1.1 NERVOUS SYSTEM
A group of organs which helps in communication between various parts of the body through nerves and their impulses is known as nervous system.
Nervous can be divided into 3 parts:
a. cell body b. axon. c. Dendrites
The cell body contains protoplasm and centrally located nucleus. Cell body is surrounded by small branches called dendrites and a long structure called axon. The axon is about 10 cm long.
On the basis of functions, nerve cells are classified into:
(a) Sensory or afferent nerve: They carry impulses from the skin and other organs to the brain.
(b) Motor or efferent nerve: They carry impulses away from the brain to various parts of the body.
(c) Mixed nerve: They consist of both sensory and motor nerves.
Types of Nervous System
a. The central nervous system that consists of the brain and spinal cord.
b. The peripheral nervous system that consists of 31 pairs of spiral nerves and 12 pairs of cranial nerves.
c. The autonomic nervous system that consists of sympathetic and parasympathetic nervous system.
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