Pancreatic Islet Cells That Secrete Insulin

The pancreas has clusters of endocrine cells called the islets of Langerhans. These islets are vital for regulating blood sugar levels by producing and secreting hormones directly into the bloodstream. Several types of cells exist within these islets, each with a specific function:

• Alpha cells (A cells): These cells produce and secrete glucagon. Glucagon's primary role is to increase blood glucose levels, essentially counteracting the effect of insulin.
• Beta cells (B cells): These are the most abundant cell type in the islets. They are responsible for producing and secreting insulin. Insulin is a crucial hormone that lowers blood glucose levels by helping cells absorb glucose from the blood for energy or storage.
• Delta cells (D cells): These cells secrete somatostatin, a hormone that inhibits the release of both insulin and glucagon, helping to regulate pancreatic activity.
• F cells (or PP cells): These cells secrete pancreatic polypeptide, a hormone involved in regulating pancreatic secretion and appetite.

Understanding the specific roles of these cells is key to comprehending glucose metabolism. When blood sugar levels rise, for example, after a meal, the Beta cells are stimulated to release insulin. This insulin then acts on various tissues (like the liver, muscles, and fat cells) to promote the uptake and utilization of glucose, thereby lowering blood glucose levels back towards the normal range.

Therefore, the pancreatic islet cells primarily responsible for secreting insulin are the Beta cells (also known as B cells).