So as the red blood cells travel along our capillary, the hemoglobin unloads that oxygen. The oxygen moves through our cell membrane into the blood plasma and then travels into the tissues and to the cells in the tissue, where it is picked up by other molecules, other proteins within those tissue cells. So the tissue and organs of our body have a low partial pressure of oxygen, about 40 mercury of mercury. Because there is a higher concentration of oxygen, a higher partial pressure of oxygen in the capillaries, hemoglobin will dissociate oxygen and it will move the oxygen into the tissues of our body. And if we plot the percent of hemoglobin saturated with oxygen versus the partial pressure of oxygen, we get the oxygen hemoglobin dissociation curve, which is shown by the following blue curve. Now, notice the blue curve has an S shape.