 I guess I didn't have to make you guess because it was written right over there in the menu. That's okay. The sodium potassium pump is going to pump ions, sodium ions and potassium ions against their concentration gradients and help establish a difference in the charges of the intracellular fluid and the extracellular fluid. Seriously? Yeah. Okay. So let's look at the specific mechanism of the sodium potassium pump. I'm going to draw a cell membrane and you're going to have to, like, you can do this. This is the extracellular fluid and this is the intracellular fluid. And it's not going to be perfect, but I'm almost perfect, right? And here's how we're going to do this thing. I'm going to draw the sodium potassium pump in its original confirmation and its original shape basically has one, two, three binding sites, those are binding sites, for sodium. I'm going to make sodium, I actually want to make sodium green but I'm afraid I'm going to have to make it this lovely pink. So that's sodium. And remember that sodium ions have a positive charge. So these are sodium ions. And I show them that they're actually going to bind to these binding sites right here. So in its starting situation, the sodium potassium pump is open to the intracellular fluid and there are three binding sites for sodium on its body. And so, of course, those binding sites are available so the sodium ions come in and bind. Here they come. Here comes another one and one more while we're at it. So sodium binds to the binding sites. So this isn't number one. Number one is that sodium binds. Now, when sodium binds, this creates an ATP binding site. Now take a deep breath and go with me on this. Here's a pump. Here are some ions that bind to the pump. The pump is a protein. And then the act of binding, the act of three sodiums binding changes its shape slightly. And when its shape changes, this is only going to happen if three sodium ions bind. When its shape changes, a new binding site is going to open up. And this binding site is a binding site for I regret my color choices, but this is ATP. ATP comes and binds to that site. If there weren't three sodiums in the sodium potassium pump, that site wouldn't even exist. So now ATP binds. The act of ATP binding, the ATP actually is going to leave a little phosphate right there, but ultimately the act of binding with the ATP changes the shape of the whole thing. And what do you think it's going to look like now? So the ATP binds and the whole thing changes shape. And guess what? It changes shape and it ends up looking like a, like a this. Oh, what? It opens up to the outside. Now take a deep breath and watch this when it changes shape. Not only does it open up to the outside, but it also changes the shape of that original sodium binding site. So the sodium is still there, but it doesn't stick anymore. It doesn't fit. Why not? Because you guys, it stuck. The shape changed when the ATP bound to the pump and changed its shape. The shape change not only opened it to the extracellular fluid, but it changed the shape of those binding sites. Dude, I mean, take a deep breath. Like, how phenomenal is that? So what happens to my little sodiums? Bye-bye. See you later, pounds. You're now on the outside. And you're not coming back in because guess what happens now? In addition to losing the sodium binding site, I'm going to remain two potassium binding sites. So check it. The ATP binds, the whole thing changes shape. Sodium binding sites change. So sodium falls off. You know what? I'm going to go 2.5 because I want to make sure that you know that the whole, it changed shape and it's now open to the extracellular fluid. So now my sodium potassium pump is open to the extracellular fluid. The sodium binding sites change. The sodium falls off. And then we're going to do like a 3.5 new potassium binding sites form. And then potassium binds. And guess what that does? That's crazy, it kicks off the phosphate. So potassium binds, just like we keep on seeing. As soon as the potassium binds, that's going to change the shape of the molecule. The shape change removes this phosphate binding site. The potassium binds and the phosphate falls off. Why did the phosphate fall off? The phosphate fell off because it doesn't fit anymore because the potassium binding sites changed the shape of the molecule. The phosphate falls off. What happens to when the phosphate falls off? What happens to the entire pump? It returns to original form, seriously. The phosphate is gone. It returns to its original form. The little potassium binding sites disappear because it returns to its original form. Potassium is now on the inside. I tell you this, all these details because number one, that's about one of the coolest things I've ever learned about in my entire life. But that is, this is critical for establishing the ability to create electricity in our neuron. Okay, so we're going to do a thing called a membrane potential. We're going to build or create, building, I don't know what word to use. We're going to somehow make an action potential, a membrane potential in our neuron. And the sodium-potassium pump, we have to understand that in order to get there. So what was the take home with our sodium-potassium pump? Are these sodiums out to potassiums in? Don't forget about that. And now let's go figure out how do we set up a membrane potential.