welcome back we're going to get into respiratory physiology here and talk about some respiratory variables that are related to exercise physiology so we're going to go through a basic review of some of the anatomy of the respiratory system and then we'll get into some of the exercise physiology principles as we move through this lecture so the functions of the respiratory system we know the primary purpose of the respiratory system is to deliver oxygen and remove CO2 from the tissue get that gas exchange to occur because metabolism is constantly producing metabolites and byproducts such as CO2 and hydrogen and we want to be able to transport that throughout the body so that we can exhale it get rid of it diffuse it whatever we need to new so that it doesn't change our pH within a localized environment we have a couple of terms here to be familiar with so pulmonary respiration pulmonary respiration is the delivery of o2 and the removal of CO2 through a process called ventilation which is just breathing that's the mechanical movement of air in and out of the lungs so it leads us to the question here what is cellular respiration big confusion that can happen when we're talking about respiration is thinking about the movement of o2 and CO2 but with cellular respiration that's the process of bioenergetics of converting a usable form of a food substrate into an energy that we can use for some type of work now when it comes to the respiratory system we can break all the processes down into two main parts we have ventilation and diffusion so ventilation is just the mechanical movement of air in and out of the lung so as I take a breath in and then I exhale that's just the process of ventilation just movement of air in and out of the lungs and then diffusion is the actual movement of the molecules so when we actually push the O2 into the blood so from the lungs into the blood and we get the CO2 out of the blood into the lungs for the exhalation so big thing to be familiar with as we're talking through the respiratory system is everything is going to function on some type of gradient whether that's a pressure gradient or a concentration gradient so when it comes to diffusion diffusion happens by way of a process called a concentration gradient so we're moving molecules from an area High concentration to an area of low concentration so as I take a breath in the concentration of oxygen in my lungs is high and it's higher than it is in the blood because the blood that's in my lungs that's coming from the right side of my heart is deoxygenated remember that's the blood that's coming back from my tissue that's already used the oxygen that was previously present so what we have now is high concentration in the lungs low concentration in the blood so the oxygen is going to move from high concentration to low concentration into the blood and then we send that blood back to the left side of the heart so that it can pump it out to the rest of the body again you can break your respiratory system down into two different zones so we have the conduction Zone in the respiratory zone conduction zone is this Pro this pathway right here kind of this upper respiratory tract and it serves as really just a passageway for air now what it needs to do is to actually filter the air and humidify the air before it gets down into the lower respiratory tree which is known as my respiratory zone so it says here we filter and humidify the air as it moves through the conducting Zone and by the time the air no matter the temperature or the humidity of the air that you breathe in by the time it gets to your respiratory zone down here at the alvioli where the gas exchange is going to occur the water or the air is fully saturated with water so it becomes a water vapor at that point and that creates the pressure that we need to drive the air the oxygen molecules across the Alvar membrane and into the blood and for that gas exchange to occur says at rest healthy humans usually breathe mostly through the nose this is one difference that uh we develop as we M as we mature so going from a stages of childhood and Adolescence children are typically mouth breathers so you'll actually see them breathe more through their mouth and then as we mature and get closer to adulthood then we start to become more of a nose breather that's one of the reasons you can determine respiratory distress and children is something that you can look for is called nasal flaring so if there's something that's going on in their respiratory system where they feel like it's difficult to breathe you'll see that the nostrils flare out that's flaring and that's an indication of respiratory distress now when we get lower in the respiratory tree so we get towards the bottom of the lungs we get the respiratory zone here so the respiratory zone is where the alvioli are located these are little balloon like sacks that as you breathe in the air comes all the way down your respiratory tree it gives to the alviola it makes that little balloon like Sac inflate so the alvioli inflate a little bit it creates a pressure within the Ola and it drives that oxygen across the membrane and into the blood so it's estimated that we have about the total surface area of 60 to 80 M squared of Alvi surface area within the lung tissue that is huge that's estimated that if we take the lungs out of the body and dissect everything out and Lay It All Out flat we have the equivalent surface area for gas exchange that would cover a tennis cord so think about that that's how much surface area present within your right and your left lungs combined to be able to allow gas exchange to occur this is one of the many reasons that the respiratory system is very rarely a limiting factor in exercise performance so it says here diffusion occurs very rapidly because the Alvar wall is extremely thin it's very very thin it's estimated that you take the thickness of a red blood cell and that's how thick your respiratory membrane is there and that's good for us because if this is side one so the inside of my lungs here and this is side two and it's just separated by this very very thin membrane then the gases don't have to travel very far to get from one side to the other so the rate of diffusion can be extremely fast because we don't have to send that gas very far however because the alveoli is so thin what could you think of might be issue with the alveolar sack one of the issues that we might be concerned with is damage because they're so thin they're fragile so that's the one of the reasons why pollutants and things that you breathe in and all of that stuff can cause damage all the way down at the Alvar sack is because they're so fragile and so thin but um we have things like surfactant at the level of the alvioli to help with the pressures on the alveolar sack to keep keep those alveolar sacks inflated so that they don't collapse on one another and create damage that way and when you break everything down in the respiratory tree so we've got the conducting Zone here you can see is this upper respiratory tract we could almost really just draw this across here and all of this is going to be your uh conducting Zone this is going to be your respiratory zone on the lower side where the gas exchange and everything is occurring so how do we get something called total minute ventilation so minute ventilation comes from how much gas is exchanged times or multiplied by how many times you breathe every minute but one thing that we have to account for is something called Dead Space air so believe it or not every time you take a breath in all of your respiratory tree doesn't move air so you may have branches within the respiratory tree that as I take a breath in when I take that breath in somewhere in my respiratory tree there may have been some air that was just quote unquote stagnant that didn't move with that breath so that's what we call Dead Space air you have anatomical Dead Space which is in the Airways leading down to your alvioli so in that respiratory tree and then you have Alvar Dead Space air so the little balloon like sacks not every single one of those is going to inflate with every breath in and deflate with every breath out so in between some of those breaths you'll have alvioli that just hold air within them and that's considered Dead Space air over here where I put the Red X so you have something called mechanical dead space but we're not going to stress too much on mechanical