What physiological change occurs when an individual moves to a higher altitude?

When an individual moves to a higher altitude, one of the primary physiological responses is hyperventilation. This occurs as a response to decreased atmospheric pressure and lower oxygen availability at higher elevations. The body detects the lower levels of oxygen, primarily through chemoreceptors sensitive to blood gases, which leads to an increase in breathing rate and depth in order to enhance oxygen intake.

Hyperventilation helps to increase the amount of oxygen entering the lungs and subsequently the bloodstream. Although it can sometimes lead to respiratory alkalosis due to reduced carbon dioxide levels in the blood, this response is a vital mechanism for acclimatization to higher altitudes. By increasing ventilation, the body works to optimize oxygen availability for tissues, countering the effects of hypoxia experienced at altitude.

In contrast, while decreased oxygen saturation and increased blood viscosity can occur in response to altitude, hyperventilation is the most immediate physiological change that directly addresses the lower oxygen availability. Increased cardiac output is a longer-term adaptation that may occur as the body continues to acclimatize, but it's the rapid response of hyperventilation that characterizes the initial physiological adjustment to changes in altitude.