What components make up the respiratory zone of the respiratory system?

The respiratory zone of the respiratory system is primarily responsible for the actual exchange of gases, namely oxygen and carbon dioxide, between the air and the bloodstream. The components that make up this respiratory zone include the respiratory bronchioles, alveolar ducts, and alveolar sacs.

Respiratory bronchioles are the smallest air passages that connect the conducting zone to the sites of gas exchange. As they transition into alveolar ducts and eventually lead to alveolar sacs, they increase the surface area significantly to facilitate efficient gas exchange. Each alveolar sac is made up of numerous alveoli, which are tiny air sacs where oxygen is absorbed into the blood and carbon dioxide is removed.

Understanding this distinction is crucial because the respiratory zone is specifically where the gas exchange takes place, differentiating it from the conducting zone, which includes structures like the trachea and bronchi that primarily serve to transport air without being involved in gas exchange. Other options provided refer to structures that either do not participate in gas exchange or represent different functional parts of the respiratory system.