Transcript for:
Understanding Respiratory System Anatomy

Welcome to chapter 21 of Anatomy and Physiology and with this chapter yet again we're just going on to another organ system and with this chapter we're now in the respiratory system and like always before we even get started you know at least one thing from this system way back from AMP1 in chapter 1 where you saw all the organ systems and this is respiratory system it kind of tells you in the name it's helping with respiration which is breathing and And most people know at least one of the organs that help you to breathe. Most people could name at least the lungs, which are part of this system. But like usual, this is an organ system, meaning that it's made up of multiple organs working together. So yes, we're going to see the lungs, but we're going to see a couple other organs. And it's a lot of organs. So like always, we're going to have to classify things. We're going to have to break things up. Well, And when we look at the organs of the respiratory system, we break them up into what we call the upper respiratory tract. Think upper, think higher up, think more superior in the body. Think nose and throat. In anatomy, we call the throat the pharynx. So they're higher up, the nose and your pharynx. So they're the upper respiratory tract. While the lower respiratory tract, again, is telling you the name, it's more inferior in the body, lower down. But still in your upper body, just below or lower or inferior to the upper respiratory tract. And lower down in the lower respiratory tract, we'll see a couple more organs. There are really a lot of tubes helping to connect the air outside of your body to your lungs. So we name parts of this tube. You'll see pictures in a moment. It's the larynx, the trachea, what we call bronchi and bronchios. There are... This part of this tubing network sending air to and from the lungs. So these are the organs of the respiratory system. And like always, we're going to be breaking down the anatomy. So we'll look at all these organs and talk about physiology. And it's really, how are they helping you to breathe? How are they helping you to exchange gases? So on this slide here, we see the basic anatomy of your upper respiratory tract. Remember your upper respiratory tract is your nose and structures associated with the nose as well as the pharynx and structures associated with the pharynx. So when we look at this image, well yes, you're going to see the nose or the nasal cavity more superiorly. And in the nasal cavity, there are things to see in and around it. For example, how do you even get the air into your body? Well, you're going to get it in through the openings of the nasal cavity. you call it your nostrils. In anatomy, you could call it the nostrils or the external nares. And when you look inside the nasal cavity, you see that there's these little curved projections. You actually saw that way back in A&P 1 when you looked at bone. Remember when you looked inside the nasal cavity of the skull, you saw these curved in portions of bone. Remember they were called your concha. Remember you have a superior. inferior and the middle nasal concha. And they're all just curved in bits of bone. Oh, but why? You may or may not have been told what they were doing. Turns out those nasal concha, the superior, middle, and inferior nasal concha, were there to temporarily hold some air to help warm it and humidify it, to help make the air a little bit warmer and to add a little moisture to it so that it's easier on your lungs. That's why you have those curved in bits of bone. We call them the concha. They're in your nasal cavity. So they're also technically a part of the upper respiratory system. There are structures in this nasal cavity. What else? Well, what else can your nose do? Well, your nose can help you to smell. And it turns out the major reason why you're able to smell is because of the cells inside of your nasal cavity. They're forming what we call your nasal epithelium. And if you were to look at this collection of cells, this nasal epithelium, We notice some of these cells are neurons. They're receptors. They're what we call chemoreceptors, helping to sense the chemicals that you call odors. That's why you get smell. It's really because of the cells in your nasal cavity. And they're sending that information on up to the brain. So there's lots of structures in the nose. Again, you still might know some of these structures. For example, there's a structure between the left and right nostril. have a little wall of tissues, really some soft tissue because it's cartilage, more anteriorly. It's what we call your nasal septum. Your nasal septum is that small little wall you feel between your left and right nostrils, between their little cavities. That's just some, again, some cartilage and epithelial tissues. So that's really nose and some structures associated with the nose. And then you remember the other organ in the... upper respiratory tract is what we call your pharynx. Remember that's your throat. Yes when you open your mouth and you say ah and you look in the mirror and you see the back of your throat. Yes that's throat. That's pharynx. But that's only a part of it. Your throat is really a longer area than just immediately behind your tongue. And you can see it on this slide. Turns out we break up the pharynx into three parts. From top to bottom. From superior to inferior. The most superior part of your pharynx is what we call the nasal pharynx. The middle part is what we call the oral pharynx. And the inferior part is what we call the laryngopharynx. All three of those sections together represent your throat. They represent the pharynx. And like always, their names give you a hint as to where to find them. The nasopharynx is called nasal because it's posterior to the nasal cavity. So it's right behind the nose, so to speak. The oropharynx tells you it's right behind or posterior to the oral cavity. And the laryngopharynx is posterior to one of your lower respiratory tract structures called the larynx. So when you... open your mouth and you say ah and you see your throat behind your tongue you're really only seeing the oropharynx. Your throat goes a little bit higher up as the nasal pharynx and lower down as the laryngopharynx and those are structures of the upper respiratory tract but again lots of organs here don't forget the organs of the lower respiratory tract starting off with the organ we call the larynx. You can always identify your larynx because of what's there. It's usually called your voice box because that's where you make the sounds of your voice. Why? Because that's where your vocal cords are. So you can always tell where your larynx is based off the vocal cords. But you can't see the vocal cords from outside the body, so what's another way to tell? How can I tell on my neck where my larynx might be? Well, there's another way to tell. Turns out... There's a big shield of cartilage. That's what you're looking at in this picture. Your larynx has a big shield of cartilage. That's all that hyaline cartilage you see in blue in the cartoons. This big shield-like structure, we call that the thyroid cartilage because the thyroid gland kind of sits over it, more superficial to it. But you might know it by another name. It's also called your Adam's apple. So whenever you look at someone's neck and in the anterior portion of their neck, and you see a little bulge in the throat, you're really looking at this big bulge of thyroid cartilage and we call it the Adam's apple. And wherever that Adam's apple is, wherever that thyroid cartilage is, well, you're at the area of the larynx. And everyone has this thyroid cartilage shield. Everyone has this technically Adam's apple, but it's just that it's a lot larger and more prominent in males typically than it is in males. But technically, Everyone has this thyroid cartilage. So technically everyone does have an Adam's apple. It's just that it's bigger and more prominent in males and smaller and less obvious in females. So that's what we're also gonna see, at least in the larynx portion. And there's one more thing in the larynx. You see it towards the top, this little flap-like bit of cartilage called the epiglottis. Oh, you might remember epiglottis way back from when we did tissues. Way back from when we looked at cartilage, in this case, elastic cartilage. Remember, elastic cartilage had elastic fibers that allowed that type of tissue to kind of bounce back, snap back, to recoil once it's been bent or stretched. Well, this is going to help the epiglottis because it's made up of elastic cartilage. The function of the epiglottis is to fold down and cover the airway whenever you... Whenever you swallow, whenever you drink liquids or eat food, you want to make sure you send food down into the esophagus and stomach and not down into the larynx, trachea and your lungs. So to help prevent that, well, when you swallow, the epiglottis folds down and covers the windpipe so you don't send food and liquid there. And then when you're done swallowing, you got to go back to breathing. So it needs to flap back. It needs to snap back. It needs to recoil. to help you to go back to breathing. And it could do that because it has the tissue that could do it. Remember, everything in your body has a certain function or role to play. So your epiglottis is also in the area we call the larynx. And like usual, epiglottis isn't perfect. How do you know? We've all almost died once by taking a sip of water. Sometimes things get past the epiglottis, but for the most part, it does a really good job. But again, more organs to look at. So here's another image. Again, we see at the top of the image, we see that big shield of thyroid cartilage. We see that Adam's apple. So that's the area of the larynx. Then after the larynx, you see this little tube that looks like it has these alternating white and blue stripes. That's representing hyaline cartilage again. This little hyaline cartilage tube, this tube with blue and white stripes on the image, that's your trachea. Your trachea. Just this long little cartilaginous tube helping again to get gases to and from the lungs as its chief function. And then again, I told you this is all a system of tubes to get air in and out of the lungs. We're just basically practically naming the different parts to the tube. So after the trachea, you notice it's going to split. And when it splits, it breaks up into a right branch and into a left branch. We call those your primary bronchi, plural, bronchus, singular. So going towards the right lung is your right primary bronchus. and going to the left lung is your left primary bronchus. Again, keep following the tube. Let's follow the left primary bronchus. If you follow that one, you see that it will also split into several branches. The next set of branches to come after the primary bronchi are going to be the secondary bronchi. And if you follow a secondary bronchus, it will also split. The branches of a secondary bronchus are what we call the Tertiary bronchi. Keep going you can see it's continuing to split. If you follow what tertiary bronch is, it will split into tiny branches we call bronchioles. And that's all you see on this picture. You see the larynx up top going down into the trachea. Then the trachea will split into left and right primary bronchi. Primary bronchi will split into secondary bronchi. Secondary bronchi split into tertiary bronchi. Tertiary bronchi split into bronchioles and the branching actually continues. But afterwards it'll become microscopic. This page is showing us more of the macroscopic anatomy, things we could see with our eyes. So those are the tubes and again I told you they're sending the air all the way into the lungs, which is what you see in this image here. The big pink fluffy organs you see on the right and left are the lungs. And before we go on, While we're looking at the lungs, you might notice something kind of off about them. I'll talk about it in a couple slides, but since we're here, let's point it out. You notice the right lung is a lot bigger than the left lung. Why? Let me give you a hint. What's something that sits closer to the left side of the chest and not the right? It's your heart. Your heart takes up room in your thoracic cavity. So your lungs on the left side don't expand or develop to as big a size as the right. Why? Because