Nervous system

 Nervous system is a group of organ that controles stimulli and response.

There are two parts of nervous system.

Central nervous system： Central nervous system consists with brain and spinal chord.

Peripheral nervous system：Peripheral nervous system expands in peripheral region of the body outside from brain and spinal chord except nail and hair.

The unit of nervous system is called neuron. Neuron is a specialized cell of nervous system. Neuron carries impulse.