And inside our exercising tissue, for example, if we're swimming or running, our partial pressure drops to about 20 mercury. So we want to use these values and the oxygen dissociation curves for myoglobin and hemoglobin to basically show why hemoglobin is a much better carrier of oxygen than myoglobin. So let's begin with the hemoglobin. So this red curve describes the oxygen dissociation curve for hemoglobin. So as we go from right to left, from the lungs to our tissue, our hemoglobin essentially unloads and releases that oxygen. So let's begin inside our lungs.