Gastrointestinal Tract

Digestion is a process conducted throughout a series of specialized organs. The human digestive system, also known as the gastrointestinal tract, consists of two components: the upper and lower tracts.

The upper gastrointestinal tract includes the esophagus, stomach and duodenum. After food is swallowed, it travels for about seven seconds down the esophagus and into the stomach. The stomach produces hydrochloric acid and enzymes called proteases which break down the food. The food then passes through pyloric sphincter (a valve at the end of the stomach) and then moves to the duodenum where certain minerals are absorbed.

The lower tract begins after the duodenum and includes most of the small intestine and all of the large intestine. Several functions occur in the small intestine—pancreatic enzymes and liver bile are combined, proteins and fats are broken down and soluble molecules are absorbed into the bloodstream. The large intestine, which includes the colon, absorbs water and several important vitamins. The leftover waste is then moved through the rectum and expelled through the anus.