Cellular Respiration: This is the most critical role of oxygen. Cells use oxygen to convert glucose into ATP (adenosine triphosphate), the primary energy currency of the cell. This process, known as aerobic respiration, occurs in the mitochondria of cells and is far more efficient at generating energy than anaerobic (non-oxygen-based) processes.
Oxidative Phosphorylation: This is a part of cellular respiration. Oxygen acts as the final electron acceptor in the electron transport chain, a series of reactions that generate ATP. When electrons are passed along this chain, oxygen ultimately combines with them and with hydrogen ions to form water.
Detoxification and Defense: Oxygen is involved in the body's detoxification processes. For example, the liver uses oxygen to metabolize toxins. Additionally, immune cells produce reactive oxygen species (ROS) to kill invading pathogens. These ROS are derived from oxygen.
Biosynthesis: Oxygen is involved in the synthesis of various biological molecules. For example, it's needed for the hydroxylation reactions, which are crucial in the synthesis of collagen, an essential structural protein in the body.
Regulation of Blood pH: Oxygen indirectly affects blood pH. Carbon dioxide (CO2), which is produced during the process of using oxygen in cellular respiration, is partly responsible for the acid-base balance in the blood. The body removes CO2 through breathing to maintain a stable pH.
Signaling: Recent research suggests that oxygen might play a role in cellular signaling processes, influencing activities like gene expression, ion transport, and immune responses.
Oxidative Stress: While oxygen is essential for life, its derivatives, such as superoxide and hydrogen peroxide, can be harmful in excess. These reactive oxygen species can damage DNA, proteins, and lipids, leading to oxidative stress, which is implicated in aging and various diseases.