A Level Biology Practice Exam

What is meant by elastic recoil in the context of the lungs?

1. the ability to expand beyond normal size

2. the capability to return to original shape after stretching

3. the failure to contract properly

4. the inability to hold air

The correct answer is: the capability to return to original shape after stretching

Elastic recoil refers to the lungs' ability to return to their original shape after being stretched or expanded during inhalation. When we breathe in, the lungs expand as air fills them, and various elastic fibers in the lung tissue and surrounding structures are stretched. Once the inhalation phase is complete and the muscles used for inhalation relax, these elastic fibers pull the lung tissue back to its resting state, effectively pushing air out of the lungs during exhalation. This process is vital for efficient breathing and ensures that air can be expelled from the lungs with little effort once inhalation is complete. Maintaining this ability is crucial for optimal respiratory function, as it facilitates the process of ventilation. The other options do not accurately describe the mechanism of elastic recoil in the lungs.