your lungs are there. What else? If you look closely at the image, you see these little faint lines running through the lungs. They try to represent deep grooves in the lungs. Oh, remember in anatomy, we call deep grooves fissures. So your lungs aren't one solid organ per se. It's kind of segmented or broken up. cut up into these these segments are what we call lobes by these fissures that are part that allow these lobes to be partially attached. So when you look at the lungs you might notice the right lung is broken up into three lobes while the left lung is only broken up into two. Why? It's these deep fissures running through them and you can see it for the right lung. You see the right lung is broken up into a soup superior lobe and in middle lobe by what we call a horizontal fissure because it's running horizontally while the middle lobe and the inferior lobe are Broken up by what we call an oblique fissure because it's running obliquely at an angle while the left lung since it's slightly lower is only broken up into two lobes a left upper lobe and a left lower lobe and again, they're also broken up by another oblique fissure this time for the left lung. So that's lower respiratory tract anatomy and again we're gonna go through these organs and again break down their anatomy just a little bit more and again hit their Physiologies just kind of in general just briefly remember the second half of this chapter is gonna go into more detail on physiology So again, this is a lot of Repetition so we saw the upper respiratory tract is made up of two major parts or two major organs. It's your nose and structures associated with the nose. Things like your nasal cavity, which contain the nasal concha to trap and warm up air, to help humidify and warm up air. Things like your nasal epithelium, containing receptor cells to sense odors. And things like your pharynx. So we're seeing these organs again. And again, I mentioned what they're doing. Your upper respiratory tract, because of the structures inside, are doing things like warming up the air, humidifying the air, filtering the air. Think your nasal concha. You can also help to filter air with your nasal epithelium and some of the hairs associated with it. Yeah, I'm talking about the hairs in your nose. They're helping partially to filter out air as well. And we also know one more thing about nose. Oh yeah, we gotta go there. I'm talking about mucus. Remember that mucus made by the goblet cells? They eventually can get coughed up or blown out of the nose. You expel some mucus, yeah, with your upper respiratory tract. You can use your pharynx to help you to cough it up, or yeah, you can blow it out with your nose. So that's upper respiratory tract. And again, don't forget the other organs. There's also the lower respiratory tract. And again, I mentioned some of these functions. Remember in your larynx, you have the epiglottis. Remember that's helping you to protect your windpipe, your respiratory system from liquids and foods whenever you swallow. Remember your vocal cords are also in the larynx. Remember your vocal cords are also helping you to give the sound of your voice. Yeah, these are just structures we mentioned before. So these are some of the things your lower respiratory tract is doing. And we saw the picture of the trachea branching into bronchi, primary, secondary, tertiary bronchi, and bronchials. And I told you it was just a system of tubes to help get air in and out of the lungs. And your lungs, most people know, are doing the gas exchange. Your lungs are swapping oxygen and carbon dioxide, helping you to bring in the oxygen and deliver it to cells in the blood and helping to withdraw that. carbon dioxide to help you to breathe it out. That's what your lungs are doing. So almost everything else is helping to get the air in and out of the lungs. So that's a little bit on your respiratory system. And we saw it's really the lungs that's the point of the matter. You're trying to get air to and from the lungs. So we got to spend some time on lung anatomy and physiology. And like usual, before I really get into it, you already know some things about this this organ. You know where to find it way back from chapter one. Remember it's trapped in a body cavity like a lot of your internal body organs. Remember it's in the pleural cavities. Remember there's technically multiple right answers if I don't ask it the right way. Remember yes the lungs are in their own special pleural cavity. But you remember where are the pleural cavity? Where the pleural cavities are located within the thoracic cavity. which is within the overall ventral cavity. You know all this from A&P 1. And also from A&P 1, you know all your internal body cavities are lined with a serous membrane, and we can name the serous membrane after the cavity. Remember, it's a lot for me to say, hey class, let's look at the serous membrane of the pleural cavities. Or I can just say, let's look at the pleura, or the pleural membranes. Maybe we can name the serous membrane. After the cavity and you know your serous membrane makes a serous fluid to separate the visceral and parietal Layers and you remember we named the fluid after the membrane remember your serous membrane makes a serous fluid Well in this case it's called the pleural membrane So we call the fluid the pleural fluid But it's still that same fluid doing the same thing helping to reduce friction and separate the visceral and parietal layers of that serous membrane. You knew this whole slide, or at least the whole half of this slide from A&P 1. What else can we add? Well, your lungs are actually really long, longer than people think. Your lungs can possibly go all the way up behind the clavicle when you take in a deep breath, and it goes all the way down towards the base of the ribs where your diaphragm is. So your lungs are pretty long. And like usual, we're gonna have to break it into different areas. We name parts of the lungs. Turns out the top of the lungs are what we call the apex. Remember apex is a pointy tip. So that pointy tip is the top of the lungs. We call it the apex. And the bottom of your lungs is kind of flatter cause it's sitting on the diaphragm. So that flat base-like bottom is what we call the base. So top is apex, bottom is base. And we saw on our slide where we saw the image of the lungs, we saw that the right was a little bit bigger than the left. Why? Don't forget the heart is taking up space for that left lung. So the left lung is a little smaller than the right. And we also saw that the lungs get broken into segments, get broken into what we call lobes. I want you to know the left lung is broken up into two lobes, while the right lung, because it's bigger, is broken up into three. So yeah, your lungs aren't one completely solid organ. It's these flaps or these segments of lungs, we call them the lobes. And when we talk about trying to deliver air, oxygen, or carbon dioxide to and from the lungs, we're really delivering that gas to a specific place, to what we call an alveolus, singular, alveoli is plural. Alveoli are just tiny air sacs in the lungs. They're where you're doing the gas exchange. So when you talk about dropping off oxygen to red blood cells or picking up carbon dioxide for you to breathe out, you're really doing it at that level of the alveoli. They're doing the gas exchange with the bloodstream. So if you were to look at a picture of an alveolus or alveoli, which is what you're seeing in this picture, you're going to see tons of very small blood vessels surrounding them. you're going to see capillaries. Because remember, capillaries are doing gas exchange. Now you know how. They're literally sitting on top of the alveoli and exchanging the gases. Why? Because remember, your capillaries are very thin walled. They're pretty much one cell thick. An alveolus is the same thing. An alveolus is made up of simple squamous epithelium. It's one cell thick. So it's really easy for gas to be swapped. between the bloodstream and the alveoli. And here you see the rest of this airflow stream. Now you can really see the full picture of the pathway of air. So you know from our previous slides, when you breathe in, you could take air in through the nose and pharynx. Then you'll deliver it to the larynx. That will send the air to the trachea and the trachea will split. Remember the trachea will split into a primary bronchus. which will split into a secondary bronchus, which will split into a tertiary bronchus, which will split into a bronchiole. And that's where we ended on that other picture. Because I told you everything else was at the microscopic level. Everything in this picture is technically what you cannot see with your eyes. It's microscopic. So technically, if you wanted to see a capillary sitting on an alveolus, you would need a microscope. But the pathway still continues. And that's what we're seeing in this picture. After a bronchiole, you'll split into what's called a terminal bronchiole. That's the top of this tube that you're seeing in the picture. And just follow the tube. It'll continue to branch. You see, if you follow a terminal bronchiole, it will split into what we call respiratory bronchiole. And if you were to follow one respiratory bronchiole, it will split into what we call alveolar ducts. And if you were to follow an alveolar duct, it would split into alveolar sacs. which will split into a single alveolus. So a single alveolus on this picture would look kind of like a grape. These look like clusters of grapes. One of those single grape-like structures would be considered one alveolus. So this cluster of alveoli is what we call an alveolar sac. That's what you're seeing. And you're seeing the blood vessels sitting on top of the alveolar sac. So that's the pathway of air. Make sure you know that pathway air has to travel through. Through the nose and pharynx, then the larynx, then the trachea, primary bronchi, secondary bronchi, tertiary bronchi, bronchioles, terminal bronchioles, respiratory bronchioles, alveolar ducts, alveolar sacs, and then into an alveolus singular. Alveoli is plural. Now you know the pathway of air. And so that's what all those other portions of the respiratory tract were doing. I told you they're all pretty much practically sending, exchanging gases to and from the lung. And again, I told you in the lungs, it's the alveoli really doing the work. It's the alveoli really doing the gas exchange. So now we got to talk about alveoli. Turns out each lung is filled with alveoli. Remember alveoli are microscopic. Turns out each lung has millions of alveoli. Hundreds of millions. That's a lot. Why? Why does the lungs need to be crammed filled with hundreds of millions of alveoli? Why can't the lung itself be one big alveolus? Well, it kind of makes sense. Again, if you think back to our earlier chapters. Gas exchange is you literally exchanging material with the external environment. Kind of thing, almost like a cell. Remember, for cells to eat, they need to exchange material with their environment. And if a cell wants to eat a lot, do a lot of exchange, remember it did things to its surface. to increase its surface area. Remember, for a cell, it did things like have microvilli. But for our lungs, well, that's what alveoli are doing. Instead of having one solid lung, where you could only exchange along the surface of that one lung, well, now you could exchange material, or in this case, gases, along the linings of each individual alveolus, which is a lot. If you were to add up the surfaces of 300 million alveoli, it would be a lot larger surface than the surface of your one lung. That's why there are so many alveoli. They're helping to increase the surface area in order to do more gas exchange. Believe it or not, you need a lot of oxygen to breathe, at least at the microscopic level. What else? And when you breathe, your lungs kind of expand. You literally fill it up with air like a balloon. So your lungs need to be a little bit flexible, a little stretchy. Your alveoli need to be able to stretch and fill with air. And you actually produce a chemical to help your lungs get kind of stretchy to allow it to expand. I want you to know what this chemical is called. It's on the slide. It's called surfactant. Surfactant is a chemical that helps to increase the flexibility of your lungs. to make it easier for your lungs to expand when