Our nervous system is made up of specialized nerve cells that transmit electrical impulses throughout our body.
There is a special kind of nerve structure called receptor. It senses temperature, light, sound, pressure and chemical stimuli.
Effector (muscles or glands) are special structure which respond to the commands of the nervous system.
Once a stimulus is detected by the receptor nerve , impulses are created. Eventually the effector muscles or glands will respond to the change.