[Music] so let's do a quick little bit of review for cardio before we get back into it with what we are going to finish up today so what is the main homeostatic variable for the cardiovascular system cardiac output which is also known as Q mean the same thing it's just flow because it's flow what are the units has to be uh a unit of measure over time this is flow how much of this can flow in a certain amount of time so we know cardiac output is always liters per minute so what is cardiac output equal what are the two variables that make up cardiac output okay stroke volume what are the two major determinants of stroke volume how do you determine stroke volume minus your n systolic volume right n diastolic volume is a greater number it's the amount of blood that gets into the heart right before all the doors close that's your enddiastolic volume whatever's left over your n systolic volume is whatever is left over after syy which should be a obviously lower number what is the major determinant of n diastolic volume preload preload so this is where preload comes into play what are the two major determinants of NC systolic volume not svr after load and contractility okay so n systolic volume is determined via after load and contractility and your endic volume is determined via preload what determines our preload Venus return so therefore blood volumes more volume you have in the system the more preload because the more blood's going to come back to the heart so preload Venus return blood volume are all going to affect your preloads afterload what are we talking about when it comes to after load what's the big thing we're worried about pressure resistance to flow right so this is your systemic vascular resistance or total peripheral resistance same thing now when it comes to resistance okay you guys like that boba tea stuff I've never had one yet but I know about it or like milkshakes when you go to get a boba tea what kind of straw do they give you it's a huge one right why because it's a very viscous material it's got to you have to exert you have to create the pressure right by you sucking up all that stuff try getting milkshake out of a coffeee stir straw how much pressure do you have to generate in your mouth to suck that liquid up a lot because it's a small radius of the straw the bigger the radius of the straw the easier flow is so keep that in mind when it comes to learning about resistances just think about a straw okay a big fat straw easier to pull up you don't need to suck as hard but a very small coffee stir draw with a very very small radius increased resistance to flow you have to generate a lot more Force contractility what is contractility determined by what are the major influences of contractility muscle function your Frank Sterling curves right okay so those Frank Starling curves affect your contractility the squeeze of the heart if you've had a myocardial infarction which means you had a lack of blood supply to a part of muscle in the heart that muscle is dead it's not going to regenerate it's not going to squeeze again so therefore your contractility has gone down because you're losing muscle mass you killed off part of the muscle therefore the entire heart is weakened contractility goes down so all we did for the beginning part of the cardio part just on the heart let's talk about these different variables so hopefully this little cheat sheet now kind of puts things together why and all those graphs that we drew those pressure volume Loops is just to reinforce that remember preload what is it a positive or an inverse relationship with stroke volume positive so if you increase preload you're going to increase your stroke volume all those graphs just proves the point and reinforces it I'm not going to ask you about the graphs I may say if your contractility decreases which way would the line shift same thing with compliance which way is that line going to shift if you strengthen or weaken compliance remember a good compliance what is compliance the ability to hold on to a volume of blood without generating a lot of pressure it's compliance think of a really good water balloon you put water in it it's going to expand um so preload stroke volume for that after load what is the relationship between after load and stroke volume inverse so if I increase after load decrease your stroke volume and again why are we decreasing stroke volume with a higher afterload what are we what phase in the cardiac cycle do we have to spend more time in when after load goes up what part of syy remember there are three phases within syy remember that wiggers diagram what is the first thing that has to happen insistently isovolumic contraction and what's the purpose of that to generate the pressure to overcome what the aortic valve your systemic vascular resistance the total peripheral resistance I'm spending more time generating force and remember this is a cardiac cycle 60 beats per minute 1 second per cardiac cycle you only have a certain amount of time if you're spending more time in isovolumic contraction generating the pressure you have less time for ejection cuz the heart's going to keep beating that sa note is going to keep going everything's going to have to repolarize and get ready to go for the next beat so that's afterload and stroke volume so the Converses are true too if you decrease after load you're going to increase stroke volume so I didn't put all that in there the last one is