Digestive Physiology MCQs

32 clinical MCQs in GIT Physiology. About some GIT hormones (true or false): - (. Kenya, Africa and global revision.

Questions, Answers & Explanations

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

   • Gastrin
   • Secretin stimulates the pancreatic acinar cells to secrete enz
   • Pancreozymin is itself CCK and it has a structural relationshi
   • Secretin causes excessive gastric secretion and accelerates ga
   • Primarily an incidental laboratory finding

   Answer: Gastrin

   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

   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:

   • GIT secretion
   • Tactile stimulation.
   • A and
   • Distension.
   • Mostly unchanged in early disease

   Answer: GIT secretion

   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.
   • Secretin
   • Reduced by routine feedback control

   Answer: Secretin

   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. The GIT is controlled by:

   • Its own intrinsic nervous system (Auerbach's and Meissner's plexuses).
   • The sympathetic N.S.
   • The parasympathetic N.S.
   • Only B &
   • Occurs only after chronic exposure

   Answer: Its own intrinsic nervous system (Auerbach's and Meissner's plexuses).

   Explanation: The GIT has complex neural control involving the enteric nervous system (intrinsic control via myenteric and submucosal plexuses) and extrinsic control via both sympathetic and parasympathetic systems. ---

6. Q6. 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
   • Limited to a single tissue compartment

   Answer: Decreased gut motility.

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

7. Q7. The secretion of gastrin ceases (stops):

   • When the stomach is distended by meal.
   • Gastrin secretion
   • If the fundic mucosa is anesthetize
   • If the vagi are stimulate
   • Primarily an incidental laboratory finding

   Answer: Gastrin secretion

   Explanation: Gastrin secretion is inhibited by very low pH (below 2) as a negative feedback mechanism to prevent excessive acid production. ---

8. Q8. 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.
   • Usually mediated by non-specific mechanisms

   Answer: Secretion of the gut.

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

9. Q9. Secretin:

   • Secretin
   • Stimulates a pancreatic secretion rich in enzymes.
   • Acts as powerful cholagogu
   • Is secreted as a result of vagus nerve stimulation.
   • Mostly unchanged in early disease

   Answer: Secretin

   Explanation: Secretin is released from S cells in the duodenal mucosa when acidic chyme enters the duodenum. It stimulates bicarbonate-rich pancreatic secretion and inhibits gastric secretion. ---

10. Q10. 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.

    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. ---

11. Q11. 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.
    • Occurs only after chronic exposure

    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. ---

12. Q12. A major part of the gall bladder contractions are due to:

    • Sympathetic contraction of the viscus.
    • The overfilling of the gall bladder with bil
    • The rate of cholesterol synthesis and excretion by the liver.
    • A hormone synthesized by duodenal mucos
    • Limited to a single tissue compartment

    Answer: A hormone synthesized by duodenal mucos

    Explanation: CCK, synthesized by duodenal mucosa, is the primary stimulus for gallbladder contraction. ---

13. Q13. The major factor that stimulates the release of Secretin into the blood stream is:

    • Secretin
    • The parasympathetic stimuli.
    • Peptones in the gastric chyme that enter the duodenum.
    • A stomach full of digested contents.
    • Primarily an incidental laboratory finding

    Answer: Secretin

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

14. Q14. It is known that gastrin:

    • It is a large protein molecule, somewhat similar in size to pe
    • Is not secreted by empty stomach when peristaltic movements ma
    • Gastrin
    • Promotes the secretion of pepsin, but not that of HCl.
    • Usually mediated by non-specific mechanisms

    Answer: Gastrin

    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. ---

15. Q15. It is known that secretin:

    • It is a large protein hormone synthesized by the pancreas, toge
    • Secretin
    • Neutralizes directly the acid chyme that passes through the pyl
    • Has an optimal activity at a pH equal to 8.4.
    • Mostly unchanged in early disease

    Answer: Secretin

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

16. Q16. Secretin is released by:

    • Acid in the duodenum.
    • Acid in the urin
    • Secretin
    • Distension of the colon.
    • Reduced by routine feedback control

    Answer: Secretin

    Explanation: Secretin is released by S cells located in the duodenal mucosa in response to acidic chyme. ---

17. Q17. About the GIP, all the following are true except:

    • It is secreted from the duodenal mucos
    • It has +ve feedback effect on gastric secretion and motility.
    • Its release is stimulated by presence of excess fat.
    • It inhibits both gastric secretion and motility.
    • Limited to a single tissue compartment

    Answer: Its release is stimulated by presence of excess fat.

