<P> Chewing, in which food is mixed with saliva begins the process of digestion . This produces a bolus which can be swallowed down the esophagus and into the stomach . Here it is mixed with gastric juice until it passes into the duodenum where it is mixed with a number of enzymes produced by the pancreas . Saliva also contains a catalytic enzyme called amylase which starts to act on food in the mouth . Another digestive enzyme called lingual lipase is secreted by some of the lingual papillae on the tongue and also from serous glands in the main salivary glands . Digestion is helped by the mastication of food by the teeth and also by the muscular actions of peristalsis and segmentation contractions . Gastric juice in the stomach is essential for the continuation of digestion as is the production of mucus in the stomach . </P> <P> Peristalsis is the rhythmic contraction of muscles that begins in the esophagus and continues along the wall of the stomach and the rest of the gastrointestinal tract . This initially results in the production of chyme which when fully broken down in the small intestine is absorbed as chyle into the lymphatic system . Most of the digestion of food takes place in the small intestine . Water and some minerals are reabsorbed back into the blood in the colon of the large intestine . The waste products of digestion (feces) are defecated from the anus via the rectum . </P> <P> There are several organs and other components involved in the digestion of food . The organs known as the accessory digestive glands are the liver, gall bladder and pancreas . Other components include the mouth, salivary glands, tongue, teeth and epiglottis . </P> <P> The largest structure of the digestive system is the gastrointestinal tract (GI tract). This starts at the mouth and ends at the anus, covering a distance of about nine (9) metres . </P>

Is the liver part of the digestive canal