Question

how does one lung collapse and not both?

Answer 1

Collapsion of lung is caused due to a condition of "pneumothorax", which occurs when the air gets leaked into the space between lungs and the chest wall. This will shrink or collapse the lung by pushing the air on the outside of the lung. Pneumothorax can collapse the either the entire complete lung or only a portion of the lung. Pneumothorax can even lead to atelectasis because, alveoli gets deflated when the lung gets smaller due to shrinkage. This pneumothorax is the reason why one lung collapse and not the both.

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