This lecture will be going over the anatomy of the respiratory system. So in the respiratory system there are three main steps involved on respiration. Um first step is pulmonary ventilation. Um this means that this is looking at the air flow of the inflow into the body and the outflow which are also known as inhalation and exhalation. Excuse me. So this is going to be where the air is exchanged to the atmosphere as well as down to the avoli of the lungs. From there once the gases have gotten into the avoli they will diffuse into the blood and then from the blood the blood is going to be pumped to what's called the external or the pulmonary respiration. So that's going to be the exchange that's occurring with the gases. Then from there it will be pumped from the lungs through the heart to the rest of the body where at the tissues that are needing the gases the exchange will occur and what happens at the tissue is that oxygen will go into the tissue it the blood will then pick up carbon dioxide and so this is known as internal or tissue respiration and then the process reverses in order to get carbon dioxide out of the body. So it's a process to go in and then it's a process reverse to go out of the body. Now at the molecular level the respiratory system is engaged in what's called the aerobic cellular respiration. Aerobic cellular respiration means that you need to have oxygen present in order for cells to do what the name implies which is breathe. Um, all of your cells need this uninterrupted supply of oxygen that is delivered by your bloodstream and then because of a waste product that occurs during cellular respiration, carbon dioxide is produced which then has to be picked up by the blood to deliver that then to your lungs so your lungs can eliminate it. So aerobic cellular respiration is at the molecular level what your body needs the oxygen for. And so therefore the respiratory system is what's going to support this gas exchange. Now respiration is defined in your book as um the process by which carbon dioxide and uh oxygen are continually exchanged between your body and the atmosphere and within your body and the cells. So again the actual act of breathing and respiration is that exchange of the oxygen and carbon dioxides between atmosphere blood and cells. All three of those then again occur via that image that you saw on the second slide. That is via the pulmonary ventilation which we call breathing. the external or pulmonary respiration which occurs in the lungs and the blood that's found in the lungs and then outside of the lungs when it's being delivered to the rest of the body is the internal or tissue respiration. So all of those processes are making sure that it's dropping off oxygen, picking up carbon dioxide and getting those gases transported throughout the body. We're going to begin by looking at the anatomy of the respiratory system. So the respiratory system is divided into what's called the upper respiratory tract and the lower respiratory tract. Now this is kind of a odd division because when you hear about people having quote a upper respiratory infection um it can involve the lungs. But the defining structure for the upper respiratory tract before it transitions to the lower respiratory tract is actually right at the point of the larynx. And so it does not involve the lungs anatomically. Then the structural organization um is one way to look at the structures. But we can also talk about the functional organization. The functional organization is talking about how the air is going to be transported through what we call the conducting zones. These are a series of interconnecting um cavities and tubes that are going to transport the air from the nose through the ferinx, larynx, trachea into the bronchi and then all the way to what's called the terminal bronchioles or the respiratory system. Then once it gets to terminal respiratory um bronchioles, it will transition to what's called the respiratory zone. And the respiratory zone is actually where gas exchange can occur. So this includes the microscopic structures of your avoli, the collection of them called the avular sacks um getting the air into them via the avular ducts by way of the respiratory bronchioles. So the respiratory zone is only where gas exchange can occur. Gas exchange cannot occur anywhere else along the conducting zone and we'll talk about why that is coming up. So a picture from your textbook to show you the difference um functionally as well as uh anatomically between your upper and your lower respiratory system. So this black line right here represents the division between your upper and your lower respiratory system anatomically. So right at the transition into the larynx is where it's then defined as being part of the lower respiratory system. Everything above it then is going to be part of the upper respiratory system. So again, that doesn't make sense when people talk about having an upper respiratory infection. It typically still involves the lungs, but here you go. That's just the anatomy of it. And then down below on the right, you can see the physical structures in a real human cadaavver. What it looks like once that rib cage, the anterior thoracic wall has been removed. Um, and so the lungs go all the way up to basically right at your shoulder level and then down to your diaphragm. and they are going to be surrounding the um heart on either side of the medial aspects or lateral aspects surrounding the medial part of the heart. So, we're going to begin working our way through the respiratory system by first looking at the structures that make up the upper respiratory system. beginning with the nose and the nasal cavity, working our way back to the fairings into the larynx um to begin looking at these structures. So, first structure up is going to be the nose. So, the nose, of course, is going to be the external portion that is sticking anterly out of the front part of your face. The nose is a combination of bone, cartilage, and skin. Um, at the very end of the nose, it is cartilage and that cartilage is able to be pliable, but if it ever is damaged to a certain point, it can't necessarily recover that damage. And so sometimes people have this misshapen nose because the cartilage has been damaged. Inside the nose, it's going to be lined with this fluid tissue that we call the mucous membrane. The mucous membrane are going to be found in places where it opens up to the external part. So like your mouth, your nose, the eye, the ear, the anus, um the urethra, and then the female vaginal canal. The mucous membrane is a normal um tissue that's present and that's going to contain all kinds of uh cells to help filter and get