all right this is going to be the part one video for the respiratory system chapter in this video we're going to focus on the major processes of the respiratory system and we'll begin uh like the trace of the respiratory tract all right so the first thing we want to do before we even get into any anatomy of the respiratory system is get a sense of like the four major processes that are going to be involved in respiration so first off we have to be able to move air into and out of our lungs and so that's going to be our first process that we're seeing here which is pulmonary ventilation so the whole idea here is that much like we might say that a room is well ventilated when there's like good air flow in and out and if pulmonary of course refers to the lungs then this is going to be the process by which we like move air from the atmosphere into our lung tissue and then eventually back out and so we'll look of course at like the physics and the muscles involved in doing that ventilation process all right well once we have moved that air into and out of the lungs we then have to do gas exchange within that lung tissue so we can phrase that as uh external respiration or we can call it alveolar gas exchange so the idea here is that oxygen from the atmospheric air that we breathe in is going to be like loaded into our bloodstream but the waste carbon dioxide gas that's arriving at our lungs from our body's tissues will be like released out into the air that we expire out into the atmosphere so that process of like doing gas exchange within the alveoli of the lungs can be referred to as that either alveolar gas exchange or as external respiration the thing though is we also have to at some point look at the various characteristics of blood that allow for gas transport you know what aspects of blood whether it be hemoglobin the plasma etc allows for oxygen and carbon dioxide transport so at some point in this chapter even though that's not even involving any respiratory anatomy it's really all just blood uh characteristics but we'll we'll look at that in this chapter like respiratory gas transport how we carry oxygen and co2 uh you know from our lungs to tissues and back all right and then finally much like gas exchange had to occur at the lungs gas exchange also has to occur at your body's tissues so we can refer to this either as internal respiration or systemic gas exchange this is where the oxygen that has been that has been carried in our blood can be provided to our uh you know tissues and those tissues that produce carbon dioxide waste can get rid of that waste into the bloodstream all right so at some point throughout the course of like our multiple videos of the respiratory system we will look at each of these processes all right but now that we've kind of summarized the major processes the next thing to start doing is looking at the anatomy of the respiratory system and the most logical thing basically to do is to eventually kind of do a trace as in like breathing in through our nose getting all the way down to like the air sacs of our lungs called alveoli and we can see that our diagram from our textbook is illustrating that we can subdivide our respiratory tract organs into upper respiratory tract and lower respiratory tract structures where upper is basically from like our nose through our voice box our larynx and then our lower respiratory tract is everything kind of like beyond that from the trachea all the way down to the air sacs called alveoli the thing though is we can also more functionally organized the structures of our respiratory tract as i'm putting in the notes over here into conducting zone structures and respiratory zone structures much like the word conducting just kind of implies like providing a pathway or a conduit that's exactly what we're implying here is that these are the structures of the respiratory tract that are just air passageways and nothing more so they're not actually contributing to gas exchange they are just passageways to get to the areas that do gas exchange and that's going to include everything from the nasal cavity all the way down to microscopic structures called bronchioles so that includes like the nasal cavity our pharynx our larynx our trachea and all sorts of branches of the bronchial tree until we get all the way down to things called bronchioles that we'll describe later the thing though is at some point we get down to the microscopic level and once we're microscopic we start to see little air sacks or pouches known as alveoli and so once a structure starts to have a few of those air sacs or alveoli it's now officially a structure that's contributing to the gas exchange process so for example like doing that external respiration or alveolar gas exchange and that's why we now no longer call it conducting zone structures but respiratory zone structures so sure enough things like respiratory bronchioles alveolar ducts the alveoli themselves anywhere those air sacs are found that's going to be contributing to that gas exchange and so hence are classified as respiratory zone structures all right so that's like the organization overall of the like respiratory tract and so now that we've kind of given a couple of like structural and functional like uh you know um you know breakdowns we can start our trace so if we assume that a person like breathes in air or inspires air through their nose and that air is then going to take a journey all the way down to those alveolar air sacs we should be able to kind of all in a row be able to name these structures and their importance of what they're contributing to like the process of ventilation or respiration all right so logically then we're going to begin at the nasal cavity so what's the benefit of specifically breathing in or inspiring air into your nasal cavity well as air moves through your nasal cavity that air becomes warmer it gets like moistened and filtered at the same time of course we should maybe even remember from a p1 that our nasal cavity right up here where the ethmoid bone is located we would find our like olfactory bulb and all the nerve endings would be coming down from there so we can also mention of course that the nasal cavity is going to contain those olfactory receptors so our nasal cavity besides more