Final answer:
The islets of Langerhans in the pancreas secrete important hormones, including insulin and glucagon, which regulate blood glucose levels and contribute to overall metabolism.
Step-by-step explanation:
The islets of Langerhans are the clusters of cells that are scattered throughout the pancreas, functioning to secrete a variety of important hormones. These islets constitute a crucial part of the endocrine system. Within the islets of Langerhans, there are four main types of cells: alpha cells which secrete glucagon, beta cells responsible for the production of insulin, delta cells that secrete somatostatin, and PP cells (or gamma cells) that produce pancreatic polypeptide. The hormones secreted by these cells play vital roles in regulating blood glucose levels and the body's overall metabolism. For instance, insulin helps lower blood glucose levels by facilitating the uptake of glucose by muscles and adipose tissues, whereas glucagon has the opposite effect, raising blood glucose levels by promoting the release of glucose from glycogen stores in the liver.