How are the alveoli designed to maximise the exchange of gases?

The alveoli provide a large surface area for the exchange of gases to take place. The walls of the alveoli contain an extensive network of blood-vessels. The blood brings carbon dioxide from the rest of the body for release into the alveoli, and the oxygen in the alveolar air is taken up by blood in the alveolar blood vessels to be transported to all the cells in the body.