Which part of the respiratory system is primarily responsible for gas exchange?

The primary structure responsible for gas exchange in the respiratory system is the alveoli. These tiny air sacs are located at the end of the bronchial tubes and are surrounded by a network of capillaries. The thin walls of the alveoli facilitate the diffusion of oxygen into the blood and the removal of carbon dioxide from the blood. This critical process occurs due to the large surface area of the alveoli and their proximity to the capillaries, allowing for efficient gas exchange.

Other parts of the respiratory system, such as the bronchi, larynx, and pharynx, have different functions. The bronchi serve as the main passageways for air to reach the lungs and do not engage directly in the exchange of gases. The larynx is involved in sound production and protecting the airway during swallowing, while the pharynx is a passage that connects the nasal and oral cavities to the larynx and esophagus, playing a role in both respiration and digestion. Thus, the alveoli are crucial for the actual gas exchange that supports respiration at the cellular level.