What is the primary function of the small intestine?

What is the primary function of the small intestine?

• A. Absorption of nutrients.
• B. Mechanical digestion only.
• C. Storage of chyme.
• D. Production of bile.

Answer: (A)

Absorption of nutrients is the primary function of the small intestine. Its lining is highly folded with villi and microvilli, giving a large surface area for taking up carbohydrates, proteins, fats, vitamins, minerals, and water. Digestive enzymes from the pancreas and enzymes on the intestinal wall finalize chemical digestion, and nutrients move into enterocytes to enter the bloodstream or lymphatic system for distribution throughout the body. While mixing and propulsion (segmentation and peristalsis) help process the chyme, the essential outcome here is absorption. The other options reflect roles of other organs or stages of digestion: storage of chyme mainly occurs in the stomach, bile is produced by the liver (stored and released by the gallbladder), and mechanical digestion alone is not the main activity of the small intestine since chemical digestion and absorption are central there.

Absorption of nutrients is the primary function of the small intestine. Its lining is highly folded with villi and microvilli, giving a large surface area for taking up carbohydrates, proteins, fats, vitamins, minerals, and water. Digestive enzymes from the pancreas and enzymes on the intestinal wall finalize chemical digestion, and nutrients move into enterocytes to enter the bloodstream or lymphatic system for distribution throughout the body. While mixing and propulsion (segmentation and peristalsis) help process the chyme, the essential outcome here is absorption. The other options reflect roles of other organs or stages of digestion: storage of chyme mainly occurs in the stomach, bile is produced by the liver (stored and released by the gallbladder), and mechanical digestion alone is not the main activity of the small intestine since chemical digestion and absorption are central there.