Sites of intestinal absorption

Absorption is the movement of substances from the intestine into the body. The small intestine is the region where nutrients are absorbed. It also absorbs most of the water taken up from the intestines.

The colon, part of the large intestine, absorbs some water too. Water absorption therefore occurs in both regions, but predominantly in the small intestine.

Intestinal villi

Villi are numerous finger-like projections in the lining of the small intestine. They increase the internal surface area available for absorbing nutrients from digested food.

The cells covering each villus have even smaller projections called microvilli. These increase the surface area further, providing more space for nutrient absorption.

Nutrient absorption in a villus

Each villus has a thin epithelial covering, so absorbed nutrients have only a short distance to travel through the covering to reach the vessels inside.

A network of blood capillaries carries away absorbed water-soluble nutrients, such as glucose and amino acids. Each villus also contains a lacteal, a lymphatic vessel into which absorbed fat products enter. The lacteal carries them away in lymph.