What is a common response when the lungs are overinflated?

• A. Increased pain tolerance
• B. Stimulation of the Hering-Bruer inflation reflex
• C. Inhibition of breathing
• D. Decreased heart rate

Answer: (B)

When the lungs are overinflated, one common physiological response is the stimulation of the Hering-Breuer inflation reflex. This reflex serves as a protective mechanism to prevent excessive lung inflation. It involves stretch receptors located in the smooth muscle of the airways and lungs, which send signals to the central nervous system when the lungs reach a certain degree of inflation.

The stimulation of these receptors leads to a decreased respiratory drive, resulting in a reflexive inhibition of inspiration. This reflex not only helps regulate the rate and depth of breathing but also prevents lung injury due to overdistension. Thus, the involvement of the Hering-Breuer reflex is crucial in maintaining normal respiratory mechanics and protecting lung function during conditions that may lead to overinflation, such as in certain lung diseases or during excessive mechanical ventilation.

In contrast, the other options presented do not accurately describe the body's response to lung overinflation. Increasing pain tolerance, for instance, is not associated with lung inflation and does not directly relate to the physiological processes in the respiratory system. Additionally, while inhibited breathing may occur as a result of the reflex, it does not capture the primary mechanism or the role of the Hering-Breuer reflex in response to overinflation, where reflex actions