Final answer:
A pneumothorax is a condition that occurs when free air enters the pleural cavity, causing the lung to collapse. Symptoms include chest pain, shortness of breath, and difficulty breathing.
Step-by-step explanation:
A condition that occurs when free air gets into the pleural cavity is called a pneumothorax. This can happen due to a puncture wound, where air leaks into the space between the lung and the chest wall, causing the lung to collapse partially or completely.
For example, a spontaneous pneumothorax is believed to occur due to subtle abnormalities in connective tissue, resulting in a collapsed lung.
Symptoms of a pneumothorax include sudden chest pain, shortness of breath, and difficulty breathing. Treatment may include the removal of air through a small tube or surgery.