contractility what is the relationship between contractility and stroke volume directly proportionate if you increase contractility you're going to increase your stroke volume okay so these are the ways we alter our stroke volume but remember cardiac output is stroke volume times heart rate so if our stroke volume is going to reduce we want to keep our cardiac output normal what has to happen to our body increase the heart rate to keep the number at five remember cardiac output is five 5 lers per minute that's a normal cardiac output remember about 40 MLS 50 MLS come out what 70 beats per minute 70 * 70 whatever it is 4900 okay now we have the heart rate portion how do we affect our heart rate what two systems are going to affect affect our heart rate sympathetic and our sympathetic nervous system and our parasympathetic nervous system those are the two ways we can alter our heart rates we can give drugs but the drugs are just going to act on one of those systems either adrenergic or what's the other one adrenergic or coleric coleric is parasympathetic acetycholine Paras syp athetic your adrenergics are sympathetics so SNS what are the receptor types that we're going to be targeting alphas and betas what are the types we're going to affect in the pns muscarinic and nicotinic okay hopefully this kind of puts everything together we learn in cardiac as far as all these interactions what's going to happen okay everyone good I will print this and I'll put it on your modules okay so I'll put this in a PDF and I'll give it to you guys so you have it on thing any questions about that Pas when we get to cardiac pathology pathophys in the fall we're going to bring these pressure volume Loops back a lot um so we're not going to lose them forever yeah question cont that's all it is yep we're going to squeeze harder now she bring up a good point when our heart squeezes harder or we have a bigger stretch of the heart due to increased preload why is the contraction that much more forceful what has our cardiac cells become sensitive to as we stretch calcium so the bigger the stretch the bigger the contraction and it's all due to calcium okay become very very sensitive to calcium obviously you know why calcium is important um within the heart okay so let's go on to oops oops do that okay we're going to finish up the regional blood flow and get into lymphatics and capillaries okay so this is where we ended yesterday or last week with auto regulation so cerebral blood flow and what other system need constant blood flow the brain and and kidneys just remember those two brain and kidneys need constant flow so they have this process called Auto regulation so that over remember over a certain map blood flow will be constant so that's what Auto regulation does if you're out of those ranges you're not going to have appropriate flow through the brain or the renal system and you'll have some problems with that so so cerebral blood flow increased neuronal activity and O2 consumption cause local vasod dilation so vessels are getting bigger in the cerebral circulation um do you ever hear that so those professional chest players at you know like like the really really high level they burn like five or 6,000 calories in a chess match because of the brain activity needed because all the different processes all the different moves that can go on they burn a ton of calories from brain power so hope you guys study more lose some weight so that's why you study more you'll help okay the next really important thing this is going to help with when we get to pulmonary tomorrow arterial CO2 P CO2 influences cerebral blood flow as you start altering your carbon dioxide levels in the blood you're going to have changes in the brain dizziness with hyperventilation when you breathe really fast is caused by cerebral Vaso constriction because we're losing CO2 when you breathe very very fast you're blowing off a lot of CO2 have you ever seen people that do those long uh breath holds underwater before they go under they're going why they want to get rid of the CO2 in their blood as low as possible so that you have a bigger Bank to hold CO2 CO2 is what causes you to breathe not oxygen the lack of oxygen you have plenty of oxygen in your blood floating around that's why CPR doesn't do breaths anymore not because of the safety issue but you have out of the 100% of oxygen in your blood whatever you have only 20% of it is used by your muscles and tissues you're still exhaling like 80% of the oxygen that you breathe in so you have a lot of reservoir for O2 CO2 is the problem when CO2 starts building up bodies don't like it because very acidic so that's why breathing really Alters your carbon dioxide levels if you breathe very very fast CO2 levels drop you get Vaso constriction and that's why you get dizzy when you hyperventilate when you guys are doing your exams and you're having them listen to into the lungs and you have them breathe all the time we tell you take a break because your partner who's breathing heavy all the time can get liad and and dizzy because they're dropping their CO2 levels that's why we tell you just take a break breathe for a little bit and then start your exam again because you don't want them passing out um so that's where cerebral blood flow and CO2 comes in CO2 is the main driving force for your breathing not oxygen it's the buildup of CO2 that causes you to want to breathe we'll get to that a lot more when it comes to uh