Pancreas is also known as mixed gland because it is both endocrine and exocrine in nature. The islets of Langerhans functions as endocrine cells and secretes into the blood several important hormones, including insulin, glucagon, somatostatin, and pancreatic polypeptide. While the acini cells function as exocrine cells and secretes pancreatic juice into the duodenum through the pancreatic duct.