Introduction: Mastering the human alimentary canal is essential for B. Pharm students preparing for therapeutics, pharmacokinetics and pathophysiology exams. This concise introduction and comprehensive Human alimentary canal MCQs With Answer collection covers anatomy, histology, enzymatic digestion, absorption, motility, secretions, gut hormones, hepatic and biliary functions, microbiota and clinical correlations relevant to drug action and delivery. Questions emphasize mechanisms—enzyme specificity, pH effects on absorption, enterohepatic recycling, first‑pass metabolism—and practical implications for oral drug formulation, interactions and disease states like peptic ulcers, malabsorption and cholera. Each MCQ is targeted to reinforce core concepts and exam readiness. Now let’s test your knowledge with 50 MCQs on this topic.
Q1. Which layer of the alimentary canal is primarily responsible for peristaltic contractions?
- Mucosa
- Submucosa
- Muscularis externa
- Serosa
Correct Answer: Muscularis externa
Q2. Which cells in the stomach secrete hydrochloric acid?
- Chief cells
- Parietal cells
- Mucous neck cells
- G cells
Correct Answer: Parietal cells
Q3. Intrinsic factor secreted by gastric parietal cells is essential for absorption of which vitamin?
- Vitamin C
- Vitamin D
- Vitamin B12
- Vitamin K
Correct Answer: Vitamin B12
Q4. Which enzyme begins starch digestion in the mouth?
- Pepsin
- Salivary amylase (ptyalin)
- Pancreatic lipase
- Peptidase
Correct Answer: Salivary amylase (ptyalin)
Q5. The brush border enzyme that converts disaccharides to monosaccharides is located where?
- Stomach lumen
- Pancreatic duct
- Small intestinal microvilli
- Hepatocyte canaliculi
Correct Answer: Small intestinal microvilli
Q6. Which hormone stimulates pancreatic enzyme secretion and gallbladder contraction?
- Gastrin
- Secretin
- Cholecystokinin (CCK)
- Motilin
Correct Answer: Cholecystokinin (CCK)
Q7. Secretin primarily stimulates which response?
- Increased gastric acid secretion
- Increased pancreatic bicarbonate secretion
- Increased bile salt synthesis
- Decreased intestinal motility
Correct Answer: Increased pancreatic bicarbonate secretion
Q8. The main site for absorption of iron (Fe2+) in the alimentary canal is:
- Stomach
- Duodenum
- Jejunum
- Ileum
Correct Answer: Duodenum
Q9. Bile salts aid lipid digestion by:
- Hydrolyzing triglycerides
- Forming micelles to solubilize lipids
- Neutralizing fatty acids
- Activating pancreatic proteases
Correct Answer: Forming micelles to solubilize lipids
Q10. The hepatic portal vein carries blood from the alimentary canal primarily to:
- Inferior vena cava
- Hepatic artery
- Liver sinusoids for first‑pass metabolism
- Systemic arterial circulation
Correct Answer: Liver sinusoids for first‑pass metabolism
Q11. Which enzyme activates trypsinogen to trypsin in the small intestine?
- Enterokinase (enteropeptidase)
- Pepsin
- Lipase
- Amylase
Correct Answer: Enterokinase (enteropeptidase)
Q12. Peyer’s patches are most abundant in which section of the intestine?
- Duodenum
- Jejunum
- Ileum
- Colon
Correct Answer: Ileum
Q13. The migrating motor complex (MMC) occurs predominantly during:
- Fed state after a meal
- Fasting state between meals
- Immediately after eating carbohydrates
- Only during sleep
Correct Answer: Fasting state between meals
Q14. Which gastrointestinal sphincter prevents reflux of duodenal contents into the stomach?
- Lower esophageal sphincter (LES)
- Pyloric sphincter
- Ileocecal valve
- Anal sphincter
Correct Answer: Pyloric sphincter
Q15. Which cell type secretes pepsinogen?
- Parietal cells
- Chief (zymogenic) cells
- Mucous neck cells
- D cells
Correct Answer: Chief (zymogenic) cells
Q16. H. pylori contributes to peptic ulcer formation primarily by:
- Stimulating excessive bile secretion
- Producing urease and causing mucosal damage
- Increasing pancreatic enzyme secretion
- Blocking gastrin release
Correct Answer: Producing urease and causing mucosal damage
Q17. Which of the following best describes enterohepatic circulation?