pulmonary tomorrow renal blood flow renal blood flow has the lowest O2 extraction of major organs it's not going to take a lot of oxygen out which means it become it can get esic very easily what's es schic reduced blood flow esema is a reduced blood flow infarction means it cut off totally and there's no blood flow past it so esia just means lack of blood flow so we need a very high perfusion for filtration again that's why we need that auto regulation we need to have the kidneys being perused if they're not being perused what can't we get rid of waste products excess water the kidneys have a big role in water balance so if you you influence water balance in the blood and we start losing a lot of blood in the urine what happens to the blood in the body does it get more concentrated or more diluted concentrated in the blood okay so we'll get to the kidney stuff a lot later not controlled by any metabolic factors the kidneys are always just going to be profused and they keep going they keep going long as their um blood's going into them they'll be okay Auto regulation is here as well okay over that map from about 60 to 160 again that's why our goal for a map is greater than 65 always because we know the kidneys will not work if it goes below that and how do we can how can we tell the kidneys aren't being perused what are you not going to create urine okay so if we're not creating any urine that means our blood is not profusing the kidneys there's no filtration going on you get aligura reduction in in urine production during increased sympathetic tone like during exercise or during a barrel receptor reflex okay remember the barrel receptor okay will reduce mean arterial pressure causing renal vasal constriction does that make sense during a sympathetic response do we want to shunt blood away from the kidneys do we want them do we want our blood to go to the kidney when we're trying to run away from a bear no we don't want to pee if the kidneys are being profused you're going to pee or create urine so by in increased sympathetic tone exercise we need some Vaso constriction so the kidneys aren't being profused as much because we don't need it we're in a sympathetic response during extreme um Vaso constriction the kidneys can get some es schic damage what lab values will you see changes in if the kidneys are causing problems cenin and bu okay have you guys gone over Fishbones okay there's a way to do your bmps very easily it's always the same sodium over potassium um I think bicarb over chloride um and this is BU over creatinin and here's your glucose this tells you your electrolytes this tells you acid base bu and creatinin kidney function and then your glucose is obviously your sugar levels so you this is no clature across the board anyone writes a note and they write that fishbat on there it's always the same setup the B carb at the top may change to a different one um because they kind of correlate but basically that's the way it goes first section tells your electrolytes sodium pottassium why is potassium so important what does it alter not the repuation resting membrane potential yes it will alter repolarization but the big influence is that membr potential is going to change okay splanchnic blood flow what's splanchnic refer to what does it referred to GI Prett much your GI your whole splanchnic is the whole bed of vascular that goes over the entire intestines and all that stuff receives highest proportion of cardiac output at rest why rest rest and digest we need more blood in the intestinal system to absorb all the nutrients you just ate and whatnot okay and that spanic system is shared amongst the liver spleen and your digestive organs obviously your sympathetic system has dominant control dealing with Vaso constriction and venoc constriction and obviously if you eat something the metabolism will go up because you have to digest whatever you just ate and that's really all you got to know for splan cutaneous blood flow is referring to what skin your skin flow this is regulated in responses to Thermo regulatory signals and general cardiovascular control of your mean arterial pressure okay stimulation via pain cold fear low map leads to contineous Vaso constriction so blood flow goes to the vital organs remember we can shunt blood away our body in a survival mode does not care about your fingers you can lose your fingers and you'll still be okay they care about your vital organs keeping the blood in the core keeping that your core body temperature raised once your core temperature drops causes hypothalamic activation of your coleric sympathetic eference this is with I'm sorry increased Core Body temp so obviously outside in Florida in the summer very hot out there as soon as you walk outside you start sweating immediately causing so sweating cutaneous vasod dilation When people's skin looks red or pinkish more than normal that is from Vaso dilation of those capillaries causing the redness to to happen during a fever and shivering vasil constriction to increase our body temp and then again we learned about this in the first in neuro when the fever breaks set point returns and we cause sweating and phaso dilation to get rid of and the excess heat and to cool ourselves off with sweating skeletal muscle okay obviously during Dynamic exercise 75 % of your cardiac output will go to your muscles it's called the muscle pump that's why those bodybuilders will start working out before they go on stage