Large intestine anatomy and functions MCQs With Answer

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Large intestine anatomy and functions MCQs With Answer

The large intestine anatomy and functions are essential topics for B. Pharm students preparing for pharmacology, pathology, and clinical pharmacy exams. This concise introduction covers colon segments (cecum, ascending, transverse, descending, sigmoid, rectum, anal canal), key histological features (taenia coli, haustra, goblet cells), major physiological roles (water and electrolyte absorption, fermentation, short-chain fatty acid production, vitamin K synthesis), blood supply, innervation, and relevant drug actions affecting motility and secretion. These focused MCQs will strengthen clinical reasoning and drug therapy understanding related to colonic disorders, constipation, diarrhea, and microbiome interactions. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which segment of the large intestine directly receives chyme from the ileum?

  • Cecum
  • Ascending colon
  • Sigmoid colon
  • Rectum

Correct Answer: Cecum

Q2. Which characteristic is typical of the colonic mucosa compared with small intestine?

  • Presence of villi
  • Abundant goblet cells
  • Paneth cells throughout
  • Long microvilli on enterocytes

Correct Answer: Abundant goblet cells

Q3. Taenia coli are:

  • Three longitudinal bands of smooth muscle on the colon
  • Circular muscle rings forming haustra
  • Folds in the rectal mucosa
  • Small fatty appendices on the serosa

Correct Answer: Three longitudinal bands of smooth muscle on the colon

Q4. Which vessel supplies the descending colon?

  • Superior mesenteric artery
  • Inferior mesenteric artery
  • Celiac trunk
  • Internal iliac artery

Correct Answer: Inferior mesenteric artery

Q5. Which nerve provides parasympathetic innervation to the distal colon and rectum?

  • Vagus nerve
  • Pelvic splanchnic nerves (S2–S4)
  • Greater splanchnic nerve
  • Hypogastric nerve

Correct Answer: Pelvic splanchnic nerves (S2–S4)

Q6. Haustra of the colon are formed primarily by:

  • Contraction of circular muscle forming fixed folds
  • Contraction of taenia coli creating sacculations
  • Tumors causing localized bulging
  • Appendices epiploicae pulling the wall

Correct Answer: Contraction of taenia coli creating sacculations

Q7. The main absorptive function of the colon is:

  • Protein digestion and absorption
  • Water and electrolyte absorption
  • Bile salt reabsorption
  • Vitamin D synthesis

Correct Answer: Water and electrolyte absorption

Q8. Short-chain fatty acids (SCFAs) produced by colonic bacteria primarily come from fermentation of:

  • Proteins only
  • Complex carbohydrates and fibers
  • Simple sugars absorbed in small intestine
  • Fatty acids from bile

Correct Answer: Complex carbohydrates and fibers

Q9. Which vitamin is synthesized by colonic microbiota and absorbed locally?

  • Vitamin C
  • Vitamin K
  • Vitamin B12 in large amounts
  • Vitamin D

Correct Answer: Vitamin K

Q10. The ileocecal valve functionally prevents:

  • Retrograde flow of colonic contents into the ileum
  • Passage of bile into the colon
  • Absorption of vitamin K
  • Movement of feces into rectum

Correct Answer: Retrograde flow of colonic contents into the ileum

Q11. Which histological structure is prominent in the colon but not in the small intestine?

  • Crypts of Lieberkühn with abundant goblet cells
  • Peyer’s patches
  • Villi
  • Brunner’s glands

Correct Answer: Crypts of Lieberkühn with abundant goblet cells

Q12. The rectum stores feces and is distinguished by which feature in the anal canal?

  • Pectinate (dentate) line marking epithelial transition
  • Peyer’s patches cluster
  • Taenia coli continuation
  • Presence of villi

Correct Answer: Pectinate (dentate) line marking epithelial transition

Q13. Mass movements in the colon are primarily triggered by:

  • Fasting state and sympathetic stimulation
  • Gastric and duodenal reflexes after meals
  • Large protein meals only
  • Defecation reflex suppression

Correct Answer: Gastric and duodenal reflexes after meals

Q14. Which ion transport mechanism in the colon is stimulated by aldosterone?

  • Chloride secretion via CFTR
  • Sodium absorption via epithelial sodium channels (ENaC)
  • Potassium absorption into lumen
  • Bicarbonate secretion into lumen

Correct Answer: Sodium absorption via epithelial sodium channels (ENaC)

Q15. In the context of drug delivery, the colon is a target for sustained release because:

  • It has high proteolytic activity that degrades most drugs
  • Transit time is relatively slow and microbiota can activate prodrugs
  • Vascular uptake is minimal
  • pH is highly acidic throughout

Correct Answer: Transit time is relatively slow and microbiota can activate prodrugs

Q16. Which of the following is a bulk-forming laxative acting in the colon?

