Now, once we form the carbon dioxide, because it is nonpolar, it can easily diffuse across the membrane of the red blood cell, then across our wall of the capillary, and finally enter the alveolar space, where we exhale. And we basically expel that carbon dioxide to the outside environment. So we see that the chloride shift takes place inside the red blood cells and it takes place not only in the tissues but also in the lungs. But the process is reversed in these two cases here to maintain an electrically neutral passageway of ions so that we don't have any build up of negative charge. What happens is, within the red blood cells of the tissues, the car, the bicarbonate exits, but the cloride interest. In this case, the opposite is true because we want to take in bicarbonate to transform it into carbon dioxide inside the lungs.