[Music] hi everybody my name is andre and welcome back to med school eu today we are going to continue on with this lengthy topic of anatomy physiology of systems in humans and more specifically today we are going to talk about the respiratory system we'll begin the unit with anatomy of the respiratory system so we have a couple of labels to go through just anatomical labels here so beginning with the upper respiratory tract we got the nasal cavity up at the top so this is the nasal cavity next this little part right here at the back of the throat that's called the pharynx that's fairings going a little bit lower past the pharynx we got the larynx and in the larynx we've got our vocal cords so this is where the sound comes from that comes from the vocal cords in the larynx now going further down there's going to be a divide here between the upper respiratory tract and the lower respiratory tract so these all of these anatomical structures are part of the upper respiratory tract and going below down here to the trachea this is the trachea and anything below the trachea is the lower respiratory tract so splitting off from the trachea to the right lung and the left lung this big part right here is called the primary bronchi and past the the bronchi of course we've got here the lungs and we're going to go into further anatomy about the lungs because there's going to be further breakdowns and splitting of these tubes from the bronchi all the way down to the alveoli and that's what we are going to discuss in this one so here of course we got our trachea as you can see it's covered in cartilage and the the next is the bronchi which we have labeled already as you can see they're pretty much identical on both sides then this moves into terminal bronchial so that's the the smaller division here from the bronchus it becomes a terminal bronchiole and from terminal bronchial we go into respiratory bronchiole and finally this goes into the alveolar duct and from the alveolar duct we're gonna have these little grape-like structures called alve oli and gas exchange occurs in the alveoli and sporadically in the alveolar duct however all these other structures the bronchioles respiratory termin terminal and the bronchi the bronchus and the trachea there's going to be no gas exchange occurring only the alveoli and sometimes alveolar duct depending on the thickness of it now the structure that goes right underneath is not shown here but the structure that goes underneath the lungs is called the diaphragm and the diaphragm is responsible for contraction of the lungs so it's going to stimulate breathing as well as the intercostal muscles so the muscles that go in between here are called inter so intercostal muscles the one that goes that go between between the ribs and the diaphragm at the bottom are going to be responsible for inflating and deflating the lungs and we're going to discuss their primary functions in the next few slides as well so there are uh three more labels here so we got the plural cavity so there's going to be a space between the two plurals so the the outer plural is called the parietal the inner plural is called the visceral pleura and of course the space in between is going to be called pleural cavity so this is just a cavity space in between the two pleura so that's the general respiratory system anatomy so now we are going to talk a little bit about gas exchange as it occurs in the alve alveoli so for breathing in the gas is primarily going to be oxygen and the gas pressure here in the capillary is primarily going to be carbon dioxide so we're going to offload the carbon dioxide and we're going to load on the oxygen and the reason that's going to happen is because of partial gas pressures so the partial gas pressure of oxygen in the alveoli is going to be much greater than in the capillary therefore the net movement of gas is going to go to the capillary and this is just a phenomenon called diffusion where it goes from an area of high concentration to an area of lower concentration in this case we're talking about gases therefore we're going to refer to as partial pressure so higher partial pressure of gas is going to move over to the lower partial pressure of gas now the same thing occurs with the carbon dioxide the atmospheric carbon dioxide partial pressure is extremely low compared to the capillary carbon dioxide partial pressure because these capillaries are going to bring deoxygenated blood from the body and which will have metabolites and carbon dioxide so carbon dioxide is going to be taken up by the alveoli again through diffusion the same concept where it goes from an area of higher partial pressure to an area of lower partial pressure of carbon dioxide now the exact opposite occurs once these travel to cells so these are not alveoli anymore these are just cells of the body now cells of the body are going to have lots of carbon dioxide in high concentrations so there's going to be high partial pressure of carbon dioxide but they're going to have low oxygen so the whole purpose of the circulatory system is to deliver nutrients and oxygen to the cells so they can operate and do their primary functions so once the blood vessels are able to circulate from the lungs over to the cells again they're going to go through the heart then the entire respiratory system they're going to end up in various cells of the body and they're going to offload their high partial pressure of oxygen onto the cells because they're going to have low partial pressure of oxygen and they're going to uptake the high partial pressure of carbon dioxide again the same concept that occurs through diffusion now before we take a look at this chart right here there's another phenomenon i wanted to mention is that the right lung the right lobe of of the lung contains three lobes and the left side so the left lung contains two lobes so it's it's a little bit smaller it doesn't split up into as many lobes the right lung has three the left lung has two so that's another thing uh to just keep in mind and here with this chart we are going to discuss various structures that are