they'll do push-ups and all the other things before to get blood flow into their muscles so they look bigger okay so let's what what's going on there um local metabolism so the local events exerts dominant control and it results in recruitment of capillaries that were not profused at rest you have capillaries that don't have they're just there as reservoirs so that when the demand goes up we have extra capillaries to feed all your muscles but unless you're not using it they're not going to be filled same thing with your lungs when we learn tomorrow about your lung zones your Apes of your lungs right now have no blood in them why gravity is keeping all your blood down in your base of your lungs just gravity thing simple like that we have different Regional distributions but when you are exercising what happens to your breathing goes up we need more oxygen we have more perfusion of blood into your lungs so all those different zones start to fill up with blood now and they are like our capacity we have reservoirs of blood that can wait to be profused with oxygen to feed our muscles so when we need it we can recruit more parts of our lungs to get profused more more oxygen to our muscles we can do more things that's it on Regional flow the next up is talking about capillaries this last little bit and then we'll be done so capillaries have the largest Collective surface area for all all of them it's not coming okay okay you only have one aorta so your aorta surface area is whatever the diameter and the radius of your aorta is but you have millions and millions and millions of capillaries and if you add up all those capillary diameters together it's going to be a bigger area than your aorta your arterials and so forth so that's what it means by the largest surface area and it allows for exchange of your nutrients and waste diffusion is the biggest mechanism for exchange diffusion takes time the faster that blood goes through the capillaries the less time you have for diffusion and that's why it's so important in our cardiovascular system that by the time the blood gets to our capillaries it's going very slow and low pressure because we need time for diffusion the blood goes too fast through the capillaries you're not going to have time to deliver O2 you're not going to be have time to get all your CO2 back out you know start getting problems obviously lipid soluble and gases will diffuse readily right through O2 CO2 very easily to go through they're lipid soluble or gases they can go right through uh lipid insoluble substances have low permeability to get out of the capillaries and are restricted to just physical openings they're called fenestrations so remember when we talked about when you have an injury well youan go through injury but clotting processes and all that stuff um those white blood cells have to get out of the capillaries but normally during a normal when our body is healthy all these gaps in a capillaries are very very tight but when you have an inflammatory process in an area those capillaries become leaky those penetrations get wider so white blood cells can get get in there macras is all that fun stuff your red blood cells can get in there remember we need blood to heal that's why diabetics have very very bad ulcers and wounds on their feet they don't have great circulation anymore you don't have any circulation you can't heal anything that's why you can't really heal carage and tendons there's no blood supply you can't get anything there so it's always better to like break a bone instead of like spraying an ankle you're better off breaking it because at least a break there tons of blood supply in a bone those will heal all the all the time you know that's how they figured out like um they found these bones from like 100 thousand years ago like human ancestors and they found that on their skeleton their bones were healed which means that they had some sort of society there that would treat sick people because otherwise in like the wild they would have just died and moved on but they found that they bones were healed they have callous formation which means they have a society that was taking care of people anyway um we talked about this before time to diffuse depends on the velocity and remember blood flow is least in the capillaries because we can split all that stuff out it's in parallel not in series so this pressure gets split out so we have to talk about transcapillary fluid flux we have to talk about movement of fluid for this so the factors that determine it are just as important for understanding edema formation when we talk about edema there's one real major pressure that we're going to talk about and that is going to be oncotic pressure oncotic pressure is the pressure exerted by proteins so whenever you see oncotic pressure it's proteins that's what drives it so the net fluid movement over a length of a capillary is a function of the driving pressure for filtration and the permeability of the capillaries are they being profused yes do we have a way for this solute to get across are they permeable to it yes then it can go and it can happen we never want proteins to go into what space I talk about in the very very first lecture I said keep it in your mind it come out itial we never want protein in the interstitial fluid we need to keep it in the blood only proteins are big molecules and because we have these fenestrations normally you can't get protein out but during problem