[Music] okay so moving on to cardiovascular we're going to just do a little little bit right now just to get started so we have the rest of the week to focus on the fun stuff okay cardiovascular system heart blood vessels and blood that's all it really consists of all the heart does is it pressurizes the blood squirt on its way and repeats itself until you die it's just a pump on off on off on off that's all it does the problems come into play is when you have alterations to how that heart pump functions if you have clogged vessels the heart's going to have to work a little bit differently to work get through those clogged vessels if you have high blood pressure it's got to work through different ways to get through that so all the alterations are doing messing up how well the heart works as a pump the only thing that the cardiovascular system cares about is cardiac output also known as q that is the homeostatic variable for the cardiovascular system cardiac output that's all it cares about heart rate stroke volume blood pressure those are all alterations to keep your card cardiac output constant that's the entire goal it's the highway system that delivers all those truck we talked about with the red blood cells and the hemoglobin it provides the Avenues for all to go um we transport materials entering the body from the external environment so when you eat food we have to absorb that food into our cardiovascular system so it can go wherever it's got to go anything moving between cells within the body and obviously getting rid of any waste products cardiovascular system will deliver it to the lungs to Exhale the liver so we can excrete it through the feces or the kidneys so they can excrete it through the urine we have to get rid of things too that's where we go and exchange of materials between blood and the intral fluid occurs across our capillaries and we'll go through why capillaries are the site for all that this kind of goes over like the anatomy of the um cardiovascular system make sure you under this is a one schematic but you'll get different ones they're all the same they all go in the same order make sure you understand how the blood travels through our system whenever we refer to the right side circulation it's always pulmonary right side of the heart right atrium right ventricle pumps to the lungs so we call that the pulmonary circulation which is the right side the left side is always the systemic circulation it's going to the body left ventricle pumps blood to the entire body okay so also the right side will be De oxidated Blood it's coming back from the system it's unloaded all of its O2 not all of it but it's unloaded its O2 to the tissues and when it comes back it's going to be a little bit hypoxic to the lung we need to go back to the lungs and load up on oxygen again so therefore all the oxygenated blood goes to the entire body so heart failure all heart failure is is inability of the heart to pump effectively it's just a pump it's not going to work as well this is where I gave you that example in the beginning of the class with the light bulb not turning on knowing which way it's going if your heart is failing we have to know what side is it failing bolt is it left side of circulation or is it right side circulation where's the problem happening it could be the whole heart or it could be just one part versus the other knowing Anatomy which way everything goes if my left side of the heart the left ventricle is not pumping well so I can't move blood forward where's blood going to get backed up to the lungs I can't pump it out through the heart the left ventricle pumps the blood to the body it re receives it from the lungs if the left ventricle ventricle can't pump the blood it's going to back up into the left atrium and then it's going to back up into the pulmonary vein then it's going to back up into the lungs and guess what happens when all that blood fills up in your lungs you get problems breathing that's why people with Left sided heart failure have breathing issues on the right side where is the right side pumping the blood to the lungs if the right ventricle is failing where's the blood going to back up to what's the mediate system chamber right before it right atrium then it's going to go into your venne cavas then all the blood that you're trying to get up from the legs can't go anymore because we're backed up the right ventricle what do they get swelling in the legs because all the blood backed up the right side of the heart can't Pump It effectively you back up that's why knowing the anatomy what's the pathway it's going to take will tell you what symptoms you're going to have so again organization our pulmonary and systemic circulations are in series which means you have the pulmonary circulation going into the heart going into the left side and then the whole thing just repeats or the body or systemic actually I'll put systemic that's in series they go one to one to one there's no mixing pulmonary system has lower pressures what is a blood pressure what's a normal blood pressure 120 over 80 that is the left side pressure that's the gener pressure generated by the left ventricle very high pressures the pulmonary side it's a lot lower like 40 over 20 40 over 5 very very very low pressures on the pulmonary side systemic circulation is in parallel meaning once the heart beats some of the blood can go to the brain some will split off and they'll go to muscles some will split off and go to the um kidneys but then they all group up together to go back into the IVC and then back up to the body so that's parallel whereas looking at pulmonary versus systemic circulation it's in series but within the systemic circulation it's in parallel that will become very important when we get to hemodynamics because our pressure is divided amongst all those parallel circuits it's a way to for us to alleviate pressure in the system okay so hemodynamics so pressure we measure pressure in millimeters of mercury that's why your