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04. Nervous System in Human Body
Nervous system is the chief controlling and
coordinating system of the body. It controls
and regulates all activities of the body,
whether voluntary or involuntary, and adjusts
the individual (organism) to the given
surroundings. This is based on the special
properties of sensitivity, conductivity and
responsiveness of the nervous system.
The protoplasmic extensions of the nerve
cells form the neural pathways called nerves.
The nerves resemble the electricity wires.
Like the electric current flowing through the
wires, the impulses (sensory and motor) are
conducted through the nerves.
The sensory impulses are transmitted by the
sensory (afferent) nerves from the periphery
Figure 4.1 (Nervous system)
(skin, mucous membranes, muscles, tendons,
joints, and special sense organs) to the central
nervous system (CNS). The motor impulses are transmitted by the motor (efferent) nerves
from the central nervous system to the periphery (muscles and glands).
Thus the CNS is kept continuously informed about the surroundings (environment) through
various sensory impulses, both general and special. The CNS in turn brings about necessary
adjustment of the body by issuing appropriate orders which arc passed on as motor impulses
to the muscles, vessels, viscera and glands. The adjustment of the organism to the given
surroundings is the most important function of the nervous system, without which it will not
be possible for the organism to survive.
Parts of the Nervous System
The nervous system can be divided into two major subdivisions: the central nervous system
(CNS) and the peripheral nervous system (PNS). The CNS is comprised of the brain and
spinal cord; the PNS connects the CNS to the rest of the body.