Oxidants vs. Carbon Dioxide: What Happens When Alveoli Experience Hypoxic Stress?
The tiny air sacs of the lungs, known as alveoli , are where life-sustaining gas exchange occurs. Under normal conditions, oxygen moves from the inhaled air into the bloodstream, while carbon dioxide (CO₂), a normal waste product of metabolism, diffuses from the blood into the alveoli and is exhaled. This delicate exchange depends on healthy alveolar cells, an intact blood-air barrier, and pulmonary surfactant that keeps the alveoli open. When the alveoli are subjected to hypoxic stress —a state in which they receive insufficient oxygen—the lungs undergo a profound biological response that extends far beyond impaired oxygen exchange. Rather than simply producing more carbon dioxide, hypoxic alveoli activate inflammatory signaling pathways that generate large amounts of reactive oxygen species (ROS) , commonly referred to as oxidants or free radicals. Hypoxia Triggers an Oxidative Stress Response Paradoxically, oxygen deprivation often increases oxidative damage. As oxygen levels declin...