What are villi and why are they important in digestion?

• A. Small finger-like projections that increase surface area for absorption in the small intestine
• B. Nerves in the stomach
• C. Blood vessels carrying oxygen
• D. Glands producing enzymes

Answer: (A)

Villi are tiny finger-like projections lining the inner wall of the small intestine. Their main job is to increase the surface area available for absorbing nutrients after digestion. Because there are many of these projections, a lot more of the digested food can come into contact with the absorptive cells at once, making absorption much more efficient.

Each villus has a rich supply of capillaries and a lacteal, so absorbed nutrients can be quickly carried away—glucose and amino acids into the blood, fats into the lymphatic system. The surface cells also have microvilli (the brush border), which adds even more surface area and houses enzymes that help finish digestion right at the site of absorption.

So, the reason this option is best is that villi are the structures whose purpose is to boost absorption in the small intestine, not nerves, not simply blood vessels carrying oxygen, and not glands producing enzymes.