What function do the lungs serve in the circulatory system?

The lungs play a crucial role in the circulatory system by supplying blood with oxygen, which is essential for cellular function throughout the body. When air is inhaled into the lungs, oxygen from that air diffuses across the thin walls of the alveoli, tiny air sacs in the lungs, into the pulmonary capillaries. Here, the oxygen binds to hemoglobin in red blood cells, allowing for its transportation through the bloodstream to various tissues and organs.

This process is vital because cells require oxygen for the production of energy through cellular respiration. Additionally, the lungs help remove carbon dioxide—a waste product of metabolism—from the blood, which is expelled from the body during exhalation. Thus, the primary function of the lungs in relation to the circulatory system is to ensure that blood is properly oxygenated, enabling the efficient functioning of all body systems.