How does altitude affect alveolar ventilation?

At high altitudes, the partial pressure of oxygen in the atmosphere decreases. This lower availability of oxygen leads to a physiological response in the body that increases the rate and depth of breathing, thereby enhancing alveolar ventilation. The body attempts to compensate for reduced oxygen availability by stimulating respiratory centers in the brain, which results in increased ventilation rates.

This increase in alveolar ventilation allows for greater gas exchange in the lungs, helping to maintain adequate oxygenation of the blood despite the lower oxygen levels present at high altitudes. Additionally, the body may produce more erythropoietin to stimulate red blood cell production, further improving oxygen delivery to tissues.

In summary, the presence of lower oxygen at altitude triggers adaptive respiratory mechanisms that ultimately lead to increased alveolar ventilation, which is why this option is correct.