  • Bisacodyl
  • Psyllium (ispaghula husk)
  • Polyethylene glycol (osmotic)
  • Docusate sodium (stool softener)

Correct Answer: Psyllium (ispaghula husk)

Q17. Loperamide reduces diarrhea mainly by:

  • Increasing intestinal secretion of chloride
  • Acting as a peripheral μ-opioid receptor agonist to decrease motility
  • Antibiotic activity against E. coli
  • Neutralizing gastric acid

Correct Answer: Acting as a peripheral μ-opioid receptor agonist to decrease motility

Q18. The most common site of appendicitis pain is related to irritation of which structure?

  • Descending colon
  • Cecum and parietal peritoneum near McBurney’s point
  • Sigmoid colon near pelvic brim
  • Rectum posterolaterally

Correct Answer: Cecum and parietal peritoneum near McBurney’s point

Q19. Diverticulosis commonly affects which part of the colon?

  • Ascending colon
  • Transverse colon evenly
  • Sigmoid colon
  • Cecum only

Correct Answer: Sigmoid colon

Q20. Which statement about the appendix is true?

  • It is a blind-ended tube arising from the sigmoid colon
  • It contains lymphoid tissue and is considered part of gut-associated lymphoid tissue
  • It secretes large amounts of digestive enzymes
  • It is supplied by the inferior mesenteric artery

Correct Answer: It contains lymphoid tissue and is considered part of gut-associated lymphoid tissue

Q21. Which layer of the colon wall houses the myenteric (Auerbach) plexus?

  • Mucosa
  • Submucosa
  • Between circular and longitudinal muscle layers (muscularis externa)
  • Serosa only

Correct Answer: Between circular and longitudinal muscle layers (muscularis externa)

Q22. Colonic ischemia most often results from compromise of which blood supply in the watershed area?

  • Jejunal arterial arcades
  • Splenic artery distal branches
  • Watershed between superior and inferior mesenteric arteries (e.g., splenic flexure)
  • Internal pudendal artery

Correct Answer: Watershed between superior and inferior mesenteric arteries (e.g., splenic flexure)

Q23. Which of the following is characteristic of ulcerative colitis (UC) rather than Crohn’s disease?

  • Transmural inflammation with skip lesions
  • Continuous mucosal inflammation starting from rectum
  • Perianal fistulas common
  • Granulomas on histology

Correct Answer: Continuous mucosal inflammation starting from rectum

Q24. Which diagnostic test is most appropriate to visualize the entire colonic mucosa?

  • Upper GI endoscopy
  • Colonoscopy
  • Abdominal ultrasound
  • HIDA scan

Correct Answer: Colonoscopy

Q25. Which pharmacologic class is contraindicated in acute severe ulcerative colitis due to risk of toxic megacolon?

  • Systemic corticosteroids
  • Antimotility agents like loperamide
  • Aminosalicylates
  • Biologic anti-TNF agents

Correct Answer: Antimotility agents like loperamide

Q26. The dentate (pectinate) line in the anal canal is clinically important because it:

  • Marks the transition from smooth to skeletal muscle in the rectum
  • Indicates change in epithelial type and differing nerve supply
  • Shows the site of taenia coli termination
  • Is the origin of the rectal venous plexus only

Correct Answer: Indicates change in epithelial type and differing nerve supply

Q27. Which enzyme-derived drug activation depends on colonic bacteria?

  • Proton pump inhibitors
  • Sulfasalazine (activated to 5-ASA and sulfapyridine)
  • Metformin
  • Warfarin

Correct Answer: Sulfasalazine (activated to 5-ASA and sulfapyridine)

Q28. Which of the following best describes colonic motility pattern called “haustral shuttling”?

  • Rapid peristalsis propelling contents to rectum continuously
  • Localized mixing movements that facilitate absorption within haustra
  • Complete inhibition of contraction after meal
  • Retrograde movement toward the ileum

Correct Answer: Localized mixing movements that facilitate absorption within haustra

Q29. The portal venous drainage of the colon ultimately goes to the:

  • Systemic circulation via inferior vena cava directly
  • Liver via the portal vein
  • Aorta through mesenteric arteries
  • Pulmonary circulation

Correct Answer: Liver via the portal vein

Q30. Which of the following is a stimulant laxative that acts on enteric nerves to increase motility?

  • Bisacodyl
  • Methylcellulose (bulk-forming)
  • Lactulose (osmotic)
  • Mineral oil (lubricant)

Correct Answer: Bisacodyl

Q31. Which substance is primarily absorbed in the colon and used by colonocytes as an energy source?

  • Glucose from dietary sugars
  • Butyrate (a short-chain fatty acid)
  • Amino acids from proteins
  • Free fatty acids from bile micelles

Correct Answer: Butyrate (a short-chain fatty acid)

Q32. Pseudomembranous colitis is most commonly associated with which organism after antibiotic use?

  • Escherichia coli
  • Clostridioides difficile
  • Streptococcus pyogenes
  • Helicobacter pylori

Correct Answer: Clostridioides difficile

Q33. Which colonic movement aids defecation by increasing intrarectal pressure?

