What is the primary function of the respiratory system?

The primary function of the respiratory system is to supply cells with oxygen. This system enables the exchange of gases by facilitating inhalation of oxygen from the air into the lungs, where it then diffuses into the bloodstream. From there, oxygen is transported to cells throughout the body, which are essential for cellular respiration—a process that produces energy. Additionally, the respiratory system is responsible for expelling carbon dioxide, a waste product of cellular metabolism, thus maintaining homeostasis in the body.

Other functions, such as hormone production, digestion, and blood circulation, are associated with different systems—the endocrine system, digestive system, and cardiovascular system, respectively. These systems work in tandem but serve distinct primary functions, making the respiratory system's role in oxygen supply vital for sustaining life.