In this lesson, we will examine how neurons communicate. But to understand how nervous system works, we have to understand what it does. It is the main communication system for the entire body. The controls things like controls are muscles. Our glands, like our sweat glands and hormones, our sensory structures like eyes and ears. But in order to do this, they got to talk to other neurons. The beauty of the nervous system, though, is that it communicates with our entire body. There is not one part of our body that does not have a nerve going to or from it. So let's take a look at the cells, the neurons. They communicate and do the thing using a combination of electrical and chemical signals. The neuron is made up of three main parts, left or right, the dendrites. The other receiving part, the axons, which carry the impulse and the axon terminal, which sends a signal like a transmission or like a cell phone to another cell. The flow always goes towards the axon terminal. So if the flow of the impulse always ends at the axon terminal, how does it transmit the signal to another cell, like another nerve? This happens all, of course, at the synapse. The synapse is where one neuron communicates with another cell. The synapse is actually a very small space between the axon terminal of one cell and the receptor portion of a receiving cell. Notice those little bubbles. Those little bubbles, as you can see here in this little bit more specific diagram, contains the neurotransmitters. Those are called vesicles, those bubbles. So these bubbles contain those neurotransmitters, actually are only found at the axon terminal. So when an impulse comes down the axon, it causes these axon vesicles to migrate to the membrane where we'll release the neurotransmitters into the synapse. Those neurotransmitters combine with the receptors on the receiving cell. Now, when the receiving cell and the receptor and the neurotransmitter come together, that causes cell to go to work, like contract or causing their action potential in the next neuron. So let's put it all together. So here we have a simple reflex. For example, you get a pin stuck in your paw. A sensory neuron located right around here, that is going to cause an impulse to be carried to the spinal cord, where the impulse is transmitted to a relay neuron, and that's going to transmit an impulse to a motor neuron. The motor neuron sends an impulse to the muscle, causing it to contract. And that's pretty much it. That's how it all comes together. And now, I think you know how a neuron transmits information.