rid of anything that doesn't belong. It's also going to um add some moisture into the air that's coming into the nose. So it's a normal thing that is present there. Once you get inside the nose, you enter the nose through what's called the nostrils or the external nars. And the external nars are going to be open to the inferior surface of the nose. And so these two openings get you into the space called the nasal cavity. The nasal cavity then is going to extend posterior until you get to what's called the internal nes. The internal nes are going to be the opening into the structure of the fairings. External nars go into the nose. Internal nars goes from the naval cavity into the fairings. Dividing the nose into the cavities is going to be the nasal septum. And the nasal septum is formed by both cartilage and bone. Anterly it is called the septal nasal cartilage. Posterly it comes from both the ethmoid bone and the vulmer bone that are um smashed or grun together. Now the thing with this is that when you look at the skull anteriorly it looks like it's just the vulmer bone but the ethmoid bone also contributes to the nasal septum. Inside the nasal cavity on the lateral walls are going to be structures that are called the nasal concha. These are also known as the turbinet bones. They look like a conch shell. That's where their name comes from. And they provide additional surface area in the inside cavity of the nose. So their role is to provide more of an area to allow what the functions of the nasal cavity are um to support the body. And so you have a superior, a middle, and an inferior nasal conscha. And then underneath each of them is going to be a space that we call the miatus. So you have a superior miatus, an inferior miatus, and then a middle miatus. And down here in this image, you can see them as as far as how they are positioned when you take a coronal section through the nose in this space to show you that they do indeed provide more surface area for the nasal um space itself. So here is a more magnified picture showing you again those nasal concha. So we have the superior nasal conscha and then underneath it is going to be this space called the superior miatus. Then we have the middle nasal concha here and again underneath it is going to be the space called the middle miatus. And then down here is going to be the inferior nasal conscha. And again the space that's underneath that is called the inferior miatus. So all three of those concha come in from the lateral wall and they provide more surface area than what would be just a flat fall wall for the nasal cavity. Now main function outside of getting air into the body of the nasal cavity is that it's going to be important to have the air that comes into your nasal cavity. It will be warmed because your nose has a lot of blood supply to it. So, that will create heat. The mucous membranes role is to help clean up that air that comes in because even though you can't see it, there's all kinds of dust and microbes and foreign substances that come in on the air that you breathe. It will also add moisture to the air that comes into your nasal cavity. And then air turbulence by the concha allows that air again to be um blown over those three concha to do that function of warming it cleaning it and adding moisture to it. Additionally the nasal cavity is where you're going to find the olfactory nerves which the olfactory nerves play a role for smell. It's also where your speech vibrations will take place which is what gives you some of your um tone of your voice. Because if you were to plug your nose, this is what we would sound like very nasally. So to be able to open it up is one of the main functions as well to give your voice its resonance. Now a couple clinical connections for you. So when we talk about the common cold, there are viruses that fit into the category called a rhino virus. The word or prefix rhino means nose in medical terminology. if you think of like a rhinoceros and then a virus of course is one of the microbes that can cause um an illness. Uh most of the time a common cold comes from uh that rhino virus and because there are so many types of them you will be afflicted with many rhino viruses throughout your life. Sometimes um it is a known rhino virus that can be treated via what's called the seasonal influenza shot. And so that can be something that we can give uh immunizations for to help um treat an individual who might be suffering or who could be at potential um from dying from the common cold and or having a really severe um form of it. Now keep in mind influenza is not the same thing as a stomach flu. Influenza is usually indicative that you have a respiratory situation involved. And so then one of the common effects of a common cold is what's called rhinora. So again, nose is rhino, ria means runny. So this is a runny nose. Runny nose can be caused by a lot of different things including a common cold. Um, but it can be caused by a buildup of mucus such as when you're having an allergic reaction. It can be due to the fact that you are crying because your lacrial glands in your eyes will produce water and that will drain through your nose. It also can cause um be from when you go outside and it's cold because the water condensation causes your celia basically to stiffen up which then is going to create more of a moisture inside the nasal cavity causing that condensation to start to run. Then from the nasal cavity the air is going to pass into what's called the fairings. Um, the fernx is a dual organ, meaning that it's going to be playing a role in both the respiratory system and the digestive system. So, it's a passageway for both food and air. And by the way, in there, food is also implied the fluids. It's also going to be a place where your voice is going to get some of its sound. So, it's a resonating chamber. And then it's going to going to house the tonsils because the tonsils again are collections of lymphatic tissue that surround the openings. So the tonsils do you remember the five of them that were discussed in the lymphatic system. So you have one fingal called the adoid. You have two near the oral fairings. Those are going to be called the palentine. And then you have two on the tongue that are called the lingual. So those collection of five tonsils are going to be surrounding your nasal and your oral cavity. Additionally in this picture down below you can see that we can subdivide the fairings into three sub regions. The nasop ferinx, the oro fairings and langio fernx. The nasop fernx means it's just behind the nose. Oralo fernx means it's behind the oral cavity. And then the langio fernx is where it transitions from the fairings