This is the first in a series of videos examining the various organ systems of the body, starting with a look at the nervous system and all it is responsible for within our bodies.
Pretty much every single animal (except for some super simple ones) has a nervous system, it allows every kind of behaviour and sentient thought and is the key to intelligent life. The nervous system (brain, spinal cord etc) is made up of neurons, special nerve cells existing nowhere else in the body. Neurons transmit electro-chemical signals from one part of your body to another. They enable us to transmit information regarding a stimulus from our bodies to our brains, and back again once the brain has formulated a response, from something being too hot to tasting incredibly good.
The nervous system is split into two sub-systems. The Central nervous system (the brain and spinal cord) is analyses and interprets all data that the peripheral nervous system (all other nerves) collects and sends to it.
From Crash Course: Biology on YouTube by Hank Green.