times those penetrations get big protein will start leaking into the interstitial space and you'll see as we get through this segment what kind of problems that's going to cause with the body so the net drop driving force for filtration is one part is your hydrostatic pressure and what is the what determines your hydro hydrostatic pressure blood pressure or blood volume the amount of blood in that area blood is exerting a hydrostatic pressure Hydro is water just think of fluid it's our case it's blood cardiovascular so the hydrostatic pressure is the push pushing fluid out okay we don't want all this fluid to stay in the third space or the interstitial space what's that going to cause if that fluid stays there Adema we don't want it so it's opposed by anotic pressure proteins and this is called we'll call it the suck protein is going to suck the fluid back into the capillary resisting edema formation it's just the oncotic pressure what's the pressure of the of the proteins in the blood versus the interal space so let's change up some colors here so there's our blood vessel here is the interstitial space okay we have proteins floating around are there any proteins in the inal space so in this example we have the pressure in the capillaries which is let's say six we have six units of proteins there we'll just say it's six there is no proteins in the inal space because proteins can't move which way is water going to want to go into the capillaries we're going to suck it back in because we have an anotic pressure there's protein in the blood there's no protein in the interal space protein is not permeable but water is and that is the suck the oncotic pressure is the suck it's sucking that fluid back in So if your anotic pressure starts to decrease because now either we're losing proteins in the blood or we have leaky capillaries and proteins getting into the interstitial space regardless our oncotic pressure is going down where is that fluid going to stay in the intertial space causing edema there's a couple of things if you ever seen nephrotic syndrome in a child where a child gets very very puffy that's because they're not they're spilling proteins in their urine like crazy they have no more oncotic pressure because they're losing all those proteins so they fill up with fluid there's no suck anymore liver failure what's one of the main jobs of our liver make proteins they make protein what's the major protein that the liver makes albumin albumin is a protein made by the liver some patients who have liver failure they're not going to make enough proteins what happens to anotic pressure goes down liver failure you'll see they have that big belly because they lost all the proteins there's no more anotic pressure there's no more suck so you start losing fluid into the interal space so again this guy Starling must have done a lot because Frank Starling curves now we got Starling mechanism for uh uh filtration pressure here so again read the words carefully it'll tell you exactly where we are and what we're talking about you don't need to memorize this whole entire thing don't worry about it okay what what is important it'll set up the equation it'll make sense capillary hydrostatic pressure p with a little C there big P stands for hydrostatic pressure the little C says we're in the capillaries which is your normal blood volume the hydrostatic pressure exerted by your vessels Force pushing fluid out it's the push okay hydrostatic pressure is usually about 35 mm at the arteriolar end of a capillary so you have a long capillary blood is going this way this is considered the arteri end and this is considered the Venus end because as you go along you'll see what happens with um capary pressure in a second so hydrostatic pressure is high here but then gets lower let me change the color of this but as you get to the end of the line hydrostatic pressure in the capillary goes down why does hydrostatic pressure go down as you go the length of the capillary well where where's that where's that volume where's that fluid going if we're losing hydrostatic pressure that fluid has to go somewhere it's going into the C uh interal space remember hydrostatic pressure is very high we're going to lose a lot of fluid right there as we get towards the end hydrostatic pressure starts to drop because we lost fluid into the space here's our interstitial fluid hydrostatic IC pressure p with a little I so that means now we are in the interal space usually it's going to be near zero so it favors fluid movement into the interstitial space High capillary hydrostatic pressure low interstitial hydrostatic pressure the flow will go from the capillary into the interstitial space with regards to hydrostatic pressure along now let's talk about capillary oncotic pressure this is a pi with a little C so whenever you see Pi in physiology terms it's oncotic pressure which is the pressure exerted by proteins this is the suck okay it's sucking the fluid back in okay interstitial fluid oncotic pressure p with a little I remember it should be very very low because proteins really should not be there so it should be very low let's put them all together now okay here is our capillary arteriolar end the venal end at the arteriolar end hydrostatic pressure is greater than the oncotic pressure when hydrostatic pressure is greater than the oncotic pressure in the um capillary we favor push okay it's going to push the fluid into the interstitial