you're breathing. That's what's helping your alveoli to expand and fill with air. And like always, there's other things here. There are actually other cells here. In this case, white blood cells. It's macrophages. You have macrophages also in between your alveoli, helping to remove anything that doesn't belong, which could be things like dust or debris. Even cellular debris. Remember, macrophages can also eat other cells. So they're almost like little vacuum cleaners in your lungs, trying to clean up things as you possibly might inhale them. But like always, they're not perfect and you can overwhelm them. I'm talking about smoking. If you smoke, that's going to be too much particles, too many things for your macrophages to really successfully remove. But they will try and you could possibly see an accumulation within your macrophages. So that's a little bit on the anatomy and a brief overview of the physiology of your respiratory system. So like usual the rest of this chapter is going to go into detail on the physiology. And for the respiratory system we're going to focus on the detail of breathing, the detail of doing this gas exchange. And like always, you basically know what's going on. You know you're going to breathe in oxygen, bring it to the alveoli of the lungs, and dump it into the bloodstream. And you're going to take out that carbon dioxide and you're going to breathe it out. You basically know what's going on. But like usual in anatomy, we're going to give fancy names to things. Okay. For example, breathing. You know that process of breathing is taking air in and blowing air out. In anatomy, we call breathing pulmonary ventilation. Pulmonary, because you're using your pulmonary system. And you're ventilating, you're moving gases. Well, that's just breathing. And you know to breathe, again, you have to take air in. Where the process of taking air in is what we call inhalation. And then you're going to have to take air out. You're going to have to blow air out. When you blow air out, that's exhalation. So you knew to breathe, you have to breathe in and out. You might have just not known to call it inhalation and exhalation. And both those processes together are called pulmonary ventilation. And that's what your lungs are doing. Remember, just fancy names for basic things. But again, we got to go into a little bit more detail. You know, when you're breathing in oxygen and breathing out carbon dioxide, it's because you've taken oxygen from the environment. and brought it to an alveoli that then dropped that gas into the bloodstream and vice versa from carbon dioxide well you're taking air in this case oxygen from the external environment and putting it into your body we basically call that external respiration think in external respiration i'm taking oxygen from the external environment and dropping it into my into my bloodstream how Delivering it to the alveoli in my lungs where they'll do gas exchange with capillaries. That's basically external respiration. And how are you moving the gases, by the way? Well, you're not really moving them as much as you think. You're driving diffusion. When we talk about oxygen entering the lungs and the bloodstream, it's really diffusing there. Oh, you remember diffusion is a solute. Gas is, oxygen is dissolvable. Turns out it's a solute, and it's going to travel from an area of high solute concentration to low. Remember that's diffusion. That's how you're breathing in oxygen. You're taking it from where there's a lot of oxygen, which is in the air in your environment, and you're bringing it to where there's less oxygen, which in this case is gonna be your lungs and then eventually your bloodstream for now. That's external respiration. And then that's not the last step. Remember, after you exchange the gases between the alveoli and the bloodstream, Well, then your bloodstream is going to take that oxygen and deliver it to the cells in your organs and tissues. I've got to talk about that. We call that internal respiration. Internal respiration is just basically what's happening internally, what's happening in your body. It's just your bloodstream exchanging the gases, again, still things like oxygen and carbon dioxide, now with your cells and tissues. And it's all happening internally. So we call that internal respiration. Again, you knew your cells need oxygen and nutrients to do things like cellular respiration. You just might not have known that overall. This is part of, at least in terms of your pulmonary system, what we call internal respiration. So put it all together now. You're going to breathe that air in. Take it from the external environment. Do your... Pulmonary ventilation, you're going to do external respiration, bring it in. And then once it's inside, you'll do your internal respiration, exchange it between the blood and the tissues. Now we're building this idea of breathing. And again, here's some images. We're seeing a blown up image, a close up image, a zoomed in microscopic image of an alveolus. And inside there are lots of cells. Remember your alveoli are pretty much one cell thick. And you see them. They're simple squamous epithelial cells. But we give them a special name because they're forming your alveoli. We call them your alveolar cells. We actually have two types of alveolar cells. There are type one alveolar cells. They're the cells forming the walls of the alveolus. And then there are what we call type two alveolar cells. They're what you see in the blue images or the blue cells in the image here. They're still helping to form the walls of the alveolus, but they do something else. I want you to know, what do your type 2 alveolar cells make? Turns out, your type 2 alveolar cells make surfactant. So it's really these cells that are helping to make your alveoli and your lungs flexible to expand when you breathe. They're helping with that flexibility. How? By making that chemical surfactant. And even in this image you see the green cell inside the alveolus in this cartoon is a macrophage. It's just hanging out between the alveoli helping to remove anything that doesn't belong. Which can be other cells or even dust and debris. Again, returning back to the physiology. We're not done with breathing. We're just hitting it level by level. We gotta go into a little bit more detail. Here's another way to help explain how you breathe. Turns out another way to help explain how some of these gases are moving are based off really physics. Some laws in physics and chemistry. Turns out you're able to fill and empty your lungs based off a relationship between pressure and volume. Turns out we've proven or at least seen over and over again to be true. So it's basically become a law, something called Boyle's Law, that pressure and volume have a relationship. Turns out pressure and volume are inversely proportional, meaning opposites. Meaning if I increase one, I will decrease the other. That's Boyle's Law. Whenever you increase pressure, you will decrease volume. pressure, you will increase volume. They are inversely proportional, opposites. And your body actually is acting on this principle when you're filling up the lungs and emptying them. So we're going to have to explain how do you do pulmonary ventilation? How do you inhale and exhale? How do you fill and empty the lungs? How do you increase and decrease the volume in the lungs? Well, it's going to have to deal with pressure changes. Let's go through that. For example, how do you fill up the lungs? How do you breathe in? How do you... inhale. Well when you breathe in you're filling up the lungs. You're increasing the volume. The volume is the amount that's making up the lungs. You're increasing the amount of air in the lungs and according to Boyle's law to do that you need to decrease the pressure in the chest. Turns out you have to make the pressure in the chest lower than the pressure in the atmosphere around you. The pressure in the atmosphere around you is what we call abscess. atmospheric pressure. So when you breathe in, you're dropping the pressure in your chest, your thoracic, your pleural cavities lower than that atmospheric pressure. And again, that volume will change. That air will rush into the lungs and increase the volume. It just boils low. To breathe in, decrease the pressure and you will increase the volume in the lung. Now, how do you do that? By the way, how do I decrease the pressure? That's to help fill up my lungs. Oh, let me give you a hint. What do you use to move? Well, it's your muscles. Well, it turns out it's muscles helping you to breathe. Most people know at least one of them. It's your diaphragm. Your diaphragm is the major organ for breathing. There are other organs like your internal and external intercostals also helping to assist you to breathe. All these muscles are really changing the pressure. in your chest to help you to breathe. In this case, for inhalation, you're going to decrease the pressure to increase the volume of air in the lungs, aka to inhale. And then, well, you'll basically do the opposite to exhale, to breathe out. For you to breathe out, you're decreasing the volume in the lungs. You're emptying it. And to decrease the volume, according to Boyle's law, well, you're going to have to increase the pressure. Kind of think you're squeezing your lungs when you're trying to empty them out. And how do you how do you do that? How do you now increase the pressure? Believe it or not it's again your muscles. But in this case the diaphragm and your intercostal muscles are going to relax. When your diaphragm relaxes then you'll exhale. That's why if you notice this. When you inhale and try to hold it, it feels like you're doing something. And then when you exhale, it feels like you've just released and relaxed. It's because you have. The muscles have relaxed to allow you to build up the pressure in the chest and blow out the air. That's how you exhale. And we prove it all with Boyle's Law. Increase the pressure to drop the volume. Exhale. Or decrease the pressure to increase the volume. Inhale. And that's how you can breathe. Now you know some ways to explain breathing, both at the microscopic level and at the theoretical level. But again, we know some other things about breathing. For example, I could do more than just normal quiet breathing. For example, if I wanted to play an instrument, I can hold a note. When you hold a note, like playing an instrument, when you blow out air for an extended... extended period of time we call that a forced exhalation think blowing out the candles on a birthday cake or blowing on your wind based instrument That's forced exhalation. You're basically still doing exhalation You're still increasing the pressure to blow out air to decrease the volume. But in this case you have to Decrease the volume even more you have to blow out extra air with extra force. How do you? decrease the volume even more. It still boils low. Just increase the pressure more. Oh, how do I increase the pressure more? Because originally it was muscles doing it. Well, it's still muscles. If you want to increase the pressure, you'll just add more muscles, have them do more work. So now, in addition to your diaphragm, you're going to add more muscles doing work. You're going to use more of your intercostal muscles. You'll even use some of your abdominal muscles, like your rectum. this abdominals you're using more muscles to generate a greater force to increase the pressure to dump out more air That's forced exhalation. And when we talk about changing pressure, we're not talking about large changes. These are really small changes in pressure. And that's what you're seeing on this picture. For example, the air's pressure, the atmospheric pressure around you is usually about 760 millimeters mercury. And when you inhale, you have to drop the pressure in your chest to allow the air to escape. air to rush in your chest. How much are you going to drop it? You can see from the picture, you're going to drop it to about 758 millimeters mercury. You can see it's just a two millimeter mercury difference between you breathing in and not. And it's a small difference also to exhale. For you to exhale, well, you have to increase the pressure in your chest to about 762 millimeters mercury. Again, that's only a two millimeter mercury difference and again help you to change the pressure either to drop or into to increase it or your