What is the main function of capillaries in the respiratory system?

The primary role of capillaries in the respiratory system is to facilitate gas exchange surrounding the alveoli. Capillaries are tiny blood vessels that form a network around the alveoli in the lungs, where the exchange of gases occurs. Oxygen from the inhaled air diffuses through the thin walls of the alveoli into the capillaries, where it binds to hemoglobin in red blood cells. Simultaneously, carbon dioxide, which is a waste product of metabolism, diffuses from the blood in the capillaries into the alveoli to be exhaled. This efficient exchange process is critical for maintaining the body’s oxygen levels and removing carbon dioxide, ensuring that cellular respiration can occur effectively.

Other functions mentioned, such as transporting nutrients, controlling blood pressure, or storing excess oxygen, are not specific to the capillaries in the context of the respiratory system. Instead, these functions may involve different systems or structures within the body, making them less relevant to this question about the respiratory system's capillary function.