All right, so like we talked about, when an action potential reaches the terminal button, it's going to get converted into a chemical message. Okay, so we had the electrical communication happening within our neuron, and now we are going to be talking about the chemical communication that happens between neurons. So one important term to know is the term synapse, and the synapse is basically the gap between the presynaptic and postsynaptic neurons, and I'm going to break down what that means. So, one cool thing about neurons is that they never actually touch each other; there's always a little gap in between them, and that gap is called the synapse. Now, presynaptic just refers to the neuron that comes before the synapse or before the synapse.

So this is going to be the neuron that is sending the message. So here, we're thinking about the axon or, like, the terminal button of the neuron that is sending the signal, and then postsynaptic refers to the neuron that comes after, or post, the synapse. So here, we're thinking about the neuron that is receiving the signal, so we're thinking about the tip of the dendrite, basically, of the neuron that is receiving the signal. Okay? We're going to go over the process of what happens here.

So in our presynaptic neuron, the action potential is going to cause vesicles to open. So remember how those terminal buttons have little vesicles in them that are full of neurotransmitters. So when the action potential reaches that terminal button, it's going to cause those vesicles to basically open up, and that will release neurotransmitters into the synapse. You can see we have our little neurotransmitters drifting into the synapse here, and neurotransmitters are just little chemical messengers within our nervous system. Okay, so these are things like serotonin and dopamine; we're going to talk about those in more detail in a future video.

So now we have neurotransmitters drifting in that synapse, and then they are going to basically connect with that dendrite, our postsynaptic neuron. So in our postsynaptic neuron, our dendrite, it has little specialized receptors, and those receptors are basically, like, specially designed to receive different neurotransmitters. So our dendrite here has these little receptors along it, and that will basically allow the neurotransmitters to bind with that dendrite. Now, what is going to happen there is that when a neurotransmitter binds to a receptor, ion channels are going to open. So you can see we have some little sodium ion channels here.

So basically, this is how I mentioned how, like, when other neurons are trying to talk to a neuron, it kind of bumps up the internal voltage just a little bit. That is what these ion channels are doing, basically. And so when neurotransmitters are binding to our dendrite, that is going to open up ion channels, which then changes the voltage of our postsynaptic neuron, which will then trigger an action potential, and then that, of course, will just keep traveling throughout all of the neurons that are connected. Alright, so that is kind of the basics of what is happening in the synapse. That's how chemical communication is taking place between neurons, and I will see you in our next one to talk about some neurotransmitters in more detail.

Bye bye.