muscles to help you to breathe it's mainly the diaphragm with help with other muscles depending on how much pressure you want to generate it could be the muscles between your ribs remember the remember those are your intercostal muscles or it can be muscles in the diaphragm like your abdominal muscles or your oblique muscles And that's all they're talking about in this slide. To change the pressure is only a 2 millimeter mercury difference. Do you really move a lot of gas with just 2 millimeter mercury difference in pressure? Yeah, you move about 500 milliliters, almost a small water bottle's worth of air, just by changing the pressure 2 millimeters mercury. And if you want to move more air, do things like forced exhalation or generate a gressure. greater pressure by using more muscle. That's all. Now you know pretty much how you're breathing, how you're doing those exchanges. It's a combination of diffusion and you changing pressure based off Boyle's law. So now like usual, since you know how things work, we could talk about when some things go wrong. And on this slide, we see two things that could go wrong. There's something called a pneumothorax. and something called a pleural effusion. I want you to know what is a pneumothorax and what is a pleural effusion. Before I talk about them, I got to remind you your lungs are located in your pleural cavities. And you remember your pleural cavity is lined with a serous membrane that makes serous fluid. Well, and you remember that fluid is separating the parietal and visceral layers of that serous membrane. Well, a problem could occur. when you introduce air into this space. We give a name to this space between the surface of the lungs and the walls of your cavity. It's called the pleural space. It's just the space, the area. There's a little gap between the surface of your lungs and the walls of your chest. We call that the pleural cavity. And there should not be anything in there except for maybe a little bit of serious fluid. Sometimes you can have air trapped in the pleural space. We call this a pneumothorax. And this is bad. This is an emergency in most cases. Why? Because when the air gets in, it can't get out. It's trapped. So it will accumulate. And as it accumulates, it's going to begin to squeeze and crush the lungs. And it can squeeze and crush the lungs to the point where your lungs collapse. That's the end result of a pneumothorax you will have lung collapse and if the lung collapses it's like it's getting squished like a pancake it's not gonna fill up with air you're not gonna do gas exchange you're not breathing you could die from a pneumothorax from this lung collapse why because you didn't get the air out so how do you get it out well it's not gonna be pretty your doctor's literally gonna cut a hole in the side of your chest not a big one and you insert a tube, a chest tube to drain out that air. And hopefully that will help the lungs to re-expand and you could go back to breathing normally. That's a pneumothorax. It's just air trapped in the pleural space. How do you get it out? Literally drain it out with a tube. And then there's something called a pleural effusion. This is still dealing with that same space, that area around the lungs, the pleural space. In this case, now you have fluid trapped there. When you have fluid trapped in the pleural space, that's a pleural effusion. It will do the same things. It will squeeze and possibly collapse the lungs. And you will treat it the same way. Still poke a hole in, still put in a tube. And in this case, you got to drain out now the fluid. So that's a pneumothorax and a pleural effusion. One more time. Pneumothorax is air trapped in the pleural space. drain it out using a chest tube. And pleural effusion is fluid trapped in the pleural space, drain that out with a chest tube as well. So now you know the anatomy and a little bit more in depth on the physiology and even some things that could go wrong with the respiratory system. But again, some other things to know. For example, how do we know all these things about your lungs and what are some names we give to them? Turns out we... know how much air we move just by changing the pressure. You know by now just by changing the pressure by two millimeters mercury you could change 500 milliliters of air. Turns out we give a name to this amount of air that you move with normal breathing. This volume of air. This amount of air. It's called your tidal volume. Your tidal volume is simply the volume the amount of air you move. with normal breathing. And we know how much it is. It's 500 milliliters. Turns out right now, just sitting down, comfortably breathing in and out, you're moving 500 milliliters of air. But of all that air, are you using all of it? Turns out no. Of that 500 milliliters of air, of that tidal volume, you're only going to use about 70% of it. Only about 70% of your tidal volume. actually makes it to the alveoli to do gas exchange. So what about the rest? What about the other 30%? Turns out that gets trapped in what we call anatomical dead space. Anatomical dead space is just where you don't do gas exchange. So think what's not lung and alveoli. Well, that's your nose, your pharynx, your larynx, trachea, all the bronchi, your bronchios, all the... tubes basically if you're not lungs you cannot do gas exchange you're a dead space you're where where i'm wasting the air that's what happens to about 30 of the air and when you breathe out you'll just breathe that air back out again so again when you're breathing in you're you're not quite as efficient as you think when it comes to breathing you You're only capable of using about 70% because some of it is still stuck in your nose, your throat, your larynx, your trachea, and all the tiny tubes, the bronchi and bronchioles. But that's your tidal volume. That's just the air you're breathing in and out normally, comfortably. But again, we know we could do other types of breathing. For example, I could take a deep breath in. I could do a deep inhale. Almost. Like a yawn. When you do a deep inhale, when you take a deep breath, we call that your inspiratory volume. It's the amount of air you take in beyond your tidal volume. That's your inspiratory reserve volume. Think taking a deep breath. How much extra air can you get in? And not only can I take in extra air, I can also blow out extra air. We call that... Your expiratory reserve volume. Can I think of the extra air you blow out beyond your normal exhale, beyond your normal tidal volume? That's your expiratory reserve volume. And if I were to try to empty my lungs, if I were to try to use my expiratory reserve volume, would I completely empty my lungs? Can I blow all the air out of my lungs on my own? Turns out no. No matter how hard or how long you exhale, there will still be some air still in the lungs. We call that your residual volume. That's the amount of air still in the lungs after a maximum exhalation. Why? You don't want to completely empty your lungs because then you risk the problem of a lung collapse. Remember, if your lung collapses, it's extremely hard for it to re-expand. So to keep it from collapsing every time you breathe, you have a residual volume, an amount still in the airway. But will you ever eventually empty your residual volume? Well, yeah, but you're not going to like it. It's called when you die. When you die, people talk about having a long, final last breath. Well, technically it's true. Now you know what? What they're exhaling. When they're dying and they do their last exhale, they're going to exhale their regular tidal volume. They're going to exhale their expiratory reserve volume and they'll finally be able to exhale and release the residual volume. So yes, technically your last breath will be your longest breath because you have to empty out all those volumes. So now you even know about the different types of air you're moving. But why do we care? Why do we care about the different amounts of air we move? Well, it's your doctors who care. Turns out. By looking at the amounts of air you move, it gives me a peek as to how well your lungs are functioning. There are some calculations you could do. I want you to know these two types of calculations. There's something called the vital capacity and something called the total lung capacity. What are these capacities? They're just talking about you moving air. Start off with the vital capacity. Turns out your vital capacity is basically all the air you can move. The maximum amount of air inhaled and exhale. So this will be, yes, your tidal volume. But remember the extra air. Remember this is the maximum amount you can move. So yes, it's tidal volume. But you'll also add it to your inspiratory reserve volume and your expiratory reserve volume. To calculate a vital capacity, add your tidal volume. to the inspiratory reserve volume and the expiratory reserve volume. Add those three numbers and you'll have the vital capacity. But don't forget, there's that air you cannot move. So your lungs are a combination of the air you can move plus the air you can't. So you got to think of the total amount of air your lungs could totally contain. The total amount of air in your lungs is what we call a total lung capacity. It tells you in the name. It's the total amount of air your lungs could contain. So basically add all those lung volumes together. Your total lung capacity is going to be your tidal volume, your inspiratory reserve volume, your expiratory reserve volume, and your residual volume added together. And that's the total amount of air your lungs can hold. And we know average numbers. On average, a male's typical total lung capacity is about 6 liters, while a female's about 4. Remember, these are averages based off the average fact that males are a little larger than females. But again, if you're Kevin Hart, I expect you to have a total lung capacity closer to 4 liters. And if you're Lisa Leslie, well, then I'll expect it to be closer to 6 liters. It's just based off how big you are overall. So that's... Things your doctors are going to look at when they're measuring your lung volumes. They're measuring these lung volumes to see if the lungs are at their typical average numbers. If I notice you're not moving as much air, your vital capacity is lower than average, then I'm going to be concerned that maybe there are some lung problems going on. And by the way, how do we measure these lung volumes? Well, you might have experienced it if you've been in a hospital. for an extended stay or if you've ever had any testing for things like asthma. You've probably breathed into a little machine, the cheaper, easier to access ones usually have a little ball in it and you'll blow and hold your breath and other things and watch the ball go up and down. Those little machines are measuring the volumes of air you're moving. We call them spirometers. And the spirometers will generate a chart, a record. Showing me all the different lung volumes you can move. And I'll do my calculations for things like vital capacity and total lung capacity to see if your lungs are hitting average numbers. Are they being used to their maximum advantage? If not, there may be lung issues. And that's all you're seeing on this picture here. The graph above is a spirogram. And the line is just showing you breathing. When the line goes up, that's you inhaling. And when the line goes down, that's you... exhaling. And so on the y-axis, you're seeing the lung volumes in milliliters, and the x-axis is over time. So you're watching someone breathe over time. And so towards the middle of the chart, going up and down, up and down, and a sinusoidal wave-like, you're seeing the tidal volume. Then you see the line go up a little above the total, or above the tidal volume. That extra line going up Up above the tidal volume is your inspiratory reserve volume. Remember, that's the extra air you could breathe in. Then the lines going down below the tidal volume are your expiratory reserve volumes that you breathe in out beyond your normal exhale. And if you notice, the line never quite hits zero. Why? Because you remember, you always have that air still left in the lungs after a maximum exhalation. You always have that residual volume, at least until you die. So I could calculate, again, things like vital capacity and total lung capacity to see if your lungs are working correctly, hopefully. And