Answer:
The central nervous
system consists of the brain and the spinal cord
(i) Brain It is the main coordinating centre in the
body It is lodged in the brain box or cranium which protects it.
It is covered by membranes called meanings, which also help to protect
it. The space between the membranes and the brain is filled with a cerebrospinal
fluid which protect the brain from mechanical shock. The brain is broadly
divided into three regions fore-brain, mid-brain and hind-brain.
(ii)Spinal cord It
is a long cylindrical structure. It begins from the medulla oblongata and extends
downwards. It is enclosed in a bony cage called Verebral column that
protects it. It is also surrounded by meninges. It is concered with spinal
reflex actions and conduction of nerve impulses to and from the brain.
Peripheral
Nervous System (PNS)
It includes
the following
(i)Cranial
nerves 12 pairs that emerge from the brain.
(ii)Spinal
nerves 31 pairs that arise from the spinal cord and spread throughout the
body.
(iii)Visceral
nerves They are special kind of nerves mostly arise from the spinal cord
and are connected to the internal organs of the body. They carry both sensory
and motor neurons. The PNS works according to our will, i.e., it is related to
voluntary acts.
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