Where does the exchange of oxygen occur in the respiratory system?

The exchange of oxygen occurs in the alveoli, which are tiny air sacs located in the lungs. This exchange process is known as gas exchange and takes place through the thin walls of the alveoli, where oxygen from inhaled air passes into the bloodstream, while carbon dioxide from the blood is transferred into the alveoli to be exhaled. The structure of the alveoli, with their large surface area and thin membranes, is specifically designed to facilitate efficient gas exchange.

The other choices pertain to different components of the respiratory system but do not serve as sites for oxygen exchange. The bronchioles are small airways that lead to the alveoli, but they themselves do not facilitate the exchange of gases. The trachea, or windpipe, is the main airway through which air travels to the lungs; it is primarily a passageway and lacks the structural adaptations necessary for gas exchange. The pleura are membranes surrounding the lungs and do not participate directly in the oxygen exchange process.