What is the primary function of the respiratory system?

The primary function of the respiratory system is to exchange oxygen and carbon dioxide between the body and the environment. This process is crucial for maintaining the body’s homeostasis and providing the necessary oxygen for cellular respiration, which fuels the body’s energy needs. Oxygen is inhaled into the lungs where it diffuses into the bloodstream, while carbon dioxide, a waste product of metabolism, is expelled from the blood into the lungs to be exhaled. This exchange occurs at the alveoli, tiny air sacs in the lungs that facilitate efficient gas transfer.

Other options represent functions carried out by different systems in the body. For instance, blood circulation is the primary role of the cardiovascular system, while digestion is managed by the gastrointestinal system. Regulation of body temperature primarily falls under the realm of the integumentary and cardiovascular systems, involving processes such as sweating and blood flow adjustments. Hence, the correct answer focuses specifically on the vital function associated with the respiratory system.