An Excerpt from the course on Anatomy and Physiology

The respiratory system is divided into the conducting zone and the respiratory zone. 

The conducting zone consists of the nose, pharynx, larynx, trachea, bronchi, and bronchioles. These structures form a continuous passageway for air to move in and out of the lungs. 

The respiratory zone is found deep inside the lungs and is made up of the respiratory bronchioles, alveolar ducts, and alveoli. These thin-walled structures allow inhaled oxygen to diffuse into the lung capillaries in exchange for carbon dioxide. 

These zones are anatomically divided the upper and lower respiratory tracts or airways. 

The upper respiratory tract structures are found in the head and neck and consist of the nose, pharynx, and larynx. 

The lower respiratory tract structures are located in the thorax chest and include the trachea, bronchi, and lungs along with bronchioles, alveolar ducts, and alveoli.