Dead Space just very briefly what that is is if somebody saying a clinical setting maybe in a hospital and they're hooked up to a ventilator within that ventilator machine there's going to be air that doesn't move with every inhale and exhale so that's mechanical Dead Space there the mechanics of breathing are broken down into inspiration and expiration so inspiration big thing to remember here is an active process what we mean by an active process is that it requires the contractions of muscles so we have muscles that are going to be contracting and changing shape of the thoracic cavity and what that does is it changes the pressures within the thoracic cavity and it forces air to be sucked down into the lungs so it's an active process because of the muscle contraction which involves the diaphragm and the intercostal muscles which we'll see on a slide in just a second so the diaphragm is this muscle that's separating your thoracic cavity from your abdominal cavity and it sits in this concave position and as you activate the diaphragm what it does is it moves down towards the abdominal cavity just a little bit and that allows us to open up the size of the ch of the thoracic cavity by changing the size of the thoracic cavity you're reducing the pressure in there because we take the same chamber and we make it bigger the volume of molecules and substances inside your thoracic cavity stays the same so the pressure within the chamber gets smaller because we made it bigger remember everything in respiration is going to happen on a pressure or a concentration gradient so now because we've dropped the pressure in the thoracic cavity the pressure in the atmosphere iic air is larger than it is in my thoracic cavity that's going to force air to come down and into my lungs expiration is a little bit different expiration is a passive process so big differentiation between the two there passive process means it doesn't require the activation of muscle tissue so what happens during inspiration we contract the muscles we pull the ribs up and out we pull the sternum up and out a little bit that opens the thoracic cavity now during expiration all of those muscles are going to relax and it lets the rib cage and the sternum come back down and in and that fores air to come up and out of the lungs there so here is just an example of the muscles of inspiration and the muscles of expiration so big muscles of inspiration right here the intercostals and the diaphragm those are the primary ones that we talk about when you go into exercise and um you need a increase in your respiratory rate will recruit things called accessory muscles which could be your scalings or your sternomastoid muscle there now on expiration the muscles that are involved is we're going to relax our intercostals we're going to relax the obliques the transverse abdominus and the rectus abdominis muscles and let everything fall back into place since we're decreasing since we're allowing the ribs to come back down and in the sternum comes back down and in what we're doing now is we're decreasing the size of the thoracic cavity which increases the pressure within the thoracic cavity so now I have a higher pressure in my thoracic cavity than the atmospheric pressure so it forces air to come up and out during exhalation now when we talk about a little bit more on inspiration and expiration diaphragm is the most important muscle of inspiration so when it contracts what it does like I said earlier it's in a concave position it contracts and it pushes down on the abdominal contents and pushes down into the abdominal cavity just a little bit and that causes us to actually change the pressures within the thoracic cavity a big unique Factor about the diaphragm muscle is it's non-f fatigable so think about that no matter what state you're in whether you're uh in a physically inactive State whether you're at a recovery State whether you're sleeping at night whether you're during exercise 24 hours a day you're doing something that requires us to actually go through the process of inhalation and expiration so when we go through that process it's definitely beneficial for us that the main muscle uh of inspiration is nonf fatigable so we still considered a muscle because it's interated by nerves and uh specific it's interated by the Fric nerve but what happens with the nerves is because of the in uh structure of the diaphragm muscle and the contents has got different fibers within it they're nonf fatigable throughout the day now we said earlier we have the accessory muscles that'll be employed during exercise especially heavy exercise to help you kind of force that rib cage up and out so that we can get inspiration to happen expiration we said is passive at rest but when you go into exercise and you're doing heavy exercise we can use accessory muscles to contract so we can use the rectus abdominis and the internal obliques to actually contract and pull the rib cage back down and in and it forcefully exhale to get rid of that excess CO2 that's being produced during exercise now these are the mechanics of breathing and what we end up seeing right here this is your diaphragm so we're going to draw over this so you can see it a little bit better there's a diaphragm diaphragm separating the thoracic cavity from the abdominal cavity and what happens is at a resting state the number of molecules this is representing the concentration of molecules and the atmospheric air and the concentration of molecules within your respiratory tree so at a resting state in other words during uh in between inspiration and expiration the molecules are in balance with each other but as I contract and I forc this diaphragm to go down which you see right here you can see that I'm making the size of the thoracic cavity much larger than it was over here in between breasts so I'm reducing the pressure within my respiratory tree here so now you can see that the concentration of molecules within the lungs is much lower than the concentration of molecules in the atmospheric air what that does is it forces all these molecules of air to be sucked like a vacuum down into your lungs and it fills your respiratory tree up with the gases there so now in between inspiration and expiration again you can see that uh the concentration of molecules is equal to the atmospheric air and then during expiration what I do is I let my diaphragm relax so I bring the size of the thoracic cavity back down small again my ribs as compared to this picture over here my ribs have moved back down and in so what that does now what you see here is I have a very high concentration of molecules within my lungs and that's more concentrated than it is in the atmospheric air so we're going to move it from an area of high to low and that forces air to come up and out of the lungs during expiration to equal the pressures back out that whole process right there is what we refer to as bulk flow so it's following the principle of bulk flow meaning it's moving from an area of high concentration to low concentration there now maintaining your pressure differences during breathing is very important so at a resting state you can see right here before we take a breath in so this is after you've exhaled and we're about to take a breath in we can see the inop pulmonic pressure and atmospheric pressure equal they're both 760 mm of mercury of pressure now see here the diaphragm moves down it opens the thoracic cavity up what that does is it drops the pressure inside your lungs intrapulmonic pressure to about 758 millim of mercury pressure notice that it's not a very big difference so atmospheric pressure is only 760 millim of mercury of pressure so we have a 2 mm Mercury pressure difference here but that's enough to create a vacuum to pull air down into the lungs during inspiration now during expiration we see the diaphragm comes back up ribs come back down and in so we decrease the size of the thoracic cavity here which changes the pressure up to 763 so that's higher than atmospheric pressure so we're going to move from an area of high concentration here to an area of low concentration so air comes up and out of the lungs like that one other pressure to pay attention to is intra plural pressure so in plural pressure is right here so you have this little plural sack that surrounds your lungs and what the plural intra plural pressure does is it makes sure that that sack that plural sack stays off or away