The human body is made up of trillions of cells. Cells of the nervous system, called nerve cells or neurons, are specialized to carry “messages” through an electrochemical process. The human brain has approximately 100 billion neurons. This lecture briefly present three types of Neurons: Sensory Neuron, Interneuron and Motor Neuron. Sensory Neuron carry impulses from sense organs to spinal cord & brain. Interneuron processes impulses in brain and spinal cord. Motor Neurons carry impulses from the brain & spinal cord to muscles & glands.