So, this bottom portion line of the title volume and the residual volume line that gives us our ERV. Now, if we take the sum of the residual volume and the expiratory reserve volume, well, that will give us something called a functional residual capacity, which is this distance here. Now, we also have this volume, which is the inspiratory or inspiratory capacity. And if we take the sum of the inspiratory capacity and the functional residual capacity, we also get the total lung capacity. Now, the final concept that I'd like to briefly discuss that relates to lung volume and capacity and breathing is known as the anatomic death space. So, every single time we take a breath let's suppose we're taking a resting breath.