 The exocrine part synthesizes and secretes digestive enzymes and other substances, including dopamine, into the small intestine.The function of this secreted dopamine after it enters the small intestine is not clearly established—the possibilities include protecting the intestinal mucosa from damage and reducing gastrointestinal motility (the rate at which content moves through the digestive system).The pancreatic islets make up the endocrine part of the pancreas, and synthesize and secrete hormones including insulin into the bloodstream.