Introduction

Coordination in the body is not achieved by the nervous system alone. Nerve-based coordination is quick and point-to-point — a signal travels from one specific place to another almost instantly — but it is also short-lived, and its reach is limited: nerve fibres do not extend to and innervate every single cell of the body. Many processes, however, need to be regulated continuously and over a much wider area than the nervous system alone can cover. This ongoing, body-wide kind of regulation is carried out chemically, through hormones. Rather than working in isolation, the nervous system and the endocrine system act together, jointly coordinating and regulating the body's physiological functions — the fast, localised nervous route and the slower, more widespread hormonal route complementing each other.