Correlation 12: Emphysema

The airspaces in this image of a lung with emphysema appear larger because of the loss of alveolar walls. The remaining large spaces have less overall surface area than the normal lung.

The normal alveolar air sacs are uniformly sized and allow sufficient surface area for gas exchange to occur (inhaled oxygen diffusing into the bloodstream and carbon dioxide diffusing out into the alveoli to be exhaled). One of the changes that occurs to the lung with smoking is loss of alveoli. This process is known as emphysema. The loss of alveoli is permanent and irreversible.