Digestive System 7, Small Intestine and absorption

Around 90% of absorption takes place from the small intestine, primarily in the jejunum and ileum. The remaining 10% of absorption from the gut takes place from the stomach and colon. In order for absorption to be efficient a large surface area is required into which the products of digestion can enter. The lining of the small intestine has circular folds. These project areas of mucosa into the lumen to increase surface area. The folds extend from about half to two thirds the way around the lumen and are up to 8 mm deep.