There are three main ways in which the lungs are adapted for efficient gas exchange. These are: the fact that structures in the lungs called alveoli provide a large surface area for gas exchange. Also, the lungs have an excellent blood supply due to a large capillary network, which means a diffusion gradient is always maintained. Finally, the alveoli and capillary walls are only one cell thick meaning there is only a small distance for gases to diffuse.