The jejunum is the region of the small intestine that is located in the middle and connects the initial part of the small intestine (the duodenum) to the very end of the small intestine (ileum). The food that has passed through the stomach and into the jejunum is further broken down by the jejunum. It is responsible for absorbing water and the nutrients (vitamins, minerals, carbs, fats, and proteins) that are found in food so that the body can make use of them. 
The jejunum is around 0.9 meters in length and accounts for approximately two-fifths of the overall length of the small intestine. The duodenojejunal flexure is where it begins, and the ileum is where it finishes. It is not possible to make out a distinct boundary between the jejunum and the ileum. The jejunum does not have either Brunner’s glands or Peyer’s patches, which is one of the histological characteristics that sets it apart from the remainder of the small intestine.