Glucagon
Introduction
Glucagon is a peptide hormone, produced by alpha cells of the pancreas. It works to raise the concentration of glucose and fatty acids in the bloodstream, and is considered to be the main catabolic hormone of the body. It is also used as a medication to treat a number of health conditions.
Structure
Glucagon is a 29 amino acid long polypeptide. It has a molecular weight of about 3485 daltons. The structure of glucagon is a single chain polypeptide, composed of 29 amino acid residues. The sequence of amino acids in glucagon is: His-Ser-Gln-Gly-Thr-Phe-Thr-Ser-Asp-Tyr-Ser-Lys-Tyr-Leu-Asp-Ser-Arg-Arg-Ala-Gln-Asp-Phe-Val-Gln-Trp-Leu-Met-Asn-Thr.
Function
The primary function of glucagon is to control the body's glucose levels. It does this by stimulating the liver to convert stored glycogen into glucose, which is then released into the bloodstream. This process is known as glycogenolysis. Glucagon also promotes the process of gluconeogenesis, which is the production of glucose from non-carbohydrate sources, such as amino acids and lipids.
In addition to its role in glucose regulation, glucagon also plays a role in maintaining the body's energy balance. It stimulates the breakdown of lipids in adipose tissue, releasing fatty acids into the bloodstream to be used as an energy source. This process is known as lipolysis.
Production and Secretion
Glucagon is produced in the alpha cells of the islets of Langerhans in the pancreas. The production and secretion of glucagon are regulated by a number of factors, including blood glucose levels, amino acid levels, and hormones. When blood glucose levels are low, glucagon secretion is stimulated. Conversely, when blood glucose levels are high, glucagon secretion is inhibited.
Role in Diabetes
In individuals with diabetes, the regulatory balance between insulin and glucagon is disrupted, leading to abnormal blood glucose levels. In type 1 diabetes, the body's immune system destroys the insulin-producing beta cells in the pancreas, leading to a lack of insulin. This results in an overproduction of glucagon, causing the liver to release too much glucose into the blood.
In type 2 diabetes, the body becomes resistant to insulin, and the pancreas cannot produce enough insulin to overcome this resistance. This leads to an overproduction of glucagon, which further increases blood glucose levels.
Glucagon as a Medication
Glucagon is used as a medication to treat severe hypoglycemia (low blood sugar) in people with diabetes who are unable to consume glucose or carbohydrates due to unconsciousness or inability to swallow. It is also used in diagnostic testing of the stomach and other digestive organs.