Question

Which of the following is correct regarding the working of the lungs?

• A. The lungs and the chest wall, both have elastic properties.
• B. The lungs have a tendency to recoil inwards.
• C. The chest wall has a tendency to recoil outwards.
• D. All of the above.

Answer 1

The correct option is D

All of the above.

Functional Residual Capacity (FRC) is the volume of air remaining in the lungs at the end of passive expiration. At the resting (muscles relaxed) volume (Functional Residual Capacity), the lungs tend to recoil inwards (elastic recoil), while the chest wall tends to expand. Thus, the opposing elastic recoil forces of the lungs and chest wall are in equilibrium, and there is no exertion by the diaphragm or other respiratory muscles. Since there is no active muscle contraction, this position is said to be relaxed or a resting state.