what are nervous system | central & peripheral nervous system | nervous system classification



What is the nervous system?

nervous system definition : The nervous system is the chief controlling and coordinating system of the body. It controls and regulates all activities of the body.

Whether voluntary and involuntary and adjust the individual to the given surroundings. 

This is based in the special properties of sensitivity, conductivity and responsiveness of the nervous system.

The sensory impulses are transmitted by the sensory nerves from the periphery (skin, mucous membrane, muscles, tendons, joints and special sense organ)to the central nervous system (CNS).

The motor impulses are transmitted by the motor nerves from the central nervous system to the periphery.




In this we are going to discuss about nervous system of human

nervous system classification or nervous system parts -
the nervous system is broadly divided into central and peripheral parts which are continuous with each other. further subdivision of each part is given below- 


A) The central nervous system (CNS) include- 1. Brain

2. Spinal cord 


B) peripheral nervous system (PNS) - it is. Subdivided into the following two components.

1. Cerebrospinal nervous system

2. Peripheral autonomic nervous system


Cell types of the nervous system- the nervous tissue is composed of two distinct types of cell


A) neuron 

B) neuroglia





A) neuron - A cell body or perikaryon or somata having a central nucleus and Nissl granules in its cytoplasm. The neurons of the only female contain Barr body. This Barr body is a planoconvex heterochromatin mass present close to the nuclear membrane.

Cell processes called neurites, which are two types many short afferent processes, which are freely branching and varicose are called dendrites.


Types of neurons- according to the number of their processes they may be 

A) Unipolar

B) pseudounipolar

C) Bipolar

D) Multipolar


According to the length of the axon, the neurons are classified as pyramidal cells, Purkinje cell

A) Golgi I

B) Golgi II


According to function sensory, motor and internuncial motor are multipolar: upper motor neuron - within the brain; lower motor neuron - in an anterior grey column of spinal cord 


Synapses - the neurons form long chains along which the impulses are conducted in different directions. Each junction between the neurons is called a synapse.


2.) Neuroglia - the non - excitable supporting cells of the nervous system form a major component of the nervous tissue. these cells include the following -


A) neuroglia cells

B) ependymal cells

C) capsular cells

D) Schwann cells





Peripheral nerves- the nerves are solid white cords composed of bundles of a nerve fibre.

 Each motor nerve fibre is an axon with its coverings.

The nerve fibres are supported and bound together by connective tissue sheaths at different levels of arrangement of the nerve.



Autonomic nervous system - this system controls involuntary activities of the body, like sweating, salivation, peristalsis etc.


Autonomic nervous is divided into two parts - 

A) sympathetic nervous system

B ) parasympathetic system 


A) sympathetic nervous system - its activities are widespread and diffuse and combat acute emergencies.


B) parasympathetic nervous system- its activities are usually discrete and isolated and provide a comfortable environment. 







sources : wikipedia , ncert text book and  BD chaurasia general anatomy