Final answer:
Pneumothorax is a condition where air enters the intrapleural space, causing the pressure to equalize with atmospheric pressure and potentially leading to lung collapse.
Step-by-step explanation:
The respiratory condition known as pneumothorax refers to the presence of air in the intrapleural space which causes intrapleural pressure to equalize with atmospheric pressure, impairing the lungs' ability to expand. In a normal lung, the intrapleural pressure is kept lower than intra-alveolar and atmospheric pressures due to the elasticity of the lungs, surface tension of the alveolar fluid, and thoracic wall forces. The negative intrapleural pressure is essential for lung function, as it allows the lungs to expand during inhalation and maintain their size and shape. When a pneumothorax occurs, air enters the intrapleural space either due to injury or spontaneously, disrupting this delicate balance and potentially causing lung collapse.