How are the lungs specialised for exchanging gases?

The lungs are made up of many air sacs called alveoli. The alveoli have many folds which create a large surface area.  The larger the surface area, the greater the area of alveolar cell membrane available for gases such as oxygen and carbon dioxide to diffuse across. Therefore the lungs will be able to exchange greater quantities of gases, in the same amount of time, than organs with a lower surface area and therefore will be better at exchanging gases.