Here we demonstrate how data from the clinical pulmonary function lab can help students learn about the principle of airway-parenchymal interdependence. We examined the relationship between airway conductance (Gaw) and lung volume (thoracic gas volume, TGV) in 48 patients: 17 healthy; 20 with emphysema, expected to have reduced airway-parenchymal interdependence; and 11 with pulmonary fibrosis, expected to have increased airway-parenchymal interdependence. Our findings support these expectations, with the slope of Gaw vs. TGV being steeper among those with pulmonary fibrosis and flatter among those with emphysema, compared to the slope of the healthy group. This type of analytic approach, using real-world patient data readily available from any pulmonary function laboratory, can be used to explore other fundamental principles of respiratory physiology.