ABSTRACT
ANATOMY AND PHYSIOLOGY OF THE SMALL INTESTINE The small intestine is between 5 and 6 metres in length and its main functions are to mix food with enzymes to facilitate digestion, to mix the intestinal contents with the intestinal secretions to enable absorption to occur, and to propel the unabsorbed materials in an aboral direction. The small intestinal epithelium has the highest capacity for nutrient and drug absorption within the gastrointestinal tract, due to the large surface area provided by epithelial folding and the villous structures of the absorptive cells.
