Small intestine anatomy and functions MCQs With Answer

by

Small intestine anatomy and functions MCQs With Answer

The small intestine anatomy and functions are central to B. Pharm curricula, covering nutrient and drug absorption, villi and microvilli structure, brush border enzymes, and regional specializations of duodenum, jejunum, and ileum. This SEO-friendly guide emphasizes key terms like small intestine anatomy, functions, drug absorption, enterocytes, Peyer’s patches, bile salt recycling, SGLT1/GLUT transporters, and enterohepatic circulation to boost search relevance. It is crafted for B. Pharm students preparing for exams and practicals, linking physiology and pharmaceutics for better clinical understanding. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which layer of the small intestine contains the intestinal glands (crypts of Lieberkühn) and supports nutrient absorption?

  • Mucosa
  • Submucosa
  • Muscularis externa
  • Serosa

Correct Answer: Mucosa

Q2. The principal cells responsible for carbohydrate and peptide digestion at the brush border are called:

  • Paneth cells
  • Enterocytes
  • Goblet cells
  • Enteroendocrine cells

Correct Answer: Enterocytes

Q3. Which transporter is primarily responsible for sodium-dependent glucose uptake into enterocytes?

  • GLUT5
  • SGLT1
  • ASBT
  • PEPT1

Correct Answer: SGLT1

Q4. Where are Peyer’s patches most densely located in the small intestine?

  • Duodenum
  • Jejunum
  • Ileum
  • Throughout equally

Correct Answer: Ileum

Q5. Enterokinase (enteropeptidase) located on the brush border activates which zymogen?

  • Chymotrypsinogen
  • Pepsinogen
  • Trypsinogen
  • Proelastase

Correct Answer: Trypsinogen

Q6. The main function of villi and microvilli is to:

  • Increase surface area for absorption
  • Produce digestive enzymes exclusively
  • Provide contractile motion
  • Secrete bile

Correct Answer: Increase surface area for absorption

Q7. Which cell type secretes lysozyme and antimicrobial peptides in the small intestine?

  • Enterocytes
  • Paneth cells
  • Goblet cells
  • Enteroendocrine cells

Correct Answer: Paneth cells

Q8. Fatty acids and monoglycerides are absorbed into enterocytes and then re-esterified to form:

  • Chylomicrons
  • Micelles
  • VLDL particles
  • HDL particles

Correct Answer: Chylomicrons

Q9. Which bile salt-related process primarily occurs in the terminal ileum?

  • Bile salt synthesis
  • Bile salt conjugation
  • Bile salt reabsorption (enterohepatic recycling)
  • Bile salt excretion in feces only

Correct Answer: Bile salt reabsorption (enterohepatic recycling)

Q10. Which brush border enzyme hydrolyzes lactose into glucose and galactose?

  • Maltase
  • Lactase
  • Sucrase
  • Peptidase

Correct Answer: Lactase

Q11. The major basolateral glucose transporter that facilitates exit of glucose from enterocytes into blood is:

  • GLUT2
  • GLUT5
  • SGLT2
  • PEPT2

Correct Answer: GLUT2

Q12. Which hormone stimulates pancreatic bicarbonate secretion in response to acidic chyme entering the duodenum?

  • Cholecystokinin (CCK)
  • Secretin
  • Gastrin
  • Motilin

Correct Answer: Secretin

Q13. The primary site for iron absorption in the small intestine is:

  • Duodenum
  • Jejunum
  • Ileum
  • Colon

Correct Answer: Duodenum

Q14. PEPT1 transporter on enterocytes primarily absorbs which type of molecules?

  • Monosaccharides
  • Oligopeptides and dipeptides
  • Long-chain fatty acids
  • Bile salts

Correct Answer: Oligopeptides and dipeptides

Q15. Which physiological factor most directly increases drug absorption in the small intestine?

  • Reduced surface area
  • Increased transit time and large surface area
  • Highly acidic pH similar to stomach
  • Absence of bile salts

Correct Answer: Increased transit time and large surface area

Q16. The migrating motor complex (MMC) during fasting is regulated primarily by:

  • Secretin
  • Motilin
  • Gastrin
  • VIP

Correct Answer: Motilin

Q17. Which enzyme on the brush border activates trypsinogen to trypsin, initiating pancreatic protease cascade?

  • Enterokinase
  • Maltase
  • Lipase
  • Amylase

Correct Answer: Enterokinase

Q18. Which of the following is a key anatomical feature that distinguishes the jejunum from the ileum?

