In our body, there is a need for coordination and integration of all the activities of the organs so that they function in a synchronized fashion. For this purpose, we have the nervous system and endocrine system.

The nervous system carries information in the form of impulses to the different parts of the body and sends it to the brain so that the action is taken. It is composed of highly specialized cells called neurons which can detect, receive and transmit different kinds of stimuli. It is simple in lower invertebrates like hydra etc. and more developed in vertebrates.


The human neural system is divided into two parts –

Central nervous system (CNS)

Peripheral nervous system (PNS)

The CNS includes the brain and spinal cord and it is the site of information, processing, and control. Whereas, the PNS comprises all the nerves of the body associated with the CNS.

The nerve fibers of PNS are of two types –

Afferent fibers

Efferent fibers

The afferent nerve fibers transmit impulses from tissues or organs to the CNS. Whereas, the efferent nerve fibers transmit regulatory impulses from the CNS to the peripheral tissues or organs.

The PNS is divided into two divisions –

Somatic neural system (SNS)

Autonomic neural system (ANS)

The somatic neural system transmits impulses from the CNS to skeletal muscles while the autonomic neural system transmits impulses from the CNS to the involuntary organs and smooth muscles of the body.

The autonomic neural system is more divided into the sympathetic neural system and parasympathetic neural system.


NEURON (Nerve cell) – It is a functional and structural unit of the nervous system. It generates and transmits nerve impulses. It is the longest cell of the body.

Consist of – Cell body and Cell processes (Dendron and Axon).

A neuron is of 5 types based on dendron and axon – unipolar, bipolar, multipolar, pseudo unipolar, and apolar.

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