Final answer:
Penetrating chest injuries disrupt negative intrapleural pressure, leading to pneumothorax. Air or blood accumulates in the pleural space, causing lung collapse and requiring medical intervention to restore normal pressure.
Step-by-step explanation:
A penetrating injury to the chest wall and lacerated lung tissue can cause the loss of negative intrapleural pressure, which normally helps keep the lung expanded against the chest wall. Thus, the collection of air or blood in the pleural space causes a pneumothorax or collapsed lung. This happens because the chest wall and lung tissue are normally kept tightly together by a negative pressure in the pleural space, and any breach leads to the equalization of pressures, allowing air to enter the pleural space, breaking the vacuum and causing the lung to collapse. This condition can be life-threatening and requires medical intervention to remove the air or blood and re-establish negative pressure in the chest cavity, often through suction.