What is the primary function of the respiratory system?

The primary function of the respiratory system is to facilitate gas exchange, specifically the uptake of oxygen and the expulsion of carbon dioxide. This process occurs primarily in the lungs, where air enters and exits through inhalation and exhalation. When air reaches the alveoli, tiny air sacs in the lungs, oxygen diffuses from the air into the bloodstream, while carbon dioxide, a waste product of metabolism, diffuses from the blood into the alveoli to be exhaled.

This gas exchange is crucial for maintaining the body’s oxygen levels, which are essential for cellular respiration, and for removing carbon dioxide, which, if accumulated, can lead to respiratory acidosis and other health issues. Thus, the respiratory system plays a vital role not only in ensuring that the body receives the oxygen it needs for energy production but also in maintaining the balance of gases in the blood for overall homeostasis.

The other functions mentioned in the options, such as circulating blood, facilitating digestion, and producing hormones, are the responsibilities of different systems within the body, namely the circulatory system, digestive system, and endocrine system, respectively.