The human nervous system is the body’s regulation and communication centre. It can be divided into two parts: the central nervous system which comprises the encephalon (brain, diencephalon, cerebellum and brain stem) and the spinal cord, and the peripheral nervous system formed by the nerves attached to the central nervous system.
The nervous system receives information about changes in the body and then decides to act on this information if necessary. One part of the nervous system is called voluntary, as it concerns nervous impulses transmitted to the muscles which we can control consciously. The other part is named involuntary as it concerns the nervous impulses on which we have no influence, like the heartbeat or digestion for example. Nervous impulses thus ensure message transmission within the body.