  • More Peyer’s patches in jejunum
  • Thicker wall and larger circular folds in jejunum
  • Presence of Brunner’s glands in jejunum
  • Shorter villi in jejunum

Correct Answer: Thicker wall and larger circular folds in jejunum

Q19. Absorption of vitamin B12 occurs in the ileum when bound to:

  • Intrinsic factor
  • Transferrin
  • Albumin
  • Ferroportin

Correct Answer: Intrinsic factor

Q20. Which transporter is most important for intestinal fructose uptake across the apical membrane?

  • GLUT2
  • SGLT1
  • GLUT5
  • ASBT

Correct Answer: GLUT5

Q21. Which structural adaptation contributes most to the small intestine’s enormous absorptive surface area?

  • Length alone
  • Villi and microvilli combined
  • Thick muscularis externa
  • Serosal folding only

Correct Answer: Villi and microvilli combined

Q22. Which intestinal cells are primary producers of mucus to protect the epithelium?

  • Paneth cells
  • Goblet cells
  • Enterocytes
  • Enteroendocrine cells

Correct Answer: Goblet cells

Q23. Which factor would reduce oral drug absorption in the small intestine?

  • Presence of P-glycoprotein efflux transporters
  • High permeability of drug molecule
  • High surface area
  • Slow intestinal transit

Correct Answer: Presence of P-glycoprotein efflux transporters

Q24. The enzyme sucrase-isomaltase on the brush border primarily digests:

  • Proteins into amino acids
  • Disaccharides like sucrose and isomaltose
  • Lipids into free fatty acids
  • Peptides into dipeptides

Correct Answer: Disaccharides like sucrose and isomaltose

Q25. Which artery is the main blood supply to the midgut-derived portion of the small intestine?

  • Celiac trunk
  • Superior mesenteric artery
  • Inferior mesenteric artery
  • Renal artery

Correct Answer: Superior mesenteric artery

Q26. First-pass intestinal metabolism affecting oral bioavailability is often mediated by which enzyme family present in enterocytes?

  • CYP1 only
  • CYP3A4
  • Amylases
  • Peptidases

Correct Answer: CYP3A4

Q27. Which physiological mechanism mainly accounts for paracellular drug absorption between enterocytes?

  • Active transport by carriers
  • Tight junction permeability
  • Endocytosis by M cells
  • Bile salt micelle formation

Correct Answer: Tight junction permeability

Q28. Which immunological structure samples antigens from the intestinal lumen to initiate mucosal immunity?

  • Brunner’s glands
  • Peyer’s patches with M cells
  • Submucosal plexus
  • Lacteals

Correct Answer: Peyer’s patches with M cells

Q29. The lymphatic vessel in the center of an intestinal villus that transports absorbed fats is called:

  • Capillary plexus
  • Lacteal
  • Portal vein
  • Thoracic duct

Correct Answer: Lacteal

Q30. Which condition is characterized by autoimmune damage to small intestinal villi leading to malabsorption?

  • Diverticulosis
  • Celiac disease
  • Appendicitis
  • Ulcerative colitis

Correct Answer: Celiac disease

Q31. Which of the following increases passive diffusion of a weakly basic drug in the proximal small intestine?

  • Lowering luminal pH making drug more ionized
  • Higher pH favoring non-ionized form for bases
  • Presence of bile salts only
  • Activation of P-gp efflux

Correct Answer: Higher pH favoring non-ionized form for bases

Q32. Brush border aminopeptidases primarily act to:

  • Hydrolyze triglycerides
  • Remove terminal amino acids from peptides
  • Synthesize disaccharides
  • Transport glucose into blood

Correct Answer: Remove terminal amino acids from peptides

Q33. Which diagnostic test assesses proximal small intestinal absorptive capacity using a monosaccharide?

  • Schilling test
  • D-xylose absorption test
  • Hydrogen breath test
  • Fecal elastase assay

Correct Answer: D-xylose absorption test

Q34. Which enteric endocrine cell secretes cholecystokinin (CCK) in response to fat and protein in the duodenum?

  • K cells
  • I cells
  • G cells
  • S cells

Correct Answer: I cells

Q35. Which process describes the formation of mixed micelles important for lipid absorption?

  • Aggregation of bile salts with fatty acids and monoglycerides
  • Direct uptake of trilglycerides into blood
  • Peptide hydrolysis by peptidases
  • Endocytosis of intact lipoproteins

Correct Answer: Aggregation of bile salts with fatty acids and monoglycerides

Q36. The proximal small intestine shows which characteristic pH relative to stomach?

