Digestive system. Computer artwork of the human digestive system. Food is ingested through the mouth (not seen) and passes down the oesophagus to the stomach (orange), where it is stored and partially broken down before digestion in the small intestine (red, centre). Food residue passes from the small intestine into the colon, the main part of the large intestine (ribbed), where excess water is absorbed. Faeces are stored in the rectum (bottom centre) before they are expelled.