Question

Describe the endocrine role of islets of Langerhans.

Answer 1

Islets of Langerhans are endocrine cells of the pancreas. They are four types of cells in Islets of Langerhans that have an endocrine role, i.e. they secrete hormones.

1. Alpha cells (α cells): They constitute 20% of Islets of Langerhans. They secrete the hormone glucagon. Glucagon stimulates glycogenolysis (the breakdown of glycogen) in the liver, which causes hyperglycemia.
2. Beta cells (β cells) constitute 70% of Islets of Langerhans. They secrete insulin, which stimulates glycogenesis (the formation of glycogen) in the liver and muscles. Insulin causes hypoglycemia by increasing the uptake of glucose by cells.
3. Delta cells (δ cells): They constitute 5% 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.
4. PP cells or F cells: They constitute 5% of Islets of Langerhans. These cells secrete pancreatic polypeptide (PP) and inhibit the release of pancreatic juice.