ANSWER:

Chewing, in which food is mixed with saliva, begins the MECHANICAL process of digestion. This produces a bolus which can be swallowed down the esophagus to enter the stomach. Here it is mixed with gastric aciduntil it passes into the duodenum where it is mixed with a number of enzymes produced by the pancreas. Saliva ALSO contains a catalyticenzyme called amylase which starts to act on food in the mouth. Another digestive enzymecalled 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 chewing of food carried out by the muscles of mastication, by the teeth, and also by the contractions of peristalsis, and segmentation.Gastric acid, and the production of mucus in the stomach, are essential for the continuation of digestion.

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 chymewhich 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.