moistening and warming and filtering air also provides of course for our sense of smell we can also structurally remind ourselves that there's a nasal septum right that goes right down the midline of our nasal cavity dividing our nasal nasal cavity into right and left halves other structures we can mention would be for example like our entrance point into the nasal cavity and of course we commonly call those our nostrils but a lot of books still use the more anatomical description of calling them their your external nares or a single one is referred to as a neris or the plural nares but simply enough those are like your visible nostrils through which air is like brought in uh to enter officially your nasal cavity what we then want to realize is that in order to do the warming and the moistening and filtering of that air we actually don't want laminar smooth air flow going through the nasal cavity we want it more turbulent the idea being that if you create turbulence of that air the air spends more time there and with more time in the nasal cavity theoretically the air becomes a bit warmer from our like body heat at the same time if the entire inside of the nasal cavity is lined with mucus then that moist mucus is adding like a you know a moisture level to that air and that mucus can trap particulate matter so we're also filtering and like cleansing the air as it like tumbles through the nasal cavity so that begs the question well what creates that like turbulence of the airflow well that's your conchae recall of course from maybe amp1 lab where the conchae are like curved bones that protrude into the nasal cavity and it's those uh protrusions that kind of create like the speed bumps if you will that cause the turbulence of the air and that turbulence again is going to you know make more efficient the whole idea of like filtering that air making it warmer and so on all right great let me get rid of all these scribbles on this slide so we can go on to the next one there we are all right so now as we're still in the nasal cavity the next thing to think about is well like what type of you know tissue are we going to find lining this hollow space well much like we learned of course in the immune system chapter right our first line of defense in our you know against any pathogen is our skin and our mucous membranes and so sure enough we have a respiratory mucosa a mu a mucous membrane that lines like the upper respiratory tract so as we can see here we have an epithelium that's part of that respiratory mucosa and that's good old pseudostratified ciliated epithelium right good old pscce we can see there right the pseudostratified layer of cells with the cilia on top we see a layer of mucus and of course that's providing like the ability to filter and adding that moisture and of course we learned in our immune system chapter that our mucous membranes will often release like enzymes and even sometimes antibodies and things like that so that we're also basically kind of cleansing the cavity and and keeping it free of pathogens much as you're also say like filtering things in the mucus so we can also point out that that's there as well various like enzymes that break down bacteria and other pathogens are going to also be mixed in with like the mucous secretions from this mucosa what we can then also mention is that if we have a pair of external nares our visible nostrils we must also then have more of an internal pair the idea there is that the nasal septum that divides our nasal cavity in half goes all the way through your nasal cavity which means if you were to say for example like have like a bendable flexible camera that could go into somebody's mouth go up their throat and look at their nasal cavity from the back much like you see a pair of nostrils at the front you would see a similar pair of nostrils at the back of the nose or nasal cavity and those go by a few names i've seen books refer to them as the internal nasal apertures the koana or as i learned them and put them here your internal mary's so if you have external areas at the front of the nasal cavity separated by the septum you have a similar corresponding pair of holes at the back of the nasal cavity and once the air has gone through those you're no longer officially in the nasal cavity you're now officially in the pharynx which would be like the beginning of the throat all right we can also mention of course that not only does the mucous membrane produce mucus but so do the hollow spaces within certain bones of your skull referred to as your paranasal sinuses so you might recall an anp1 lab that you might have learned that like the frontal ethmoid sphenoid and maxilla all contain hollow spaces and they're lined with respiratory mucosa and also them producing mucus that mucus is going to then drain through like uh ducts that lead into the nasal cavity so you not only produce mucus in the mucous membrane itself but also in the linings here of these hollow sinuses we can also of course remind ourselves though that any you know protective immune system structure like a mucous membrane can become inflamed uh due to say irritation uh or from infection so if it happens to be specifically within the nasal cavity that our mucus our mucosa becomes inflamed then we specifically specifically refer to it as rhinitis however if that inflammation spreads into the sinuses and that's where a person might actually feel tenderness like in the bones above their eyes or below their eyes and may even feel like pain like when they bend over and like th and mucus like shifts within those sinuses that's at that point that a person might say oh i have a sinus infection and the inflammation within there is now referred to as specifically sinusitis so of course a mucous membrane is there to protect us but of course it can become either irritated or infected and then our inflammation specifically you know in the nose or sinuses is classified as such all right let's clear all those scribbles okay so the next idea is that we could now assume that the air has entered through the external nares tumbled here through the nasal cavity then passed through the hole right here the internal nares and now officially the air is no longer in your nasal cavity it's now in your pharynx which is what