What regulates nasal airway resistance?

Nasal airway resistance is primarily regulated by the swelling of the inferior turbinate. The inferior turbinates are structures within the nasal cavity that can expand or contract, influencing the amount of airflow through the nasal passages. When the inferior turbinates swell, often due to inflammation or irritation from allergens, the nasal passageway is narrowed, increasing resistance to airflow. This can lead to symptoms such as nasal congestion.

The other options relate to different physiological processes affecting breathing and airflow but do not directly control nasal airway resistance in the same manner. Lung inflation and diaphragm contraction are more involved in overall breathing mechanics rather than localized control of nasal resistance. Vasodilation of nasal vessels can contribute to swelling of the turbinates but is one of the mechanisms that ultimately lead to increased nasal airway resistance rather than a primary regulator. Thus, the swelling of the inferior turbinate is the most accurate choice linking to the regulation of nasal airway resistance.