The organ that secretes glucagon is the pancreas. Specifically, glucagon is secreted by the alpha cells within the pancreas.
Glucagon and the Pancreas
The pancreas is a vital organ located in the abdomen that plays a crucial role in both digestion and hormone regulation. Its endocrine function, which involves hormone secretion, is performed by specialized clusters of cells called the islets of Langerhans. These islets contain several types of cells, including:
- Alpha cells: These cells are responsible for producing and secreting glucagon.
- Beta cells: These cells produce and secrete insulin.
- Delta cells: These cells produce somatostatin.
- PP cells: These cells produce pancreatic polypeptide.
The Role of Glucagon
Glucagon is a peptide hormone that plays a key role in maintaining blood glucose levels. When blood glucose levels drop too low (hypoglycemia), alpha cells in the pancreas release glucagon. Glucagon then acts primarily on the liver to:
- Stimulate glycogenolysis: This is the breakdown of glycogen (stored glucose) into glucose, which is then released into the bloodstream.
- Promote gluconeogenesis: This is the synthesis of new glucose molecules from non-carbohydrate sources, such as amino acids and glycerol.
By stimulating these processes, glucagon helps to raise blood glucose levels back to a normal range. Insulin, secreted by beta cells, has the opposite effect, lowering blood glucose. The interplay between insulin and glucagon is crucial for maintaining glucose homeostasis.
