<prompt> Somatostatin is secreted by:Alpha cellsBeta cellsGamma cellsDelta cells  <response>: Ans. D Delta cellsRef: Guytons Physiology, 11th ed. pg. 961 The human pancreas has 1 to 2 million islets of Langerhans cells These islets contain three major types of cells: alpha, beta, and delta cells Beta cells--60 of all the cells of the islets, lie mainly in the middle of each islet and secrete insulin and amylin. Alpha cells--about 25 of the total islets- secrete glucagon. Delta cells--about 10 of the total islets- secrete somatostatin.Extra MileThe hormones secreted act as control of secretion of some hormones by other hormones: Insulin inhibits glucagon secretion Amylin inhibits insulin secretion Somatostatin inhibits both insulin and glucagon secretion.In addition to these, somatostatin has other functions: It decreases the motility of the stomach, duodenum, and gallbladder. It decreases both secretion and absorption in the gastrointestinal tract.Doing so, somatostatin has following effects: It extends the time period over which the food nutrients are absorbed into the blood. By inhibiting insulin and glucagon secretion, it prevents rapid utilization of nutrients by the tissues.Remember: Somatostatin is also known as growth hormone inhibitory hormone, which is also secreted in the hypothalamus and suppresses anterior pituitary gland growth hormone secretion. 