<Tr> <Td_colspan="2"> Anatomical terminology (edit on Wikidata) </Td> </Tr> <P> Intestinal villi (singular: villus) are small, finger - like projections that extend into the lumen of the small intestine . Each villus is approximately 0.5--1.6 mm in length (in humans), and has many microvilli projecting from the enterocytes of its epithelium which collectively form the striated or brush border . Each of these microvilli are much smaller than a single villus . The intestinal villi are much smaller than any of the circular folds in the intestine . </P> <P> Villi increase the internal surface area of the intestinal walls making available a greater surface area for absorption . An increased absorptive area is useful because digested nutrients (including monosaccharide and amino acids) pass into the semipermeable villi through diffusion, which is effective only at short distances . In other words, increased surface area (in contact with the fluid in the lumen) decreases the average distance travelled by nutrient molecules, so effectiveness of diffusion increases . The villi are connected to the blood vessels so the circulating blood then carries these nutrients away . </P> <Ul> <Li> <P> Vertical section of a villus from the dog's small intestine . X 80 . (Simple columnar epithelium labeled at right, third from top .) </P> </Li> <Li> </Li> </Ul>

What purpose do villi serve in the small intestine