into the larynx. So the larynx is also called the voice box and the larynx is a very short as far as not very tall structure. Um the purpose of the larynx is that it's going to be continuation of the air passageway to either go inferior from the fairings into the lungs or from the lungs up through the fairings and through the mouth or nose. Additionally, it will try to protect the respiratory tract by being a place where anything that doesn't belong there will get caught um hopefully before it gets down to the lungs. The larynx is also used in a maneuver called the valva maneuver. And you use the valva maneuver when you are bearing down for example to um go to the bathroom or defecate. It's also what you do when you are um bearing down to hold your breath. You use the larynx to cut off the air flow. So that way it increases the pressure in your abdominal cavity. But most commonly you know the larynx for its function ofo housing the vocal cords. And the vocal cords are where your voice comes from. So the air goes over the vocal cords, they vibrate and then that's going to be producing your speech sounds. So in the anatomy of the uh larynx, you can see that there's quite a few delicate structures in this area. The larynx is going to be positioned right above your thyroid gland. So this kind of reddish looking structures, the thyroid gland and it's going to be held open by a series of cartilage. The main cartilage you will have to know is the thyroid cartilage. Um, and that's going to contain the prominence that we also call the Adam's apple. Um, and so sometimes that's called the larynal prominence. Additionally, you're going to have the uh cartilage over here called the epiglatus. This is going to be kind of a leaf structure that can move. It will cover the larynx when you swallow to ensure food will go posterior into your esophagus. And then there's various ligaments and membranes that also are found in this area um to help keep the thyroid or the thyroid to help keep the larynx space nice and open. So just to identify a couple things of the sagittal view here again this is the epiglatus the leafike structure that can move and then we have the thyroid cartilage. So the big piece of cartilage above the thyroid gland that keeps your larynx open. And right here would be that Adam's apple or the um laryngal prominence, the vocal folds and the vestibular folds right through here. This is where your voice sounds going to come from. So there are two basic um small little ligaments that are going to be attached through cartilage here that as air goes through them, it vibrates causing your voice to sound the way that it does. We'll talk more about that shortly. So again, the important structures to know in the larynx are going to be the thyroid cartilage, which is going to be producing that Adam's apple. It's the largest projection. You can feel this in your neck if you feel around for your Adam's apple. And then we have the cartilage called the epiglatus. This again is leaflike shaped. And so it it will um move about and it will close off the larynx when you swallow to ensure food will go down to your esophagus. Then we when we actually look at the structure of the voice box, there's going to be a couple ligaments involved. So the two divisions of the ligaments are what's called the vocal ligaments and the vestibular ligaments. The vocal ligaments are also called the true vocal cords. Sometimes we also call them the vocal folds. This is where your voice is actually going to be produced from is these ones and these ones are inferior. Whereas your vestibular ligaments, these are going to be found above the vocal folds. And these are sometimes called vestibular folds, also called false vocal folds, because they do nothing for voice. They simply are there for protecting your inferior true vocal cords. So the opening between your vestibular ligaments in particular is called the remma vestibuli. And so that's allows space and air to pass through your vestibular ligaments that again are found above your vocal ligaments. So a frontal section to show you this is the trachea and here's your thyroid gland. Right here we can see the various folds. So remember that superiorly it is the vestibular folds. Inferiorly this is going to be the vocal folds. The vocal folds then is where your voice is going to come from. The vestibular folds is going to be protection of your vocal folds. And then in between your vestibular folds is going to be the rema. And here's another image showing you um the movement of the vocal folds. Um, and that way you can also see from a superior view down. And so right here are your vocal ligaments. And as they abduct, which means they are spread apart, air flows through and vibrates those vocal ligaments. Your vestibular folds will also move, but they are found again superior to your vocal folds. And then when they come together, your two vocal folds will meet in the middle as well as your vestibular folds on top of them will be coming towards the medial aspect in order to protect your inferior vocal cords. A clinical connection for you then is laryngitis. So itis means inflammation and this particularly is inflammation of the larynx. When it comes to this, uh, typically it means that you have a respiratory infection or irritance that caused the larynx to swell. And so sometimes people will have a horse voice. Um, maybe there'll be a fever, maybe be a sore throat that accompanies it. Laryngitis can be caused by bacteria or viruses. It can also be caused by overuse. So if you're at a concert or a sporting event and you yell excessively that can cause laryngitis. In some very severe cases it can extend to the epiglatus which means you to have trouble breathing and that's really of concern especially in young children. Uh because if it's so swollen you're not going to get air flow. Connected to the larynx is going to be the trachea. The trachea, you also have heard it being called the wimp pipe. It is p positioned anterior to the esophagus, meaning it is found in front of the esophagus, which is part of your digestive system. What helps hold the trachea open are tracheal cartilagages. So, C-shaped rings, which means on the posterior aspect of the C-shaped rings, there is no um cartilage. It is going to be replaced by muscle. And then the C-shaped rings are going to be connected to each other by membranes called an annular ligaments. So that's what's going to help keep all the C-shaped structures anchored together. The purpose of the cartilage is that it's going to make sure that your trachea is open at all times. And that is incredibly important to make sure that air flow is constant. If you've heard of someone being