So let's wrap up this video series. The upper airway consists of the nasal cavity, pharynx, and
larynx. The upper airway warms, moistens, filters, and delivers air to the lower respiratory
system. The lower airway consists of the trachea, bronchi, and lungs. Lower airway facilitates
gas exchange at the bronchioles and the alveolar ducts. Now gas exchange occurs only in
the alveoli which are thin walled, really thin walled parenchymal cells. Alveoli are in direct
contact with the capillaries of the circulatory system so oxygen diffuses from the alveoli into
the blood and is distributed to the rest of the body. Carbon dioxide or CO₂ will diffuse from
the blood into the alveoli to be exhaled. Thank you for watching our video today.