 I can do it. I can do it. Here I am. We're talking about the terminal bubble. We're talking about, okay, we made it through the bronchi. We made it through the bronchi hole. Where are we going? You guys, we're ending up in the alveoli. Alveoli are bubbles. Alveoli are bubbles, I know you can't read that, but they're lined by a tissue that is phenomenal at diffusion. What is it? Simple squamous epithelial tissue. And look, each one of these things, this is one alveolus. This is one alveolus, and it doesn't show you the actual simple squamous epithelial tissue that is lining each one of those bubbles. Not only are the bubbles lined with simple squamous epithelium, and the air that went through all your tubing ultimately ends up in these bubbles, but the bubbles are intimately connected, surrounded by a net of capillaries. And this allows the blood to come in very close contact with these bubbles that are extremely thin, allowing for very quick diffusion in gas exchange. So carbon dioxide that is found in the blood travels into the alveoli, and oxygen found in the alveolus travels into the blood. And it happens, take a breath. Done. It happened like halfway through my breath. My blood and my air switched gases. And then I breathe out, and the carbon dioxide is gone, and the oxygen is in. Like, really, it's that fast. It's amazing. What else do you need to know about the alveoli? I'll tell you something about alveoli. Are you ready? They're elastic. They're actually surrounded by elastic fibers, made out of the protein elastin. And are you ready for this? When you smoke, those elastic fibers, okay, you're smoking, and you're bringing in all this crap into your lungs, and your lungs are like, dude, knock it off. We're killing all our cilia. This is gnarly, this is awful, please stop. You get a whole bunch of macrophages, which are immune like amoebas, that come into your lungs, and they hang out in your alveoli, and they say, oh my God, if you have crap that gets all the way to your alveoli, hey, you want to smoke, awesome, we'll eat the crap that comes in there. And so they just start yumpsializing all the cigarette poison that you just put in there. They're getting it all out, they're yumpsializing it. And that's what happens. As these alveolar macrophages are yumpsializing the crap, they produce an enzyme. They like barf out an enzyme called elastase. I have to write that down for you because this is why you have to stop smoking right now. Elastase, elastase, elastic, ace, break up the elastic fibers in your alveoli and guess what happens. If your alveoli, if your alveoli, you expand, when you take a deep breath, the air comes in, but then the alveoli, do not have elastase in them anymore because you don't smoke that elastase, you can't, your alveoli can't squish out the air and you can't exhale. And if you can't exhale, that's emphysema, truly. Plus you, your alveoli break down and lose surface area. So not only you take a deep breath, like, oh, hallelujah, oxygen, and then you can't breathe it out to exchange differently because you can't get all the bad air out because you've broken down your elastic fibers that surround the alveoli. Structure determines function, quit smoking.