involved within each of these anatomical positions that we discussed earlier so the trachea number of trachea there's only one trachea that splits off into two bronchi so for each side of the lung or each bronchus i should say is going to split off into thousands 48 000 of terminal bronchials and something very important happens here is that the trachea and the bronchus have cartilage these are they're going to have cartilage in in their structures in order to support that volume and the air that's coming in so they're going to have cartilage there they're also going to have goblet cells that will will produce mucus and they're going to be responsible to keep out any viruses or any bacteria that may enter the respiratory system they're going to keep out the flu the cold as we are we get in contact with the flu virus the coronaviruses and just the regular respiratory viruses that we get in the winter they are going to be caught up by these goblet cells and the cilia goblet cells and cilia they're responsible for creating mucus where all of these respiratory illnesses and all of these viruses are going to be caught up and the cilia so these are little projections the cilia are going to be pushing up up the wall down to the trachea and in reverse so that you can just cough it out or breathe it out without the virus attaching to receptors inside the lungs and causing an illness now another thing to know is the trachea the bronchus and the terminal bronchial have smooth muscle so this this means they could dilate they could stretch a little bit which involves the elastic tissue as well so up to the point of the terminal bronchiole they are going to have smooth muscle which could control how wide the airway is going to be so for example if you are out in a colder environment the smooth muscle is typically going to contract a little bit to create resistance for the air so the air is not going to pass as quickly and you are not going to get cold air entering the alveoli because that obviously could cause problems for the alveolar cells therefore in order to buffer that temperature of the air you're going to have smooth muscle they're going to contract and they're going to reduce the diameter of the trachea and the bronchus and something very similar happens with anaphylactic shock or an allergic reaction where the trachea and the bronchus the smooth muscles there are going to contract and they're gonna make a narrow airway and that's when problems occur uh with with breathing and anaphylactic shock so as you can see here as i mentioned previously the site of gas exchange so the exchange that occurs here and here in terms of the carbon dioxide and the oxygen only occurs in alveoli and the alveolar duct primarily in the alveoli however in some cases alveolar duct as as well there's going to be no gas exchange in any of the bronchioles or the bronchus or the trachea important thing to remember is that trachea and bronchus have goblet cells that produce mucus smooth muscle and cilia are going to be all the way down to the terminal bronchial but not the respiratory bronchioles and cartilage will only reside with the trachea and the bronchus so when we discuss the immune response we are going to talk about the goblet cells and the smooth muscle cells in greater detail next we have a quick slide about the gas content of the blood so you should be familiar with how carbon dioxide is going to be transported within the blood because for oxygen of course it's going to be loaded onto hemoglobin and then hemoglobin is going to be caring for oxygen molecules per one molecule of hemoglobin and there's going to be millions molecules of hemoglobin within each erythrocyte so that's typically how oxygen is going to be carried within the red blood cell however when when we have carbon dioxide inside circulatory system we're going to have a bit of a different story so first from the respiring cells so from our cells we're going to get carbon dioxide that will enter the erythrocyte five percent of carbon dioxide will be carried in solution meaning it's going to be carried in the plasma now the the rest the highlighted areas is is what's going to be important because the carbon dioxide is going to combine with water in some cases using an enzyme called carbonic anhydrase and and it's going to create a molecule of hydrogen carbonate so most of carbon dioxide is going to be transported as hydrogen carbonate which is this molecule right here hco3 minus 85 percent of the carbon dioxide will go there and 10 percent of the carbon dioxide will be converted to carbon amino hemoglobin which is simply when carbon dioxide combines with the hemoglobin within the erythrocytes so only about 10 percent will be carried the same as oxygen however the rest of the carbon dioxide most of it will be carried in the plasma as hydrogen carbonate so now we're going to talk about the physiology of respirations and we're going to begin with inspiration which is going to be inhaling so getting oxygen and air into our lungs so we are going to first make a couple of labels here so of course we got the diaphragm now this i this yellow structure right here this is more going to be like a zoom in of an alveoli so i'm just going to label it as alveolar pressure p alveolar so the gas pressure in the alveoli then the gas pressure that's going to be within the lung is called intrapulmonary pressure inside the pleural cavity we are going to have intrapleural pressure now the pressure difference between the intrapleural pressure and the pressure inside the lung is called transpulmonary pressure so these are all the important and also we got atmospheric so p atm atmospheric pressure so all of these are going to be involved in the breathing anatomy and the physiology of breathing now of course we have intercostal muscles that go around the side of the lungs and that's going to be the ones in between the ribs so let's go over some of the sequences of events that occur so we first are going to begin with the inspiratory muscles that are going to contract and that's going to be the diaphragm so the diaphragm the