In this sub-unit we are going to explain the concepts of: The contraction of circular and longitudinal muscle of the small intestine mixes the food with enzymes and moves it along the gut Enzymes digest most macromolecules in food into monomers in the small intestine The pancreas secretes enzymes into the lumen of the small intestine Villi increases the surface area of epithelium over which absorption is carried out Villi absorb monomers formed by digestion as well as mineral ions and vitamins Different methods of membrane transport are required to absorb different nutrients