Figure 1.

Model schematic. (A) Model geometry. Erythrocytes are represented as solid cylinders, whose length and diameter depend on vessel diameter. Oxygen is assumed to diffuse radially from the alveolar space into the erythrocytes. (B) Model for pulmonary oxygen uptake. Blood is assumed to take up oxygen from alveoli in the lung (top) during transit through a set of equivalent pulmonary capillaries arranged in parallel. The parameter t represents distance along the capillary.