from the lung tissue so that they're separated from one another if you've ever heard the terms of a collapsed lung what happens is the pressure between these two the surface of the lungs and this plural membrane here drops to to equal to one another so what happens is the plural sack collapses down on the lungs and it doesn't allow the lungs to open up and expand properly like they're supposed to and that's what we consider a collapse lung going into pulmonary diffusion this is when we get the exchange of o2 and CO2 uh between the lungs and the blood this right here is the most important factor of what is needed for pulmonary diffusion to occur we have to to have a concentration gradient present for the diffusion to happen because we have to move from an area of high to an area of low so we need that to occur so that we can replenish the oxygen in the blood and we can get rid of the CO2 that was in the veins that's coming back from all of our tissue gets to the right side of the heart we move that blood over to the lungs so that we can exchange it into the lungs the CO2 and get that out of the body but you have to absolutely have to have concentration gradient present for all of these things to occur here's a me respiratory membrane that I was talking about earlier if you compare that to the thickness of a red blood cell you can see that the respiratory membrane is about the same thickness as a red blood cell which allows diffusion of o2 and CO2 to happen very quickly so we move uh oxygen you can see here coming from the alvioli we get diffusion of o2 from the lungs into the blood so that it can attach to the hemoglobin on the red blood cell and then we release the CO2 so that it can go back over to the Alvi get into the lung so that it's ready to be exhaled so this is what the alvioli look like this is that balloon like sack and as it inflates you can see here it's surrounded by these capillaries all these red blood vessels are your capillaries so the capillaries are present so that as you inflate the Alvi with air we have a high High concentration so this is during inspiration we have a high concentration of o2 in the Alvi and the blood that's circulating through those capillaries is low O2 through here so we're going to move everything from inside the lungs into that through that capillary into the blood get O2 attached to the hemoglobin on the red blood cell move all of that back to the left ventricle of the heart so the left ventricle can pump it out through the systemic circuit now partial pressures are very interesting partial pressures are this idea that every gas in the air that we breathe has its own pressure that if you take all of the individual pressures and add them up together that's what atmospheric pressure total pressure comes from so that's the principle here of Dalton's law so Dalton's law says that the total pressure is this PT right here equals total pressure erase that total pressure so total pressure equals the sum of all the independent pressures of gases within the atmospheric air so each pressure exerts its own individual pressure within the total pressure of the air that we live in in the environment so standard atmospher pressure at CA level is roughly about 760 mm of mercury of pressure so the way that we determine the partial pressure of every individual gas within the atmospheric pressure is we look at the percentage of the gas within the air so it's estimated that nitrogen makes up about 79.0 4% of the normal air within the environment oxygen makes up about 20.93% in carbon Dio oxide very small percentage here of 0.03% so the way the way that we determine our partial pressure is we take atmospheric air pressure so at sea level that atmospheric pressure is about 760 millim of mercury we multiply that by the percentage of the contribution of that gas so that 79.0 4% expressed as a decimal point is 0.794 do that math right here and we say that nitrogen contributes 6.7 mm of mercury of pressure to that 760 total oxygen do the mass 760 multiplied by the 20.93% we get oxygen has a partial pressure of 159.000 and then CO2 during the math contributes about 0.2 mm of mercur pressure so if we take the 6.7 the 15 9.1 and the 0.2 and add all of that up together we get the 760 mm of mercur of pressure that makes up our atmospheric air at sea level partial pressures are very important to understand because the individual pressure of the gas is what's driving that gas to one side or another of the membrane of the capillary or the respiratory membrane so again you come back and say that different difference in pressure is the most important the most critical Factor when it comes to gas exchange and respiration here you can see here if we start at the left ventricle the gas or the blood as it leaves the left ventricle has a partial pressure of oxygen of about 100 millimeters of mercury and pco2 the partial pressure of carbon dioxide is about 40 so relatively low now as the gas comes through or the blood comes through our arteries and arterials it gets to the capillaries here and we have gas exchange that occurs so we get O2 that leaves the blood and goes into the body cells CO2 that was a byproduct from metabolism leaves the body cells and comes into the blood now as that blood leaves the capillaries and gets into the veins here you see that because we exchange so much oxygen into our tissues from the blood into our tissues the partial pressure of the gas gas drops to 40 because the concentration of o2 is low in the veins because we use so much of it in our body cells and because we pushed uh CO2 from the body cells into the blood it brought our pco2 up from 40 to 46 so we bring all of that blood back to the right side of the heart right side of the heart pumps it over to the lungs as the blood gets to the lungs P2 is still 40 pco2 is still 40 six same as it was when it entered the veins there so now I'm going to take a breath in I fill my lungs up with air so I have a high concentration of oxygen here and a low concentration of CO2 during inspiration because of that I'm going to move everything from an area of high to low so I'm going to take the air oxygen here is 100 and it's 40 when it got back to the lungs so what we do is move from high to low so I'm moving the oxygen from the lungs into the blood bringing my po2 back up to 100 and the pco2 is 46 in the blood coming back to the lungs so it's higher than it is inside the lungs excuse me so I'm going to move the air from an area of high concentration in the blood to an area of low concentration inside the lungs so now I can exhale that CO2 can bring my P CO2 back down send that blood back to the left atrium and left ventricle and I'm ready to send this through the systemic circuit all over again so you can see here definitely now from a numerical standpoint that the concentration gradients and the pressure gradi gradients are what's driving everything to happen within your respiratory system now fixed law of diffusion explains everything about how we diffuse our gases across the membrane so what this says right here is the volume of gas diffused is proportional to surface area so we'll write it up here a equals surface area D here equals the diffusion coefficient and then this variable right here here P1 minus P2 is the difference in pressures from one side of the membrane to the other and then down here on the bottom of the formula T is representing the thickness of the respiratory or the blood vessel membrane all right so let's talk about this formula this is a very important formula to be familiar with and how gas exchange occurs so what it's telling you is the volume of gas diffused is equal to or proportional to surface area it's equal to all of these VAR Ables are on the top the numerator of the formula it's equal to or proportional to the diffusion coefficient and it's equal to or proportional to the difference in pressures however the volume of gas diffused is inversely proportional to the thickness of the membrane all right so let's look at this picture over here to try and explain this so let's talk about the numerator variables first the greater surface area that I have represented right here all this shaded area here is surface area so the greater surface area I have to be able to exchange gas across the membrane the more gases I can exchange if my Surface area was only about the size of my finger here that's not much area for me to uh be able to make contact with the gases