The main function of the respiratory system is to facilitate the exchange of gases between the body and the environment. This system is responsible for taking in oxygen (O₂) from the air, which is essential for cellular respiration, and expelling carbon dioxide (CO₂), a waste product of metabolism. The respiratory process begins in the nose or mouth, where air travels down the trachea into the lungs. In the lungs, oxygen diffuses into the bloodstream while carbon dioxide is removed. This continuous exchange is vital for maintaining the body's oxygen levels and supporting various metabolic processes essential for life.