endocrine pancreas

The endocrine pancreas consists of the islets of Langerhans, containing alpha cells (glucagon), beta cells (insulin), delta cells (somatostatin), PP cells (pancreatic polypeptide), and epsilon cells (ghrelin). These cells form compact clusters scattered throughout the exocrine pancreatic tissue.

When blood glucose rises, beta cells secrete insulin to promote cellular glucose uptake and glycogen storage. When blood glucose falls, alpha cells secrete glucagon to stimulate glycogen breakdown and gluconeogenesis in the liver, maintaining glucose homeostasis.

The islets of Langerhans are highly vascularized relative to their size, receiving about 5-10 times the blood flow of the surrounding exocrine pancreas per unit mass. This rich blood supply allows rapid hormone secretion in response to changing blood glucose concentrations.