 What's the problem? What's the problem with having too much? What are we going to have too much of if we have too much carbon dioxide? Hello, this is the culprit. We're going to end up with too many hydrogen ions. Who cares? What, I mean, nobody cares about hydrogen ions. If you don't care about hydrogen ions, you are going to, this is what color I think of you in my head if you don't care about hydrogen ions. Hydrogen ions, if you have a lot of them, you have a very acidic substance. And if you have very few of them, you have a very basic substance. Hydrogen ions determine pH. So the more hydrogen ions you have, the more acidic, the lower the pH, the fewer hydrogen ions you have, the more basic, the higher the pH. Look into my eyes. Guess what your pH of your blood is. What would you guess? Hopefully you'd be like, dude, my pH is probably seven because I'm neutral. Close. It's actually 7.35 to 7.45. Really? Really. If you go outside of that range, it's like a tenth of a hydrogen ion concentration thing. It's not very much room for flex. That's not a very big change in hydrogen ion concentration in your system. And you will be going to the hospital. If you get too low, 7.2, then you are, your blood is too acidic. And why do we care? Why does it matter if your blood is acidic? Aw, I can't help it. I have to go back and show you why you care because I don't want you ever to forget this. Guess what happens if you add acid to a protein? You change the shape, you guys, and sometimes you change the shape permanently. And if you change the shape permanently, are you going to function anymore? No. If your protein stopped functioning, you will die. So let's make sure we're maintaining our pH. This chemical reaction that is in equilibrium, we're coming back to that bad boy. We're talking about that bad boy when we talk about the urinary system. We're going to talk about that bad boy when we talk about the respiratory system. And we're going to do a whole lab on... Oh, well, I'll just tell you what we're doing the lab on because, you know, I started to, but why didn't I just finish and tell you what I was going to do the whole lab on? Because sometimes my brain does interesting things in my head. We're going to do a whole lab on buffers. And buffers are systems that prevent changes in pH. So a buffer system will actually absorb hydrogen ions and prevent large shifts in pH, and it's super handy since this is the range that we need to maintain our pH in. Are you good? It's important to be comfortable with the idea of the hydrogen ions. If you want a review of pH, I will try really hard. I'm going to forget this. So when you watch this lecture, somebody email me and remind me that I said I would post the pH part of the Bio1 lecture because I flipped Bio1. I have pH videos out there that can, like, walk you through acids and bases and go into a little bit more detail. I will spare us the rest of that. Now, the last thing that we're going to talk about is this idea, hmm, it's just a little thing. We're going to talk about concentration gradients. Everything, everything in today's lecture literally is foundational knowledge that you will use to understand everything else that we're going to talk about. So concentration gradients provide energy that we will use to do work in our bodies. And our lab all next week, we're talking about those concentration gradients and what we can do with them. So we'll be right back and we'll talk about that.