space along with that your nutrients whatever else needs to get in there your O2 will go and so forth and then your fluid as we get to the venal end the oncotic pressure is now greater than the hydrostatic pressure at the cap at the venu side of the capillary and because we're there this is the suck net fluid reabsorption net fluid filtration so the filtration occurs at the beginning of the arteriolar end of the capillary the hydrostatic pressure is greater than the oncotic pressure pushing it out on the venal side of the capillary the oncotic pressure now is strongest provides a suck to bring that fluid back in So essentially if all systems are working well there really should be no net movement so whatever you pushed out if you pushed out 5 MLS you should suck back in five MLS as well in a normal working environment everyone good on hydrostatic pressure I'm not going to ask you to calculate it but just understand hydrostatic pressure if I give you numbers just math if hydrostatic pressure is greater than oncotic push is favored if oncotic pressure is greater than hydrostatic suck is favored and you're going to suck the fluid back into the capillaries okay any questions about capillaries okay lymphatics lymphatics is what saves us from the fluid buildup the lymphatic system it takes all that excess fluid puts in the lymphatic system then usually it's going to go back into our Venus circulation and get recycled that way so lymphatic capillaries are found in all tissues except the brain and the Heart everything else has lymph tissue associated with it permeable to fluid and protein and that's the big part if remember we said we don't want protein in the intral space if it gets there the lymph system will take those proteins out and pull them away so the anotic pressure gradient goes back to normal that's why lymph system helps resist edema formation it gets rid of that protein in the intal space so that push and suck gradients are back to normal net formation about 3 to four liters of lymphatic fluid a day and enters a lip and goes back into the Venus system and your Ducks okay and everything else I explain so proteins that enter the in system from plasma are taken out by your lymph system that's why a lymph system is so important they think that a clogged lymph system can also help not help but it could be one of the underlying causes for cancer formation um because we especially morbidly obese people all the weight in the especially in the groin area there's a lot of lymph tissue there if it can't get out that's why it's called some people get what called lymphadema in the legs because there's nowhere for that fluid to go so Claus of em we've already gone through already most common increased Venus pressure which causes what is that going to favor hydrostatic or oncotic pressure increased Venus pressure is that going to increase hydrostatic pressure or oncotic pressure hydrostatic this is a volume we're talking about increased Venus pressure means there's more volume of blood anytime we talk about volume of blood it's hydrostatic pressure p in the capital poies so heart failure heart can't pump so nothing's going out of the heart but stuff is still coming back and you're going to fill up with blood in the legs because it can't get into the heart if you have more blood sitting in your Venus system hydrostatic pressure goes up the push and if that push is really accentuated because of heart failure all that fluid goes into your legs and you can't get it back out unless you give them other things generalized edema we talked about this before too low serum protein liver failure we're not making enough albumin nephrotic syndrome where we start spilling proteins into the urine and there's no oncotic pressure for the suck everything is push hydrostatic you get edema and so forth here's your lymphatic blockage inflammation or sepsis also has problems um usually due to um leaky vessels leaky vessels during like sepsis those capillaries are like wide open everything flies out okay so when are you talking about edema where you have to look at the legs this is a clinical correlation is to prove some things to you if they have bilateral pulmonary edema both legs are swollen it's probably due to congestive heart failure heart can't pump all the blood is pulling hydrostatic pressure goes up in the legs you get a Dema formation with a deep vein thrombosis we have a clot in one of the art veins in the leg not both legs just one of them because we can't have any Venus return that leg because like you're greater sainis can clog up that vein everything below that gets stuck so you get increased hydrostatic pressure in the leg because of the obstruction to flow blockage you have a thrombosis you guys learn about clotting so a deep vein thrombosis a thrombos is a clot in the leg causing a blockage you got an increased hydrostatic pressure only in that one leg and you get one leg swollen so if someone comes in and they have one leg swollen start thinking could be DBT if both legs are swollen probably heart failure or something else going on if that makes sense there a correlation and we're done okay cardiovascular system is done tomorrow we'll start palm palm goes along with cardio it's not that bad um if you have any questions please reach out um for Pas uh what time is it now 1:20 um I'll tell professor pres heart at 145 okay so PA is anatomy at 145 you have any questions come see [Music] me I remember everything