- Direct absorption of drugs into systemic veins bypassing liver
- Bile constituents reabsorbed in the ileum and returned to the liver
- Portal blood draining directly into the systemic circulation
- Pancreatic enzymes recycled to the pancreas
Correct Answer: Bile constituents reabsorbed in the ileum and returned to the liver
Q18. The primary site of water and electrolyte absorption is:
- Stomach
- Small intestine
- Colon
- Rectum
Correct Answer: Small intestine
Q19. Which of the following decreases gastric emptying most markedly?
- High carbohydrate meal
- High fat meal
- Hypotonic fluid
- Anticholinergic drugs
Correct Answer: High fat meal
Q20. The pH of the unstirred water layer near enterocyte apical membrane affects drug absorption according to:
- Henderson‑Hasselbalch and pH partition theory
- Michaelis‑Menten kinetics
- Bohr effect
- Osmotic pressure gradients
Correct Answer: Henderson‑Hasselbalch and pH partition theory
Q21. Which vitamin is absorbed primarily in the terminal ileum along with bile salts?
- Vitamin A
- Vitamin B12
- Vitamin E
- Vitamin C
Correct Answer: Vitamin B12
Q22. Pancreatic bicarbonate secretion is stimulated mainly by which mechanism?
- Gastrin directly on pancreatic ducts
- Secretin acting on ductal cells to increase cAMP
- CCK binding to acinar cells to increase calcium
- Somatostatin release from D cells
Correct Answer: Secretin acting on ductal cells to increase cAMP
Q23. Which of the following enzymes is secreted by the pancreas in inactive zymogen form?
- Amylase
- Trypsinogen
- Pancreatic lipase
- Ribonuclease
Correct Answer: Trypsinogen
Q24. Which substance is essential for absorption of fat‑soluble vitamins from the gut?
- Intrinsic factor
- Bile salts
- Gastric acid
- Pepsin
Correct Answer: Bile salts
Q25. The enteric nervous system plexus responsible for secretions and blood flow is:
- Myenteric (Auerbach) plexus
- Submucosal (Meissner) plexus
- Celiac plexus
- Hypogastric plexus
Correct Answer: Submucosal (Meissner) plexus
Q26. Which lipid carrier transports long‑chain fatty acids from enterocytes to systemic circulation?
- Chylomicrons via lymphatic lacteals
- HDL via portal vein
- Albumin‑bound free fatty acids to the portal vein
- Short‑chain fatty acids in chylomicrons
Correct Answer: Chylomicrons via lymphatic lacteals
Q27. A drug subject to significant first‑pass metabolism will have reduced:
- Oral bioavailability
- Renal clearance
- Volume of distribution
- Plasma protein binding
Correct Answer: Oral bioavailability
Q28. The ileocecal valve separates which two anatomical regions?
- Stomach and duodenum
- Jejunum and ileum
- Ileum and cecum
- Transverse and descending colon
Correct Answer: Ileum and cecum
Q29. Which immune cell population in gut‑associated lymphoid tissue provides IgA for mucosal immunity?
- Cytotoxic T lymphocytes
- B cells (plasma cells) producing secretory IgA
- Natural killer cells
- Neutrophils
Correct Answer: B cells (plasma cells) producing secretory IgA
Q30. The major digestive function of the colon is:
- Protein digestion
- Absorption of salts and water and formation of feces
- Secretion of intrinsic factor
- Primary nutrient absorption
Correct Answer: Absorption of salts and water and formation of feces
Q31. Gastrin release from G cells is primarily stimulated by:
- Low gastric pH
- Protein peptides and vagal stimulation
- Secretin from duodenum
- High duodenal fatty acids
Correct Answer: Protein peptides and vagal stimulation
Q32. Chloride secretion into the intestinal lumen that drives secretory diarrhea is commonly increased by:
- Vagal stimulation only
- Activation of CFTR channels by toxins like cholera toxin
- Inhibition of adenylate cyclase
- Decreased intracellular cAMP
Correct Answer: Activation of CFTR channels by toxins like cholera toxin
Q33. The main proteolytic enzyme active in the stomach is:
- Trypsin
- Pepsin
- Chymotrypsin
- Enterokinase
Correct Answer: Pepsin
Q34. Which diagnostic test assesses small intestinal mucosal absorption capacity?
- Urea breath test
- D-xylose absorption test
- Fecal occult blood test
- Serum amylase
Correct Answer: D-xylose absorption test
Q35. Which drug class directly inhibits the H+/K+ ATPase in parietal cells?