and force the gases to go across but if the surface area is a size of my hand here now I have a greater area for the gases to be exchanged across the membrane now when it comes to the diffusion coefficient we won't worry too much about the variable D here that's diffusion coefficient because that's not going to change that much even the only thing that really changes diffusion coefficient is the temperature um so we won't talk too much about it but difference in pressure this variable here P1 minus P2 if I increase the difference in the pressures from one side to another so let's say the pressure difference here on or the pressure on side one is 100 millimeters of mercury of pressure and the pressure on side two is 60 millimet of mercury of pressure that only gives me about 40 millimeters of mercury of pressure difference because we take a 100 minus our 60 and that leaves us with 40 millim of mercury of pressure so that's about 40 millim of mercury of pressure that's pushing the gases from one side to the other however if I change this and say that the pressure on this side is 20 millime of mercury of pressure now I have 100 minus 20 that gives me 80 millim of mercury of pressure to push the gases across the respiratory membrane so the greater the pressure pressure difference the more volume of gas we can diffuse the reason that the volume of gas diffused is inversely proportional to the thickness of the membrane let's get rid of this here is this is representing the thickness of the respiratory membrane right here if I increase the thickness of the membrane that's a further distance that the gas has to travel for instance oxygen has to travel a further distance from one side to the other so if the membrane is only this thick doesn't have to travel very far to get from this side to this side but if the membrane is this thick it has to travel all the way through this membrane to get to the other side so it's going to slow everything down which reduces the volume of gases that are being fused there now looking at oxygen transport we carry oxygen in the blood in two ways so it's going to be dissolved in plasma which represents about 2% of the oxygen transportation and then it's going to be bound to hemoglobin so that represents about 98% of the oxygen that's being transported in the blood so the primary way if you were asked what's the primary way that we transport oxygen in the body it's going to be bound to hemoglobin when we talk about uh hemoglobin saturation you have something you've probably seen these before if you've ever been to the doctor at the hospital we have something called puls oximeters and these are the little clamps that they put on the end of your finger it has a red light in it and it lights your finger up red and all of that stuff but what it does is it checks your pulse and it also checks your O2 saturation within the blood so what we should see when they put that on your finger is a number somewhere roughly around 98% what that means is your hemoglobin is 98% saturated with oxygen that's more than any physiological demand you can place on the body so say I go do this big exercise session and everything else and I start to breathe really hard your natural thought is your thinking golly I need more oxygen but that's actually not the case we have more oxygen in the body than what we can place a demand through any physiology and we can supply that demand because we're 98% saturated on our hemoglobin remember every red blood cell can uh says here each hemoglobin molecule combine four molecules of o2 and we have 250 million molecules of hemoglobin on every red blood cell so every red blood cell can carry one billion with a B one billion molecules of oxygen and every one of those hemoglobin and from all the red blood cells in your body are 98% saturated with oxygen so that is an astronomical amount of oxygen that we carry throughout the body um on a daily basis and every breath that we take so it says here the oxygen carrying capacity is very seldom uh a limiting factor when it comes to exercise performance how do we carry CO2 in the body uh three different ways here we have about 7 to 10% that's dissolved in the plasma and that's where your partial pressure of CO2 comes from we have about 20 to 30 or 20 to 33% it says here bound to your hemoglobin which is called a carboxy hemoglobin and then we have our third mechanism which is the primary way here 60 to 70% is transported as a bicarbonate ion so where bicarbonate ions come from is as CO2 is produced and it gets out of the metabolic tissue it combines with water and when you combine Co to with water you get something called carbonic acid and the body is very just naturally built to diffuse and and dilute these acids within the body so we break them down very quickly so almost immediately as carbonic acid is made we disassociate it so what happens with carbonic acid as we can see right here CO2 binds with water it becomes carbonic acid so you can see here that we have this hydrogen there now what we do is we're going to disassociate that hydrogen we're going to break that acid down and when we break it down we get a free floating hydrogen and we get a bicarbonate ion so we'll transport that bicarbonate ion back and we get rid of it and then the hydrogen what the hydrogen can end up doing is it can stimulate your chemo receptors and your chemo receptors are going to sense that information and they're going to send the information to the respiratory zone in your brain and then that's going to trigger a response to increase your respiratory rate so that it makes sure that we can get rid of all these byproducts and it doesn't change your pH we've mentioned this variable before avo2 difference which is the difference in the oxygen content of the blood between the arteries and the veins so what it does is it represents how much O2 was extracted at the level of the capillaries as the blood pass through the tissues comparing a resting state here we have have about 20 MLS of o2 in the blood per 100 milliliters of blood as the blood exits the tissue if we measure the O2 content in the blood in the veins we'd see that it drops to about 15 to 16 so what we say at a resting state is our avo2 difference is roughly about four to 5 milliliters of o2 per 100 milliliters of blood so where that comes from is we're taking the difference between the arteries and the veins so we have 20 coming from the arteries we drop it to 15 in the veins 20 minus 15 leaves us with the 5 MLS of o2 that we see right here so avo2 difference is a very intriguing variable when it comes to exercise physiology to see how effective and how efficient you are at exchanging your gases at the level of the tissue compare avo2 difference here at maximal EX ex size we still have the same that we have at rest in the arteries at 20 MLS per of o2 per 100 of blood but notice during the veins this drops all the way down to 5 MLS of o2 per 100 milliliters so we take the 20 minus the 5 and we see that that's going to leave us with the 15 that you see right here so avo2 difference during exercise is going to go up what that tells us is during exercise we're extracting more O2 out of the blood as it passes through the tissues and the capillaries and gas exchanges occurring what changes with exercise with your respiration so one you're going to see changes in breathing frequency and you're going to see changes in breathing depth now I'll ask you a question which one of these do you think is going to change more so you'll notice that exercise places a very large Demand on your respiratory system so as you go into exercise and your respiratory rate and your respiratory depth is increasing which one of those is going to change more and Supply more of the demand hopefully you can say that breathing frequency is going to change more than breathing depth I'm limited on how much my thoracic cavity's depth can change so my ribs move up and out my sternum moves up and out I'm limited on how much those can actually move so I can increase my respiratory rate your breathing frequency more than I can increase my breathing depth so when it comes to exercise your breathing frequency your respiratory rate is going to be the primary factor that's actually leading to supplying that demand why are these important is because we have to maintain oxygen supply to the tissue we have to get rid of CO2 and we have to maintain our pH within that localized environment in the