Describe and explain how the alveoli are adapted to perform efficient gaseous exchange

The alveoli are arranged in clusters at the end of the bronchioles in the lungs. The lungs contain an extremely large surface area of alveoli (around 70m2) which acts to provide the maximum space for the exchange of oxygen and carbon dioxide. The alveoli themselves are covered in vast networks of capillaries, this close contact with an efficient blood supply maintains a steep concentration gradient in both directions, with oxygen diffusing from the alveolar space into erythrocytes in the capillaries, and carbon dioxide diffusing from the erythrocytes back into the alveoli to be expired.In addition to this, the walls of the alveoli and capillary are made of squamous epithelium and are only one cell thick, thus there is an extremely short diffusion distance to maximise the rate of exchange.Furthermore, the alveoli contain cells that release a surfactant, which acts as a moist lining to dissolve gases in order to maximise the rate of exchange.