Endocrine System : The Classical World

Introduction

The endocrine system is an internal secretion system which, unlike the exocrine glands (e.g. the sudoriferous and sebaceous glands), provides a network of ductless glands – i.e. they have no specific channels. These affect the function of various organs by secreting chemical messengers directly into the bloodstream. These messengers, called hormones, are substances with specialized functions originating in organs and glands which are conveyed through the blood to another body part to stimulate that part to increase or decrease its functional activity.

It differs from other systems in that its organs and glands are located in different parts of the body, and not physically connected. The blood is the common passageway for the various hormones.

It is one of the two key communicating systems that together produce and maintain Homeostasis. The Nervous System provides information to the brain through its sensory, or afferent, nerves and gives commands through its motor, or efferent, nerves. The neurotransmitters are its chemical messengers. The Endocrine System, through its hormones, provides the work force. That is why the hypothalamus and the pituitary (hypophysis), the master gland, are located together and work hand in hand.