tissue so we control our breathing by way of a lot of different mechanisms so your voluntary control so if I tell myself I need to increase my respiratory rate that information that signal is going to come from your cerebral cortex it's going to send an information down to your respiratory centers and that's going to cause an increase in the stimulation to the respiratory muscles and increase your respiratory rate chemical changes in the environment out in your periphery are going to stimulate chemo receptors so we have chemo receptors that are primarily located in the aortic Arch and then the cored arteries arteries I can spell arteries so the chemo receptors located primarily in those two locations are going to be sensing any change in the chemical environment of the blood as the blood is pumped out of your left ventricle and into your systemic circuit so once the chemical environment of that blood changes and say it has a higher concentration of hydrogen within it then that hydrogen is going to stimulate the chemo receptors chemo receptors are going to send information to the respiratory centers and say hey I need you to pick up the respiratory rate because I've got a change in my pH hydrogen's going to change your pH towards acidity so the chemo receptors are telling your respiratory centers look man your blood is moving towards the acidic environment that can damage your tissue as in organs and other structures in the body such as proteins so I need you to be able to increase your respiratory rate let's get rid of that hydrogen and that CO2 and then we have something called our lung receptors so these are systemic receptors out in the lungs so you have two different types of systemic receptors you have stretch receptors and then you also have something called irritant receptors so irritant receptors are what's making you sneeze so as you breathe in and say pollen you're definitely susceptible to it here in south Mississippi um pollen gets in the air allergies are triggered it's going to stimulate an irritant receptor which means that it's irritating your respiratory system and that causes you to sneeze so that we can try and force that irritant out of the respiratory tree stretch receptors are really interesting in how they work so you have systemic stretch re receptors located in your lungs and as I take a breath in they give me feedback to my respiratory Center that allows me to gain information about how much my lungs have moved what's your inflation what's the size of my thoracic cavity and all those things because all of those structures are going to stretch as you take an inhale one thing that they'll do is they'll try to protect you from over over inhaling and over stretching your lung tissue so if I take this Max inhale and I inhale too much and I stretch too far I'm going to stimulate we write it here stimulate the stretch receptors and what that does I don't know if you've ever experienced this you'll definitely experience it if the temperature ever gets cold here outside but when the air temperature is cold and you take a big breath in a lot of times you'll end up coughing and the reason for that is because lung tissue is a little bit stiff because of the ambient temperature and all those factors and you're breathing in some cold air so when you take that breath in and you stretch and you do a little bit of an over stretch there it stimulates the stretch receptors the stretch receptors send an immediate reflex response back to your lung tissue and your respiratory muscles and it causes you to cough so that you bring everything back down and in think about it when you cough you're flexing the abdominal muscles and the intercostals because you're bringing your rib cage back down and in so you stimulate those stretch receptors and it causes the cough reflex which is also known as the hering [Music] Brewer reflex so the hering bre hering Brewer reflex is helping to prevent you from overstretching your lung tissue now look at the this is just kind of details and verbal description of everything on the previous slide we talked about the chemo receptors and the chemical changes in the body the chemo receptors located in the aortic Arch and the cored arteries and they send that information to the respiratory centers and then we have the stretch receptors that are in the lungs in the alvioli and in your bronchial tree that protect you from overstretching you also have the ability to consciously so voluntarily control your respiratory rate so if I'm thinking about it and I tell myself I need to increase my respiratory rate I can do that so you're purposely breathing more rapidly and more deeply to be able to increase that ventilatory process pulmonary ventilation is a variable represented right here by V and it's the product of tital volume and your resp rate so we can see here we're taking tital volume and multiplying it by how many breaths you take per minute what that does is this is the respiratory equivalent of cardiac output remember cardiac output is stroke volume how much uh fluid is pumped per contraction multiplied by how many times you contract in a minute ventilatory or pulmonary ventilation here is how much air is moving per breath your tital volume multiplied by how many times do you breathe per minute so ventilation is going to change as you go into exercise based on different phases you've got phase one immediately when you start exercising you're going to see an increase in ventilation as it says right here phase one is that initial increase in ventilation that happens because of the change in your posture of your body as you move the body it changes the pressures in my thoracic cavity and that's going to force air to move in and out now phase two is be because you're seeing changes in temperature and stimulating your chemo receptors so as you continue to exercise metabolism is producing the CO2 and the hydrogen the CO2 and the hydrogen are then stimulating your chemo receptors like we said earlier sending that information back to your respiratory centers and telling your respiratory Center to increase the respiratory rate and the depth of your breathing so we get rid of those byproducts right there and then after exercise ventilation remains elevated because we have to bring our pH temperature and CO2 all back down into balance so that we can get our metabolism back under control and we can maintain everything relatively constant inside the body so comparing light exercise to moderate to heavy exercise here this is what happens with pulmonary ventilation light exercise we see that it increases pulmonary ventilation and we recover very quickly moderate exercise we get a little bit greater of an increase in V pulmonary ventilation and it takes us a little bit longer to come back down to rest and then heavy exercise we get a big spike in pulmonary ventilation and it takes us even longer to come back down to a resting state and get everything being back regulated under control the ventilatory equivalent is a variable that's used in exercise physiology to tell how effective and how efficient are you at supplying the demand so what we're going to do is take the variable we were just looking at the pulmonary ventilation and create a ratio as compared to how much oxygen was presented to the tissue so what this is telling us right now is we're taking the amount of a air that's moved every minute and dividing that by V2 how much oxygen was extracted out of that air uh every minute and what that tells us is how well are you matching the body's need for oxygen are you supplying the demand that exercise has placed on the body and then the last variable here that we'll talk about with exercise physiology before moving on is something called ventilatory breakpoint or what I like to call ventilatory threshold so ventilatory threshold is a point in exercise when the arobic metabolism that go all the way back to unit one in bioenergetics the kreb cycle and the electron transport chain your aerobic processes at a certain point in exercise when you get to a high enough intensity your aerobic metabolism can't keep up with the energetic Demand anymore remember that in unit one we talked about it with lactate threshold so at that point when aerobic metabolism can't keep up with the Demand anymore we have to switch back into anerobic P Pathways so when we switch back into anerobic glycolysis we're producing an excessive amount of hydrogen remember the byproduct