Very short answer question.
Describe the endocrine role of islets of Langerhans.
Islets of Langerhans are endocrine cells of the pancreas. They are four types of cells in Islets of Langerhans which have an endocrine role i.e. they secrete hormones.
i. Alpha cells (α cells): They constitute 20% of Islets of Langerhans. They secrete hormone glucagon. Glucagon stimulates glycogenolysis (the breakdown of glycogen) in the liver which causes hyperglycemia.
ii. Beta cells (β cells): They constitute 70% of Islets of Langerhans. They secrete insulin which stimulates glycogenesis (formation of glycogen) in the liver and muscles. Insulin causes hypoglycemia by increasing the uptake of glucose by cells.
iii. Delta cells (δ cells): They constitute 10% of Islets of Langerhans. These cells secrete somatostatin which inhibits the secretion of insulin and glucagon. It also lowers gastric secretions, motility, and absorption in the digestive tract. Somatostatin inhibits the release of growth hormone.
iv. PP cells or F cells: These cells secrete pancreatic polypeptide (PP) and inhibit the release of pancreatic juice.