 Hello, everybody. Today we're going to finish our conversation about how the nervous system communicates information all around the body. In the last lecture, we learned about the action potential. And the action potential is essentially the tool, the strategy that allows for electrical communication down a neuron. In today's topic, we didn't go beyond the action potential in the previous lecture. So today we need to figure out, okay, what happens next? So an action potential comes along, sodium ions and potassium ions move in and out awesome. But then what happens when you get to the end of a neuron? And what we reach at the end of a neuron, what we reach at the axon terminal, we usually reach a space and we have to actually communicate information across that. Now, I say we usually end up with a space. It is possible. And it does happen that we end up with a gap junction. Oh, so imagine this for a second. Imagine an electrical synapse. And this is all I'm going to say about electrical synapses. We're not going to talk about them very much. We will see them in action when we talk about the heart and how heart muscle communicates electrical information all around it. So electrical synapses are important to understand, but essentially an electrical synapse is there is no space. You connect, look. You throw a gap junction between, go with me on this, all right, between the cell one that has electrical information traveling through it. Here comes the electrical information. Here comes the action potential, the ions moving in and out. And then that electrified action potential of fide cytoplasm can pass directly through the gap junction and into cell number two. That's a cell number two. And you can imagine that if a shift in action potential, if the cytoplasm itself travels through a gap junction into a new cell, it's going to change the membrane potential in the new cell. And then that's all we're going to do is stimulate the opening and closing of various voltage gated sodium and potassium channels, which is going to propagate the action potential onward. That electrical synapse is found in certain places. It's really, really fast, but the rest of our entire lecture is going to be talking about a chemical synapse. This image right here is illustrating the chemical synapse. This synapse is the space. Look at this. The synapse is not the end of a neuron. It's the space in between the neuron and the next person in line, whether it be an effector or another neuron. In this image, you can see that we actually have another neuron. This is the recipient of the electrical impulse that's passing down. So let's talk about a chemical synapse. Let's look at the anatomy of our chemical synapse since that's what we're spending the rest of our time on.