How does the digestive system relate to your body?

Every organism must have a way to get nutrients, and to expel waste. The digestive system in humans performs both of those functions, with skill and efficiency. The stomach, in conjunction with the gallbladder, begins the process of breaking down foods with stomach acids and bile salts. The upper and lower portions of the stomach have sphincters that prevent back-flow, especially from the small intestine back into the stomach. The small intestines have the unique ability to pull fluid from the cells in the intestinal walls, in order to further soften foods and break down nutrients from waste. Then, as this "mush" is let into the large intestines, the large intestines have a unique function in which the excess fluid is pulled back out and sent to the kidneys for elimination, while solid waste continues through to the lower colon then the rectum to be excreted.

Without a digestive system, humans could not live. In severe intestinal illness, though, humans can live even after having 1 to 2 feet of intestines removed.