Physiology, MBBS Second Year. This chapter is split into 10 topics and has
355 practice questions. The topics covered are listed below, followed by
10 free sample questions from the chapter.
Topics in this chapter
GI secretory glands & basic mechanism of secretion29 questions
Bile secretion, composition & gallbladder storage42 questions
Enterohepatic circulation, bile salts & gallstones42 questions
Secretions of the small intestine32 questions
Secretions of the large intestine & diarrhoea25 questions
Sample questions: Secretory Functions of the Alimentary Tract
10 sample questions with the correct answer and an explanation. Try to answer each one before reading the explanation.
Q1. Parasympathetic stimulation increases secretion in which structures?
A. Only the large intestine
B. Salivary glands, oesophageal glands, gastric glands, pancreas, Brunner's glands in the duodenum and glands in the distal portion of the large intestine(correct answer)
C. Only the pancreas
D. Only the salivary glands
Answer: B.Parasympathetic stimulation (via the glossopharyngeal and vagus nerves) increases secretion from the salivary glands, oesophageal glands, gastric glands, pancreas, Brunner's glands and glands in the distal part of the large intestine.
Q2. Sympathetic stimulation alone usually has which effect on GI secretion?
A. It doubles secretion
B. It strongly inhibits secretion
C. It slightly increases secretion(correct answer)
D. It has no effect
Answer: C.Sympathetic stimulation alone usually slightly increases GI secretion, but if parasympathetic or hormonal stimulation has already increased secretion, superimposed sympathetic stimulation reduces it by vasoconstrictive reduction of the blood supply.
Q3. Which statement correctly contrasts parasympathetic and sympathetic effects on GI secretion?
A. Both always increase secretion equally
B. Parasympathetic increases secretion, whereas sympathetic alone slightly increases and can reduce already-stimulated secretion(correct answer)
C. Sympathetic always abolishes secretion
D. Parasympathetic decreases secretion
Answer: B.Parasympathetic stimulation increases secretion in the salivary glands, oesophageal and gastric glands, pancreas, Brunner's glands and distal large intestine; sympathetic stimulation alone slightly increases secretion but reduces an already-stimulated secretion via vasoconstriction.
Q4. Which sequence correctly describes the nervous pathway increasing salivation?
D. Taste/smell/tactile stimuli → taste and smell areas of the cortex or amygdala → parasympathetic centres of the anterior hypothalamus → superior and inferior salivatory nuclei → parasympathetic nervous signals → increased salivation(correct answer)
Answer: D.Taste, smell and tactile stimuli reach the taste and smell areas of the cerebral cortex or amygdala, which project to the parasympathetic centres of the anterior hypothalamus and then to the superior and inferior salivatory nuclei, generating parasympathetic signals that increase salivation.
Q5. Why does the stomach need both parietal and peptic cells acting together for protein digestion?
A. Because peptic cells secrete acid and parietal cells secrete pepsin
B. Because parietal cells provide the acid that creates the optimal pH for pepsin, which peptic cells supply as inactive pepsinogen(correct answer)
C. Because protein digestion occurs without either cell
D. Because both cells secrete gastrin
Answer: B.Parietal cells secrete HCl, creating the acidic environment (pH 1.8–3.5) needed for the protease pepsin; peptic cells provide pepsinogen, which is activated to pepsin. The two cell types are therefore functionally coupled for protein digestion.
Q6. Why is a pancreatic enzyme deficiency worse for fat digestion than for carbohydrate digestion?
A. Because amylase is secreted in excess
B. Because only pancreatic lipase can efficiently digest neutral fat, whereas salivary and intestinal enzymes can partly handle carbohydrate(correct answer)
C. Because fat is not absorbed at all without bile
D. Because protein digestion compensates for fat
Answer: B.Pancreatic lipase is the principal enzyme for digesting neutral fat, and its absence causes marked fat maldigestion (steatorrhoea), whereas salivary amylase and intestinal disaccharidases can partially compensate for the loss of pancreatic amylase.
Q7. Why does the gallbladder concentrate bile rather than simply store it?
A. Because the liver cannot secrete concentrated bile
B. Because concentrating bile allows a larger quantity of bile salts to be stored in a small volume, providing a powerful bolus of bile when a fatty meal arrives(correct answer)
C. Because bile is toxic unless concentrated
D. Because concentration destroys bacteria
Answer: B.Water and electrolyte reabsorption (about fivefold, up to twentyfold) allows the gallbladder to store a large amount of bile salts in its small volume (30–60 ml), releasing a potent bile bolus for fat digestion when CCK is triggered.
Q8. Assertion: The bile salt pool is efficiently conserved. Reason: About 94% of bile salts are reabsorbed by the enterohepatic circulation and resecreted by the liver.
A. Assertion is false but Reason is true
B. Both Assertion and Reason are true, and the Reason correctly explains the Assertion(correct answer)
C. Both are true, but the Reason does not explain the Assertion
D. Assertion is true but Reason is false
Answer: B.Because about 94% of bile salts are reabsorbed (half by diffusion in the proximal small intestine and half by active transport in the distal ileum) and returned to the liver for resecretion, the bile salt pool is recycled many times a day and efficiently conserved.
Q9. Why is the small intestine considered the principal site of digestion and absorption?
A. Because it secretes hydrochloric acid
B. Because it secretes an alkaline enzyme-containing juice, receives pancreatic enzymes and bile, and has a huge surface area with brush-border enzymes for terminal digestion and absorption(correct answer)
C. Because it stores faeces
D. Because it lacks enzymes
Answer: B.The small intestine secretes alkaline intestinal juice and brush-border enzymes, receives pancreatic enzymes and bile, and presents a very large absorptive surface — allowing it to complete digestion and absorb the products into the blood, its primary function.
Q10. Why is mucus more important in the colon than in the small intestine?
A. Because the colon absorbs most nutrients
B. Because the colon contains a very large bacterial population and semi-solid faeces, so it needs lubrication, protection against excoriation and defence against bacteria and faecal acids(correct answer)
C. Because the colon secretes more enzymes
D. Because the colon has villi but no crypts
Answer: B.The colon's heavy bacterial load and semi-solid faecal contents require a continuous mucus barrier for lubrication, protection against mechanical excoriation, containment of faecal matter and defence against bacteria and the acids they produce.