it's pretty straightforward things to understand. For example... I could use a spirogram and a spirometer to tell if you have something like asthma or something like pulmonary edema or COPD. I could tell possibly if you have a certain lung disease. And there's lots of them. So like usual, we're going to break them down. When we look at the different types of lung diseases or disorders that can be detected or hinted at using a spirometer and spirogram, there are groups that we call the obstructive. pulmonary diseases and there are groups that we call the restrictive pulmonary diseases. And the obstructive pulmonary diseases kind of give you a hint in the name. They're obstructive because they're obstructing, they're blocking airflow. So think of disorders where airflow might be blocked. Things like asthma. Asthmatics are, it's hard for them to breathe when they're having an asthma attack because they're having a blockage of airflow or restriction or a blockage of airflow. Same thing with COPD, which is chronic pulmonary obstructive disease. Something is kind of obstructing the airflow. So what would it look like? Well, let me give you a hint. In some of these cases, it's a lot easier to get the air in than it is to get the air out. It's hard for them to get the air out. So what would that look like in terms of our numbers? If it was hard to get the air out, it would actually accumulate. So if you were to look at them, They would usually have higher than normal lung volume. You'll see a higher than normal total lung volume or residual volume. Why? Because it's harder to get the air out. You'll see increased lung volume. Why? Because there's something blocking the air from getting out. Or, on the other hand, you might have what's called a restrictive type of pulmonary disease. Again, they give you a hint in the name. They're called restrictive because now something's restricting lungs. Really, in this case, restricting lung expansion. So it can expand. And if it can expand, it's not going to fill up to its normal volume. So what would that look like? Well, they wouldn't possibly have lower than normal lung volumes. Why? Because the lungs are getting restricted, squeezed. It cannot expand. You'll see that in things like pulmonary edema. Remember, edema is swelling. If you have pulmonary edema, that could restrict the lungs. That extra fluid can restrict the lungs and cause you not to expand. And I'll see that as a lower lung volume when I look at your spirogram. Remember, a lot of medicine is not anything new. It's just us understanding anatomy. Again, other things to talk about when it comes to the respiratory system. We're basically talking about some extra things now. For example, you have patterns to how you breathe. You breathe in and out, usually with a pattern. And this is anatomy. We're going to give names to them. We give names to the different patterns of breathing. For example, there's normal breathing. In anatomy, normal breathing is eupnea. That's normal breathing. It's this shallow in and out that you're doing at rest. But again, we have other types of breathing. Another type is what we call costal breathing. Sometimes called chest breathing. This is you using more of those accessory organs, your external and internal intercostals in your chest. That's why it's called chest breathing. Remember, costal means rib. So think the muscles associated with your ribs. If you use those, that is costal breathing. Keep going, other types. There's something called diaphragmatic breathing. This one's name is a little kind of misleading. It's called diaphragmatic breathing. So you would think diaphragm, but it's really you breathing with your abdominal muscles. So think you trying to do the forced exhalation for you to hold that note. If you're a singer, they usually talk about singing from your gut. They don't mean your intestines. They're really talking about your abdominal muscles to generate a greater force. So you can generate a greater pressure, eject more of that volume of air. out of the lungs and hold your note longer and louder. You're just doing diaphragmatic breathing. Again, lots of patterns. We give names to everything. We even give the name to when you stop breathing. An absence of breathing, when you're not breathing, is called apnea. And people probably heard of certain types of apnea. One is when you stop breathing in your sleep, so we call it sleep apnea. Well, but there are other types. Turns out you could stop breathing if you get too cold from hypothermia. Turns out you could get apnea. Or if you're a premature infant, if you're born too early, you're actually not... capable of making surfactant yet. And if you're not, well, your lungs can expand and you won't breathe. Or there's also the situation where you could just have plain old difficulty breathing. Difficulty breathing is what we call dyspnea. There are multiple reasons for difficulty breathing. And in general, we just give it a name. It's called dyspnea. Could be because of a lack of exercise. Maybe you try to run a marathon when you weren't ready. You'll have difficulty breathing. Maybe you're a smoker, long-time smoker. You'll have a history of difficulty breathing. Maybe you have an infection in the lungs. Maybe pneumonia, some type of respiratory disorder or infection. They could cause difficulty breathing. It's just called dyspnea. So remember, in anatomy, we name lots of things. And that's what you're seeing in this chart. You do not need to know this chart. It's just showing you examples of how anatomy names things. You know them. A lot of them make it into our everyday vocabulary. You know what it means to yawn, for example. But oh, what would the definition of a yawn be in anatomy? What type of pattern is that? Well, it's when you take a deep inhalation followed by opening the mouth. Impression of the mandible meaning to lower your lower jaw. That's a yawn. It's just us defining things in anatomy. Or one more. You can have an inhalation followed by short exhalations which involve vibrating the vocal cords. Oh, what is that? What is an inhalation followed by an exhalation and the vocal cords vibrating? Oh, babies know what to do. It's called crying. Crying is when you inhale. And then you exhale with sound coming out. It's a cry. So remember, in anatomy, we name everything. No, you do not need to know this table. But back to, again, the physiology. So you now know you're going to do some external respiration. Take the air from outside and bring it inside. How? By dropping the pressure in your chest to increase the volume of air. Then you'll use diffusion to do gas exchange. Oh, we gotta talk about that step. Oh, we gotta talk about the internal respiration. How you doing the diffusion? How you exchanging the gases between the blood and the tissues and cells and vice versa? Oh, to help explain that again, we're gonna use some principles, some laws. Now we're gonna use what's called Dalton's Law. What is this one relating? Turns out, it has to deal with what we call a partial pressure we're talking about gases we're talking about air turns out yes to you gases mainly oxygen and carbon dioxide are the gases we're breathing yes there is a lot of it around this but you can't see it because it's microscopic but it's still there and it exists remember everything that exists has matter and that matter is taking up space and has mass turns out Well, these gases, they exist and they exert a pressure. Kind of think they're pushing on each other in the room around you right now. And that force they're exerting, that pressure they all push on each other with, is what we call our partial pressures. So when you fill a balloon up with air, the balloon will have a pressure to it. The total pressure. It's the pressure of all the individual partial pressures of the gases in your balloon. So all the air around you is constantly pushing against each other and exerting a force or pressure. We call that the partial pressures of gases. So it turns out if there's more gases, there's going to be more of them to push on each other. The partial pressure will be higher or vice versa. If there's not that many gases or there's not going to be that much pushing, not that much pressure. So when you think... or hear the term partial pressure, you could kind of replace that phrase, partial pressure, with the word concentration. Because you know if there's more of them, there's going to be more pressure. So whenever you think a high partial pressure, you're really saying something is concentrated. There's lots of gases there. And when you say something has a low partial pressure, you're saying it's less concentrated. There's not that many gases. So to help ease your brain, whenever you hear partial pressure, think concentration. Okay. And what else? We're doing internal respiration now. We're talking about swapping this gas between blood and cells. It's all in a liquid environment. Remember, blood is mainly liquid, mainly water. Remember the environment around the cells has interstitial fluid. You're exchanging gases in a watery environment, so to speak. How is that possible? Well, I kind of briefly mentioned earlier, these gases can dissolve in liquids. When you can dissolve, well, you have what's called solubility. Remember, solutes get dissolved. So solubility is your ability to dissolve. Gases are solids. Oxygen and carbon dioxide are solids. They have some solubility. So yes, we are talking about a watery environment, but don't worry. Why? Because gases can dissolve. And when they dissolve, you're gonna be able to move them around. So what's going on when you're breathing? Well, when you're breathing, you're really just trying to control partial pressures. Remember, it's pressure changes that will lead to volume changes. and its pressure changes at even the individual molecule level. It's these partial pressures, aka these concentrations, because we're doing diffusion, that's really gonna matter. And you know, you actually already know the answer, because you know the direction we blow gases out. You already know we're gonna take in oxygen overall, and we're gonna blow out carbon dioxide overall. This is diffusion. So you know what's going on. Remember, diffusion is you moving from an area of high concentration to low. So when you breathe in, well, you're just using partial pressures. You're just going from where there's a lot of oxygen, a higher pressure. Remember, that's in the environment. And you're bringing it into the lungs. And vice versa for carbon dioxide. You're taking carbon dioxide from where there's a lot of it in your tissues and cells. And it's going down its concentration gradient to where there's fewer of it, which is in the air around you, in the environment. So again, when you think partial pressure, think concentration. They're going from an area of high concentration to low. So that's what we're going to see as we look at breathing. For example, again, think about moving oxygen. These next two slides just talk about us, again, moving oxygen and carbon dioxide. You already know. You're going to take the oxygen from the air and put it in your lungs, into your alveoli. And your alveoli are going to drop it into the bloodstream. And then once it's in the bloodstream, you'll drop it off at your cells and tissues. Why? Because that oxygen has been traveling down its concentration gradient. It's been going from where there's a lot of it, a higher pressure to low. So when you think about it, you could trace the pressures. Highest pressure or... partial pressure of oxygen aka the highest concentration of oxygen is going to be in the environment then the concentration or partial pressure will drop a little bit lower in the lungs and alveoli will be even lower in the bloodstream and it will be its lowest at the cell and tissue level because that's where you're delivering the oxygen to the cells you're just going down that partial pressure or concentration gradient. You're using diffusion. And again, carbon dioxide is going the opposite direction. You blow out carbon dioxide. You get it from the cells. So the highest concentration, aka the highest partial pressure of carbon dioxide is in the cells and tissues. Then it'll be slightly lower in the bloodstream. So you'll drop it into the bloodstream. Then it'll be slightly lower in the lungs and alveoli. So you'll drop it into the lungs and