intubated, intubated means that a tube is being inserted into the mouth or sometimes the nose and it passes through the fairings into the larynx into the trachea. Um the purpose of that tube is that it pushes aside any flexible obstruction and also provides for a passageway of air from the external to the internal because if you are under anesthesia, you will need that external air to move in and out to keep you alive. So, just to show you what the trachea will look like here, you can see the C-shaped ring. So, C-shaped cartilagynous ring and then we have the muscle right here called the trachealis. On either side is going to be the thyroid gland. And then posterior is that esophagus. The C-shaped cartilagynous rings ensures that the trachea stays open at all times. Then, if we look at the inside of the trachea, this is what it looks like. Now again, somebody's colored this nice tissue the way that it is, but it commonly reminds me of shag carpet. Um, and that shag carpet is called psyia. It which is going to be a mechanism to move mucus from inside the lungs to the outside when you need to cough it up or vice versa. Then the trachea is going to divide into the beginning of what we call the bronchial tree. Um the bronchi are going to be the first division of the trachea after it has bifurcated. Um also known as splitting. Right at that bifurcation though is an important structure called the corina. And the corina is where there's lots of tiny little neurons that are going to be sensitive to any sort of um substance that doesn't belong or any sort of cough reflex. that is elicited elicited here at the corina. So now we're going to go from the trachea and work our way through the main structures of the bronchi up until the bronchioles to where the conducting portion ends at the terminal bronchioles. Remember conducting means it's conducted through tubes of um structures and so we have to get to the respiratory portion yet. So here's a picture of your lungs showing you where we're headed. We have the trachea and the single trachea held open by those C-shaped cartilagynous rings. Divides right here to form the corina. And then we have the two main bronchi. Left main bronchus, right main bronchus. Sometimes the word primary is also used. Then from there it will go into your lowbar. Lowbar has to deal with how many loes your lungs have. You have three on the right and two on the left. I have more information coming up about those. And then from there it will turn into what's called segmental bronchi. Now beyond the scope of this class it will continue to branch and branch and branch and branch about 23 generations worth of branching. So you don't need to know that for the purposes of our class but you need to know that there's quite a bit of branching. It ultimately gets to these microscopic structures called bronchioles. And bronchioles um are called uh or can will transition into the terminal bronchioles which means that is the end of the conducting portion and will now transition to the respiratory where the gas exchange can occur. The bronchial tree then is this inverted tree that as it passes through the lungs, the bronchioles and bronchi themselves, the structures become smaller as they are conducting the air deeper into the microscopic parts of your lungs. Again, where it bifurcates, which means it divides, it divides into what are called the main bronchi or primary bronchi. These are going to enter the lungs on the medial aspect. Now the right broncus we know is going to be shorter, wider and more vertically oriented. So this means the left one is just the opposite. The left one left one is longer, narrower and more horizontal. So the reason that is the case is because of the presence of the heart because the heart projects slightly to the left which causes the bronchus on the left side to have to go a little bit further to get to the lungs than on the right side as well as making that um bronchi much more horizontally oriented. So each of your main bronchi then will branch into what are called lowbar bronchi. We also call those secondary bronchi. They extend into the lobes of the lungs. So you have three loes on the right, two loes on the left and then from there the lobar bronchi or secondary bronchi will divide even further into what are called segmental bronchi or tertiary bronchi. Now again for our purposes that's where we're going to end with the name of the bronchi because the tree continues to divide roughly about 23 more times um until it gets to your terminal bronchioles. So your terminal bronchioles is the last place where air is going to be conducted via what's called the conduction zone. And now it's going to turn into your respiratory bronchioles which can begin the process of the gas exchange. Gas exchange doesn't actually occur here but this is a place where the walls are thin enough where it can start the process of preparing to do that gas exchange. So again trachea main bronchi also called primary bronchi lowar bronchi also called secondary bronchi segmental bronchi also called tertiary bronchi into bronchioles then to the terminal bronchioles and at the terminal bronchioles that's where the conducting zone ends and it transitions into the respiratory zone. The main bronchi right after it divides from the trachea is going to be supported by mainly cartilage. There's not much muscle involved um at this point in the respiratory system because there's more cartilage. But as it continues to branch for those 23 branching generations, what eventually happens is that your bronchioles lose the cartilage and gain smooth muscle. And that plays a role in causing the bronchial tree to either do what's called bronco constrict or bronco dilate. Bronco constrict means your bronchioles are going to narrow. Bronco dilate means that your bronchioles are going to increase in size. And so that is controlled by the muscle which is why it's important to know the transition that goes from mainly cartilage in the beginning of the branching to hardly any cartilage to no cartilage at the end to then be mainly replaced by smooth muscle. So here's to show you goes from those C-shaped cartilagynous rings to where it divides into your bronchus. Um and then from there to your low bar bronchi segmental into your smaller bronchioles and you can see right here is the transition from having some cartilage to no cartilage and then after that now the walls are thin enough because they don't have cartilage present. So roughly 23 generations to get to the avioli. When it comes to your bronchioles, if they vaso vaso, if they bronco constrict, the lumen space narrows. And so sometimes people with asthma feel like they can't get air in and out