we commonly call our throat so the thing we have to realize is your pharynx or throat is actually a common passageway for both the things we swallow and for the air that we breathe so air and food and of course and liquids too right we swallow water drinks right so what that then means then is is that we should be able to follow like theoretically if we were following air air would go through the nasal cavity down through the pharynx and then enter the larynx and then eventually trachea on its way down to the lungs however when we eventually cover the digestive system we'll find that we ingest food into our oral cavity chew it swallow it through the pharynx and go back here into the esophagus so notice how there's like a criss-crossing that happens right here of both air and things we swallow so hence the idea then that our pharynx is like a common passageway for both our respiratory tract and our digestive tract and that as we get to like the inferior aspect of it it splits into the larynx which leads to our trachea and that's what we're going to follow today as part of the respiratory tract but we'll revisit the pharynx when we learned about the digestive tract because that's when we'll follow the pharynx leading also to the esophagus we then have to though realize is that if your throat or pharynx runs all the way from behind your nasal cavity and all the way down to where it does that splitting into larynx and esophagus then in that as we kind of follow it downward we're actually going to pass through three separate segments of the pharynx so what they're highlighting in red up here is what we call the nasopharynx given that name because literally it's the space of your throat that sits posterior to your nasal cavity the thing is if you think about it no foods or liquids that we swallow should pass through that segment because it's kind of sitting above your palate and so in that regard in that segment of your pharynx you find the same mucosa that you find in the nasal cavity itself so we still have that lining of the pseudostratified epithelium the thing though is once we move a little bit further down the throat that is where we now have that passageway also for food and that's where we then need more protection so the oropharynx and the laryngopharynx name for the fact that one sits behind the oral cavity and one sits behind the cartilages of the larynx that is where because food and liquids are also going to pass through there that that lining is going to need more protection so instead of having that same pseudostratified epithelium that we found up in the nasal cavity and nasopharynx it's instead going to be stratified squamous recall that stratified squamous epithelia is where we have many many cell layers stacked on top of each other and that acts as a good physical barrier for protection and so that's the idea that because our oro and laryngopharynx are both passageways for food as well as air but we're going to need that protection from that kind of stratified squamous epithelium all right well if we're going to continue our trace we have of course to enter next the larynx right we wouldn't we would enter the esophagus if we were following like a swallowed uh bolus of food but we're following the pathway of air on its way to the lungs so after leaving the pharynx we're next going to enter the larynx all right so let's clear all the scribbles from this slide go on to the next one okay so first thing to realize is our larynx is going to be a continuation of the tract so it's going to be an air passageway that connects the pharynx above to the trachea below so for example we can even see that this diagram now on the slide here actually the larynx itself stops here because what we're seeing then below that like down here is already the beginning of the trachea so if we were up here above the larynx we would still be in the throat the pharynx passing through the larynx then eventually brings us into here the trachea so hence our larynx is an air passageway connecting the pharynx above to the trachea below structurally what we can see even in all the images down here all this like blue is of course representing cartilages and we can point out that your larynx or voice box is made mostly of hyaline cartilage however we'll see in a moment there is one exception to that and that's the epiglottis here i just use the phrase voice box for describing the structure the larynx and the reason for that is because inside your larynx are your vocal cords so this structure then is not just a respiratory passageway it's also the structure utilized for your voice production and just to point out one more thing not that i bothered putting it in the notes but remember that in amp1 you might have learned about this bone here called the hyoid that sits like basically at the very uh you know upper neck and we can see that that hyoid bone helps to give support to the entire larynx in fact we can even see musculature that connects the hyoid to the larynx and we'll discuss that in a moment when we talk about now that or pretty much right now as we learned about the epiglottis okay so let me get rid of the scribbles i've done so far we now have to realize is that because the throat is a common passageway for both the foods and liquids we swallow and the air we breathe then that means we have to make sure that every time we swallow you know a mouthful of food or you know a liquid that it doesn't come here into the larynx and instead enters only the esophagus well as we'll see in a few moments the gap through which air travels into the larynx is called the glottis therefore if there's a flap that goes over the top of that opening then fittingly we would call it the epiglottis because it's on top of or upon the glottis so for example if the glottis is the gap in between your vocal cords and air has to go through that then if you don't want liquids or foods to go through that opening you cover the top of that opening so if the opening is the glottis the flap that covers over the top is the epiglottis so it's the fact that that epiglottis has to be flexible that's the reason why it's the only piece of your larynx that is not made of hyaline cartilage but is instead made of elastic cartilage that being that you needed to have elasticity