Final answer:
Paradoxical motion of the diaphragm in pneumothorax occurs when air enters the pleural space and causes the lung to collapse. This abnormal movement impairs respiratory function by preventing proper lung expansion and gas exchange.
Step-by-step explanation:
Paradoxical motion of the diaphragm refers to the abnormal movement of the diaphragm during breathing. In the context of pneumothorax, a condition where air enters the pleural space, the affected lung collapses and the diaphragm moves paradoxically. Instead of descending during inhalation, the diaphragm moves upward, compressing the lung further. This leads to impaired respiratory function as the collapsed lung cannot effectively exchange oxygen and carbon dioxide. The mechanism behind paradoxical motion of the diaphragm in pneumothorax is due to changes in pressure within the thoracic cavity. Normally, the negative pressure inside the pleural space keeps the lung inflated. When air enters the pleural space in pneumothorax, the pressure equalizes and the lung collapses. The diaphragm, in response to this collapsed lung, moves in the opposite direction during inhalation, causing the paradoxical motion. To summarize, in the context of pneumothorax, paradoxical motion of the diaphragm occurs when air enters the pleural space and causes the affected lung to collapse. This abnormal movement of the diaphragm impairs respiratory function as it prevents proper lung expansion and contraction, leading to ineffective gas exchange.