How is the effectiveness of gaseous exchange surfaces in humans increased?

Gaseous exchange in humans takes place in the alveoli in the lungs, the aim is to remove carbon dioxide from the lungs and increase oxygen content of the blood.Increased surface area of the exchange surface to allow a greater area for molecules to move across, to allow faster diffusion (for example there are many alveolar in the respiratory system, overall this provides a large SA)Thin exchange surface so shorter distance to diffuse across, the alveolar walls are only one cell thick.System to maintain concentration gradient, in respiratory system the blood in the nearby capillaries is constantly moving. This means there is always a higher concentration of carbon dioxide in the blood than the alveolar and a higher concentration of oxygen in the alveolar so constant diffusion in the correct direction