alveoli. And the lowest partial pressure of carbon dioxide, the lowest concentration of carbon dioxide, is in the air and the atmosphere around you. So you'll blow it out there. So just by tracing the pathway of where these two gases go, you can interpret the partial pressure. Again, this same slide is continuing. The partial pressure of oxygen higher in your blood than it is in the interstitial fluid. And you remember that interstitial fluid is really the fluid around your cells. So this first bullet is saying the partial pressure, a.k.a. the concentration of oxygen, is higher in the blood than it is around the cells. Because again, you remember you're going down that pathway to deliver it to the cells. And again, vice versa for carbon dioxide. The partial pressure of carbon dioxide, or the concentration of carbon dioxide, is lower in the blood than it is. is in that interstitial fluid than it is at the cell level. Why? Because you're delivering the carbon dioxide to the blood so you could kick it out eventually. Just know those pathways. You'll know the order of partial pressure changes or concentration changes. And that's all you're seeing on this diaphragm. And like usual, we're not talking about big changes in partial pressure. For example, to get the air from inside your alveoli into the bloodstream, the partial pressure of oxygen needs to change. Because remember, you're going down your concentration gradient. So you can see from this picture, The partial pressure, that's big P with the subscript O2, that's partial pressure for oxygen, PO2, is equal to about 105 millimeters mercury in the alveoli. But in the blood, you can see the partial pressure of oxygen is only 100 millimeters mercury. Even though it's only a five millimeter difference, it's still a difference and it's lower in the blood. So that oxygen will go down its concentration gradient, or in this case, partial pressure gradient into the bloodstream. And then if you look down at the bottom of this slide, you see the cell level. And you can see the partial pressure of oxygen here around the cells. And that interstitial fluid is only about 40 millimeters mercury. So again, that oxygen will now go again down its concentration gradient from the blood. into the cellular environment. And so it's almost the same principle that happened to get bulk air into the lungs. It was pressure relating to volume changes. You're still just seeing things go down their concentration or partial pressure gradient. And yes, you're going to have to need some help to carry these gases. Even though they're using diffusion, you still need some help to transport. So we're going to have to talk about that. How do you carry oxygen and carbon dioxide? Well, let's do oxygen first. You already know, again, the answers. Remember back from our blood chapter, you know red blood cells carry oxygen. But from our blood chapters, you also know it's really the hemoglobin inside the red blood cell that's carrying oxygen. And that's what we're talking about on this slide. Hemoglobin. is a transport protein and it's helping to transport oxygen. And when we're transporting oxygen, is it transporting all of it? Turns out no. It's transporting most of the oxygen in your body. It's transporting about 98.5%. So what about the rest of the oxygen? What about the other 1.5%? Turns out that 1.5% of oxygen in your body that's not carried by hemoglobin It's just dissolved in your blood. Remember, oxygen, it has solubility. It can dissolve, but only a little bit. Only about 1%. The rest of your oxygen gets carried by hemoglobin. And remember, one more thing from our blood chapter. Remember, we gave the function to hemoglobin for carrying blood. But remember, it's really something inside or making up hemoglobin that's carrying the oxygen. Remember, it's really the... iron inside. You remember the anatomy of hemoglobin. Remember it has four globin chains, each with a heme group that contains an iron. So one oxygen molecule technically has four irons in it. And each iron molecule can bind an oxygen. So technically, one hemoglobin molecule could bind and attach to four oxygen molecules. I want you to know that. One hemoglobin molecule can carry and transport four oxygen molecules. One for each of the ions in each of its heme groups. And you remember hemoglobin is also a pigment. Remember it makes things look pinkish red. The more hemoglobin you have, the redder you're going to look. That's why red blood cells are red because they have this reddish pigment. They have hemoglobin transporting the oxygen. So that's how most of your oxygen is carried. Four for each hemoglobin. Oh but then what about carbon dioxide? Well there's also options for this one. Turns out just like our oxygen, some carbon dioxide is soluble. So it has some solubility. So it can dissolve in the plasma, in the blood of the plasma of the blood. Only about seven percent. Turns out our hemoglobin could also bind to and transport carbon dioxide. And remember when they bind, this is a chemical reaction. So when hemoglobin binds to carbon dioxide, you get a compound called carboaminohemoglobin. This is just hemoglobin bound to carbon dioxide. But it's only about 20%. Most of your carbon dioxide is transported as a compound. Turns out you need an enzyme to help you to trap carbon dioxide into what's called bicarbonate. Bicarbonate is just the compound that helps us to transport carbon dioxide. And for us to make it, we need an enzyme. I want you to know what's the enzyme that allows us to make, or turn, carbon dioxide with other compounds, or other molecules, into bicarbonate. It's called carbonic anhydrase. Carbonic anhydrase is the enzyme that allows you to form bicarbonate from carbon dioxide. and other compounds like water. And it's also carbon, carbonic anhydrase that's gonna allow you to break it back down so you can release and breathe out the carbon dioxide. So these are really how you're carrying around that carbon dioxide. Some of it gets dissolved in your plasma. Some of it will get carried by hemoglobin. And most of it will get carried around by carbonate. Thanks to an enzyme called carbonic anhydrase. No, you don't need to know the chemical reactions showing how you make bicarbonate. You don't need to know those chemical reactions. So again, carbon dioxide is going to do the same thing as oxygen. It's going to go down its concentration gradient. It's going to go down its partial pressure gradient. Going from the highest concentration or highest partial pressure. that interstitial fluid around the cells at the cell level then it'll go down a bit drop the partial pressures when you get into the blood then the partial pressure will be lower in the alveoli and lowest in the environment it's just using diffusion it's just going down its concentration gradient but yet you just have to trap it as bicarbonate using carbonic anhydrase to help move it when it's in the blood and that's all you're seeing on these cartoons that is showing you how you're transporting these gases. Even on this one here, we're seeing how you're transporting oxygen and carbon dioxide. They're just both going down their concentration gradient. And this slide is showing how you're trapping the carbon dioxide and moving it around as bicarbonate. When you get the carbon dioxide from around the cells, you would trap it in bicarbonate using your carbonic anhydrase, which will then take it on to the lungs. where you'll break it back off. Or in this case, in the picture, you could combine it to hemoglobin and allow your red blood cells to carry it. There are multiple ways to transport your gases. That's all you're seeing on these slides. So now you know, even at the really cellular, microscopic levels, how you're transporting these gases. So you pretty much know how to breathe now. You know, all the ways we could look or approach breathing, respiration. And like usual, you could control this. If you wanted to, you could temporarily hold your breath. But now that you know how breathing works, we got to talk about controlling it, regulating it. For example, how do you regulate inhalation and exhalation? Because you don't think about it. Hopefully, you don't think about breathing in and breathing out. So something must be doing it for you. Turns out it's your brainstem. Turns out it's the last part of your brainstem. It's your medulla oblongata. Remember, your medulla was responsible for a lot of reflexes. And breathing is basically a reflex. So your medulla oblongata will help to regulate it. And to do so, it has specialized areas in the medulla to do it. There are two special areas in the medulla to help regulate breathing. There's something called the inspiratory area and the expiratory area. Again, like always, don't be intimidated. They're just giving you hints in the name. Starting off with the inspiratory area. It's called inspiratory because it's allowing you to inhale, to inspire, to take air in. So this area of your medulla is responsible for allowing you to inhale. While you also have an expiratory area. And again, don't worry, don't be intimidated by the name. Your expiratory area also gives you a hint. It's stimulating muscles actually still to inhale, but also to exhale. So think of the forced exhalation. You have to hold that note. You're using your expiratory areas primarily. So you have areas to help you to control inhalation and exhalation. You can see on this cartoon here, they are both located within the medulla of lingata. But this is just you controlling or regulating regular breathing. Think moving that tidal volume, regular in and out breathing. Remember, we have other patterns of breathing. For example, I could hold my breath momentarily or pause inhalation or pause exhalation or extend either one. Kind of thing to talk. For you to talk, well, you have to alter your breathing pattern. Maybe you're going to pause inhalation or pause exhalation or extend it. We got to talk about what's helping you to kind of interfere with this pattern of breathing. Turns out, again, it's your brainstem. But now we're moving a little higher up in the brainstem. We're going to the pons. Turns out your pons could also help to regulate breathing, kind of interfere with breathing. And again, there's also two areas now within the pons. There's the pneumotaxic area and the aponeuristic area. What's going on? How are these two areas helping to regulate breathing? Well, first is the pneumotaxic area. Turns out it periodically, cyclically, sends inhibitory signals to those inspiratory areas in the medulla. Meaning every once in a while, it tells the medulla to stop. working and when that happens well that's going to cause you to disrupt and limit inhalation and in some cases that will promote exhalation so when do i need to limit inhalation by sending inhibitory signals to the inspiratory areas of the medulla oblongata well it turns out you do that when you do things like panting that short breath panting you That's you just limiting your inhalation. How? By using the pneumotaxic areas of your palms. You don't have to physically think about it. It helps your body to do it. Same thing with vocalization. When I'm talking right now, well, when I'm talking, that's me blowing air out. And for me to talk and not take a breath, well, I'm limiting my inhalation. I could say a long sentence without inhaling by using the pneumotaxic areas of my palms. And then I'll take a breath later. And then there's the abnuistic area. This one does the opposite. It sends stimulatory signals to the inspiratory area. It's going to stimulate you to inhale. So you'll promote inhalation and limit exhalation. Think a long, slow inhale like a yawn. When you're doing that long, slow inhale of your yawn, You're limiting exhalation and promoting inhalation. You're using your apneuistic area. So those are two areas in the pons that help you to regulate breathing. Pneumotaxic to inhibit inhalation and promote exhalation by inhibiting the inspiratory area of the medulla oblongata. And the apneuistic area to stimulate or prolong inhalation. by stimulating the inspiratory area of the medulla oblongata. Oh, but keep going. Lots of things have a say on how and when you breathe. Turns out you could kind of temporarily take control. If you wanted to, you could hold your breath temporarily. Or if you wanted to, you could hold a note as long as you want to hold a note, as