Where does air proceed after leaving the nasal cavities? Why are the respiratory and digestive systems mixed in the pharynx? How is food prevented from entering the respiratory system during swallowing?
The air passes from the nasal cavities through the internal nares into the pharynx, a passage through which food also must travel on its way to the esophagus. The mixing of the respiratory and digestive systems is the result of the fact that the nasal passages and mouth arose evolutionarily first as organs of smell and taste and only later as organs for breathing. To prevent food from entering the respiratory system during swallowing, the soft palate at the back of the mouth covers the internal nares while the epiglottis covers the glottis, the opening through which the air leaves the pharynx and enters the larynx.
