Glucagon is a polypeptide hormone produced by the alpha cells of the Islets of Langerhans cells in the pancreas. They increase blood glucose concentration by stimulating the formation of glucose from glycerol and protein rather than from carbohydrates (gluconeogenesis) and breakdown of glycogen to glucose in the liver (hepatic glycogenolysis). Glucagon, inthe form of a "Glucagen" injection, is administered intramuscularly, intravenously or subcutaneously for severe hypoglycemia or hypoglycemic coma. Hypoglycemia sometimes occurs in diabetic patients treated with insulin.
Insulin is a polypeptide hormone produced by the beta cells of the Islets of Langerhans cells in the pancreas and stored and stored in intracellular granules. The human pancreas stores approximately 10 g insulin of which 2 g are released daily into the portal vein. The release of insulin is stimulated by ingestion of sugar and the secretion of certain GI hormones.
A deficiency of insulin as well as insulin resistance of the tissue, cause the disease diabetes mellitus.1
This hormone is not as well known as insulin and glucagon. It is produced by delta cells, which make up 3% to 10% of islet cells. It is believed to inhibit the production and secretion of insulin and glucagon, thereby controlling their levels in the bloodstream.3 This hormone decreases the rate of nutrient absorption and also inhibits the secretion of growth hormone and other GI hormones. IT also has various effects on the nervous system.4
This hormone is produced by gamma or PP cells which make up a mere 1% of the islet cells. Although its precise function is unknown, it is thought to inhibit appetite. Secretion of this hormone increases after a protein meal, after exercise, and acute hypoglycemia. Somatostatin and IV glucose decrease its production.4
Amylin is a peptide hormone produced by the beta cells of the Islets of Langerhans cells in the pancreas. IT supplements insulin actions by reducing blood glucose levels. It also inhibits the secretion of glucagon, slows the emptying of the stomach and sends the satiety signal to the brain.
Function of Insulin
The physiological functions are many. Insulin reduces the levels of circulating amino acids, fatty acids and glucose by promoting their conversion to storage forms of each and by inhibiting the formation of glucose from glycerol and protein. Most cells of the body rely on insulin for uptake of glucose because it cannot penetrate the cell membrane.2
- Pharmacology for Nurses and Other Health Workers. M.S. Dreyer
- Hormones and signaling. Bert W. O'Malley
- Anatomy Coloring Workbook. I. Edward Alcamo, John Bergdahl
- Fluids & electrolytes made incredibly easy. Springhouse