A collapsed lung is know as Pneumothorax. It occurs when there i s no air in lungs.The air fills out of the lungs i.e. between the lung and the chest which then exerts pressure on the lung as the lung cannot expand as much as it during when we take  breathe. This the reason why lungs collapse.
1 5 1
The Brainliest Answer!
  • Brainly User
 Pneumothorax also means a weak lung. When the lungs pain when we breathe in air it is described as a collasped lung.
1 5 1