The main byproduct of respiration in humans is carbon dioxide (CO2). During the process of cellular respiration, cells utilize oxygen to convert glucose into energy, producing carbon dioxide as a waste product. This carbon dioxide is transported back to the lungs through the bloodstream, where it is expelled from the body when we exhale. This exchange of gases is vital for maintaining the body’s pH balance and ensuring that cells receive the oxygen necessary for energy production. The process highlights the importance of respiration in maintaining homeostasis in living organisms.