What is the main function of the respiratory system?

The primary function of the respiratory system is to provide oxygen for body tissues. This system facilitates the exchange of gases, specifically oxygen and carbon dioxide, between the atmosphere and the bloodstream. When a person inhales, oxygen from the air enters the lungs and diffuses into the blood, where it is then transported to cells throughout the body. This oxygen is essential for cellular respiration, the process by which cells produce energy.

Moreover, the respiratory system also plays a role in removing carbon dioxide, a waste product of metabolism, from the body. By ensuring that a sufficient supply of oxygen is delivered to tissues and that carbon dioxide is expelled, the respiratory system supports overall health and function of the body.

Other options, while they signify important bodily functions, are not the main focus of the respiratory system. For instance, filtering the blood is primarily the responsibility of the kidneys and liver; transporting nutrients to body tissues is mainly the role of the circulatory system; and protection from pathogens is a function that involves multiple systems, particularly the immune system.