1.9 For the following data, determine the oxygen con- sumption rate Vo, under rest and exercise conditions. Rest Exercise Pulmonary blood flow (L min¹) 5.8 25 Arterial Po, (mmHg) 40 15 Venous Po, (mmHg) 100 100 Note that oxygen in blood is present in red blood cells bound to hemoglobin and freely dissolved in the red cell and the blood plasma. Equation (1.6.3) relates the partial pressure (mmHg) to the concentra- tion in plasma and the total concentration of oxygen in blood is given by Equation (1.6.4), where 4CHb is 0.0203 M; the hematocrit or volume fraction of red cells, Hct, is typically 0.45 for males and 0.40 for females; Ho₂ is 1.33 × 106 M mmHg; and HHb is 1.50x 106 M mmHg¹. S ==1 (Po,/Pso) 2.6 1+ (Po,/Pso)2.6 (1.6.5) moglobin dissocia through Co₂ Po₂ == Ho₂ (1.6.3) where Ho, represents the oxygen solubility in plasma. At 37°C, the solubility of oxygen in plasma is 1.4 x 106 mol L1 mmHg. The quantity Pso shown in Figure 1.14 is the oxygen partial pressure at which 50% of the sites on hemoglobin have bound oxygen. Under normal conditions, P50 for oxygen binding to hemoglobin is 26 mmHg. Arterial blood ranges from 95 to 100 mmHg pressure and is about 95%-97% saturated. Oxygen partial pressures in tissues are about 40 mmHg, and oxygen partial pressure in the pulmonary artery is typically 38 mmHg. Even at these partial pressures, hemoglobin saturation is about 70%. The total concentration of oxygen in blood is then Co₂ = Ho,Po,(1 - Het) + (4CHS + HHbPo₂)Hct, (1.6.4)