Small Intestines

Anatomically speaking, the small intestine is a segment that belongs to the gastrointestinal track or the “gut.”  This organ, located between the stomach and the large intestine, is the home to majority of the processes in digestion.

The small intestine is further divided into three small parts: duodenum, jejunum, and ileum. The duodenum is a hollow tube (about 10-12-in in size) that connects the stomach to the jejunum. It is the first part of the small intestine and is the one that performs the breakdown of food. The duodenum also regulates the “emptying of the stomach” rate through hormonal pathways. If acidic and fatty stimuli is present, the duodenal epithelium, secretes “Secretin” and “Cholecystokinin” to aid further digestion.

The jejumum is the center of the three main parts of the small intestine. Almost half of the length of the whole small intestine belongs to jejunum. Jejunum's responsibility is to finalize the food digestion process. It also contains muscles that help aid the movement of the digested food.

Ileum, the final section of the small intestine, is the one that absorbs B12, bile salts, and/or whatever products of digestion the jejunum failed to break down.

The organ's incredible length of 5.5-6m (approximate in human adults), made it a popular exhibit and diagram to museums and science fairs.