How are lungs are adapted for gaseous exchange?

The alveoli are cell wall is one cell thick = short diffusion pathway. The alveoli are moist - so gasses can dissolve and move quicker. The alveoli are small and increase the surface area - diffuse quicker. The capillaries are cell wall is one cell thick = short diffusion pathway. There are many capillaries - short diffusion pathway. The chest is elastic - so recoil expels air with high CO₂ and low O₂ to maintain a high diffusion gradient.