How are the lung's alveoli adapted for efficient diffusion?

The alveoli are like small sacks present at the base of the lung, and are the site of exchange between the air we breathe and our blood. This exchange occurs by the process of diffusion, for which alveoli are highly adapted. They allow efficient diffusion by having a large total surface area and presenting a short diffusion distance (as they are only one cell thick). In context, they are also located in the "core" of the body, where the temperature is warm. (this is end of GCSE level)These features help to increase the rate of diffusion according to Fick's Law:Rate of diffusion = k x A /D x (P2-P1) where k is a diffusion constant determined by the local temperature and the solubility of the gas,A = surface area for gas exchange, D = diffusion distance , (this is end of A Level level)P2-P1 = difference in partial pressure either side of the barrier to diffusion (This is a point of extension for able students. We can discuss Partial pressure (mmHg) = Total pressure exerted by the gas mixture x Percentage composition of focus gas)