of Anor robic glycolysis is perate perate is going to be converted into lactate or we shuttle perate into the CB cycle as a cetal COA try try to tie everything back together from unit one material here so at about 60 to 70% of your V2 Max your aerobic pathway says look I can't keep up with the energy Demand anymore so I've got to switch back into anerobic metabolism because I need to break down those immediate fuel sources the carbs uh the glucose and the glycogen and the phosphagens very quickly so that I can get energy to supply this high-intensity demand because because of that I'm going to produce an excessive amount of hydrogen and an excessive amount of CO2 since I'm producing more hydrogen and CO2 that I can buffer out what those are going to do is they're going to stimulate my chemo receptors now the chemo receptors are stimulated it's going to cause me to increase my respiratory rate and my respiratory depth to try and get rid of that excess stuff what that's called This is creating something known as the blowoff effect of exercise where I'm producing so much CO2 and so much hydrogen my body says look you need to get rid of this stuff because you're changing your pH so I'm going to increase my respiratory rate and create this excess blowoff I'm going to blow off all this extra amount of hydrogen and CO2 and try and get rid of it the way that you identify this time point in exercise like we said it's usually going to happen somewhere around 60 to 70% of V to Max or Max Capacity for most people but the way that we identify it is looking for a disproportionate increase in pulmonary ventilation as compared to oxygen consumption as compared uh to without a concent and increase in ventilatory equivalent for carbon dioxide so that sounds a little bit confusing but let's look at it right here so V2 and vco2 or V2 and V2 you can look at it in two different ways these up here are the ventilatory equivalent so we're looking at V2 as compared to V2 up here so we'll talk about these first what you end up seeing here is this point in exercise where there's a crossover between V2 and be2 what we're seeing right now is there's a dis proportionate increase in beo2 the ventilatory equivalent of oxygen as compared to the ventilatory equivalent of C CO2 and we see the same thing here V2 we have a disproportionate increase in V2 there where those cross over with each other is known as the ventilatory threshold now you can also use V2 and vco2 and what you're looking for here now is when the volume of carbon oxide produced becomes larger than the volume of oxygen consumed so we can see here the line in yellow we have this increase in V2 where is V or vco2 where V2 stays on this linear path we can see that here as well we have V2 that's increasing but then all of a sudden we have V vco2 disproportionately increase as compared to V2 so this is representing that time point where we have to switch back into Anor robic metabolism now look at this comparing trained versus untrained what do you notice the trained subject one can go a lot longer into an exercise test so this was a test that we did in a trained subject and an untrained subject where we put them on a treadmill and every couple of minutes we increased their speed and their incline on the treadmill trained subject could go out to about 15 minutes in the exercise test where the untrained subject lasted only about 6 minutes but you'll notice that the trained subject was able to push this ventilatory threshold to about 85% of their Max Capacity what that means is they could exercise all the way up to 85% of their Max Capacity and Supply that energetic Demand with aerobic metabolism they didn't have to switch back into anerobic metabolism until they went from about 85% all the way to 100% of their Max capacity compare that with the untrained subject the untrained subject had to switch back into Anor robic metabolism at about 30% of their Max Capacity that is extremely poor meaning that their aerobic metabolism was only able to supply the energetic demand for about two minutes in that exercise test that we did and you see the same results here no matter how you graph it with your variable so about 85% uh Max Capacity the aerobic metabolism could Supply the demand and the trained versus about 30% of Max Capacity and the untrained so very very we'll write that very very poor cardiorespiratory Fitness in the untrained individual on that exercise test so respiratory limits to perform performance can your respiratory system limit performance we've already said that respiratory system and the diffusion and oxygen and all of those things are very seldomly a limiting factor in performance however when it comes to the very highly Elite trained individual the respiratory system can potentially become a limiting perfor in performance in that aspect the reason for that is your ventilatory muscles are are very fatigue resistance especially the diaphragm however you take the highly trained or the elite athlete they can exercise at such a high intensity for a prolonged duration that they could get to the point where the respiratory muscles especially the accessory muscles become fatigued at that point so in that case then respiratory uh system could limit performance but really for everybody else in general population uh recreational athletes even just your typical uh athletes on a daily basis are not going to experience a limiting factor when it comes to Performance from the respiratory system diffusion is very rarely a limiting factor as long as there's not an underlying concern so if we had something underlying within the respiratory system such as COPD COPD is a destruction is comes from the destruction of the alvioli down in the respiratory zone in your lungs so when you get the destruction of the alvioli they're not inflating and deflating like they're supposed to so we don't get the amount of pressure difference there to drive the oxygen across the membrane and into the blood so because there's an underlying concern there that could create a limitation when it comes to Performance but as long as there's not an underlying concern like COPD or asthma chronic bronchitis or anything like that osma then we don't really have anything to worry about that's going to limit our performance in exercise have you ever been exercising and you get that sharp pain right here in your side typically right here around your rib cage so a lot of people call that the stitch in the side as you're exercising what's typically causing that is as you're exercising you'll notice that you don't get this at the beginning of exercises after you've been exercising for a little while so what happens is you've been exercising for a while and we need to shunt blood away from the core and get it to your exercising tissue because that's the active tissue that's Contracting during the exercise performance so because we're pulling blood away from the core and we're sending it out to the active muscle tissue it creates a state of an esea the lack of oxygenated blood in those respiratory muscles that can lead to a muscle spasm in the diaphragm or the intercostal muscles and when you get those muscle spasms in the inter costal muscles you have these paranal ligaments that are in this viscera down here in your thoracic cavity and when the muscle SP or when the intercostal muscles go through this spasm it pulls on those paranal ligaments and when you pull on the paranal ligaments it's actually going to pull on the VIS and on the diaphragm so now what you'll notice next time you get a stitch in your side is you really feel it when your foot hits the ground so when you get into that foot strike phase of your gate cycle when your foot hits the ground it pulls that paranal ligament and that's that sharp pain that you feel as it's pulling on your diaphragm ACSM the American College of sports medicine recommendation for getting rid of this is to apply pressure Bend forward and take deep breaths we're going to tie this into unit two remember in unit two we talked about the Gogi tendon organs so GTO are responsible for prot ing you from too much tension within the tendons so they send that information to the spinal column sends an inhibitory signal back to the muscle and makes that muscle relax so the reason that we say apply pressure Bend forward and breathe deeply is it puts a lot of tension on the tendons we stimulate GTO GTO send an inhibitory signal back to these muscles