  • Haustral shuttling
  • Segmental contraction only
  • Mass peristaltic movements
  • Reverse peristalsis

Correct Answer: Mass peristaltic movements

Q34. The omental appendices (appendices epiploicae) are:

  • Glandular mucosal folds in the rectum
  • Fat-filled peritoneal pouches attached to colon serosa
  • Sphincter muscles at the anal canal
  • Vascular arcades supplying the mesentery

Correct Answer: Fat-filled peritoneal pouches attached to colon serosa

Q35. Constipation caused by anticholinergic drugs is due to:

  • Increased colonic secretions
  • Decreased parasympathetic-mediated colonic motility
  • Direct damage to colonic mucosa
  • Increased activity of pelvic splanchnic nerves

Correct Answer: Decreased parasympathetic-mediated colonic motility

Q36. The proximal two-thirds of the transverse colon develops embryologically from the:

  • Hindgut
  • Midgut
  • Cloaca
  • Allantois

Correct Answer: Midgut

Q37. In ischemic colitis, which symptom is most characteristic?

  • Painless, chronic constipation
  • Sudden abdominal pain with bloody diarrhea
  • Upper abdominal burning relieved by antacids
  • Jaundice without abdominal pain

Correct Answer: Sudden abdominal pain with bloody diarrhea

Q38. Which layer contains abundant lymphoid aggregates in the colon?

  • Muscularis externa
  • Mucosa and submucosa (GALT)
  • Serosa only
  • Adventitia exclusively

Correct Answer: Mucosa and submucosa (GALT)

Q39. Which drug is used to treat refractory constipation by activating guanylate cyclase-C on enterocytes?

  • Lubiprostone
  • Linaclotide
  • Loperamide
  • Bisacodyl

Correct Answer: Linaclotide

Q40. The clinical sign of rebound tenderness in right lower quadrant suggests irritation of:

  • Left colon serosa
  • Peritoneum overlying the cecum and appendix
  • Rectum mucosa only
  • Transverse colon flexure

Correct Answer: Peritoneum overlying the cecum and appendix

Q41. Which of the following is true about colonic epithelial renewal?

  • Villi contain stem cells renewing enterocytes
  • Crypt base stem cells proliferate and migrate upward to replace epithelium
  • Enterocytes live for several years in colon
  • There is no regenerative capacity in colon

Correct Answer: Crypt base stem cells proliferate and migrate upward to replace epithelium

Q42. A colonoscopic biopsy showing non-caseating granulomas suggests which diagnosis?

  • Ulcerative colitis
  • Crohn’s disease
  • Ischemic colitis
  • Pseudomembranous colitis

Correct Answer: Crohn’s disease

Q43. Which electrolyte disturbance is commonly seen with severe secretory diarrhea originating from the colon?

  • Hypernatremia and metabolic alkalosis
  • Hyponatremia and metabolic acidosis with loss of bicarbonate
  • Hyperkalemia due to renal retention
  • Hypocalcemia with elevated bicarbonate

Correct Answer: Hyponatremia and metabolic acidosis with loss of bicarbonate

Q44. The gastrocolic reflex primarily causes:

  • Relaxation of the colon after eating
  • Increased colonic motility and mass movements after a meal
  • Decreased secretions in colon
  • Closure of ileocecal valve

Correct Answer: Increased colonic motility and mass movements after a meal

Q45. Carcinoma of the colon most commonly arises from:

  • Normal mucosa without precursor lesions
  • Adenomatous polyps (adenoma-carcinoma sequence)
  • Appendiceal mucoceles only
  • Transmural inflammatory scars exclusively

Correct Answer: Adenomatous polyps (adenoma-carcinoma sequence)

Q46. Which receptor type on enteric neurons mediates increased secretion and motility in secretory diarrhea?

  • Adrenergic β2 receptors
  • Serotonin (5-HT3/5-HT4) receptors and enteric cholinergic receptors
  • GABA-B receptors
  • Opioid μ receptors centrally only

Correct Answer: Serotonin (5-HT3/5-HT4) receptors and enteric cholinergic receptors

Q47. Which statement about the distal colon’s blood supply is correct?

  • It is supplied entirely by the superior mesenteric artery
  • The sigmoid arteries, branches of the inferior mesenteric artery, supply the sigmoid colon
  • The rectum is supplied only by branches of the superior rectal artery
  • The colon has no collateral blood supply

Correct Answer: The sigmoid arteries, branches of the inferior mesenteric artery, supply the sigmoid colon

Q48. Bowel sounds in colonic obstruction are typically:

  • Hyperactive high-pitched early, then diminished
  • Always normal
  • Absent from the onset
  • Only heard in the small intestine

Correct Answer: Hyperactive high-pitched early, then diminished

Q49. Which laboratory test aids in identifying inflammatory bowel disease activity originating in the colon?

  • Fecal calprotectin
  • Serum lipase only
  • Serum amylase only
  • Urine ketones

Correct Answer: Fecal calprotectin

Q50. The anal sphincter complex includes which muscle under voluntary control?

  • Internal anal sphincter (smooth muscle)
  • External anal sphincter (skeletal muscle)
  • Taenia coli
  • Puborectalis only involuntary

Correct Answer: External anal sphincter (skeletal muscle)

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