What is the primary function of the Respiratory System?

The primary function of the respiratory system is to exchange gases between the external environment and the blood. This process involves inhaling oxygen from the atmosphere into the lungs, where it diffuses into the bloodstream. Simultaneously, carbon dioxide, which is a waste product of metabolism, is transferred from the blood into the lungs and then exhaled out of the body. This gas exchange is vital for maintaining homeostasis, as it ensures that the body's cells receive adequate oxygen to perform their functions and that carbon dioxide levels are kept in check.

In contrast, preparing foods for absorption into the bloodstream is the role of the digestive system, not the respiratory system. The removal of nitrogenous wastes is primarily managed by the excretory system, specifically through the kidneys. Additionally, while transporting oxygen to tissues is part of the circulatory system's function, the actual exchange of gases occurs within the respiratory system. Therefore, the correct answer highlights the essential function of the respiratory system in maintaining the body's oxygen and carbon dioxide levels.