What does the respiratory system primarily do?

The respiratory system primarily functions to take in oxygen and expel waste gases, particularly carbon dioxide, from the body. This process occurs through a series of organs, including the nose, trachea, bronchi, and lungs. When air is inhaled, oxygen is absorbed into the bloodstream through the alveoli in the lungs. Simultaneously, carbon dioxide, a waste product of cellular respiration, is transported from the blood into the alveoli to be exhaled. This gas exchange is crucial for maintaining the body’s oxygen supply and regulating carbon dioxide levels, which are vital for overall health.

In contrast, the removal of liquid waste is primarily the role of the urinary system, the circulation of blood is managed by the cardiovascular system, and the regulation of other body systems is the function of the endocrine system, which produces hormones to control various bodily functions. Thus, the correct choice highlights the specific and essential role of the respiratory system in gas exchange and maintaining metabolic balance.