The digestive tract is a long muscular tube lined with epithelium specialized for digestion and absorption of food and water. Food moves along the digestive system from the mouth where it is ingested, to the anus where the undigested and unabsorbed remnants of food and some additional waste are eliminated.

The digestive tract (a.k.a alimentary tract), starts in the oral cavity and continues through the pharynx, to the esophagus, stomach, duodenum, small intestine, large intestine, rectum, and terminates in the anal canal. Food moves along the digestive tract by peristalsis, the rhythmic contractions of the smooth muscle within the walls of the tube. Food moves in one direction (except in unusual circumstances such as vomiting), and multiple circular muscles called sphincters, located at critical junctions, prevent the food in transit from going backward. The mucosal (epithelial layer) secretions aid in digestion, and later provide the mechanisms for the absorption of nutrients.

In addition to the digestive tract, the digestive system includes several accessory glands that secrete various enzymes and fluids to assist with digestion and transport. The major accessory glands of the digestive system include:

three pairs of salivary glands,
the pancreas
the liver with the gallbladder.

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