Now, we can subdivide the peripheral nervous system into the somatic nervous system and the autonomic nervous system. Now, within the autonomic nervous system we have special type of motor and sensory neurons known as pre ganglionic neurons and post ganglionic neurons. Now, the autonomic system can be divided into the sympathetic and the parasympathetic system. Now, in the next several lectures we're going to basically discuss the details and the functionality of each one of these systems individually. In this lecture, we're going to focus on a terminology that we're going to need to know that we're going to come across in our discussion on the human nervous system. So let's discuss and define what a motor neuron is what a sensory neuron is, what an inter neuron is.