So as soon as the blood enters the capillary, we have this relatively thin wall that consists of the endothelium of the blood vessel, the capillary, the basement membrane, as well as the epithelium of our alveolus. And this entire layer allows our diffusion of these gas molecules. And this layer that consists of these three different things is known as the respiratory membrane inside the capillary that allows diffusion to take place. And so carbon dioxide will diffuse down its pressure gradient from a high pressure to a low pressure. And oxygen will also diffuse down its gradient, but it will move from the outside to the inside of the capillary, also down its gradient from a value of 105 to a value of 45 mercury. So this is exactly why our exchange takes place in the first place because there is a pressure gradient that exists between the space of the alveolis and the lumen of our capillary where the blood actually flows.