The small intestine is made up of the duodenum, jejunum, and ileum. The duodenum, the first and shortest section of the small intestine, is a key organ in the digestive system. The digested mass is further pushed into the large intestine which is a highly specialized organ responsible for processing waste. The waste left over from the digestive process, is passed through the colon by means of peristalsis, first in a liquid state and ultimately in a solid form. The large intestine function is mainly about making the process of emptying the bowels easy and convenient.. The small intestine is a hollow, muscular tube about 20 feet long that comprises the longest part of your digestive system. Together with the esophagus, large intestine, and the stomach, it forms the gastrointestinal tract. Your small intestine connects your stomach above it to your large intestine (or colon) below it. Specifically, it is part of the alimentary canal, which is the tract that runs from the mouth to the anus. Your small intestine has three parts. The small intestine’s most important function is to digest nutrients and pass them into the blood vessels—located in the intestinal wall—for absorption of the nutrients into the bloodstream. The small intestine is part of the digestive system, which is also called the gastrointestinal (GI) system. The small intestine is the part of the intestines where 90% of the digestion and absorption of food occurs, the other 10% taking place in the stomach and large intestine.