An athlete trains at high altitude for a marathon. Why does their blood's oxygen saturation at a given partial pressure of oxygen increase after several weeks?

💡 Explanation

The oxygen saturation increases because, with acclimatization to high altitude, the concentration of 2,3-BPG decreases in red blood cells, increasing hemoglobin's affinity for oxygen. Therefore, oxygen saturation at a given partial pressure rises, rather than decreases from increased BPG, reduced surfactant, or myoglobin changes.

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