Which cells secrete insulin?

Which cells secrete insulin?

• A. Alpha cells
• B. Beta cells
• C. Delta cells
• D. Gamma cells

Answer: (B)

Insulin is produced by the beta cells in the islets of Langerhans of the pancreas. When blood glucose rises, these cells release insulin, which helps cells throughout the body take up glucose—especially in muscle and adipose tissue—while the liver reduces glucose production. The release mechanism involves glucose entering beta cells, increasing the ATP/ADP ratio, closing KATP channels, depolarizing the cell membrane, opening voltage-gated calcium channels, and triggering exocytosis of insulin-containing granules. Other endocrine cells in the islets have different roles: alpha cells secrete glucagon, which raises blood glucose; delta cells secrete somatostatin, which modulates the activity of insulin and glucagon; and gamma (PP) cells secrete pancreatic polypeptide, involved in regulating digestive processes.

Insulin is produced by the beta cells in the islets of Langerhans of the pancreas. When blood glucose rises, these cells release insulin, which helps cells throughout the body take up glucose—especially in muscle and adipose tissue—while the liver reduces glucose production. The release mechanism involves glucose entering beta cells, increasing the ATP/ADP ratio, closing KATP channels, depolarizing the cell membrane, opening voltage-gated calcium channels, and triggering exocytosis of insulin-containing granules.

Other endocrine cells in the islets have different roles: alpha cells secrete glucagon, which raises blood glucose; delta cells secrete somatostatin, which modulates the activity of insulin and glucagon; and gamma (PP) cells secrete pancreatic polypeptide, involved in regulating digestive processes.