Somatostatin is secreted by:

Ans. D Delta cellsRef: Guyton's 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.