Structure facilitating absorption from small intestine is:September 2003

Ans. A i.e. VilliIntestinal villiThey are small, finger-like projections that protrude from the epithelial lining of the intestinal wall.Each villus is approximately 0.5-1.6 (millimetres) in length and has many microvilliThe intestinal villi should not be confused with the larger folds of mucous membrane in the bowel known as the plicae circulares.Villi increase the internal surface area of the intestinal walls.Increased surface area allows for increased intestinal wall area that is available for absorption.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 sho 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.