitter of the vagal nerve endings that terminate on G cells.
    • stimulates gastrin release, which increases gastric and pancreatic secretion. It does not significantly inhibit intestinal motility.

    Answer: It inhibits the intestinal motility (through liberating gastrin).

    Explanation: GRP (Gastrin-Releasing Peptide) stimulates gastrin release, which increases gastric and pancreatic secretion. It does not significantly inhibit intestinal motility.

16. Q16. All the followings are correct about gastrin except:

    • It is stimulated by distension of antrum.
    • It is stimulated by insulin-induced hypoglycemi
    • Its secretion is increased by secretin.

    Answer: It is stimulated by distension of antrum.

    Explanation: Secretin inhibits gastrin secretion as part of the negative feedback control of gastric acid.

17. Q17. A patient with trigeminal lesion would have the greatest difficulty with which of the following?

    • Swallowing.
    • Chewing.
    • Receptive relaxation of the upper esophageal sphincter.
    • Secondary peristalsis in the esophagus.

    Answer: Chewing.

    Explanation: The trigeminal nerve (CN V) provides motor innervation to the muscles of mastication.

18. Q18. Mastication:

    • Is entirely a voluntary act.
    • Includes both voluntary and reflex components.
    • Is performed by muscles supplied by 7th (facial) nerv
    • It is normally initiated by conditioned reflexes.
    • Is important for digestion of carbohydrates only.

    Answer: Includes both voluntary and reflex components.

    Explanation: Mastication has both voluntary initiation and reflex components. Muscles are supplied by the trigeminal nerve (CN V).

19. Q19. About salivary secretion (true or false):

    • At rapid rate of secretion, its Na+ & Cl- concentrations increase while its K+ concentration decreases.
    • It plays a significant role in digestion of lipids.
    • It is best stimulated by sour foo
    • It is entirely under nervous control.

    Answer: At rapid rate of secretion, its Na+ & Cl- concentrations increase while its K+ concentration decreases.

    Explanation: Saliva becomes more isotonic at higher flow rates. Sour stimuli are potent stimulants. Control is neural.

20. Q20. About salivary secretion (true or false):

    • It is an alkaline hypertonic flui
    • Its enzymes come mainly from the parotid and submaxillary glands.
    • It is largely under hormonal control.
    • Its mucus comes mainly from the submaxillary, sublingual and buccal glands.
    • Enzymes come from serous glands; mucus comes from mucous glands. Control is neural.

    Answer: It is largely under hormonal control.

    Explanation: Saliva is alkaline but hypotonic. Enzymes come from serous glands; mucus comes from mucous glands. Control is neural.

21. Q21. About salivary glands, which of the following statement is true?

    • Their secretion is mainly under hormonal control.
    • The sympathetic system is the only natural pathway for stimulation of their secretion.
    • Bradykinin decreases their blood flow rat
    • Their secretion increases in conditions of dehydration.

    Answer: Bradykinin decreases their blood flow rat

    Explanation: Both sympathetic and parasympathetic stimulation increase salivary secretion.