And what the fluctuating blue curve essentially describes is it describes the process of breathing. Every time the blue curve increases, we essentially allow air into our lungs. And every time the blue curve decreases, we expel air from our lungs. So the increasing portion of our blue curve is the process of inhalation and the decreasing portion of the blue curve is the process of exhalation. So let's begin by describing something called the title volume. So earlier we asked how much air, on average is exchanged by our lungs when the individual is actually at rest every single time we take a breath.