islets of Langerhans; pancreatic islets

Structure: - regions of the pancreas that contain endocrine cells, the islet cells - constitute ~1-2% of the mass of the pancreas - ~1,000,000 islets are distributed throughout a healthy adult human pancreas - combined mass is 1-1.5 grams Function: Cell types: - alpha cells produce glucagon (15-20% of total islet cells) - beta cells produce insulin & amylin (65-80%) - delta cells produce somatostatin (3-10%) - epsilon cells produce ghrelin (<1%) - PP cells produce pancreatic polypeptide (3-5%) Paracrine feedback: - insulin: secreted by beta cells, inhibits alpha cells - glucagon: secreted by alpha cells, inhibits beta cells & delta cells - somatostatin: secreted by delta cells, inhibits alpha cells & beta cells Pathology: - islet cell transplantation for type 1 diabetes Note: not to be confused with Langerhans cell

References

Wikipedia: Islets of Langerhans http://en.wikipedia.org/wiki/Islets_of_Langerhans