The pancreas is a mixed gland because it has both endocrine and exocrine functions. As an endocrine gland, it secretes hormones into the bloodstream. Only one percent of the weight of the pancreas serves as an endocrine gland. The remaining 99 percent of the gland has exocrine functions. The acinar cells (also called acini, from the Latin meaning “grapes” because their structure resembles clusters of grapes) are responsible for secreting digestive enzymes.The pancreatic islets (islet of Langerhans) are cluster cells that secrete hormones. There are between 200,000 and 2,000,000 pancreatic islets scattered throughout the adult pancreas.
