What is the main function of the respiratory system?

The primary function of the respiratory system is to exchange gases between the body and the environment, which encompasses the intake of oxygen and the removal of carbon dioxide. This process is vital for maintaining homeostasis in the body, as oxygen is essential for cellular respiration, the metabolic process that generates energy within cells. The respiratory system comprises several structures, including the nose, trachea, bronchi, and lungs, all of which facilitate this gas exchange.

In the lungs, oxygen from the air is diffused into the bloodstream while carbon dioxide, a waste product of metabolism, is expelled from the blood into the alveoli and then exhaled. This continuous cycle of inhaling oxygen and exhaling carbon dioxide is crucial for sustaining life and supporting various body functions. The other options, while vital processes in the body, do not accurately describe the role of the respiratory system. Circulating blood pertains to the circulatory system, producing hormones relates to the endocrine system, and digesting food is the function of the digestive system.