Neural circuits performing the same
functions form neuronal systems. We can divide neural systems in sensory,
motory and associative systems. Sensory systems acquire the environmental
information. Motory systems allow the individual to respond to stimuli.
Associative systems mediate complex functions (Parves, Augustine, Fitzpatrick,
Hall, LaMantia, White, Neuroscience, Sinauer Associates Inc).
From anatomical point of view, we can
divide nervous system in central and peripheral nervous system. Central nervous
system includes the brain and the spinal cord. Peripheral nervous system
instead includes a motory and a sensory portion. In sensory portion, sensory
neurons connect sensory receptors with central nervous system.
Motory portion comprises somatic and autonomic
division. In somatic division neurons connect central nervous system with
skeletal muscles. In autonomic division neurons connect central nervous system
with smooth muscles and internal organs.
In peripheral nervous system ganglia group
the cell bodies. Axons, however, form the nerves.
In central system instead nuclei are
clusters of neurons with similar functions. Bark instead represent a layered
arrangement of nerve cells. In autonomous system axons form the beams.
Autonomic system includes a sympathetic
and a parasympathetic division. In autonomic system, impulse starts from pre-ganglionic
efferent neuron that is located in the brainstem or spinal cord. The signal then
reaches the ganglion of autonomic nervous system and from here gets to post
ganglionic neuron. This neuron conducts signals until the
target organ receptor. In sympathetic system pre-ganglionic fibers are short,
because ganglia are located near spinal cord. In parasympathetic system,
however, pre-ganglionic fibers are long, since the ganglia are located near effector
organ (Parves, Augustine, Fitzpatrick, Hall, LaMantia, White, Neuroscience,
Sinauer Associates Inc).
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