Pancreas is a digestive gland found in the folds of the duodenum. Inside this gland, there are a large number of patches of cells which are small in size. Theses patches are called islands or islets named after a physiologist, Langerhans. Each patch or group of cells is called the islet of Langerhans. Each islet has at least 3 different types of cells with respect to the kinds of hormones it secretes.
Types
(a) Alpha cell:
Secretes glucogen hormone. It causes the breakdown of glycogen to release glucose in the blood. Thereby glucose becomes available to the tissues and organs of the body.
(b) Beta cell:
Secrets insulin hormone. After a heavy meal and its digestion and absorption, the blood accumulates large amount of glucose which must be taken away to the liver for the synthesis of glycogen. This is what is done by insulin. If insulin is not present or not secreted, blood glucose level will keep on rising and after a limit, the kidney will let it go out in the urine. Liberation of glucose in the urine is termed diabetes mellitus, which is a disease.
(c) Delta cell or Gamma cell
Secrets somatastin which is akin to growth hormone.