[Campbell Biology P.995] If a small hole were torn in the membranes surrounding a person's l... | Practice Question

If a small hole were torn in the membranes surrounding a person's lungs e.g., the pleura , what immediate effect would this likely have on lung function and how might the body's control mechanisms respond?

  • A: The lung would expand more easily, leading to increased oxygen uptake, and the body would decrease breathing rate.
  • B: Air would enter the space between the lung and chest wall, collapsing the lung, making inhalation difficult or impossible, and the body would likely increase breathing effort due to reduced gas exchange.
  • C: The lung would become overinflated, triggering the negative-feedback mechanism to inhibit inhalation, leading to slower, deeper breaths.
  • D: Blood flow to the lungs would immediately cease, causing a rapid drop in blood CO2 levels and a compensatory decrease in breathing rate.

Explanation

The lungs are held against the chest wall by the negative pressure within the pleural space. A hole in the pleura pneumothorax would allow air to enter this space, breaking the negative pressure and causing the lung to collapse. This would severely impair gas exchange oxygen uptake and carbon dioxide removal . The body's control mechanisms, sensing reduced O2 and/or increased CO2, would attempt to compensate by increasing the rate and depth of breathing, though this would be ineffective if the lung is collapsed.