 All right, let's think about our different volumes of air that we can move. And there are different volumes that have names. I'm going to do volume on the y-axis. And I'm going to do time on the x-axis. I don't want a line there. So what I'm going to show you, okay, watch. I'm going to show you a breath. And inhale and exhale. And inhale and exhale. And inhale and exhale. How long would you like to continue this? A long time. Now, I'm now going to go to the bottom of an inhale, the end of an inhale. Now I'm going to say, okay, you ended your inhale. And now I want you to take the deepest inhale that you possibly can. Watch. Look how much more you can inhale beyond what you normally just breathe. Now you exhale all of that. But I say, I say, don't stop there. Give me all you got. Give me the biggest exhale that you possibly have. And you have more. You totally have more that you can exhale, right? And then I'll say, okay, thank you very much for playing with me. And now you can go back to your regular little breaths. Okay, are you good? Now watch. Let's label some volumes. First of all, your normal little breath. This is called tidal volume, tidal volume. And we kind of use tidal volume as the basis for almost the whole thing. Now, this entire space right here from the top of your biggest inhale to the bottom of your biggest exhale, that's your vital capacity. We're going to measure all these things in lab using eye works. The bigger your vital capacity, the more air you're able to move through your lungs. You have this difference right here from the base, from the end of a tidal exhale, that little breath, you get to the end of the exhale. The volume that you exhale total there, that is called your expatory, reserve volume. So does it make sense that we would also have an inspiratory reserve volume? And indeed it is so. An inspiratory reserve volume comes from the top of the tidal breath. So the end of the tidal inhale to the top of your vital capacity inhale, maximum inhale you have, that's your inspiratory reserve volume. Irv and irv, there's more. Guess what? This, okay, I need a new color, new color, orange. There is volume here. And guess what? That is called your residual volume. It doesn't matter how much you exhale, you're not going to be able to exhale your residual volume. Perhaps if your lung collapsed, maybe then you could exhale your residual volume, but not, like, go ahead, try it. I will not try to exhale my residual volume because I can't. It's not going to happen. So watch this. Here's the last one. This whole thing from the peak of your inspiratory reserve volume to the bottom of your residual volume, that, my friends, is your total lung capacity. Let's throw an exclamation point on that one. When you breathe into a spirometer, during a spirometry lab, you can measure these different volumes and then you can collect data on these different volumes and then you can actually measure the volumes based on the graphs that you're going to get in Iwerx land. Oh, Iwerx is going to be cool this time. I think that's everything I want to tell you, but I feel like I'm going to miss you while I'm gone. You're going to miss me too, right? Okay. Happy breathing. Next time we'll talk about gas exchange.