Explanation

The source of somatostatin is same as that of insulin and glucagon because all are secreted from pancreas. Alpha cells secrete glucagon hormone beta cell secrete insulin hormone and delta cells secrete small amount of gastrin and somatostatin. Somatostatin also secreted by hypothalamus and some cells of digestive tract. The major action of pancreatic somatostain is to inhibit the secretion of both insulin and glucagon.