Transport of Gases

Diffusion across the alveolar membrane, described in the previous section, brings oxygen into the blood and removes carbon dioxide from it at the lungs; but the blood must then physically carry this oxygen to every respiring tissue of the body, often at some considerable distance from the lungs, and must equally carry the carbon dioxide generated by those same tissues all the way back to the lungs for elimination. Because oxygen and carbon dioxide differ considerably in how readily they dissolve directly in blood plasma and in how they interact chemically with haemoglobin, the blood relies on somewhat different transport mechanisms for the two gases, examined in turn in the two sections that follow: the transport of oxygen, dominate …