    Explanation: GIP (Glucose-dependent Insulinotropic Peptide) inhibits gastric secretion and motility. ---

18. Q18. About Cholecystokinin-pancreozymin (CCK), all the following are true except:

    • It is GIT hormone secreted by the duodenal mucosa in respo
    • It causes contraction of the gall bladder wall being a nat
    • It produces a pancreatic secretion rich in enzymes.
    • It potentiates the action of secretin on the pancreas.
    • Primarily an incidental laboratory finding

    Answer: It produces a pancreatic secretion rich in enzymes.

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

19. Q19. 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
    • Usually mediated by non-specific mechanisms

    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. ---

20. Q20. 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.

    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. ---

21. Q21. Concerning the gastrin, all the following are true except:

    • Gastrin
    • It is released from almost the whole GIT mucosa and its secret
    • It has a trophic effect on gastric mucosa and increases the ga
    • Its release is stimulated by gastric distension and inhibited
    • It stimulates insulin secretion from pancreas. - (F) It is rel

    Answer: Gastrin

    Explanation: Gastrin is released during cephalic, gastric, and intestinal phases and affects both parietal (oxyntic) and chief cells. ---

22. Q22. 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.
    • Occurs only after chronic exposure
    • Alternative related mechanism 5

    Answer: Occurs only after chronic exposure

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

23. Q23. 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.
    • Limited to a single tissue compartment

    Answer: Chewing.

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

24. Q24. Mastication is important because:

    • Minimizes the mechanical damage to the gut mucos
    • Allows the salivary enzymes to act for a longer tim
    • Increases the surface area of the food particles.
    • Destroys the protective coating present around some foods.
    • Primarily an incidental laboratory finding

    Answer: Allows the salivary enzymes to act for a longer tim

    Explanation: Mastication reduces particle size, increases surface area for enzymes, and breaks down protective coatings. ---

25. Q25. 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.
    • Usually mediated by non-specific mechanisms

    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). ---

26. Q26. Man is unable to digest dietary:

    • Glycogen.
    • Dextrin.
    • Saccharos
    • Cellulos
    • Mostly unchanged in early disease

    Answer: Cellulos

    Explanation: Humans lack the cellulase enzyme required to digest cellulose. ---

27. Q27. The salivary amylase:

    • Is also called ptyalin and it is beta amylas
    • Is the only amylase in GIT.
    • Digests mainly cooked starch.
    • Is activated by either HCl or Ca++.
    • Reduced by routine feedback control

    Answer: Is activated by either HCl or Ca++.

    Explanation: Salivary amylase (ptyalin) is an alpha-amylase that works best on cooked starch. It is inactivated by stomach acid. ---

28. Q28. 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.
    • Occurs only after chronic exposure

    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. ---

29. Q29. During the chewing of a bolus of food, but before swallowing, salivary secretion, gastric secretion and pancreatic secretion are stimulated by which of the following?

    • Acetylcholine, gastrin, histamin
    • Acetylcholine, CCK, nitric oxid
    • Nitric oxide, VIP, histamin
    • VIP, gastrin, somatostatin.
    • Limited to a single tissue compartment

    Answer: Acetylcholine, gastrin, histamin

    Explanation: During the cephalic phase, acetylcholine stimulates saliva, while gastrin and histamine contribute to gastric secretion. ---

30. Q30. The salivary secretion:

    • Is rich in glucos
    • Salivary secretion
    • Digests starch to glucos
    • Has the largest volume relative to other digestive juices.
    • Primarily an incidental laboratory finding

    Answer: Salivary secretion

    Explanation: Salivary secretion is under nervous control and is hypotonic. ---

31. Q31. 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
    • Usually mediated by non-specific mechanisms

    Answer: Bradykinin decreases their blood flow rat

    Explanation: Both sympathetic and parasympathetic stimulation increase salivary secretion. ---

32. Q32. The saliva (true or false)?

    • Contains no organic substances.
    • Is markedly increased in amount after sympathetic stimulation.
    • Secretion is increased after injection of atropin
    • Secreted by submandibular glands is about 70% of the total secretion.
    • Mostly unchanged in early disease

    Answer: Secreted by submandibular glands is about 70% of the total secretion.

    Explanation: Submandibular glands produce approximately 70% of resting saliva.