Major objective of this lecture is to present on the Nervous System. Main function of Nervous System is to controls and coordinates functions throughout the body and responds to internal and external stimuli. A nerve is an organ containing a bundle of nerve cells called neurons. Neurons carry electrical messages called impulses throughout the body. The nervous system is a complex collection of nerves and specialized cells known as neurons that transmit signals between different parts of the body. It is essentially the body’s electrical wiring.