- H2 receptor antagonists
- Proton pump inhibitors (PPIs)
- Antacids (aluminum hydroxide)
- Prostaglandin analogues
Correct Answer: Proton pump inhibitors (PPIs)
Q36. Gastric acid secretion is increased by which neurotransmitter acting via vagal stimulation?
- Noradrenaline acting on beta receptors
- Acetylcholine acting on muscarinic receptors
- Dopamine acting on D2 receptors
- Serotonin acting on 5‑HT3 receptors
Correct Answer: Acetylcholine acting on muscarinic receptors
Q37. A decrease in bile salt concentration impairs absorption of which nutrient most?
- Glucose
- Amino acids
- Long‑chain fatty acids and fat‑soluble vitamins
- Sodium and chloride
Correct Answer: Long‑chain fatty acids and fat‑soluble vitamins
Q38. Which cell type in the liver acts as a macrophage clearing bacteria and debris from portal blood?
- Hepatocytes
- Kupffer cells
- Endothelial sinusoidal cells
Correct Answer: Kupffer cells
Q39. Which of the following increases risk of drug‑induced GI bleeding when combined with NSAIDs?
- Proton pump inhibitors
- Aspirin co‑administration
- H2 receptor antagonists
- Antacids
Correct Answer: Aspirin co‑administration
Q40. Short‑chain fatty acids produced by colonic bacteria are primarily absorbed by colonocytes and used as:
- Precursor for bile salts
- Main energy source for colonocytes (e.g., butyrate)
- Substrate for pancreatic enzyme synthesis
- Transporters for vitamin B12
Correct Answer: Main energy source for colonocytes (e.g., butyrate)
Q41. Which factor most increases oral drug absorption in the small intestine?
- Large molecular weight of drug
- High lipid solubility and unionized form at luminal pH
- Extensive degradation by intestinal enzymes
- Poor blood flow to the mucosa
Correct Answer: High lipid solubility and unionized form at luminal pH
Q42. The primary anatomical site of peptic ulcer disease associated with H. pylori is:
- Esophagus
- Gastric antrum and duodenal bulb
- Jejunum
- Sigmoid colon
Correct Answer: Gastric antrum and duodenal bulb
Q43. Which mechanism explains bile acid malabsorption causing diarrhea?
- Excess bile acids in colon stimulate secretion and motility
- Decreased bile in colon increases water absorption
- Bile acids form insoluble complexes with sodium
- Bile acids inhibit enteric hormones
Correct Answer: Excess bile acids in colon stimulate secretion and motility
Q44. Which test detects active Helicobacter pylori infection noninvasively?
- Serologic IgG antibodies only
- Urea breath test
- Complete blood count
- Fecal occult blood test
Correct Answer: Urea breath test
Q45. Absorption of vitamin B12 requires which combination?
- Intrinsic factor and ileal receptors
- Pancreatic enzymes and jejunal brush border
- Gastrin and gastric mucus
- Bile salts and colonic bacteria
Correct Answer: Intrinsic factor and ileal receptors
Q46. Which condition is characterized by transmural inflammation that can affect any part of the GI tract?
- Ulcerative colitis
- Celiac disease
- Crohn’s disease
- Irritable bowel syndrome
Correct Answer: Crohn’s disease
Q47. Which gastric cells secrete gastrin?
- Parietal cells
- G cells in the antrum
- Chief cells
- Mucous neck cells
Correct Answer: G cells in the antrum
Q48. Which mechanism leads to fat malabsorption in cholestatic liver disease?
- Overproduction of bile salts
- Reduced bile salt delivery to intestine impairing micelle formation
- Increased pancreatic enzyme secretion
- Enhanced intestinal motility
Correct Answer: Reduced bile salt delivery to intestine impairing micelle formation
Q49. The primary stimulus for CCK release from I cells is:
- Low gastric pH
- Presence of fats and amino acids in the duodenum
- High luminal glucose concentration only
- Distension of the colon
Correct Answer: Presence of fats and amino acids in the duodenum
Q50. Which transport process in enterocytes is most important for absorption of glucose?
- Facilitated diffusion via GLUT2 only
- Sodium‑dependent secondary active transport (SGLT1)
- Endocytosis of disaccharides
- Simple diffusion down concentration gradient
Correct Answer: Sodium‑dependent secondary active transport (SGLT1)
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