  • Much lower pH than stomach
  • Neutral to slightly acidic, higher than stomach
  • Extremely alkaline around pH 9–10
  • Constantly identical to colonic pH

Correct Answer: Neutral to slightly acidic, higher than stomach

Q37. Which transport process is responsible for most peptide and amino acid entry into blood from enterocytes?

  • Facilitated diffusion via GLUT transporters
  • Active transporters and facilitated diffusion for amino acids
  • Paracellular diffusion only
  • Bulk flow into lacteals

Correct Answer: Active transporters and facilitated diffusion for amino acids

Q38. In Crohn’s disease affecting the ileum, which nutrient absorption is most commonly impaired?

  • Vitamin C
  • Vitamin B12 and bile salts
  • Vitamin K only
  • Vitamin D only

Correct Answer: Vitamin B12 and bile salts

Q39. Which structural component connects intestinal epithelial cells and regulates paracellular permeability?

  • Desmosomes only
  • Tight junctions (zonula occludens)
  • Basal lamina only
  • Lacteal endothelium

Correct Answer: Tight junctions (zonula occludens)

Q40. The majority of oral peptide drugs are degraded in the small intestine primarily due to:

  • Low pH like stomach
  • Brush border and luminal proteases
  • Pancreatic lipases only
  • Intestinal mucus barrier only

Correct Answer: Brush border and luminal proteases

Q41. Which cell type senses luminal nutrients and releases hormones such as GLP-1?

  • Enterocytes
  • Enteroendocrine cells
  • Paneth cells
  • Goblet cells

Correct Answer: Enteroendocrine cells

Q42. A drug that is a P-glycoprotein substrate will likely have which intestinal fate?

  • Enhanced absorption due to carrier-mediated uptake
  • Reduced absorption due to efflux back into lumen
  • Absorbed unchanged into lymphatics
  • Immediate hepatic uptake without absorption

Correct Answer: Reduced absorption due to efflux back into lumen

Q43. Which molecule is essential for emulsification of dietary fats in the small intestine?

  • Intrinsic factor
  • Bile salts
  • Secretin
  • Pepsin

Correct Answer: Bile salts

Q44. The surface area of the small intestine amplified by villi and microvilli is approximately:

  • 1–2 square meters
  • 10–20 square meters
  • 200 square meters (order of magnitude)
  • 10,000 square meters

Correct Answer: 200 square meters (order of magnitude)

Q45. Which of the following is a consequence of removing the terminal ileum surgically?

  • Impaired iron absorption only
  • Loss of bile salt reabsorption and B12 malabsorption
  • Improved fat absorption
  • Increased intrinsic factor secretion

Correct Answer: Loss of bile salt reabsorption and B12 malabsorption

Q46. Intestinal epithelial renewal is rapid. The stem cells that replenish the epithelium reside mainly in:

  • Villus tips
  • Crypts of Lieberkühn
  • Submucosal glands
  • Serosa

Correct Answer: Crypts of Lieberkühn

Q47. Which pharmacokinetic concept is most influenced by extensive metabolism in enterocytes before a drug reaches portal blood?

  • Volume of distribution
  • First-pass intestinal metabolism reducing bioavailability
  • Renal clearance only
  • Rate of gastric emptying

Correct Answer: First-pass intestinal metabolism reducing bioavailability

Q48. Which feature helps the duodenum neutralize gastric acid and optimize enzyme activity?

  • Brunner’s glands secreting alkaline mucus and bicarbonate
  • Peyer’s patches producing acid
  • Lacteals absorbing acid
  • Villi secreting hydrochloric acid

Correct Answer: Brunner’s glands secreting alkaline mucus and bicarbonate

Q49. Absorption of water-soluble vitamins (except B12) in the small intestine is primarily by:

  • Passive diffusion only
  • Specific transporters and passive mechanisms
  • Endocytosis into lacteals
  • Sequestration in Peyer’s patches

Correct Answer: Specific transporters and passive mechanisms

Q50. Which pathological change reduces absorptive surface and leads to malabsorption in tropical sprue or celiac disease?

  • Increased villus height
  • Villus atrophy and flattening
  • Hypertrophy of Peyer’s patches only
  • Enhanced microvilli density

Correct Answer: Villus atrophy and flattening

Leave a Comment