- Alveolar gas has a Po2 of 100 mm Hg.
- Pulmonary capillary blood is "arterialized" by the diffusion of 02 from alveolar gas into blood, so that the Po2 of pulmonary capillary blood also becomes 100 mm Hg.
- The very high affinity of hemoglobin for 02 at a Po2 of 100 mm Hg facilitates the diffusion process. By tightly binding 02, the free 02 concentration and 02 partial pressure are kept low, thus maintaining the partial pressure gradient (which drives the diffusion of 02).
-The curve is almost flat when the Po2 is between 60 mm Hg and 100 mm Hg. Thus, humans can tolerate changes in atmospheric pressure (and Po2) without compromise of the 02-carrying capacity of hemoglobin.
Was this article helpful?