because of the fact that these this has constricted. Whereas bronco dilate means that the bronchus has gotten bigger, more air being able to be exchanging at that point. So the conducting zone is going to end at the terminal bronchioles which then is going to begin the respiratory zone. The respiratory zone is going to be the place where air can exchange can occur. It doesn't actually happen right there at the respiratory bronchioles but it's where the walls are thin enough with this process can start preparing. It then ends at structures called the avoli. Avoli are similar to grapes. Each avioli is a single basically out pouching and when you group them together they form a collection of grapes that we call the aviolar sacks. And then leading into each aviolar sack is going to be an aviolar duct that's transitioning from the wall transition of the respiratory bronchioles into the avular ducts to be super thin. So again how this works is the respiratory bronchioles will subdivide into your avular ducts. Avolular ducts lead to that collection of um grapes called the avolar sacks and then each individual grape is called the avoli. So if I have a circle here those are my individual avioli. Sorry that's a really crappy circle. And then your collection of them are known as the aviolar sacs and they are going to be delivered air to them via the aviolar ducts and then those are going to be connected to the respiratory bronchioles. So avoli is the actual place where gas exchange can occur even though the walls have been thinning up to this point. So gas exchange can't occur at the avular ducts to the respiratory bronchioles. It can only occur at the avioli because the walls are designed for this gas exchange to occur. So here's a picture from your textbook showing you those structures. So it goes from your respiratory bronchiole right here to your grape stems called the aviolar ducts into that collection of grapes that we call the aviolar sack. And then each one of the grape clusters themselves are called the avoli. In these two images that come from your textbook, we can also see the real life as to what the structures look like at this point. So we see the terminal bronchial which is the last part of the conduction system. That will then transition to the respiratory bronchial. Notice that the wall thickness has dramatically decreased from terminal bronchial to respiratory bronchial. Then from there the respiratory bronchial is going to divide into two aviolar or into aviolar ducts. And then each one of the circles that are found here are known as your avoli. And when they group together, they form the avular sacks. And then over here is a image that's been colored to show you the lung tissue, which is being junip. It in real life it's kind of pinkish purple, but not as purple as what you see here. But you can see in the size comparison between the structure of the avolus versus the bronchial as well as then your blood vessels. So aviola structures are microscopic to do that gas exchange. So a little bit more about the avioli themselves. Each of the avoli in your lung you contain about 3 to 400 million. And the purpose of the avioli is that it provides much more super uh much more surface area for gas exchange to occur because gas exchange actually happens here. Each one of your avoli so every single one of those 3 to 400 million avoli are surrounded by pulmonary capillaries in order to support that exchange of oxygen and carbon dioxide. So what makes up the aviolar walls themselves are actually three types of cells. We have what's called the type one aviolar cells. These are going to form the surface area of 95% of the whole avoli and it'll also be producing some mucous cells to keep the environment in this area um much more full of fluid or moisture. Then the type two cells are a small portion of them. Type two aviolar cells secrete a really important substance called pulmonary surfactant. And pulmonary surfactant is this atapost lipid substance. And its role inside the avoli is to oppose any sort of force that's put on the avoli. That is a normal force mind you to try to cause the avoli to collapse. And so your pulmonary surfactant helps to keep your avoli open for that gas exchange. And then the final cell that's found in this area are the avular macrofasages. These are also known as dust cells. So these are a form of a white blood cell that's found to be able to remove any fine dust particles or other debris. They are the vacuum cleaner of the lungs. So they can be either anchored in the avoli or they can move if necessary. So again let's identify those three cells of the avoli. So most of the aviolar wall is made up of the type one avular cell found here in the purple. So that's most of the wall. Then we have the type two avular cell that's producing that pulmonary surfactant. And then here we have the avular macrofase. So all three of them come together to form the structure of the avoli. Um and then the avoli is incredibly thin. You can see in the top right here image of showing you the thinness of the wall. But there you can see the avular macrofase. You can see a type one aviolar cell and type two and what it would look like in real life. So at the structure of the avoli and capillary, this forms what's called the respiratory membrane. And the respiratory membrane is incredibly thin. And it has to be incredibly thin in order for oxygen and carbon dioxide exchange to occur. There's actually four layers to the respiratory membrane. The first layer is those type 1 and type two avolar cells coming from the avoli. Then this is going to then there's going to be an epithelial basement membrane deep to that. Then deep to that is going to be the capillary basement membrane and then outside of that is going to be the capillary endothelium. So although these four layers seem like when you group them together they'd be super thick, they are incredibly thin which supports the function of the oxygen carbon dioxide purpose of your lungs. So let's again identify those four structures. So we have the layer of the type one and the type two avular cell. You can see that there in the purple. And then from there we have the epithelial basement membrane. So right behind it here. Then we have the capillary um basement membrane shown here in the red. And then we had the capillary endothelium. So that is the thinnest part of the lungs to allow for that oxygen and carbon dioxide exchange. How the oxygen and carbon dioxide exchange occurs is that the oxygen is going to diffuse from the avoli into your lung from your avi and your lungs into the capillaries. And so this is going to be um when your blood is going to be picking up oxygen and