intercostal muscles are going to make the rib cage to push outward and up so the rib this is how we are going to create more volume within the lungs so we must remember that volume and pressure are inversely related so if we increase the volume we are going to decrease the pressure if we increase the pressure we're going to decrease the volume so what this does what the sequence this first sequence does is it increases volume because we are going to expand the lungs and when we increase volume we are going to decrease the pressure and we're going to decrease the pressure to the point where the atmospheric pressure is going to be above the pressure inside the lungs and ultimately the the pressure inside the alveoli therefore the air can simply flow through the fusion from the atmosphere inside the lung and into the alveoli because it's going to move from by the definition of diffusion it's going to move from the higher partial pressure of gas to lower partial pressure of gas so this what this uh what this really does the ultimate thing is that the intrapro plural pressure pip is going to decrease because our lung volume has increased so now because this has decreased number three the p atmospheric is going to be above p i p and we have air flows inside so that's that's typically how it occurs because as the gases flow into the lungs down its pressure gradient until that intrapulmonary pressure is zero so then by the end of it once we fully have inhaled the atmospheric pressure is going to equal to intrapulmonary pressure because of course the more air we get inside the more pressure it's going to create and eventually it's going to equate itself with the atmospheric pressure and you can no longer breathe any further you cannot breathe in any further you cannot take up more air now with expiration so breathing out we're going to have something pretty much the opposite occur so we're going to have the inspiratory muscles relax so the diaphragm and this is all due to the recoil of the coastal cartilages so if you stretch the cartilage of the rib cage it's obviously going to want to recoil back because it's got its elastic fibers and the elastic fibro fibers will naturally want to recoil back to its original form so that's going to create that pressure that tension that is going to counteract the pressure that is created by the diaphragm rising and the intercostal muscles contracting next we're going to have the thoracic volume or the thoracic cavity volume decrease meaning that it's going to increase the pressure and as soon as the p i p pressure is above the atmospheric pressure then obviously the air is going to flow out out into the atmosphere because it's going to move from higher pressure to lower pressure environment and again it's going to occur until finally the pip the intrapleural pressure is going to equate to atmospheric pressure and you can no longer breathe out any further and the final thing that i'm going to introduce you to is called a spirogram so this is basically just a measurement of lung volumes and lung capacities so what we have here is the general breathing rate if we are just breathing at a resting rate you're sitting down on your chair you're listening to this lecture your breathing is going to be the tidal volume it's only going to be about maybe 500 milliliters of of gas that's going to come in and out in and out and that's going to be labeled as tidal volume now the entire capacity of the lungs so how how much air we could possibly have inside the lungs if you fully breathe in and all the air that was already in there that's going to be called the total lung capacity now there's something called residual volume and residual volume is something you cannot breathe out of course if you were to breathe out all the air that's inside your lung your lung is going to collapse in on itself so there's always going to be some sort of a little bit of air and that's typically you see 1200 milliliters of of air inside the lungs that is constantly there even if you forcefully expire you're still gonna have that residual volume there and you cannot get rid of it unless you puncture it along and it flows out and at that point you're gonna have a collapsed lung and of course that's gonna create a lot of problems so that's the residual volume it's extremely important for our vital functions now the volume that you could breathe out and in addition with the residual volume is called functional residual capacity so that's the that's how much that's the uh expiratory reserve volume plus the residual volume so both of these together an expiratory reserve volume is how much air you could forcefully breathe out so if you're regularly breathing right now and watching this lecture try to breathe out as much as you can to the point where you can no longer breathe out anything else that's your expiratory reserve volume from the point of breathing out normally to the point of fully forcefully breathing out that's the expiratory reserve volume now if you add that together with the residual volume that makes up functional residual capacity that is labeled here next we're going to look at the inspiratory reserve volume so that's completely the opposite of the expiratory inspiratory reserve volume is when you are doing your tidal volume you're normally breathing and you normally breathe in however the rest that you can breathe in up to your full potential of breathing in that's going to be the inspiratory reserve volume now if you combine the expiratory reserve volume plus tidal volume plus inspiratory reserve volume so if you were to fully breathe in and then fully breathe out that's your vital capacity that's what's called vital capacity so all of these these three different capacities and four different types of volumes you should know by heart so if they are identified on a question you would not be struggling to to know what the question is really talking about so this concludes our lecture on the respiratory system in the next video we are going to discuss the diseases involved with the circulatory system as well as the respiratory system [Music] you