Welcome to week five of Vital Signs. This week, we're going to be dealing with the vital sign respiration rate. But before we get there, we have to deal with a little bit of respiratory system anatomy. And that is going to be the topic of the lecture. So, when I think about the respiratory system I may think about things differently than you do. So I'm wondering when you think about the respiratory system are you thinking about breathing, what's the first thing you think of? Yeah? >> The lungs. >> The lungs, of course. And why do you think about the lungs and breathing? >> Because that's where the gas exchange actually takes place. >> Exactly. Exactly. So the lungs are a key site because that's where gas exchange between the atmospheric air and the blood gases, takes place. Right? But the lungs don't work all by themselves. Right? There are other parts of the respiratory system. So, if you think about some other structures that might be associated with the respiratory system, what do you think of? Naomi. >> The trachea. >> You think in the trachea? Wow, is that the first thing you think of? >> Mmh. >> Good job. [LAUGH]. >> Well, I guessed the first thing you think of is like the mouth and nose area, where the air comes in. >> Yes. Because that's where air initially enters the airways, right? So I, probably I would think, after I think about the lungs I would probably think next about ooh, the nose and maybe the mouth if I'm breathing through my mouth, right? So let's just first of all, think about the fact that when we deal with respiratory system we, we have to deal with the lungs. But we also have to deal with the airways that conduct gasses in and out of the lungs. And so, I think with the focus on anatomy, the first place I'd like to begin is to just take us through those initial structures that first bring the gas into the system, and then serve as the exit of gases from the system. Okay? So, we'll start at the nose and we can take a look at this model and compare it to the figure that you have open in front of you. And just think about specifically what these structures are. So this model is a model of a head that has been kind of sliced down the middle, right? And we can see that the first structure that the air is going to pass through as it gets into the respiratory system, externally we call it the nose, right? That nose area has two passages, you know, you can see the two openings into the nasal region and after the air passes through the nares. It gets into this part of the respiratory system which we would call the, yeah, yeah, >> The nasal cavity? >> Exactly, it would get into the nasal cavity, and from the nasal cavity then it would pass into a tube that extends from the back of the nasal cavity the whole way down to the area in the throat where you larynx and your esophagus are located. Now I'll talk more about the larynx in a minute, but what do we call this tube? Lydia. >> The pharynx? >> The pharynx, exactly. So we could even subdivide the regions of the pharynx. This part of the pharynx that's back behind the nasal cavity, we would call it the? >> Nasopharynx. >> The nasopharynx, and then the part of the pharynx that's behind the oral cavity, or the mouth, is the? >> Oropharynx. >> Oropharynx, and the air gets conducted through the oropharynx into the, yeah, you know. >> Laryngopharynx? >> The laryngopharynx, exactly. So the pharynx, the pharynx, just like the the nasal cavity, and the. All of those are just passages that air flows through as it's moving into and out of the lungs. Does anything happen to change the air that you inhale, as it flows through these portions of the respiratory system? Lydia? >> Does it get warmed and also moistened? >> Exactly. So, I talked in an early lecture, when we were talking about how the lungs function in helping us thermoregulate. I talked about the fact that we can actually lose some moisture in the airways because the airways humidify the incoming air. They warm it, they humidify it. Does anything else take place as air passes through those early portions of the airways? It's really important in terms of protecting. Yes? >> It gets filtered? >> It gets filtered. Yes. So the lining of the nasal cavity in the pharynx filters and traps particles and maybe harmful pathogens that might be coming in by the, the air, helps filter them out so that those particles don't make their way down into the lungs, right. Okay, so the larynx is the first structure that we think of as doing something other than. Just serving as a passageway for air. The larynx is sometimes called the voicebox because it's it's structure allows us to vocalize, right? We can actually produce sounds because of the vocal folds that are present in the larynx. We shape those sounds into words or other meaningful vocalizations using our mouth, and our lips, and tongue but the sound originates in the larynx or the voice box. And one of the distinguishing features that you should be aware of with the larynx is something called the epiglottis. What does it do? Yes. >> Does it cover the passageway to keep particles and items from going down into our lungs? >> Yes. Because the other structure that's present here in this region is the esophagus, and when we swallow food and beverages, we don't want them to end up in the lungs, right? So, when we swallow, you can actually feel your larynx in your anterior throat. When you swallow, you can feel your larynx rise up. And as it rises up, the epiglottis tips down, to cover the opening to the larynx, right? And that directs whatever you are swallowing down the esophagus into the stomach. If if we are inhaling, we inhale and the epiglottis is tipped upward and that allows air to flow into the airways. So we can see the the larynx on our model, who I affectionately call pink guy. We can see the larynx represented here, and the larynx is going to carry air into the next structure of the airways which is the? >> Trachea. >> Trachea, exactly. Now what happens to the, what happens with the trachea as it passes down into the thoracic cavity? Yes. >> The trachea splits. >> It splits or divides to form what? >> The bronchials? >> No, not yet. Lydia? >> Is it the primary bronchi? >> Exactly. The primary bronchi. So we have a right primary bronchus, and a left primary bronchus. Right? And they carry air to the right or left lung respectively. Then the primary bronchi branch into what? >> Secondary bronchi. >> Secondary bronchi, now what's the distinguishing thing about secondary bronchi? >> On the left side there's only two of them, and on the right side there's three. >> Yes, now why would that be the case? Do we have any idea? I'm going to put my lungs back in to pink eye. Lydia. >> Does each secondary bronchus serve one of the lobes of the lungs? >> Exactly. So now we're looking at the lungs again, and there are literal marks on the lung models that show us that the, when we think of the left lung it looks like it's one big continuous structure. But it actually is subdivided into lobes, right? And a secondary bronchus serves a lobe of the lung. So on the left side we have how many secondary bronchi? Two. >> Two. And so that tells us we have how many lobes in the left lung? >> Two. >> Two, yeah. And on the right side, we have how many secondary bronchi? >> Three. >> Three. And so that tells us we have? >> Three. >> Three lobes. We're going to get into lung anatomy later in the week. And I think we've covered a lot of ground, for now. Good job.