Tuesday, January 6, 2009

Intestinal Villus

Intestinal villi are small finger-like projections that extend from the wall of the small intestine and increase the absorptive area of the intestinal wall. The villi have additional extensions called microvilli which protrude from epithelial cells lining villi. Digested nutrients such as sugar and amino acids seep through into the villi and are carried away by circulating blood.

In all humans, the villi and microvilli together increase intestinal absorptive surface area 30-fold and 600-fold, respectively, providing exceptionally efficient absorption of nutrients in the lumen. There are also enzymes on the surface for digestion. Villus capillaries collects amino acids and simple sugars taken up by the villi into the blood stream. Lymph capillary collects absorbed fatty acids, which are reconstructed into triglycerides, combined with cholesterol and amphipathic proteins to form chylomicrons, and are taken to the rest of the body through the Lymph fluid.