and make that muscle spasm stop it's an inhibitory signal you can also accomplish this a more recent recommendation is by standing up straight so standing up straight roll your shoulders back put your hands up above your head and take deep breaths so you actually accomplish the same thing as squeezing applying pressure bending forward and breathing deeply but it's a little bit easier to actually do this stand up straight hands over the head and that'll end up stimulating GTO and make that kind of pain from that muscle spasm and the pulling on your diaphragm and the paranal ligaments go away all right that gets us into pulmonary volumes so pulmonary volumes when we do things like spirometry which is the method of measuring the different volumes of your lungs we get all these variables right here so we have a variable called tital volume which is the amount of air that you move per breath we have vital capacity which vital capacity is if I tell you to take in as much air as you can Big Max X inhale and now I want you to Exhale as much as you possibly can that's your vital capacity which is often abbreviated as VC title volume you'll see abbreviated as TV residual volume RV and then we have TLC down here but vital capacity Max inhale and then Max exhale and typically when we're testing somebody using spirometry and we're looking to measure their vital capacity what I'll tell people to do is exhale as much much as you can and as you're exhaling I want you to Bend forward as you do that because bending forward will help to contract the muscles of the abdomen and the thoracic cavity and also gets gravity to work in your in your assistance to be able to get as much air out of the lungs with that breath as you can because what we're trying to do when we measure vital capacity is see how much air is left in the lungs no matter if you feel like you can exhale every bit of air out of your lungs you can't it's physiologically impossible we have a little bit of air that's left in the lungs after a Max exhalation because that's going to allow us to maintain pressures within the lungs and keep the int plural pressure and the intop pulmonic pressures the way that they should and keep those pressure differences there that allows our respiratory system to function like it's supposed to if you take vital capacity Plus residual volume here that's where we get total lung capacity so how much air can you exhale plus how much air was left in the lungs after that Max exhale and that tells us how much air your lungs can actually take in total in itself so on an average we generally see vital capacity is about 3.1 lers for females and 4.2 L uh for males and the difference just comes from the size of the thoracic cavity so typically males have broader shoulders and a larger thoracic cavity which allows for the lungs to expand a little bit more and a little bit larger lungs and males as well tidal volume you should be uh around 12 to 20 breaths per minute during normal respiration that's what we want to see is every minute you take somewhere between 12 and 20 breaths per minute if it goes too low then we have uh respiratory variables or disturbances that represent that something like hyperventilation would be when you have a breast per minute that is greater than 20 we'll write it here equals we'll talk about hyperventilation in a second but that's hyperventilation is when respiratory rate goes above 20 breaths per minute so breathing irregularities disia disia is the clinical term for a shortness of breath so usually comes from poor conditioning of your respiratory muscles and meaning that they're going to fatigue quickly so if I go into exercise and I haven't been exercising very long but I get this shortness of breath this dmia sets in that's really related to a poor conditioning of my respiratory muscles they're starting to fatigue and they can't keep up with that uh supply and demand that we've created from exercise we said hyperventilation is greater than 20 breasts per minute so you're breathing too rapidly here however you can do this voluntarily I can I can force myself or I can make myself uh breathe too rapidly by doing that I'm blowing off an excessive amount of carbon dioxide so I'm reducing my uh partial pressure of CO2 in the blood CO2 is what's driving you to breathe it's not the oxygen I don't take a breath in and exhale because I need more oxy o I do my breathing process in diffusion because I need to get rid of CO2 no matter if I'm holding my breath if I'm a resting state or if I'm at a exercise state I'm always going to be producing CO2 so my respiratory changes are being stimulated because of carbon dioxide so by reducing the partial pressure of carbon dioxide I reduce the drive to breathe to have to take a breath so what that can do is it can allow me to hold my breath longer I encourage you to do this in a face-to-face setting I usually make people do this in class but I encourage you to do this on your own I want you to uh take a increase your respiratory rate to greater than 20 breasts per minute so that's going to be at about of a rate of in two three out 2 three in two three out two three in two three out 23 if you can breathe at that rate that's hyperventilation what that'll end up doing do about 20 breaths of hyperventilation and after you do that take in the 21st breath hold it and see how long you can hold your breath compare that to breath holding without uh hyperventilation and I can almost guarantee you that you'll be able to hold your breath longer after you've hyperventilated yourself as compared to during normal respiration another breathing irregularity is the Val solva maneuver so the Val solva maneuver is taking in a breath and trying to Exhale against a closed gatus in other words holding your breath so what that does we've talked about this several times before it increases the intraabdominal pressure naturally it's a natural mechanism to try and stabilize your spine as you're doing something but some people use it in resistance training during heavy lifts but like I've said before I highly caution you against doing that now hyperventilation we said is a breathing rate that's too high uh CO2 is depressed so we get the partial pressure of CO2 is reduced that's known as hypocapnia is when you have a reduction in CO2 there and to get hyperventilation to go away if you're not voluntarily hyperventilating so say something maybe uh anxiety caus you to hyperventilate one way to make hyperventilation go away is the rebreathing technique so it says here you can breath into and out of a bag so if you take a paper bag and put it over your mouth and you breathe in and out of that paper bag what you're doing is you're rebreathing carbon dioxide so it brings the partial pressure of carbon dioxide back up and it balances CO2 and O2 back out and makes the hyperventilation go away now most people don't carry a a paper bag around with them everywhere so what you can do is you can actually create the rebreathing technique by cupping your hands so you cup your hands around your mouth like this and rebreathe the exhaled CO2 to do the same thing and bring that carbon dioxide back up into balance breath holding so if I hyperventilate like we said before I hold my breath I can hold my breath all the way until my CO2 reaches the breaking point so you're going to reach a threshold where CO2 gets high enough it's going to force you into the Gasping reflex so the Gasping reflex is where you're going to automatically drop your jaw and you're going to gasp for air so this is something you'll see swimmers do go watch some videos of Michael Phelps when he swims everybody knows he's famous for standing up on the boards and he does the Big Arm swings to get loose before he dives into the pool and starts the race but you'll notice what he also does is he hyperventilates himself so by hyperventilating himself when he Dives off into the water he can hold his breath for a longer period of time now from a physics standpoint if I dive off into the pool and I stay on this linear path of motion without having to come up for air I can travel a further distance usually the one that's going to win the race is the person that can travel the furthest distance keeping their momentum going in a linear path and not having to change that direction and then re accelerate after they come up for air I encourage you to go watch those videos but also caution you on doing a technique like this