The human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion. Digestion involves the breakdown of food into smaller and smaller components until they can be absorbed and assimilated into the body. The process of digestion has three stages. The GI tract is a series of hollow organs joined in a long, twisting tube from the mouth to the anus. The digestive system -- which can be up to 30 feet in length in adults is usually divided into eight parts: the mouth, the oesophagus, the stomach, the small intestine (or "small bowel") and the large intestine (also called "large bowel" or "colon") with the liver, pancreas, and gallbladder adding secretions to help.