What is the main function of the pulmonary system?

The primary role of the pulmonary system is to facilitate gas exchange, which is essential for respiration. This system includes the lungs and associated airways, where oxygen from the atmosphere is taken into the bloodstream, and carbon dioxide, a waste product of metabolism, is expelled from the blood into the air to be exhaled. This exchange occurs in the alveoli, tiny air sacs in the lungs, where the blood comes into close contact with the inhaled air, allowing oxygen to diffuse into the blood while carbon dioxide diffuses out.

Gas exchange is critical for maintaining the body’s oxygen levels and for removing carbon dioxide, thus ensuring that the body's metabolic processes continue effectively. The other options relate to different bodily functions that are handled by other systems: for instance, nutrient transport is managed by the circulatory system, waste removal is the responsibility of the excretory system, and temperature regulation involves the integumentary and circulatory systems. Therefore, the focus on gas exchange underscores the essential function of the pulmonary system in sustaining life.