Emphysema is a condition in which there is over inflation of air sacs (alveoli) in the lungs. This occurs as a result of irreversible destruction of a protein called as elastin. Normally this protein is important for maintaining the strength of the alveolar walls. Loss of elastin also causes collapse or narrowing of small air passages called as bronchioles which in turn limits the airflow out of the lungs.


Hence, Emphysema is a lung disease in which there is permanent destruction of the walls of air sacs.