Nervous system

The nervous system of an animal coordinates muscle movement, monitors the
organs, constructs and processes impressions from the senses, and initiates
actions. In animals with brains, it also generates and conducts thoughts and
emotions. Thus it is the system that animates "animals" (sponges are the
exception). Chemicals that target the activity of nerves generally are the
most rapidly acting toxins, typically causing paralysis and/or death.

The nervous system consists basically of two types of cells:

   * Neurons
   * Glia

Neurons are the primary cells of the nervous system, in that they more or
less independently conduct the system's moment-to-moment activities, whereas
glia play what at least appears to be a more supporting role, such as
nourishment and structural support.

Rapid signalling within the nervous system occurs by two primary mechanisms:

   * Within nerves and neurons by way of action potentials
   * Between neurons by way of neurotransmitter diffusion across synapses.

For heuristic and other purposes, the nervous system is divided into the
central and the peripheral nervous systems, of which the autonomic nervous
system is part.

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