From which cells of the islets of Langerhans is glucagon secreted?

Correct option is B

Sol. Glucagon is secreted by alpha-cells of the islets of Langerhans in the pancreas. It plays a crucial role in glucose metabolism by stimulating glycogen breakdown in the liver, increasing blood sugar levels. This process helps maintain glucose homeostasis, especially during fasting or low blood sugar conditions.
Explanation of each option:
· (a) Beta-cells – Incorrect. Beta-cells secrete insulin, which lowers blood glucose levels by promoting glucose uptake into cells. Insulin and glucagon work antagonistically to regulate blood sugar levels.
· (b) Alpha-cells – Correct answer. These cells produce glucagon, which raises blood sugar levels by stimulating glycogen breakdown and gluconeogenesis in the liver. This process is essential in preventing hypoglycemia.
· (c) Delta-cells – Incorrect. Delta-cells secrete somatostatin, a hormone that regulates the secretion of both insulin and glucagon by inhibiting their release. It plays a role in maintaining overall endocrine balance.
· (d) F-cells – Incorrect. F-cells (or PP cells) produce pancreatic polypeptide, which influences digestive enzyme secretion and gastrointestinal motility but has no direct role in blood sugar regulation.