What substance do alpha cells secrete?

Alpha cells, which are located in the islets of Langerhans in the pancreas, secrete glucagon. Glucagon plays a crucial role in glucose metabolism by promoting the release of glucose from the liver into the bloodstream, particularly during periods of fasting or low blood sugar levels. This action raises blood glucose levels, counteracting the effects of insulin, which is secreted by beta cells and lowers blood glucose. The secretion of glucagon is essential for maintaining homeostasis, especially in situations of hypoglycemia.

In contrast, insulin, which is secreted by beta cells, works to decrease blood sugar levels by facilitating the uptake of glucose into cells. Cortisol is a steroid hormone released by the adrenal cortex and is involved in a variety of metabolic processes, including the regulation of blood glucose, but it is not secreted by alpha cells. Ghrelin, known as the "hunger hormone," is produced in the stomach and plays a role in appetite regulation but is unrelated to the function of pancreatic alpha cells.