diffusing means it moves from high to low movement. And then carbon dioxide is going to diffuse from the blood to the avoli which is then going to allow it to be expired to the external environment. And again diffusion means it moves from high to low. So you have more carbon dioxide in your blood than you do oxygen which is why it's going to move. And also because you have less oxygen in your or blood you have less carbon dioxide in your avioli than you do in your blood. So that's why it diffuses. So here you can see the arrow diffusion of oxygen going into the bloodstream. Diffusion of carbon dioxide coming out of the bloodstream. Now let's get to the final structure of the respiratory system um anatomy by talking about the lungs. So the lungs are the very big structures of the respiratory system. They are going to be found in the thoracic cavity above the diaphragm and a person who studies and treats the lungs are called the pulmonologist. Um they are typically compared to shaping like a pyramid or a cone while they are found within your thoracic cavity. Each of the lungs is enclosed and protected by a double- layered cirrus membrane that we call the plural membrane. And we talked about this way back in the beginning of AMP1. So just a refresher for you, if it's outside the lungs lining the thoracic cavity, we call it the parietal plura. If it's directly on the lungs itself, we call the visceral plura. And then the small little space in between the parietal and visceral is called the plural cavity. And that's where we find just a small amount of fluid to allow for the um friction less movement of your lungs when it expands and when it relaxes in conjunction with your ribs. So here's the lung. Directly on the lung itself then is going to be the visceral plura. Remember visceral viscra means organ. So it's directly on the organ itself. Then lining the outside of the thoracic cavity. So if you were to remove the lungs, you would see this thin saran wrap tissue. That's going to be the parietal plura. And then in between is going to be the space cut we call the plural cavity where you can find just a small amount of plural fluid. Because the lungs are often times compared to being shaped like a pyramid or a cone, they have a wider base and nar narrower apex. The base is what's sitting right on top of the diaphragm and the apex goes all the way up to your shoulder. So it's a fairly decent sized structure. On the lungs there are three main surfaces. We have the costal surface. Costal means ribs in medical terminology. So those are going to be the surface of the lungs in contact with the ribs. Medialininal means it's next to the space called the mediainum. The space in the mediainum is going to be everything of the thoracic cavity except for the lungs. And the diaphragmatic um surface is the same thing as the base. So they are one and the same. It just depends upon how you refer to them. It's what's going to be in contact with the diaphragm. On each of the lungs, there is the structure called the hilum. And the hilum is a fancy name in medical terminology for where structures enter and exit. Because in the lungs, they don't enter and exit all over the place. They only enter and exit right here in what's called the hilum. Things that are entering and exiting the lungs right here would be things like the bronchi, the pulmonary vessels, which would be your pulmonary artery, pulmonary vein, nerves, and lymphatic structures. Collectively, we also call this the root of the lung because that's where those structures originate as they pass through um the um hilum of the lung. So here we can see the apex of the lung and then the base of the lung. And then because we're looking at the costal surface, that's what we can see hanging out here. If we could see the inside of the lungs, we would identify them as being the medial spinal surface. And then the diaphragmatic surface is the same thing as the base because it's what'sever sitting on the diaphragm. Then on the medial aspect, we have the medial surface because it's facing the mediainum. But we also can see the hilum. And remember the hilum is the structure where um space structures enter and exit. And so the hilum is this space of the lungs and it's showing the pulmonary artery and pulmonary vein. Pulmonary artery is going to be the blue because that's taking deoxxygenated blood from your heart to your lungs. The pulmonary vein is going to be red because this is going to be bringing blood back from your lungs um to your heart to go with the circulation of the cardiovascular system. Couple other things about the lungs is that the right lung overall is about 10% bigger and wider than the left lung. And that is because the heart projects slightly to the left. So it makes your left lung about 10 to 15% less in size than your right one. Additionally, the right lung is subdivided into fissures. There are two fissures, which means there are three loes. You have the horizontal fissure and then the oblique fissure. So horizontal means it's at a hor horizontal position. Oblique means it's going to be at an angle. So this divides your right lung into three loes. Superior, middle, and inferior, which then correspond with those three loes of the bronchial tree. Then the left lung is going to be the smaller and narrower because of the heart's position. It only has one fissure called the oblique fissure. So both lungs have the oblique fissure but the left lung is only going to have a superior and inferior lobe whereas the right lung had all three and then the left lung has a unique structure that the right one doesn't have called the cardiac notch. Cardia of course means heart. This is where the heart is projecting to the left. Now the heart or heart to lung communication itself is really laden with blood. So there's lots of blood going from your heart to your lungs at any given time. What's taking blood into your lungs is called the pulmonary arteries. Arteries take blood away from the heart. And then there's also going to be bronchial arteries because these are going to be bringing blood from your systemic circulation versus your pulmonary. Pulmonary of course means lungs. So this means those structures are coming into the lungs and then the bronchioles are coming from the systemic circulation. Blood is then going to exit the lungs. You have four pulmonary veins. So two from the right side, two from the left side and then they will empty into the left side of the heart um from the lungs carrying oxygenated blood. Bronchial veins are al also going to be transporting blood from the bronchial space to hopefully unite to empty into your pulmonary vein space. So in general when we look at um the lungs