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The endocrine (i.e., hormone-producing) cells of the pancreas are grouped in the islets of Langerhans. Discovered in 1869 by the German pathological anatomist Paul Langerhans, the islets of Langerhans constitute approximately 1 to 2% of the mass of the pancreas. There are about one million islets in a healthy adult human pancreas, which are interspersed evenly throughout the organ, and their combined weight is 1 to 1.5 grams. Each islet contains approximately one thousand cells and is 50-500 μm in diameter.
Hormones produced in the Islets of Langerhans are secreted directly into the blood flow by (at least) four different types of cells:
- Beta cells producing Insulin and Amylin (65-80% of the islet cells)
- Alpha cells releasing Glucagon (15-20%)
- Delta cells producing Somatostatin (3-10%)
- PP cells containing polypeptide (1%)
The paracrine feedback system of the islets of Langerhans has the following structure:
- Insulin: Activates beta cells and inhibits alpha cells.
- Glucagon: Activates alpha which activates beta cells and delta cells.
- Somatostatin: Inhibits alpha cells and beta cells.
Electrical activity of pancreatic islets has been studied using patch clamp techniques, and it has turned out that the behavior of cells in intact islets differs significantly from the behaviour of dispersed cells.
As a treatment for type I diabetesEdit
Since the islets of Langerhans are destroyed in type I diabetes, clinicians and researchers are actively pursuing islet transplantation technology as a means of curing this disease.
Anatomy of torso, digestive system: Digestive glands
Bile ducts: (Bile canaliculus, Common hepatic duct, Cystic duct, Common bile duct)
Human anatomy, endocrine system: endocrine glands
|Islets of pancreas|
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