to be able to be bent out of shape and then the second you're done swallowing you want that elasticized structure to swing back and like recoil back to its original shape so that you can reopen that glottis and commence breathing again so the whole idea of how this works is that when a person swallows these muscles that attach the hyoid bone to the larynx kind of lift the larynx up and as the larynx gets lifted up that tilts the epiglottis over that means that that opening that air would go through is now kind of covered so the food or the liquids that were swallowing theoretically then wouldn't have the option of going down into the larynx because this epiglottis has flopped over bent and now is covering that glottis opening but of course as soon as we finish swallowing we need to start breathing again and that's where we want the elasticity of the epiglottis to spring back to its original shape so that the air can go back to you know ventilating into and out of our lungs so that's the whole idea we can probably even see actually since of course right you know my being male means that we can see my adam's apple and notice that when i swallow you can literally see like the larynx move up and down and it's that movement that tilts over that epiglottis protecting the larynx as we're swallowing making sure that the foods or liquids we are swallowing enter the esophagus and not here into our respiratory tract all right so that's the idea of our larynx of course what we also have to take a closer look at is what's going on inside the larynx to get a better sense of how it contributes to that like voice production process but let's uh clear all these scribbles and move on to the next slide to see that all right there we go okay so what are we seeing now we're now seeing that glottis right so for example here's the opening called the glottis here's the vocal chords on either side so air has to go down through there we're kind of looking from like a superior view as if you're looking down through somebody's voice box so for example here's like the top of the epiglottis that would have to like bend over to protect this glottis and cover it up in the middle of swallowing well now that we're in seeing this view this is why your larynx is called your voice box these white flaps here and here are your vocal cords otherwise called the vocal true vocal cords or vocal folds and because those structures produce your voice that is why of course your larynx is also called your voice box so these structures are made of basically like elasticized connective tissue and so a great way to kind of imagine how they work is that when we force air over them they vibrate those vibrations produce sound waves and those sound waves can then be shaped by our like you know uh tongue our our lips and our facial features into actual like language so much like for example plucking a guitar string makes the string vibrate and that produces like the sound of that instrument similar that when we force air over our vocal cord which is like string like structures that vibrate very similarly they produce sound and then we shape it of course into our actual vocalizations all right and of course then the glottis as we've already phrased right is that gap between them so the glottis is literally the space in between the vocal cords and what's interesting is that's another important like landmark for changing the lining of this respiratory tract because above these vocal cords you were still basically in like the laryngopharynx where food could be passing by and that was where then we would want to have stratified squamous epithelium for protection but once you go below these vocal ligaments or vocal cords that's where theoretically food and liquid should not be traveling and we can switch back to the epithelium and mucosa that we found up in the nasal cavity and that's the landmark for switching back to the pseudostratified epithelium all right what's interesting is that we can point out that the vocal cords are sometimes referred to as the true vocal cords because the flaps that are kind of lateral and just superior to those vocal cords are often referred to as the false vocal cords because they kind of look like an extra set of folds as if there's like another pair of vocal cords but they're not and they actually also have another name to refer to them as the vestibular folds but here's what's interesting when we swallow for example there's actually kind of two levels of protection to make sure things don't go down the wrong pipe so to speak and go through this glottis that being one we know the tilting over of the epiglottis the elasticized cartilage that we described a few moments ago that when our larynx moves up that flips that epiglottis to cover over the top of this whole opening at the same time though your vocal cords can actually be adducted as in like squeezed together and that is the job there of these false vocal cords otherwise called the vestibular folds when we swallow we trigger that adduction of the vocal ligaments and so notice it's like we closed the glottis so we not only use the epiglottis to cover the glottis itself but we actually pinch the glottis closed with the help of those false vocal cords otherwise called vestibular folds all right and no surprise right whenever we put the suffix itis on the end of anything we're talking about the inflammation of that structure so laryngitis is the inflammation of the larynx especially the vocal ligaments well no surprise you might be familiar with saying that when some person has laryngitis they have lost their voice the idea there is much like if you took a guitar string and like coated it in something like thick like a jelly or something and tried to then use that stringed instrument it wouldn't produce the right sound because you'd be like preventing its normal vibration well similarly if our in if inflammation refers to like the swelling and enlargement right of a structure that's not going to vibrate normally and hence then the inability to kind of vocalize at that point so that could be brought on by like overuse like you know a lot of yelling or sometimes viral infections can trigger inflammation in the upper respiratory tract but simply enough that's the idea of laryngitis