blood pressure that you me register on the machine is in millimeters of mercury that's the pressure unit we use flow is a difference pressure between two points flow will always go from high to low pressure and if these pressure changes in the cardiovascular system that allows our blood to flow effortlessly our entire cardiovascular system is closed so no matter whatever goes in has to go out and because it's all a closed system the difference between the aorta and the large Central veins your IVC is what drives the flow through the entire cardiovascular system for example the aortic pressure let's say is about 120 IVC we also call it right atrial pressure is about five that difference allows for flow to go from the aorta through the entire body back up to the IVC as that IVC pressure starts to rise let's say now we're still 120 but say we're volume overloaded and now our IVC pressure let's say it's 15 now what do you think is going to happen to the flow through the system slow down or speed up slow slow down because the gradient got smaller that's what flow was referring to Blood by itself it's a liquid it can't compress so when The ventricle squeeze it starts to pressurize the blood causing potential for flow I told you there' be physics involved okay it's a lot of physics in this whole system um so all we're doing when your heart squeezes we're pressurizing the blood so when that blood gets released it flies out so like you have a hose and you pinch off the end so no blood no flow of the water can happen then you release it and it just flows out same thing uh with this the amount of flow between two points also depends on Resistance what is resisting flow that's what's very important as we get to pressure ohms law the flow is proportional to the pressure gradient the bigger the gradient which we discussed before remember 120 to 5 is proportional to FL low so pressure and inversely proportional to resistance so the bigger the pressure gradient the better the flow if you increase the resistance to blood flow your cardiac output goes down so resistance the more resistance I give you the harder it is to flow the bigger the difference between the two points the easier it is for flow to occur so we're going to be talking about pressure gradients how does that affect cardiac output what's going to happen with pressure gradients and how we alter resistance to flow here is the formula for resistance there are three things we need to worry about when it comes to resistance length of the tube how thick the blood is which is kind of a negligent factor in the body um the only real times that the viscosity can really change and it's very rare that it happens is when you have that polycythemia what's that too many red blood cells the more red blood cells you're adding the thicker your blood can get so viscosity can go up another one is in severe dehydration all the solvent is coming out of the blood so the gets thicker if you ever like reduce sauces with heat if you're cooking you want to boil off the water so you're left with more of the stuff same thing with viscosity but it's very rare that it happens much so we don't really worry about viscosity radius of the tube is the big one what's the radius and if you look at the formula where is the radius on the numerator or the denominator denominator also look at that equation the resistance is to the power of four it's a fourfold change with changes in resistance resistance is the big thing that we can alter okay what uh which nervous system autonomic nervous system which parasympathetic or sympathetic will cause constriction Pare sympathetic well parasympathetic will uh causes some tone to happen more relaxation but we want to constrict our vessels we need Alpha Agonist to do that so we can alter our vessel we can relax our vessels to make them bigger to reduce the pressure so P R4 so resistance is the bigger I radius is the biggest Factor radius of Your Vessel and we know the radius is all under smooth muscle control and we know we can alter that with drugs so resistance is the biggest factor of resistance is the radius so if the radius of the vessel decreases what happens to the pressure going through that area increases pressure or you can say also increases resistance if we're increasing the resistance we're increasing the pressure the length of the tube also matters but it mainly matters with IVs so again radius is the dominant variable if you double The Vessel radius it increases the flow 16 fold so that's why increasing the radius of the vessel a little bit will produce big changes in resistance and change and pressure and again through Vaso constriction Vaso dilation we can alter the radius alter the resistance alter the flow so IV catheters a catheter with a large radius but a short length reduces the resistance to flow large bore peripheral IV is better than a long central line for fast infusion of products so if you're ever infusing fluids it's faster to go through an IV line because you have less resistance to flow because the vessel is the the radius is bigger and the length of that IV tubing needle that's actually in your arm is smaller that provides greater flow through it a central line goes to the neck and it's got to come all the way down it's got a long tube that's going to impede the flow with having a very very long tube very good for medication administration through a cenal line because it doesn't matter the speed at which you get the medication but fluids that those things do matter another definition word you got to know is compliance compliance is the distensibility of a structure okay for example compliance if you're catching a baseball and you have a glove and your glove is pretty well like it's it's loosened up when you catch the ball the compliance of the glove is going to absorb the impact of the ball so your hand doesn't go flying backwards if I caught a ball like this my compliance is good but if I it hits my hand my glove comes flying back that means my compliance