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 which food 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. Differentiating features between various parts of digestive system and differentiating features between various parts of small intestine are also discussed in this chapter. Clinical images are also provided in the chapter.