inflammation that impedes normal vocalization all right so at this point we've traced through our nasal cavity pharynx larynx so where we go next is the trachea right we even saw in previous diagrams that when usually whenever you see a diagram that shows the larynx they show the trachea at least part of it and kind of like continuing just below so we can generally describe that your trachea is an air passageway again connecting the larynx above and eventually branching into a pair of what we call bronchi no surprise of course right we have paired lungs let me just move myself so i'm not blocking too many notes there right we have paired lungs so at some point our like once we're into like the lower respiratory tract we have to actually branch and subdivide to head to the two different lungs so that's going to happen at like the distal end of the trachea so our trachea connects the larynx above and branches into the bronchi below no surprise we can also point out that our trachea is what we commonly call our windpipe another interesting thing to mention about our trachea is that actually at the posterior side of it so for example we're seeing a cross-sectional slice slide right here and what they're pointing out is that if this is the anterior side here like facing the front here's the posterior side here notice at the posterior side of the trachea there's actually a muscle there called your trachealis muscle well the whole idea here is that that muscle is used as in like clearing your throat or coughing so for example if a person ever gets like a little bit of something going down the wrong pipe like they go to swallow a drink of water and a little bit goes down into the larynx or trachea and they clear their throat coughing that up it is your trachealis muscle that is creating kind of like an upward current of air in that kind of clearing your throat or coughing process all right but what we can then do is um kind of zoom in so to speak on the wall of the trachea itself and we would see that when we do this cross section of the trachea there are four distinct layers there so let's make a like let's kind of take a closer look even though we can't really exactly zoom in on that slide right there we can get an idea of like what are the major layers in this cross-sectional anatomy of the trachea so first thing we're going to find a mucosa and because we're still below the vocal cords we have that same mucosa as we did up in the nasal cavity that being our pseudostratified ciliated columnar epithelium otherwise called of course the pscce so we see that right here we see the pseudostratified cells with their cilia i see goblet cells mixed in there for making mucus that mucus sits on the surface of the um of the mucosa and the cilia create like a sweeping action that sweeps the mucous specifically in the upward direction right the last thing you want to do is that the mucus that is trapping particles and filtering things from the air we don't want that to become stagnant and drip down into our lung tissue we want it swept up out of the respiratory tract toward our throat where we can swallow it and then of course like our stomach acids can kill any you know bacteria or other pathogens that might have been trapped there within that mucus so that's our first layer lining the hollow lumen there of our trachea is the mucosa with its pseudostride a pseudostratified epithelium with mucus producing goblet cells all right wherever there's a mucosa beneath that there's going to be a submucosa and as always a submucosa is largely made of connective tissue but it's also where we typically find glands as well so for example we're going to find glandular tissue in the submucosa producing more of that mucus that we know of course is helping to filter and you know protect us well much like our larynx was composed of mostly hyaline cartilages and that gives the structure shape and support and holds the lumen open for you know constant breathing the same is going to be true in our trachea where we want to have hyaline cartilage there for structural support what's interesting though is we what we don't want here in the trachea is for those cartilages to be complete rings why don't we want complete rings of cartilage because that wouldn't that be good to hold the lumen open at all times well there's an issue we just figured out before that sitting just posterior to your larynx in your trachea is your esophagus which of course is the muscular tube that when we swallow brings a bolus of food or liquids from our oral cavity through our throat uh and down to our stomachs the idea then is the last thing you'd want as our esophagus is like doing peristalsis and squeezing things down that tube to hit a series of like speed bumps so to speak on the back of your trachea so for that reason inside the trachea the cartilages are kind of c-shaped only going so far around that way instead of having cartilage we have that muscle right that we mentioned earlier at the back and that way that is what is interacting with the esophagus so when the esophagus has to expand as a bolus of food is pushed down by peristalsis there isn't like cartilage here getting in the way so that's why we have like incomplete like c shape or u shape however you want to think about it right cartilages to give support without interrupting the ability of the esophagus to expand when doing peristalsis and then finally whenever there's a tract or tube that needs to get like connective tissue support and be anchored in place for that we're going to find an adventitia so on the outer outermost surface of the trachea we're going to find that connective tissue layer and again that's just literally just like mostly collagen fibers wrapping around the trachea acting as a means of support kind of holding it in place within the neck all right so that's the idea of our trachea connecting our larynx above and then branching eventually to the bronchi below but again of course under like a microscope we could literally look at a sliced view of the trachea and see its four distinct layers all right let's clear all those scribbles and i think this is where we're actually going to end this first video because we'll maybe do uh yeah the bronchial tree all the way down to alveoli in our video part two