And ultimately, what our body wants to do at a high altitude is it wants to increase the number of hemoglobin molecules inside our blood and also increase the number of red blood cells found in our cardiovascular system. Now, the question that I want to answer in this lecture is why does our body actually want to increase the number of two three BPG molecules? Well, recall that two three BPG, two three biphosphoglycerate are allosteric effectors of hemoglobin. And what that means is they can bind into the center pocket found in hemoglobin. Now, by binding to the center pocket of two three of the deoxyhemoglobin, the two three BPG stabilizes the T state of that deoxy hemoglobin molecule and that lowers deoxy hemoglobin's affinity for oxygen. And that means this entire curve is shifted to the right side.