Anatomy and Physiology of the Gastrointestinal Tract The gastrointestinal tract extends through the body from the mouth to the anus, taking in the pharynx, oesophagus (gullet), stomach, small intestine, colon and rectum. The purpose of the gastro intestinal tract is to carry out the four functions necessary to keep the body supplied with carbohydrates, fats, proteins, water and essential vitamins and minerals, obtained by processing food: ingestion of food and water digestion of food products absorption of nutrients and water elimination of waste products The inner surface of the gastrointestinal tract consists of a lining of connective tissue, secretory cells and glands known as the mucosa. This mucosal surface plays a vital role in the processes of digestion and absorption. Food products are broken down in the gastrointestinal tract by acids and enzymes. Food and the products of digestion are propelled along the gastrointestinal tract by rhythmic contractions of the smooth muscle layer called peristalsis. Gastrointestinal motility refers to the pace and direction of the peristaltic contractions of the gastrointestinal tract, particularly the stomach. Normally, motility ensures that the contents are propelled in a smooth and gentle way down through the tract, so that the individual is not usually aware of movement. Any disruption to normal motility gives rise to symptoms of gastric disturbance. Copyright © 2004 McNeil Ltd. A Johnson & Johnson Company.