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.
beta cells, 1 insulin-producing cells situated in the islets of Langerhans. Their insulin-producing function tends to accelerate the movement of glucose, amino acids, and fatty acids out of the blood and into the cellular cytoplasm, countering glucagon function of alpha cells.