Intestinal villus
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| Intestinal villus | |
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| 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. |
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| 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. [1]
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[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 the transfer rate 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 transfer digested food in.
[edit] Additional images
 different stages of Coeliac Disease |
[edit] References
[edit] External links
- Histology at BU 11504loa - "Digestive System: Alimentary Canal: pyloro/duodenal junction, duodenum"
- Histology at BU 11513loa - "Digestive System: Alimentary Canal: pyloro/duodenal junction"
- Histology at BU 11609loa - "Digestive System: Alimentary Canal: duodenum, plicae circularis"
- Histology at USC gi/c_36
- Histology at USC gi/c_39
- Dictionary at eMedicine Intestinal+villi
