Digestive system. Computer artwork of the human digestive system. Food from the mouth travels sequentially through the oesophagus (top centre), stomach (green, upper right), duodenum, small intestine (centre), large intestine (colon, clock- wise from lower left to lower right) and rectum (bottom centre). It is propelled through the system by muscular contractions (peristalsis), which also aid the digestive process. Enzymatic breakdown of food in the stomach, duodenum and small intestine releases nutrients. These are absorbed into the blood and lymphatic systems through the intestinal linings. Undigested matter passes into the rectum and is expelled.