 It's true. We can shift this curve. Shifting the curve has nothing to do with just drawing a new curve on here at all. Shifting the curve has to do with changing the shape of the hemoglobins in different chemical environments. So there are a couple of factors about the plasma but if those characteristics of the plasma change, the hemoglobin will change. Do you remember when we added milk and vinegar together? If you have never done this, go do it because it's fascinating. When you add vinegar, which is an acid, to milk, all you're doing is taking hydrogen ions. Seriously, just, that's it. It's just a hydrogen ion. And yet, hydrogen ions wonkify proteins and you will see the effect of wonkified proteins as affected by the hydrogen ions in vinegar. That's the visual that lets me go, yeah, I can accept that changing the environment, changing various qualities of the environment, can change the chemical characteristics of different proteins. So if I were to change the hemoglobin and make it less sticky for oxygen, I'm actually going to shift the curve to the right and look at what I'm doing. I've got the same curve going on. I've just shifted the curve to the right. Do you agree with that? I don't like that I went outside of that. It didn't mean to go above it. You're cool with that? Do you agree? I just shifted the curve to the right. I could also shift the curve to the left. If I were to shift the curve to the left, I still am going to follow the same basic shape of the curve and there's a point at which, you know, we have the same curve, but I shifted it to the left. I'm going to make a left here and then I'm going to take a right. So shifting curves, left, right, all I did. I'm going to tell you the characteristics. I actually changed the hemoglobin. The molecule of hemoglobin itself changed and now the hemoglobin is less sticky for oxygen. Now the hemoglobin is more sticky for oxygen. It cares. Well, I want you to think really fast of a time when you would like hemoglobin to maybe get a little less sticky for oxygen, where it would actually be willing to give up the oxygen that's stuck to it a little bit easier. Maybe you can pull more oxygen off. How about when you're exercising? This is how I remember this whole thing. When you're exercising, exercizing, you want more oxygen. In yourselves, they're working hard. They're burning a lot of fuel. You need more oxygen to supply the energy requirements necessary. So in my brain, I want to shift the curve to the right. I want to let my hemoglobin let go of the oxygen easier. So some things that happen to you when you are exercising. Number one, your body temperature goes up. And guess what? Increased temperature shifts the curve to the right. Increased temperature affects the shape of the hemoglobin molecule and makes it let go of oxygen faster. Increased pH. If your pH drops, if you become acidotic, oxygen is going to fall off your hemoglobin molecules easier. How would you get low pH? How would you get your pH to drop? How about increasing the amount of carbon dioxide? Because remember, carbon dioxide plus water equals carbonic acid. Do you remember that? Of course you do. If you don't remember that, I mean, you might as well commit that to memory now because seriously, we're going to see it about 8 billion times in the rest of the semester. We increase carbon dioxide. That's actually how we ended up decreasing our pH because we increased carbon dioxide. All of these are going to happen when you're exercising. But all of them result in hemoglobin changing such that the percent saturation curve shifts to the right. Flip them. If we want to know how to shift our curve to the left, decrease body temperature, increase pH, decrease carbon dioxide, done. And we shift our curve to the left. In that scenario, we hang on to the oxygen more. It's less likely to let it go and give it up to your cells. And we can think about all sorts of applications for that. We spent a lot of time talking about oxygen. The last thing I want to talk about is carbon dioxide. How does carbon dioxide get shifted around and carried from the cells back to the alveoli in the blood? Now that we've looked in detail at oxygen, now we can probably start to appreciate similar patterns with carbon dioxide, but a different mechanism. Let's not leave carbon dioxide out. Let's talk about it next.