there is four main parts to it. Uh the first one is called pulmonary ventilation. This is also known as breathing. So this is what you're doing when you are exchanging gases between your the atmosphere which is outside of your body and the avoli of your lungs. And they can do this because of the differences in pressure that are created by your respiratory muscles causing that movement. And then the second thing is once that gases um or those gases get into your lungs, then you're going to have what's called aviolar gas exchange. So this is where your avoli and your lungs are going to be utilized to do the exchange of oxygen and carbon dioxide from your lungs into the pulmonary capillaries. So if we're going from the outside in, your pulmonary capillaries are gaining oxygen and losing carbon dioxide. Then step number three is that there's going to be transportation in the bloodstream where your blood is going to be moving oxygenated blood to your cells called the systemic cells. So your cells of your body known as your system. And then once they get to those cells that it needs to give the gases to, this is known as systemic gas exchange, also known as internal respiration. So this is when your blood is going to drop off oxygen and gain carbon dioxide. So this is that process of going into the lungs and then it's just a reverse of it going out. So then from the systemic cells the blood carrying the carbon dioxide will move into the lungs and then be transported or transported it will be exchanged in the lungs to allow the carbon dioxide then to be um ventilated out. So, if you're having any trouble understanding all of the processes that occur here, this is a really good slide to get to know because the air comes in for pulmonary ventilation. It then gets into the avioli where oxygen gets in the blood and then the oxygenated blood is going to be transported to the cells that need it inside the body. Then oxygen will be dropped off. Carbon dioxide will be picked up and then it will be transported back to the heart to the lungs. And then from the lungs, it's going to breathe out the carbon dioxide. So it goes in and out. So a little bit more specific things about these processes. So again, respiration is also known as pulmonary ventilation, which is the same thing as breathing. There's two main cyclic phases. You have inhalation and exhalation. Um, inhalation is also known as inspiration. And this is how air is getting into the lungs. And then expiration is you breathing air out of the lungs, also known as exhalation. There's two main types of breathing that help support this. One is called quiet breathing and one is going to be called forced breathing. Quiet breathing is your everyday normal breath. And so this is what's occurring when you are probably watching this lecture or when you are sitting at home or when you're just hanging out with people. Um that is your quiet breathing. Forced breathing is when you are doing some sort of vigorous activity such as exercising, perhaps singing, perhaps coughing, yelling, something that's going to require additional above and beyond normal breath. That is what forced breathing is referring to. So in order to do that inspiration and expiration, it is a very simple process of how air moves. But it's kind of hard to imagine because this is something that you cannot see. The reason that you can move is that there's a change in air pressure. What happens is that the air pressure outside of your lungs is greater than inside of your lungs and so therefore air moves in. This is then inspiration also known as again inhalation because air pressure outside of your body is higher. So it is a high to low movement from outside in. Now the reason then that you exhale or expiration is that the air pressure inside your lungs now becomes greater than the air pressure outside. So that's going to be your expiration. And again it is going to be a high to low movement of going inside or coming from inside the body to outside. So it goes this direction and then this direction. That's all that it is. But because we don't have a way to necessarily visualize it, to see it in action, to have a pressure gauge, it can be hard to to understand that that's as simple as it gets. Um, but that's honestly why you can breathe is just because of the pressure differential. Now, what helps with the pressure differential is actually your muscles. So, it's not the lungs, it is the muscles. And that is a huge misconception. Your muscles are what's creating the differences in pressure inside your thoracic cavity. On a previous slide, there was a difference between quiet breathing and forced breathing. So quiet breathing is what you are doing when you are just normally breathing when you're relaxed at rest. The main main muscle involved in breathing is the diaphragm. I can't even explain to you how crucial the diaphragm is for the part of your body for breathing. So the diaphragm is what's going to basically cause the differences in your um processes of inhalation expiration. The diaphragm then will move up and down to cause the change of the volume of your lungs as well. For quiet breathing, the inhalation process is active, meaning that it requires energy. So anytime you see the word active, it means that there's energy. But your exhalation process is going to be passive. So you expiring air does not require any energy but you bringing air in does require energy for forced inspiration. So this is the additional air that you're bringing in like if you were exercising, if you're singing, if you're playing an instrument, if you're yelling, you will bring in additional air. And so you need additional muscles to help with that. So you have your sternoclamastoid, which is a muscle of your neck. your scalings also muscles of your neck and then pectoralis minor which is a muscle of your chest. So this is going to help increase that size of your thoracic cavity. Now again as previously mentioned inhalation is active and because this is still inspiration this recruitment of additional muscles also means this process is active that you have to have additional energy to recruit those muscles to get that larger space. And then exhalation we have forced expiration. So this is going to be the process by which one is perhaps controlling their breath again during like playing an instrument um playing or singing a song that's going to be expiration um as well as like coughing or exercising. There are muscles that helps with the expiration process. So the internal intercostals the muscles in between the ribs and then the abdominal muscles which if you play an instrument or you sing you know that controlling your abdominal muscles is what's