The human body is composed of different types of cells like bone cells, muscle cells, body cells, etc.  It is the sum totals of the tissues that record and distribute information within individual.

The complex network of neurons that regulates bodily processes and responsible for all aspects of conscious experience. The nervous system is composed of two kinds of cells, the glial cells and nerve cells.

It is composed mainly of two types of cells i.e. neuron and glial cell where glia cell provide a mechanical framework supporting the network of neurons. The human brain is composed of about 150 billion nerve cells. Information travels in the nervous system through three types of neurons: Sensory Neurons, Motor Neurons, and Inter Neuron.


  • structural and functional unit of nervous system that processes and transmits information of nervous system
  • Responsible for all activities of nervous system thus guides in our behaviors. example:- if we touch candle flame for more than an instant, pain nerves(receptors)in our finger sent a message up through our hand and arm to the spinal cord and brain

Functions of Neurons

  • Neuron receives the change that occurs around the environment of an organism.
  • It circulates the changed information all over the body.
  • Finally, coordinate to adapt to that changed situation.


Division of Nervous System

Nervous system can be divided into two major divisions: Central nervous system ( CNS) and the Peripheral Nervous System (PNS). CNS can further be sub-divided into brain and spinal cord. PNS also has two subdivisions: Automatic nervous system and somatic nervous system. 

Central Nervous System

Brain and the spinal cords are the two important parts of the CNS. It is also called old brain because its evolutionary aspect can be traced to more than 500 million years back. It contains three importance divisions: Hindbrain, Midbrain, and the Forebrain.

  1. Hindbrain: The information received by the spinal cord is passed through hindbrain. It is the lowest part of the brain regulating the routine “housekeeping” function for daily activities. Medulla oblongata, pons and cerebellum are the three major structures of the hindbrain.
  2. Midbrain: It is a small area that serves as a centre for several postural reflexes, associated with the senses.
  3. Forebrain: The information after hindbrain and midbrain travels to the forebrain.

Spinal Cord

Spinal cord is a rope like segment about the thickness of a pencil connects nerves tissues extending down the back. It works like an information highway. It has basically two important functions:

  1. It connects higher brain centers to and from and regulates reflexes.
  2. It exchanges several messages between brain and the body.

Peripheral Nervous System

The Peripheral Nervous System connects the outer portions of the body with CNS. It is like the key board, monitor, and a printer which passes information in and out in a computer.

Divided into two divisions:

  1. Somatic nervous system
  2. Autonomic nervous system

1. Somatic nervous system

  • Receives the sensation from external sense organs and controls skeletal muscles
  • Connects cans to voluntary muscles
  • Involved in voluntary action like reading, raising hand
  • Has both sensory and motor functions

1. Autonomic nervous system

  1. Connects cans to internal organs and glands and to muscles
  2. Controls the muscles like muscles of heart, stomach

Divided into two parts:

i. Sympathetic nervous system

connected to spinal cord on either side and carries out messages to muscles and glands in case of emergency

ii. Parasympathetic nervous system

connected to brain and region of spinal cord connected to brain, active in internal maintenance during relaxed stage and involved in conserving energy