The jejunum is the midsection of the small intestine, connecting the duodenum to the ileum. It is about 2.5 m long, and contains the plicae circulares, and villi that increase its surface area. Products of digestion (sugars, amino acids, and fatty acids) are absorbed into the bloodstream here.
Not to be confused with the cells of the islets of Langerhans, found in the pancreas, or Langhans giant cell.
The islets of Langerhans are the regions of the pancreas that contain many endocrine (i.e., hormone-producing) cells. Hormones produced in the islets of Langerhans cells are secreted directly into the blood flow by at least five different types of cells: alpha, beta, delta, PP and epsilon.