The process of digestion begins in the mouth during mastication, where chewing breaks food into small bits and mixes it with saliva. In the small intestine, nutrients are absorbed through the lining of the intestinal wall, and finally, indigestible waste products are pushed into the colon and excreted.
Food passes from the mouth, through the esophagus and into the stomach, before finally emptying into the small intestine. By the time food reaches the small intestine, it is a mostly liquid mixture called "chyme," because digestive enzymes from the mouth and stomach have already disintegrated foods into their constituent nutrients. In the small intestine, more digestive components from the pancreas, liver and intestine continue the process, until the nutritive elements are small enough to be absorbed.