Enzymes and nutrient absorption Knowledge-Based Practice

Questions

1. 1.

   Which enzyme is primarily responsible for hydrolyzing dietary triglycerides into 2-monoacylglycerols and free fatty acids in the lumen of the small intestine?

   • A) Lingual lipase
   • B) Phospholipase $\text{A}_2$
   • C) Pancreatic lipase
   • D) Cholesterol esterase
2. 2.

   Which brush-border enzyme embedded in the microvillar membrane of the duodenum initiates the activation cascade of pancreatic proteolytic zymogens by converting trypsinogen into active trypsin?

   • A) Enteropeptidase
   • B) Carboxypeptidase
   • C) Dipeptidase
   • D) Aminopeptidase
3. 3.

   Following the enzymatic breakdown of dietary triglycerides in the small intestine, absorbed fatty acids and monoacylglycerols are reassembled and packaged into chylomicrons within enterocytes. Into which vascular structure are these chylomicrons predominantly released to begin transport through the body?

   • A) Hepatic portal vein
   • B) Interlobular bile ducts
   • C) Lacteals of the lymphatic system
   • D) Submucosal venules
4. 4.

   Following the enzymatic hydrolysis of dietary carbohydrates in the small intestine, by which mechanism are glucose and galactose primarily absorbed across the apical membrane of enterocytes?

   • A) Facilitated diffusion mediated by apical GLUT5 transporters
   • B) Passive paracellular diffusion driven by osmotic pressure
   • C) Secondary active transport coupled with sodium ions via SGLT1
   • D) Primary active transport directly powered by an apical ATP-hydrolyzing pump
5. 5.

   Which of the following enzymes acts at the brush border of the small intestine to complete the digestion of peptides into absorbable amino acids?

   • A) Pepsin
   • B) Trypsin
   • C) Dipeptidase
   • D) Amylase

Answers and step-by-step solutions appear after you finish the test.