far as long as you can. Think when you consciously take control. Well you, when you think about your brain, are more the higher areas. Think cerebral cortex. Your cerebral cortex allows you to take voluntary control. Remember voluntary means you control it. It allows you to control breathing temporarily. Why? Well your brainstem can override you. Your brainstem is really overseeing breathing. You're just temporarily taking control. So kind of thing holding your breath. If you notice if you hold your breath you cannot hold it that long or if you try you might pass out and you'll wake up later breathing again. That's your body taking back control of the breathing. Remember your body kind of thinks you're stupid. It'll even try to protect itself from you, even try to protect itself from you trying to hold your own breath. But how does your body do that? For one, how does your body even know that you're trying to hold your own breath sometimes? How can your body notice when your oxygen and carbon dioxide levels change? Well, we can monitor it. Your body literally monitors your gas levels, mainly looking at carbon dioxide. Whenever you have a buildup of carbon dioxide, your brainstem will notice and it will promote breathing. It will stimulate those inspiratory areas of the medulla oblongata. And other things could also have an impact on breathing as well. That's all you're seeing on this chart. It's just showing the different areas. And the... impacts they'll have on breathing and I told you they're able to kind of have an impact because they monitor your your oxygen and carbon dioxide levels they monitor your gas levels how well these gases oxygen and carbon dioxide they are chemicals they are on the periodic table oxygen is the O carbon dioxide is carbon and oxygen so throw in the carbon the C these are chemicals And so when your body is monitoring them, they're monitoring chemicals. And remember, we're really monitoring changes. Remember, this is the job of receptors. There are receptors that kind of notice or sense chemical changes. We call them chemoreceptors. And you have a lot of these chemoreceptors in the medulla. That's how the medulla could tell if your carbon dioxide levels get too high, because they literally have chemoreceptors to sense that chemical. But you have chemoreceptors in other places. There are chemoreceptors in the medulla for obvious reasons, but you also have chemoreceptors in your carotid arteries and even in the arch of the aorta. So in your neck, in the aorta above your heart, and in your medulla, you have cells whose only job is to sense these chemical changes in things like carbon dioxide levels and oxygen levels. And when they notice, they will use those feedback pathways to tell brain sensors to either get you to breathe or stop breathing, stop, minimize breathing. So let's look into this a little in a little bit more detail. I told you you have these chemoreceptors in a lot of places. Why? Because you have a lot of chemoreceptors. And like usual in anatomy, when we have a lot of something, we have to classify them, categorize them. When we look at all the chemoreceptors in your body. They fall into one of two groups. There are central chemoreceptors and there are peripheral chemoreceptors. Like usual, don't be intimidated by the names. Just break it down. They're giving you a hint. Your central chemoreceptors, think central nervous system, think brain, think medulla. Your central chemoreceptors are the chemoreceptors in the medulla. And they're just doing their job. They're monitoring changes in carbon dioxide and also your pH levels. Turns out, whether or not your acid or basic can actually have something to deal with your respiratory system. We'll see that next chapters. So you'll have central chemoreceptors in the medulla, again, monitoring chemical level. But then remember, I mentioned on the other slide, you have chemoreceptors in blood vessels. like the carotid arteries in your neck or in the arch of your aorta. They're further out. They're in the periphery. So we call them the peripheral chemoreceptors. They're the chemoreceptors in your blood vessels. But they're still chemoreceptors. They're still doing the same thing. They're still monitoring carbon dioxide levels, acid levels, that's the pH, and your oxygen levels because it's the bloodstream. So we'll see the blood. And so it's kind of like what I mentioned. If it notices certain levels, it's going to have a response. If your chemoreceptors notice your oxygen levels, your oxygen concentration, your oxygen partial pressure drops, well, that must mean you don't have enough oxygen. And if you don't have enough oxygen, well, what is your body going to do? It's going to tell you to breathe. It's going to stimulate those inspiratory areas to increase your breathing rate so you can bring that oxygen level back up. And the opposite for carbon dioxide. If it notices your carbon dioxide levels are too high, well, you're building up carbon dioxide, maybe because you're not blowing it out. Well, it will also lead to you stimulating breathing to help get the air out. Get that carbon dioxide out. Or the opposite. If your oxygen levels are too high, yes, you will be told to breathe less. And your respiratory rate, your breathing rate will decrease if your oxygen levels are too high or your carbon dioxide levels are too low. And that sounds familiar. When your oxygen levels are too high, you will breathe less to drop it. Or if your oxygen levels are too low, you'll breathe faster to increase it. That sounds like opposites. That sounds a lot like negative feedback. It's because it is. It's thanks to negative feedback and these chemoreceptors that are allowing you to maintain homeostatic levels of oxygen and carbon dioxide. Now you know a little bit more about breathing. But like usual, there are limits to things. Turns out, yes, when your chemoreceptors notice your oxygen levels drop, they will typically promote breathing to raise the oxygen level again. Except for when you have severe oxygen deficiency. When your oxygen levels are severely low, you'll actually have fewer impulses to breathe. Meaning you're going to actually breathe less. Why? It kind of makes sense if you think about it. When your chemoreceptors notice there's extremely low oxygen, one possibility could be because there's no or very little oxygen in the atmosphere. So what's the point of breathing if it's not even helping? So you're not even going to stimulate those inspiratory areas. So you kind of need oxygen to even breathe beyond the mere fact that you need it. That oxygen is helping to stimulate some breathing. If there's not enough of it, you could actually stop and that would be fatal. So yes, chemoreceptors work except for in severe oxygen deficiency. Again, kind of going back to things that could regulate breathing. Turns out, again, you know other things that might regulate your breathing. Like your limbic system. What's your limbic system? Think back to a nervous system. Remember your limbic system is where you're really processing memories and emotions. Remember limbic system is responsible for memories and emotions. And most people might know when they're emotional their breathing pattern might change. Remember there's something called a cry and usually people cry when they're emotional. So your limbic system can under emotional stress change your breathing pattern. Usually. It will help to increase the breathing rate. What else can influence it? Turns out, proprioceptors could do it. Proprioception, remember, is your body's ability to tell where other body parts are in space. Remember, you could close your eyes and touch the tip of your finger to your chin, to your nose, to your elbow, without looking, because you know where your body parts are in space. You have proprioception, thanks to proprioception. your receptors sensing where body parts are. How can that lead to changing breathing rate? Again, it makes sense if you think about it. For example, you might hop on a treadmill at home. And if you hop on a treadmill, your legs might go faster. Your body will notice because your body could tell where body parts are in space. Well, if your body notices your legs are going faster, well, you might need some energy to continue going fast. So you're going to need some oxygen to help you to make that energy and you will breathe faster. Remember when you're exercising that requires energy and one major way to get the energy is via aerobic respiration which requires oxygen. So whenever your proprioceptors notice you're moving quickly it will increase your respiratory rate because it knows eventually you're going to need oxygen to supply energy. And then one last thing that could control breathing is temperature. Remember, when you're moving these gases, it's just a lot of chemical reactions. Oh, think back to A&P 1. Remember, there are lots of things that could affect the rate of a chemical reaction. Remember, temperature was one of them. Remember if you increase the temperature that makes reactions go faster and when you decrease the temperature reactions go slower. Breathing is a chemical reaction so when you increase the temperature well you're gonna typically breathe faster and if you decrease the temperature if it's cold well you'll breathe slower. You're just seeing those principles of temperatures effects on chemical reactions. And there's one special situation. Turns out if you get exposed to an extreme cold suddenly, kind of thing jumping into a frozen lake, you might stop breathing altogether. Turns out cold stimuli, sudden extremely cold stimuli, can trigger apnea, can trigger you to stop breathing. Again, you're just seeing the effects of temperature on chemical reactions. So you actually knew the temperature effects already, way back from A&P. Two more things that affect your breathing. Again, you might understand. Other things are pain. External resources or external stimuli can trigger pain. And pain can alter your breathing, depending on the type of pain. If it's things like a sharp, acute pain, well, that will usually trigger apnea. Remember, if you're walking at home barefoot and you hit your pinky toe on the side table and you almost die, What's one thing you might do? You might do that little cry where no sound comes out. Why? Because you weren't breathing. Why? Because you experienced an acute extreme pain. And acute extreme pains could cause apnea, a brief sudden stop in breathing. But on the other hand, you might have visceral pain. When you hear visceral pain, think internal pain. Think a bellyache. Turns out when you have visceral pain, you actually tend to breathe slower. So depending on the type of pain you'll have, you'll see different responses and how fast you breathe. And then there's something called the inflation reflex. So what's this? Your inflation reflex, it kind of gives you a hint. It has to do with inflation and something that reflexively happens. What happens possibly when you're inhaling? Well, if you notice, when you inhale, you could only inhale so much before you stop inhaling. That is your inflation reflex. It's when you've hit a maximum inhalation. Inhalation will be inhibited and you will stimulate exhalation. You will inhibit the inspiratory areas of the medulla and initiate exhalation. Why? Kind of think of your lungs almost as a paper bag or a balloon. You could overfill it. All right. And you don't want to overfill the lungs. You don't want to overinflate and possibly... See? almost literally pop a lung. So to help you from over-inflating your lungs, you have an inflation reflex. That's why when you inhale, you would eventually hit your limit and then you'll begin to exhale. Why? Because you've hit your inflation reflex and you don't want to over-inflate the lungs. Remember, your body thinks you're stupid. It will try to protect itself from you. And now you know the different things that have an impact. your breathing rates and that's all all what you're seeing on these pictures like this picture here is just reminding us that we have our chemo receptors monitoring our chemical levels if our oxygen levels drop or carbon dioxide levels get too high we'll breathe faster and vice versa if our oxygen levels get too high or our carbon dioxide levels drop we'll breathe slower This slide, again, is just showing you other things that will help to regulate breathing. It's