An astronaut in a damaged spacecraft experiences gradual cabin pressure loss. Which consequence follows regarding alveolar gas exchange?

💡 Explanation

As cabin pressure decreases, the partial pressure of oxygen in the inspired air also decreases. This reduces the alveolar partial pressure, because the diffusion gradient for oxygen between the alveoli and pulmonary capillaries diminishes, therefore hindering oxygen uptake rather than increasing saturation or affecting CO2 exhalation directly.

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