- A long tube-like organ that connects the stomach and the large intestine. It is about 20 feet long and folds many times to fit inside the abdomen. The small intestine has three parts: the duodenum, jejunum, and ileum. It helps to further digest food coming from the stomach. It absorbs nutrients (vitamins, minerals, carbohydrates, fats, proteins) and water from food so they can be used by the body. The small intestine is part of the digestive system.