Intestinal villus

From Wikipedia, the free encyclopedia

Intestinal villus

Microvilli show electron dense plaques (open arrow) at their apices. These plaques may be the anchoring point for the microfilaments which run up through the core of the microvilli. While an extensive glycocalyx is present on the microvilli of many mammals, the microvilli observed in this study do not demonstrate any visible glycocalyx. The junctional complex (thin arrow) at the apices of the epithelial cells is supplemented by numerous spot desmosomes (arrow head) on the lateral surfaces of the cells.
Image:Gray1058.png
Section of duodenum of cat. X 60.
Latin	villi intestinales
Gray's	subject #248 1174
Dorlands/Elsevier	v_08/12857047

For other meanings of villus/villi, see villi.

Intestinal villi (singular: villus) are tiny, finger-like structures that protrude from the wall of the intestine and have additional extensions called microvilli (singular: microvillus) which protrude from epithelial cells lining villi. They increase the absorptive area of the intestinal wall. Digested nutrients (including sugars and amino acids) pass into the villi. Circulating blood then carries these nutrients away. <ref name="tiscali">[1] Tiscali UK - Reference encyclopedia</ref>

1 Function
2 Homologue of alveolus
3 Additional images
4 References
5 External links

[edit] Function

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. This increases the surface area of the intestine to around the area of a small parking lot or a tennis court.

There are also enzymes on the surface for digestion. Villus capillaries collect amino acids and simple sugars taken up by the villi into the blood stream. Villus lacteals collect absorbed fatty acids.

[edit] Homologue of alveolus

Villi serve the same purpose as the alveoli in the lungs. Both increase surface area, which helps to increase transfer of nutrients into the blood through diffusion, although alveoli also transfer wastes out. Alveoli transfer carbon dioxide out and oxygen into the bloodstream, while villi tranfer digested food in.