The
nervous system is an
organ system containing a
network of specialized cells called
neurons that coordinate the actions of an
animal and transmit signals between different parts of its body. In most animals the nervous system consists of two parts, central and peripheral. The
central nervous system of
vertebrates (such as humans) contains the
brain,
spinal cord, and
retina. The
peripheral nervous system consists of sensory neurons, clusters of neurons called
ganglia, and
nerves connecting them to each other and to the central nervous system. These regions are all interconnected by means of complex neural pathways. The
enteric nervous system, a subsystem of the peripheral nervous system, has the capacity, even when