 We need to get our air in so that we can carry out the functions of the respiratory system. And we're going to start out in the upper respiratory tract. From here on out, we're looking at plumbing. We're looking at structures that influence how the air flows through the plumbing. And so even though there's two ways we can get in, we can get into the respiratory system through the mouth and into the oral cavity, or through the external nares and into the nasal cavity. The nasal cavity, there are a couple of structures in here that I want you to be aware of. First of all, this is actually skull. And these are holes in the skull bones themselves. These are your sinuses. They're called perinazle sinuses. Hopefully we have a half head prep that we can look at to examine these different structures. Once we are through the external nares, air is through the external nares and in the nasal cavity, remember the nasal cavity is the space that's superior to the hard palate. You'll notice that there are some, I don't know, little, what are those, bumps? They are bumps. These are actually epithelial covered pieces of skull. These are bones that are part of your skull. And make sure that you understand that this image right here is actually a sagittal section down the midline. It's a mid-sagittal section with the nasal septum removed so that we can actually see this. If it truly was a mid-sagittal cut, we go right down the middle of the nasal septum, which separates the left nostril from the right nostril. If we remove the nasal septum, we can look into that nasal cavity space. And you'll see these bumps. These guys are your nasal conchy, nasal conchy. And when we cover the skull, you'll learn the names of the bones that lie beneath the epithelium and create that structure of a nasal concha. This guy is my inferior nasal conchy. That's his inferior. This is my middle nasal concha. And this is my superior nasal concha. And what's the purpose? Why do we have these things? Because the lovely air that you breathe in when you are not smoking comes in and your nasal conchy, like, move it all around. Like, they make the air turbulent. It helps you smell better because it moves the air all around and touches your olfactory epithelium. It helps condition the air, helps warm it up, helps moisten it before you send it onward into the rest of the respiratory tract. All right, so once we get turbulent, that's totally a word, let's go into the nasopharynx. I'm just gonna, no, I can't make a line over it. This is my nasopharynx. We already know that. The nasopharynx is superior to the soft palate. And remember this little friendly guy, do you remember that guy? That's the uvula. The uvula is the extension of the soft palate into the back of your throat. It's the worm thing hanging down in the back of your throat. This might be one of my favorite structures ever. Do you see that right there? Okay, you saw where I drew. Do you agree that you might argue it might be a hole? It is. It's a hole in your nasopharynx that connects, are you ready for this, to your middle ear. Really? Yes, really. I'm not telling you a lie. This time, it's true. This is your auditory tube. Auditory tube. Auditory tube? No, Eustachian tube is a way cooler name. Eustachian tube or pharyngeal tympanic tube. Eustachian, who in their right mind would ever remember that except for me, because that's how I learned it. Auditory tube lets you know that, yeah, this probably does connect to your ear, so that's cool. Pharyngeal tympanic tube, that's a good one. Pharyngeal, it's in the pharynx. Tympanic, it goes to the part of your ear that is attached or connected to the tympanic membrane, which is your eardrum. What? This thing, that thing, you experience that guy every day and if you did, maybe not every day, but it clutch moments in your life. The auditory tube does its thing. And if it didn't, you would be crying right now. The auditory tube is what helps you equilibrate the pressure in your ears when you change, okay, it helps you equilibrate the volume of gas in your middle ear when you change elevation, changing atmospheric pressure, do you really? Yeah, because you have air in your middle ear and when you go to a higher elevation, you are going to a low pressure environment and the low pressure when a gas is at a low pressure, it actually expands its volume. Well, the gas in your middle ear expands its volume and it pushes against the tympanic membrane, it pushes against the oval window. It's expanding in your middle ear and how does that feel to y'all? That hurts. That done hurt. And if it hurts, you don't like that, so what do you do? You go like this. Right, do it right now. You can totally hear your auditory tube open. And when it opens, it allows gas to go in or out. If you go to a higher pressure, hard for us at sea level unless we go into the water, but if we were on Mount Everest and we decided to come down, then as the pressure increases, the gas in our middle ear actually shrinks, which same thing happens. Your ears start feeling funky because there's like pressure pushing in on your tympanic membrane. Ow! And so all you have to do is pop your ears, right? That's just opening the auditory tube and allowing gas to go back and forth. I love the auditory tube. You can't see it unless we have a half head. So I hope we have a half head too. Okay. We've got our pharynxes. The pharynxes we know already. Here was nasopharynx. Here is oropharynx. And this guy is laryngeal pharynx. And we're going to spend the next entire section talking about the larynx. So we already know what pharynxes are, especially the fact that this, I'm drawing a green line through my what structure is that? That's my esophagus clowns. So our esophagus, you can send air down your esophagus, but let's not because there isn't going to be any gas exchange that occurs there. There will be only belching. All right. Are you cool? Is there anything else that you need to know? I don't think so. Let's move on to the larynx, which will explain how and why you can hear me know I can make sound right now.