Final answer:
The tendency for the lungs to recoil back to their original size after inflation is due to the elastic properties of lung tissue, aiding in passive exhalation as the diaphragm and intercostal muscles relax.
Step-by-step explanation:
Elastic Recoil of the Lungs
The tendency for the lungs to return to their original size after being distended is known as the elastic recoil of the lungs. This occurs during exhalation, when the lungs recoil to expel the air. During this process, the intercostal muscles and the diaphragm relax, causing the thoracic cavity to decrease in volume and increase the intrapulmonary pressure. Consequently, air is passively pushed out of the lungs due to the pressure gradient between the intrapulmonary pressure and the atmospheric pressure. Furthermore, substances like surfactant play a crucial role in reducing surface tension allowing the alveoli to remain open, facilitating easier lung function.