Which hormone is produced by the alpha cells of the islets of Langerhans and increases plasma glucose levels?

Which hormone is produced by the alpha cells of the islets of Langerhans and increases plasma glucose levels?

• A. Insulin
• B. Glucagon
• C. Somatostatin
• D. Thyroxine

Answer: (B)

The hormone produced by the alpha cells of the islets of Langerhans that increases plasma glucose levels is glucagon. This hormone plays a critical role in glucose metabolism by promoting gluconeogenesis and glycogenolysis in the liver, processes that convert stored glycogen into glucose, thus raising blood glucose levels. Glucagon acts as a counter-regulatory hormone to insulin, which lowers blood glucose levels.

Understanding the function of glucagon is essential in the context of metabolic regulation. When blood glucose levels drop, such as between meals or during fasting, glucagon is released into the bloodstream to stimulate the liver to release glucose. This mechanism is vital for maintaining homeostasis and ensuring that the body has a continuous supply of energy, particularly for cells that depend on glucose, such as brain cells.

In the context of the other options, insulin, produced by the beta cells, acts to decrease blood glucose levels by facilitating the uptake of glucose into cells. Somatostatin, produced by the delta cells, has an inhibitory effect on both insulin and glucagon secretion, helping to maintain balance. Thyroxine, produced by the thyroid gland, primarily regulates metabolism but does not significantly influence plasma glucose levels directly.