How are the alveoli adapated for gas exchange

Blood leaves the right side of the heart via the pulmonary artery, which takes deoxygenated blood to the lungs so gas exchange may occur. Numerous alveoli are found here and these alveoli possess many invaginations or infoldings. Both of these factors contribute to a very large surface area, which increases the rate of gas exchange between the alveoli and the bloodstream. The walls of the alveoli are also extremely thin (as is the capillary endothelium), meaning that the diffusion distance is very short, again increasing the rate of gas exchange. Furthermore, alveoli are coated in a surfactant which lowers the surface tension, and prevents the alveoli from collapsing. The alveoli are moist, allowing the gases to dissolve. A steep concentration gradient is also maintained between the blood and the air spaces in the alveoli, ensuring a fast rate of diffusion. This is achieved by constant ventilation of the alveoli when we inhale and exhale, as well as the copious blood supply surrounding the alveoli. The good blood supply ensures that freshly oxygenated blood is taken away from the alveoli, and deoxygenated blood is brought towards the alveoli.