Main bronchi

(and upper airways)

This part of the respiratory system is characterized with one parameter R that reflects the resistance of the main bronchi (and resistance of the upper airways) to airflow. It depends on bronchial lumen. Resistance increase reflects either smaller lumen, or a local but significant obstruction (e.g. tumor).

Note: Bronchial lumen depends on the size of the respiratory system. For example, murine bronchi are smaller than those of an elephant.