What type of cellular transport occurs with the movement of oxygen and carbon dioxide gases across pulmonary capillaries in the alveoli?

The movement of oxygen and carbon dioxide gases across pulmonary capillaries in the alveoli occurs via simple diffusion. This process allows these gases to move from areas of higher concentration to areas of lower concentration—oxygen diffuses from the alveoli into the blood, while carbon dioxide diffuses from the blood into the alveoli. This passive transport does not require energy and relies on the concentration gradients of the gases.