The human digestive system

The system used in the human body for the process of digestion. The human digestive system consists primarily of the digestive tract, or the series of structures and organs through whichfood and liquids pass during their processing into forms absorbable into the bloodstream. The system also consists of the structures through which wastes pass in the process of elimination and other organs that contribute juices necessary for the digestive process.

The digestive tract begins at the lips and ends at the anus. It consists of the mouth, or oral cavity, with its teeth, for grinding the food, and its tongue, which serves to knead food and mix it withsaliva; the throat, or pharynx; the esophagus; the stomach; the small intestine, consisting of theduodenum, the jejunum, and

the ileum; and the large intestine, consisting of the cecum, a closed-end sac connecting with the ileum, the ascending colon, the transverse colon, the descending colon, and the sigmoid colon, which terminates in the rectum. Glands contributing digestive juices include the salivary glands, the gastric glands in the stomach lining, the pancreas, and the liver and its adjuncts—the gallbladder and bile ducts. All of these organs and glands contribute to the physical and chemical

breaking down of ingested food and to the eventual elimination of nondigestible wastes. Their structures and functions are described step by step in this section.