is bad I wasn't able to absorb the impact of the ball same thing with hockey if you have a hard stick and you're waiting for a pass to come in the Puck's going to bounce off the stick but if you have good compliance and you accept the puck then it just goes right in and you're okay another example is stiff structures so like a stiff garden hose that has very little compliance you can't bend it it's going to break if it gets very brittle when they get very stiff so we don't like non-compliant hearts we want very good compliance and this is where it comes into play changes in compliance of cardiac muscle affect the ability of the heart to fill with blood that's the compliance your heart should be like a water balloon it should accept all that blood the chamber size gets bigger if you had a very stiff water balloon that would not expand when you put water in there because it can't expand the pressure builds up and it's going to squirt out the top we want a compliant vessel uh chamber so compliance this is the definition the ability of the heart to hold a volume of blood with low pressure buildup we want to hold a large volume of fluid blood in this case with minimal changes in pressure because we are a cardiovascular system the system is closed we are dealing with fluids if you increase the pressure of the volume of the fluid you increase the pressure they go together so compliance changes in volume over changes in pressure okay so this is how I want you to know this one we're going to be doing these graphs a lot come later this week we have pressure and we have volume on the bottom so obiously as we go up the line pressures get heavier or greater and volume as we go across the x- axis volume goes up so we're talking about compliance compliance is always filling of blood okay compliance is one of those words you got to know the definition of because we're talk about compliance a lot so knowing what the definition is very important so compliance chain is in volume chain is in pressure we're going to talk about the blood in the heart and our heart is going to fill with blood so we're filling heart's going to get bigger we're going to fill with volume of blood so do it in Red so we have this line here let's draw these lines down and we have a certain volume right we have a change in volume let's say that the change in volume for this example let's just say it's 20 units or whatever it is it doesn't matter we're just using it for art for math just to show you guys the principle now let's look at the pressure on the y axis and we compare this increase we have this line and we have this line everyone get that part that change in pressure is very minimal compared to that big change in volume right so we're able to hold a lot of volume with very minimal changes and pressure and let's just say for math that this change in pressure is five compliance is volume over pressure we divide it out we get a compliance of four everyone good there okay we want High number for compliance higher the better now let's say our heart became very stiff let me just change the color here okay so our heart became stiff we are losing compliance which means this same volume of blood that we're adding to the heart is going to cause bigger changes in pressures so instead of being the line like that the line may be like this I'll in green that could be our new compliance line now look still the same still 20 but let's look at the green difference now let's say this change in pressure we have a bigger swing let's say it's 10 now that change in pressure what happened to our compliance here where is it now two it's gone down so we want our compliance to be high it's the ability to have large volumes of blood with minimal changes in pressure that's compliance okay so as you're studying again know what compliance is ability to hold on a large amount of blood with minimal changes in pressure because as your compliance goes down guess what happens to your blood pressure it's going to go up because the heart is getting stiffer so that's the compliance one don't worry about this for now we kind of went over that and okay so here's our heart have you guys started this we for anatomy yet so the next section you will know also when diast is filling of the heart syy is squeezing so syy has a smaller size than diast a diastolic heart is a filling heart so whenever you see the word or hear the word diaso think it's filling Cy is pumping so diast the heart's filling with blood it's got more contents the heart's going to get bigger that's why there's a dash line for diast syy the heart squeezes and squirts out the contents of the blood cardiac muscle again is stri has intracellular sarir like the skeleton muscle so it's in striatus so we have all those uh cross Bridges the actin and the myosin occurring that's still going to be here same as before in skeletal muscle different thing here is that cardiac cells have these transverse tubules or t tubules that extend into the cell there is a sarcoplasmic reticulum with every t tubule what is the purpose of the pyop plasmic reticulum as far as for this purpose CCI calcium storage remember all that internal calcium is in the sarcoplasmic reticulum myocytes also have these Gap Junctions and that means that when one heart cell will depolarize the entire heart will depolarized because of the Gap Junctions so all the cells go that's that All or Nothing principle of the heart that once one goes then the all go excitation contraction coupling so we talk about this a little bit with neuro we have to excite the cell first then you could have a contraction so cardiac muscle um Can contract without nervous stimulation if you took out the Heart by itself and it had no no ination at all you cut all the nerves to the heart the heart will have an intrinsic rate of about a 100 it goes down to 80 because what system is in control of our body the majority of the time parasympathetic which is rest and digest so because that system is mainly in charge our