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b. Spinal Cord

Spinal cord is an extension of the central
nervous system. It begins at the bottom
of the brain stem and ends in the lower
back. It is surrounded by the back bones
(vertebrae). It is about 45 cm in length and
cylindrical in shape. There are 31 pairs of
Spinal-~-===
spinal nerves and roots. These spinal nerves cord Thoracic
emerge from different segments of the T1 · T12
spinal cords. It carries nerves signals from
the brain and vice versa. It also regulates
the reflex action. The damage of spinal cord
is called spinal injury. The spinal injury is
caused by direct injury to the spinal cord
Coccygeal
itself or from damage to the tissues and
bones that surround it. This injury affects other organs of the body
and severe injury can cause disability.
B. Peripheral Nervous System

Peripheral nervous system is composed of 12 pairs of cranial nerves
and 31 pairs of spinal nerves that branch out from brain and spinal
cord respectively. It establishes communication network between
central nervous system and body parts.

C. Automatic Nervous System
Some activities are continuously happening in our body, but we are
not conscious about them. The auto1natic nervous system is an auto-
running system. It is divided into the sympathetic nervous system and
the parasympathetic nervous system. The sympathetic system speeds
up the respiration rate and heartbeat. It also enlarges the pupils, and
slows down the rate of digestion. The parasympathetic systen1, on
the other hand, lowers the heartbeat, increases the rate of digestion,
contracts the pupils, etc.
Functions of Nervous Syste1n

The essential functions of our body are coordinated and controlled
by the nervous system. As a result, the balance among the systems
of the body is maintained. Major functions of the nervous system are
4 Health, Physical ai1d Creillive arts, grade 8