What is the role of villi in digestion?

Mar 12, 2016

It is the primary site for nutrient absorption into the blood stream after being digested into small molecules with enzymes.

Explanation:

Villi are tiny, tentacle-like structure that line the inner surface of the small intestine. They are about $0.5 - 1.6$ mm long and are covered with microvilli that give them a brush-like structure.

Most of the digestion occurs in the stomach by its enzymes and in the small intestine by the pancreatic enzymes. Afterward, further enzymatic secretion occurs in the villi to completely break down all carbohydrates, proteins, and lipids into their respective micromolecules to be absorbed by the villi.

The reason for the villi's tentacle-like structure and being covered by microvilli to give it a brush-like structure is to increase the surface area available for absorption. This structure will increase our intestine's surface area $300 - 600$ folds. Resulting in a very efficient absorption mechanism in the small intestine.

They are also very rich in blood vessels to provide direct and easy flow of nutrients into the blood.

Villi
Pancreas