Question Bank [2022] — BIOLOGY STD 12 Science — Question

Islets of Langerhans are endocrine cells of pancreas. They are four types of cells in Islets of Langerhans which have endocrine role i.e. they secrete hormones.

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