What are the islets of Langerhans?
The islets of Langerhans (islets of Langerhans, Langerhans cells, islet cells) consist of about 2000 to 3000 glandular cells surrounded by numerous blood capillaries and have a diameter of only 75 to 500 micrometers. They are irregularly distributed throughout the pancreas, but are found clustered in the tail region of the organ. The islets of Langerhans make up only about one to three percent of the total mass of the pancreas.
What is the function of the islets of Langerhans?
The islets of Langerhans produce hormones. Depending on which hormone is involved, there are four different types of islet cells:
The A cells release the hormone glucagon when the blood glucose concentration drops (hypoglycemia). This is because glucagon stimulates the formation of glucose in the cells and its release into the blood, causing the blood glucose level to rise again. High glucose levels in the blood, on the other hand, inhibit the A cells. This cell type accounts for about 15 percent of the hormone-producing cells in the pancreas.
The B cells (beta cells) produce insulin, which is used to increase glucose uptake into the cells and thus lower blood glucose levels. They make up about 80 percent of all cells in the islets of Langerhans.
The PP cells produce the pancreatic polypeptide. It inhibits the release of digestive secretions from the pancreas and conveys a feeling of satiety. PP cells make up less than two percent of islet cells.
What problems can islets of Langerhans cause?
If the B cells that produce insulin are working inadequately or have even been destroyed by the immune system, type 1 diabetes (insulin-dependent diabetes) results. It occurs mainly in children and adolescents.
In type 2 diabetes, the body’s cells react insufficiently or not at all to the insulin released.
Benign and malignant tumors of the islets of Langerhans can affect hormone production.
