And this is what happens inside our lungs, specifically inside each alveoli. So now let's actually zoom in on one of these alveoli. And this is what a single alveolis actually looks like. So we have this connecting point, this region here that connects number eight, the alveolar space, to number seven, the alveolar sack space. And because we have this direct connection, the concentration of our air molecules inside eight is the same as inside seven, which is the same as actually no, it's not the same. So in seven and eight we have the same exact concentration of gas molecules.