The human digestive system processes food that we eat. It is made up of multiple organs and glands that digest the food, extract energy and nutrients, and later expel the waste byproducts. The digestive system has two major parts - upper and lower gastrointestinal (GI) tracts. The upper GI tract comprises of mouth, pharynx, esophagus, and stomach, while the lower GI tract consists of the small intestine, large intestine and the anus. Organs such as liver, gallbladder, and pancreas are also part of the digestive system.