What is the primary effect of decreasing atmospheric pressure on human physiology?

Decreasing atmospheric pressure primarily affects human physiology by reducing the availability of oxygen. As altitude increases, the pressure decreases, which means that the partial pressure of oxygen in the air also decreases. This results in fewer oxygen molecules being available for the body to inhale with each breath. Consequently, the oxygen saturation of hemoglobin can decrease, leading to potential issues such as altitude sickness due to hypoxia, which is a deficiency in the amount of oxygen reaching the tissues.

In lower atmospheric pressure conditions, the body struggles to obtain sufficient oxygen to meet physiological demands, particularly during physical exertion. This reduced availability can necessitate adaptations, such as increased respiratory rates or changes in blood biochemistry, to compensate for the lack of oxygen. Understanding this concept is fundamental in aerospace physiology as pilots and aviators often operate at altitudes where atmospheric pressure drops significantly, affecting their performance and health if not adequately managed.