in water because once your CO2 reaches that that uh breathing point or that threshold you're going to create the Gasping ref reflex and try and get air into the lungs also you have to be careful when you get a low O2 content that can cause um the actual blacking out or dizziness passing out that you may experience now the oxygen hemoglobin disassociation curve so this curve right here is showing as the relationship between the partial pressure of the gas and the percent of saturation on the hemoglobin so let's look at um the partial pressure here remember we said partial pressure earlier of oxygen in the arteries is around 100 millimeters of mercury of pressure and if we draw this up to where it meets the curve and then draw it across we see that that leads us to about a 98% saturation on our hemoglobin now when you go into exercise it says down here what do temperature and pH do to the curve it creates something known as the bore effect so the bore effect is when we have changes in the shape of the curve or not necessarily the shape but the position of the curve so what we end up seeing here is when you increase temperature increase CO2 um or decrease pH towards acidity those cause a right shift in the curve and by Shifting The Curve right if we draw up from the same let's get rid of this line here we draw our line up from 100 uh millimeters of mercury on our partial pressure where it meets the curve and draw that over our saturation level is going to drop to let's just say 82% here so what we end up having um in that case this makes sense these are all things that are going to be present during exercise you're going to increase body temperature increase CO2 and decrease pH what this means is my hemoglobin at this given partial pressure my hemoglobin is going to let go of the oxygen easier so that I can get the oxygen into the tissue because I need it during this state right here now if you reverse the symbols and do a decrease in temperature a decrease in CO2 and an increase in PH towards alkalinity we end up seeing a left shift in the curve there so at that given same given partial pressure and draw it across will have a higher saturation of o2 at that point because we don't need to let go of it in the tissue so these all lead to a left shift in the Curve all right last thing here is talking about Mets remember Mets represents we talked about this in unit one this represents the metabolic equivalence so it's a way that we can express exercise intensity in relation to your metabolism so rest right here is equal to one met which is equal to about 3.5 MLS per kg per minute of V2 so the volume of oxygen consumed there so let's look at how do we use Mets to actually Express oxygen cost of an activity so what this question asked you here is how many Mets is a measured maximum uh oxygen consumption of 64.7 MLS per kg per minute equal to so remember one met is equal to 3.5 so what I'm going to do here is if I want to determine what my uh metabolic equivalent is of this oxygen consumption of exercise I'm going to take my oxygen consumption during exercise my MLS per kg per minute and I'm going to divide that by my metabolic equivalent my resting meth there and what I end up getting is roughly 18.5 Mets so if somebody would ask you what does that mean you would say when you're exercising at 18.5 Mets you're exercising at 18 times or 18.5 times higher than your resting metabolism ISM so my metabolism at this state right here is 18.5 18.5 times greater than my resting metabolism so it's in a way that we can express exercise intensity from oxygen consumption in relation to your metabolic rate now when we're talking about intensity range changes remember rest is one met which is equal to 3.5 MLS per kg per minute moderate intensity is 3 to six Mets and vigorous intensity is anything greater than six Mets so go back right here this individual exercising at 18.5 Mets is Max effort that's a Max Capacity and it's much greater than six Mets so very high intensity at that point so we can use Mets to do exercise prescription in these techniques so definitely a beneficial tool to express exercise intensity in a way of metabolic equivalents now this is just an example I want you to go through and work through this on your own so figuring out if somebody does an exercise that's at 10 Mets what's the oxygen cost so what we'd have there is 10 Mets we're going to express this in terms of V2 so we have to multiply it by 3 .5 if the person doing that exercise weighs 50 kgs What's the total oxygen cost so you're going to get an oxygen cost here I'll just go ahead and fill it in it's 35 MLS per kg I'm running out of room here per minute but I want you to be able to convert that 35 MLS per kg per minute into liters per minute go back to unit one material and look at how do we convert relative V2 to uh absolute V2 and then how how many calories is that equal to so I think we have another example here yeah we have another example two examples here so what we can do we can work through this one real quick we just did this so we just answered this question up here of converting 10 Mets into oxygen cost so that's going to let's make it a little more clear here that's going to be 10 Mets multiplied by 3 3.5 m MLS per kg so that gets us 35 MLS per kg per minute so that's the oxygen cost of 10 Mets here so 10 Mets there now I want to convert that into uh lers per minute so remember this is relative V2 here because we're taking into account that person's body weight so it's relative to that individual but what I want is I want you to convert it into absolute V2 which is the unit of measure of lers per minute here so to convert from relative to Absolute we have to get rid of the body weight out of this uh unit so we have 35 MLS per kg per minute I need to get rid of the body weight to get rid of something to get rid of the body weight out of this I have to multiply by the body weight so I'm going to multiply by 50 kgs and then to get rid of or to go from milliliters to liters I have to divide because milliliters is a smaller unit here I've got to get to the larger unit so I have to divide by a th so when I do that math here let's see we end up getting 8.75 or no sorry what the next one 1.75 L per minute on my absolute V2 and then how how many calories is that equal to I have 1.75 L per minute remember to convert from oxygen consumption to ccals we burn about five kcals for every one liter of oxygen consumed so I'm going to have 1.75 lers per minute of oxygen multiplied by my standard conversion of 5 kcals and that gives me 8.75 kcals per minute so that's your energy expenditure if somebody's exercising at 10 Mets so we can tie all of these different variables together because of the conversions and the relationships that they have with one another take it a little bit further and say this person did this exercise for a total of 30 minutes and I want to know what's your total energy EXP expenditure for that exercise session what I'm going to do is I'm going to take 8.75 kcals per minute and multiply that by the total minute of exercise session so then I'm going to have a total energy expenditure of this exercise session of 262.50 kcals so just simple ways of doing math to look at Metabolism from a numerical perspective and it's going to be very important to understand and learn how to do that especially when you're working with populations that may be interested in weight loss or even weight gain we need to know what's the energy out as compared to the energy in so that we can maintain the weight in the proper direction for weight loss or weight gain or weight maintenance or whatever your client patients uh or athletes goals are so we're going to stop right there I want you to go to these next two examples here and actually work through these so this one you're going to have to uh do the math for an individual that walks for 17 minutes and does 20 minutes of vigorous calisthenics here's the metabolic equivalents that go along with each one of those activities so do the math for those and then answer the questions um on total energy expenditure total oxygen cost and so on if you need any help with those feel free to reach out to me I'm happy to work with you uh on figuring out how to do these mathematical equations for metabolic equivalents and if you have any questions about the material also reach out to me or post your question on the canvas page and I'll take a look at it as soon as possible