The endocrine system is a series of ductless glands which manufacture an internal secretion. These internal secretions (or hormones) are absorbed directly by the bloodstream. There are eight important glands or groupings in the body, each with its own distinct function but all bearing an inter-relationship with each other. The islets of Langerhans of the pancreas are part of the endocrine system. They have The function of the posterior lobe is to produce: Pitocin (pituitrin) and also provide an antidiuretic function