Introductory biomechanical engineering course: Pig lung laboratory. Porcine lungs were treated to simulate human disease, where lung B was restricted (stiff, formaldehyde treatment), lung C was healthy (saline), lung D was obstructed (bronchial narrowing and obstruction), and lung E was obstructed (loss of alveolar structure, collagenase treatment). Students recorded the pressure required to inflate each lung to a given volume and used these data to determine which lung simulated which disease.