things, again, like those chemoreceptors. But don't forget those areas in the medulla, inspiratory area for inhalation and expiratory area for exhalation. So lots of things have a factor on how you breathe. So to finish off this chapter on respiratory system, we just talked about talk about a few more facts about breathing. Back to the fact that you have lots of breathing patterns. Hiccups are just another type of breathing pattern. And it's due really to a problem. Turns out hiccups are the result of an asynchronicity between the respiratory centers of the brain and your respiratory muscles. Meaning, think those inspiratory and expiratory areas of the medulla. They're not in sync with things like your diaphragm and muscles. And when they're out of sync... you feel that as a hiccup kind of thing when you're normally breathing in and out all of a sudden you have this extra breath this extra muscle contraction you're seeing this asynchronously they're not in sync at the moment when you're having that hiccup remember we give names to everything in a net So now you know why it's important to have good respiratory health and how. Now you know your respiratory system is really exchanging these gases between the environment and your cells. So it's very important to make sure you maintain this pathway of airflow, this kind of concentration gradient for your gases. Why? Because you're really delivering oxygen and removing carbon dioxide. You know why you need oxygen. You need it to do things like cellular respiration, aerobic respiration to make energy. And that energy you could use to help your cells to function and to help you to perform overall as an organism. That's why you need to make sure you're maintaining your respiratory health. So now you know about the respiratory system. We could put it into a big picture now. We could help to explain things now. You could help to explain things like what you see. When you exercise, that's all this slide is talking about. When you exercise, I mentioned when you hopped on that treadmill and you started running, your legs are going to be moving and your body's going to tell, thanks to propyl receptors. They'll tell your respiratory centers in the brain, the inspiratory center, hey, she's moving, she needs oxygen to power her workout. You're going to increase your breathing rate, and you'll use that oxygen delivered to your cells to make energy to power the workout. At the same time, you're making carbon dioxide at the cells, and you're going to have to get those out. It'll go the opposite way from cells to blood to lungs to environment. And remember, you're moving both oxygen and carbon dioxide thanks to them going down their partial pressure gradient or their concentration gradient from high to low. And if you need to move a greater amount of these compounds, you'll just increase the rate. That's all. So now you know how your breathing changes with things like exercise and why. So like usual, to finish off this chapter, we finish off with when things go wrong. Or what happens when you get older. On this slide, we see what happens when you get older. You know by now it's not good. Turns out respiratory system is like any other system. For example, when you get older, turns out... the tissues in your respiratory system organs become less elastic or more rigid, meaning they get stiff. This is why older individuals typically tend to get things like pneumonia. They're not moving gases in the ways they usually do. That might lead to you holding on to things like some bacteria and not being able to feel like you're totally catching your breath because your lungs are stiff. And if they're stiff, they're not going to expand. expand to their maximum capacity. You're not gonna be delivering as much oxygen as you used to. Not only do the organs get stiff, your walls of your chest get stiff as well. To become less pliable still means stiff again. And because of all this stiffness, again, your lungs won't expand. You'll actually be able to see decreased lung capacities. If I were to give you a spirometer and look at your spirogram. As an older individual, I will see decreased lung capacities because of all the stiffness in and around the lung. And you're not going to be able to move that much air. I'm going to see decreased vital capacities. And for some, your vital capacity, remember that's the amount of air you can move, that could decrease to by about 35% by you're 70 for some individuals. And remember, when you get old, your cells get old. And when you get old, cells like your macrophages get old and they don't work as well as they used to. Turns out, as you get older, your macrophages tend to have decreased activity. And when they have decreased activity, well, they're not going to remove things that don't belong, like possible microbes, which will lead to things like infections. That's why older individuals tend to get things like pneumonia more often. Or things like respiratory infections are more of a concern because their macrophages have decreased activity. They're not helping to fight that infection as well. So these are all different things that tend to happen when you get older. And to finish off, we talk about three last things that could go wrong. We could talk about infections, something called pulmonary edema. and the effects of smoking. These are three situations. Starting off with infections. You could get different types of infections, bronchitis, pneumonia. When you get these infections, these are a problem. Why? Why is pneumonia such a problem besides the fact that you have an infection? Well, that infection is restricting airflow. That infection is literally taking up room in your lungs. It's almost like it's causing an obstruction. So you'll see obstruct lung disease features in people when they're having certain infections like pneumonia. And not only are you decreasing airflow, turns out you're decreasing lung volumes. Not only is it obstructing pathways, those infections when that pneumonia and mucus builds up, it almost provides a restriction to the lungs also. So you might even see a combination of these two things. depending on the type of infection. And that infection literally builds a wall. So diffusion will likely occur at a less frequent or rapid rate. Why? Because that infection, again, is blocking the membranes of the cells. It's like a wall. It's hard for things to diffuse past it. So lots of features are possible when the lungs get infected. Decreased airflow, decreased lung volumes. and even decreased gas diffusion. And not only that, some infections destroy the lungs themselves. They'll destroy the membranes around the cells, and this will lead to irritation of the tissues. You'll lead to inflammation. And you'll see some other factors as well. You'll see increased mucus production and accumulation. That's why you get phlegmy when you're sick. You're just seeing the results of inflammation in the respiratory system. We're just talking about when things go wrong. Another thing that could go wrong is that you could get what's called a pulmonary edema. What's a pulmonary edema? In a pulmonary edema, this is when you have, again, buildup of fluid. But now this is a buildup of fluid in the interstitial spaces, in the spaces around the cells, in the alveoli. Think those super thin cells, those simple squamous epithelial cells, those alveolar cells. forming the alveoli, you could get fluid trapped around those cells. So think at the cellular level, tissue level, fluid in the tissue. That is pulmonary edema, and it's in the lung tissue itself. And like usual, this fluid is pretty much forming a wall, and it's going to be hard for the gases to diffuse through this wall of fluid. So this fluid buildup will stop diffusion. And if you do that, well, it'll feel like you're not breathing. So if you have a pulmonary edema, you're going to have some dyspnea. You're going to have some difficulty breathing. You're going to feel like you're not catching your breath, shorter breath. Why? Because this wall of fluid is blocking that gas exchange. And so even though you're taking in oxygen, you could still be breathing with a pulmonary edema. That's all this slide is talking about. But that gas, once it's inside, is not diffusing. So even though you're exchanging gases. With your breath, you're not exchanging the gases at the cell level because of that fluid buildup. And not only does it block the diffusion, again, it's a fluid buildup. It's going to block your lungs flexibility. It's not going to be able to expand to its maximum capacity. So those are some effects you'll see in someone with a pulmonary edema, fluid buildup. And then the last thing we talk about are smoking effects. We already know smoking is bad. You already know by now smoking leads to things like lung cancer. But there are other details to smoking that might convince you to stop if you are a smoker. For one, when you smoke, you're taking in smoke. And in smoke, there are bad chemicals. One type of chemical just in plain old smoke. Doesn't matter. If you set it on fire, there will be combustion and you will get something called carbon monoxide. It's a gas. It's an odorless gas, a colorless and odorless gas. And this gas is deadly. Why? Why is carbon monoxide so bad? You always hear about carbon monoxide when you hear about someone who died in their car when their exhaust fumes were on, or filling up the car. Or when you hear about a family that passed away and there was a problem with their AC. These are usually leaks in carbon monoxide. So how can carbon monoxide kill you? Well turns out it has to deal with the its affinity. Carbon monoxide has a great affinity. for hemoglobin meaning it could bind to hemoglobin really well and it turns out carbon monoxide binds to hemoglobin better than oxygen it could even displace oxygen to displace oxygen literally means you will knock it out the way so whenever you breathe in carbon monoxide it will push out any oxygen and take its place that's bad why turns out your body cannot use carbon monoxide. So when it takes oxygen's place, it's basically taking up room because your body can't use it. So you'll feel like you're breathing in and out because you will be. You'll be doing your ventilation, breathing in and out, but you're breathing in and out a gas you cannot use. That's why it's so deadly. You can't see it. It's colorless. You cannot detect it. It's odorless. And when you breathe it in, it pushes oxygen out of the way. That's how people die from this gas. They're inhaling a gas that their body can't use. So that's one reason not to smoke. You're literally putting in a gas that could kill you. And there are other problems with smoking. Turns out there are lots of chemicals in cigarettes. And some of these chemicals could do weird things. Some of these chemicals could do things like paralyze the cilia lining your respiratory tract. Remember cilia we saw in things like pseudo-stratified ciliated columnar epithelium, which you find in places like the trachea. Remember the cilia, the little hair-like structures, help to push things past the cell like mucus for you to cough up. Well, if you paralyze the cilia, they're not going to push things past the cell like mucus. Like mucus that might have trapped bacteria that you were going to cough up. And if you don't cough it up, well it will stain your lungs and possibly cause an infection. That's why smokers typically get more respiratory infections more often. For one, they've paralyzed their cilia that are helping to get rid of stuff. Not only that, some of the chemicals could even make your lungs less elastic. They'll make them stiff again. So being a smoker is almost like you fast forwarding to old age. You're stiffening the lungs. You're making it less elastic. and it won't fill up to its maximum capacity and you'll feel short of breath. That's why smokers kind of feel short of breath all the time. You're just seeing them have less elastic lung. And then we already mentioned earlier some of these chemicals in cigarettes can even lead to uncontrolled cell growth. It could lead to cancer. So these are just a few of the things that have a negative effect on your respiratory system. Things like old age where you'll get stiffening of lung tissue and chest tissue and smoking bringing in lots of chemicals that have negative effects so that's your respiratory system