And this curve describes Boils Law PV multiplied by constant, where v is the volume is equal to a constant, where vs the volume, and p is our pressure. So when we essentially inhale the diaphragm flattens down, the ribcage expands as a result of the external intercostal muscles contracting. And we basically move down the following curve from the initial point where we're fully relaxed to this final point on the curve where we're fully contracted. So fully relaxed and fully contracted. Now, as we move down the volume inside the space increases and that decreases the pressure inside the intraplural space. Eventually, the pressure at the end of the contraction is less than the atmospheric pressure that is given by the following blue line.