The small, finger-like projections in the small intestine are called "villi," which is the plural of "villus." These structures stem from the intestinal wall's lining and increase the surface area of the small intestine.
The small intestine is about 20 feet long and has a diameter of approximately 1 inch. A major function of this organ is to absorb nutrients from ingested food. Surface enzymes present on the villi aid in the digestion of food. Because of the increased surface area provided by the villi, their thin walls and their proximity to blood vessels, they facilitate quick, efficient nutrient absorption and distribution. Another function of the villi is to help move food through the small intestines.