Transcription
We use these for taking a breath; oxygen in. I say this with chest CO2 that needs to leave. Let me explain to you how we breathe. A go straight down through the wind pipe, or the tracha—of saying it right at this point here—we see that it splits. Now it's the bronchi; gets into bits, raising the surface area—the goal, so they know to branch—into bronchioles, ending with these—numbers are high—remember the name—that the alveoli. Take a look, and I will explain. This is a site of gas exchange; oxygen goes through these membranes, flows down from high to low concentration into the blood; it's gone. We call out process diffusion. Then, by the cells, oxygen's consumed. We call that one respiration. Carbon dioxide—there's no room—has to go back to the lungs by noon—to fill up the space in these balloons—take a breath out. I'll see you soon.