going to be important for controlling the movement. So even though in your exhalation process of quiet breathing it is passive because you have recruited additional muscles down here. Muscles of force expiration would be active. So again that requires additional energy to get those muscles utilized. So this image is to show you the function of the diaphragm because the diaphragm again is the main driving force of causing those pressure changes. So the pressure changes in the lungs have to do with that diaphragm moving up and down which then causes volume changes. And the most important muscle of course is going to be the diaphragm. What happens is that during inhalation, so when you're bringing air into the lungs, the diaphragm goes down which makes the lung space larger. Whereas when you are expiration or exhalation, your diaphragm goes up because it's going to reduce the space of your lungs. And by reducing the space that affects the volume and the pressure inside your lungs which is ultimately what drives the air in and out. So again inhalation the diaphragm goes down expiration the diaphragm goes up. So the muscles again that are involved in this process of breathing we have the sternoclyam mastoid scalines um external intercostals that's going to be for when you are doing forced inspiration you recruit the top two muscles to help out with that. Whereas just when you're doing your everyday normal breathing it's your external intercostals and diaphragm with your diaphragm being the key one. And remember the everyday normal breathing inhalation is active, expiration is passive. Then when you are having forced expiration, you are recruiting your abdominal muscles which are all of these and then your internal intercostals to help with that control which then is going to be more active to be able to recruit those muscles. So um just quickly a couple medical terminology words for you. Upinia means normal breathing. Apnea means temporary sensation of breathing. You've heard apnea being used in like sleep apnea where someone temporarily stops breathing when they're sleeping. Dispia is painful breathing. Attachnneia is fast breathing. Um when someone is breathing shallowly just using their um ribs. It's known as costal breathing. So costal means rib. When someone's doing deep breathing, they are doing diaphragmatic breathing. So using their diaphragm. And depending upon the disease state as well as what the person is doing for exercise, you can alter between costal breathing, diaphragmatic breathing or a combination of both. So respiratory center is going to be found in the brain. Now the size of the thorax is altered by the action of your breathing muscles which contract due to nerve impulses that come from the brain and these nerve impulses are going to be sent from clusters of neurons that are found in the brain stem. This is known as a respiratory center and there are two main groupings of them. There's the medillary respiratory center. This is made up by two collections of neurons that are called the dorsal respiratory group and the vententral respiratory group. The dorsal respiratory group is commonly known as your inspiration area. What happens here is that the neurons of your dorsal respiratory group generate impulses to the diaphragm. That's going to cause the diaphragm to um go down in order for your body to bring air in. Then your vententral respiratory group is going to alter your rhythm of your breathing. So it's not necessarily having to do with your expiratory process. It just has to do with the ability to control and alter your basic rhythm of breathing. That's your vententral respiratory group. And then the pontene respiratory group. This is also known as your pneumotaxic area. These neurons are active in your inhalation and exhalation. And again, similar to your vententral respiratory group, they're trying to modify your basic rhythm in conjunction with your vententral respiratory group during things like exercising, speaking, or sleeping. So, they work together to help alter your breathing. So control of breathing can come from cortical influences which means your conscious control. You can consciously alter your respiration rate to a certain extent. So if you refuse to breathe for a little bit of time, if you hold your breath, um if you are underwater, you are controlling your breathing, but you can only do it to a certain extent because otherwise your body will kick in with your normal breathing um once your carbon dioxide levels and hydrogen levels get to a certain level. This is because you have what are called chemoceptors. Cheo receptors are receptors that are detecting the chemicals and in particular they are very very very sensitive to changes of carbon dioxide. You have central ones which are located near the medulla oblangata near that central nervous system and then you have peripheral ones that are going to be found in your aorta in your kurateeds in order to again detect the level of chemicals. Yes, oxygen you would think would be the more important, but it's actually carbon dioxide that's going to cause the most issues once it gets out of balance. So, it's much more sensitive to carbon dioxide than oxygen. So, chemo receptors are monitoring those levels of oxygen and carbon dioxide. Again, central ones are located near the medulla oblangata, so up here. And then peripheral runs are in your corroted bodies and your aortic bodies. They're monitoring the chemical levels of carbon dioxide, hydrogen, and oxygen. But hands down the one again that they're most concerned with is carbon dioxide because carbon dioxide swings are very detrimental to the body as compared to oxygen. So a couple terminologies that can be applied here due to those changes is hypercapnea. Hypnapnea means that you have an increase excuse me of your carbon dioxide levels which then due to that reaction of carbon dioxide transportation means you also have an increase in hydrogen ions. This really will cause a a huge alarm to go off during the central chemo receptors um because this is going to alter your breathing. Hypocapnea means that you have a lower amount of carbon dioxide which means you have a lower amount of hydrogen ions present. So again this is going to stimulate those central chemo receptors to um alter your breathing due to the changes of the lower carbon dioxide. Hypoxia means that you have low presence of oxygen at the tissue level. And although although this is very not good for your body, the more important factor is going to be of your carbon dioxide level as opposed to your oxygen levels because your oxygen levels can survive down to a fairly low level before the body gets really worried about oxygen at that