Diffusion: Blood Transit Time in the Areo Alveolus Blood capil Time for exchange P mm Hg 100 g Saturated very quickly Reserve diffusive capacity of the 40 Ing Co2 Time 0.75 sec8 Alveolus Blood capillary Time for exchange PO2 Time 0 0.75 sec 40 100 Saturated very quickly Reserve diffusive Capacity of the lung 45 mm Hg PCO2 Diffusion: Blood Transit Time in the Alveolus