Figure 1 - Intersection of respiratory and gastrointestinal (GI) tracts.

The proximity of respiratory and GI tract has resulted in a complex set of morphologic and reflex adaptations that permit separation of respiratory and GI functions in the aerodigestive tract. For example, breathing requires airflow between the nose or mouth and trachea. On the other hand, the lungs must be protected from aspiration during swallowing or vomiting by closing the epiglottis and larynx, and movement of fluid out the nose is prevented by sealing the soft palate.