And these two processes are actually opposite with respect to one another. Inhalation is when we bring air into the lungs. And exhalation is the process by which we expel the air from the lungs into the outside environment. And more specifically, inhalation, we bring in oxygen and exhalation we expel, we remove the carbon dioxide that is produced inside our cells as a result of a byproduct of, let's say, cellular respiration, which once again, is not the same thing as respiration breathing that we're focusing on in this lecture. So let's begin by describing how inhalation is carried out by the lungs. So let's take a look at the following diagram.