heart rate goes down to 80 normally resting but if you took everything away it would just be on its own at 100 beats per minute same thing p maker cells generate X potentials what generates the ACT potential or the depolarization movement of what ion sodium okay causes that same depolarization that depolarization goes along the T tubules and it's this location where we have our voltage gated calcium channels and calcium comes into the cell from the outside however in cardiac muscle they have a very special thing it's called calcium induced calcium release as the calcium is coming in from the outside it causes the SR to dump calcium into the cell as well calcium induced the calcium coming in from the outside stimulates the SR to release calcium into the cell calcium induced calcium release same procedure happens what does this calcium bind to in the muscle troponin C that's where calcium goes it's and the same exact thing happens everything else is the same how do we relax the heart we have to get rid of that internal calcium remember as long as calcium ATP are there you're still going to have that crossbridge cycling but the heart is on a cycle we have to have it squeeze we have to have it relax it's got to squeeze it's got to relax so we can't just have all that calcium sitting there all the time we have to get rid of it we have our we have two things we have a sodium calcium exchanger and that's going to get it out of the cell we also have our calcium ATP pump that puts calcium back into the Sr so two pumps well one's exchanger but still two ways to get rid of all that extra intracellular calcium we have the sodium calcium exchanger which gets it out of the cell and that calcium atpa pump which pumps it back into the SR and that's how you get rid of calcium in the heart U let's see where we're at here okay we're almost done so here is our sarcolemma T tual whatever you want to call it here is the extracellular space and here is the intracellular space ECF and ICF first thing that's going to happen what has to happen first action potential right okay there's our X potential happening it's going across the nerve right across that muscle cell okay as it goes across this is the actual T tubule this whole structure right here that whole thing is a t tubule as the active potential comes down into the T tubules what is here here's our action potential comes down what is what type of voltage gated channels are at the very end calcium okay so these are our calcium molecules and and they go right through and go right inside the cell now these are the SRS sarop reticulum remember there's one for each T tubule what's inside the SRS calcium okay calcium's got to get out so calcium comes out and this whole process is called what when the calcium comes in Sparks the calcium to leave the SR calcium induced calcium release okay so calcium now will bind to troponin C and we get crossbridge muscle contracts same we did in the first unit nothing changes calcium ATP are both required so we have a calcium reduced calcium released so we have calcium coming into the cell from two sources extracellular fluid and the SR now we have to get rid of the calcium so how do we get rid of the calcium we have a sodium calcium exchanger which is going to get calcium out and bring sodium in we also have calcium atpa pump which is going to bring calcium back into the SR okay so the AC potential comes down hits the T tubule in the t tubu is where our calcium gated channels are located calcium comes in from the outside causes a spark of calcium to be released from the sarop plasma reticulum calcium induced calcium release all that calcium will bind to the dpon and C caused C crossbridge cycling we have to get rid of the calcium sodium calcium exchanger and the calcium atph pump how yep so this is just a review just about different things this I want you to bring up though and then we're done so any drug that can increase intracellular calcium will cause an increase in myoc cardio contractility the more calcium you have the stronger the contraction is going to be so we can give drugs for example one of them is called digitalis increases myo cardio contraction Sorry by bringing in Greater calcium stores how does it do it so digitalis blocks the sodium pottassium atpa pump if you block the pump you're going to get an increase in intracellular sodium because the pump is there to get it back out again pump's not working sodium starts to build up inside the cell because it's starting to build up with intracellular sodium it's going to alter the driving force for your sodium calcium exchanger so that exchanger is not going to work what's the purpose of that exchanger get calcium out of the cell but it's not working so where's Calcium going to stay in inside the cell we get increased intracellular calcium more calcium would be stored in the SR and then the next excitation more calcium comes out a greater contraction it's going to happen every single time once you're at therapeutic levels for doxin but this you don't have to memorize this thing but what is this showing you it's showing you a couple of things one how important calcium is to contraction of our heart the greater the calcium the greater the contraction of our heart that's why we give calcium channel blockers to bring your blood pressure down we don't want you to have that much calcium so we give you medicine to do that another way to do it is by altering your sodium potassium ATP pump by shutting that down sodium builds up inside the cell that's going to alter that sodium calcium exchanger calcium is going to stay inside the cell more more Cal in the cell the greater the contraction that's how digitalis produces a greater contraction by blocking that sodium pottassium pump so if we understand how that blocking of that pump works it makes everything else make more sense that's pretty much all we had for right now for this one um remember with this first lecture is just definitions tomorrow we go through all this fun stuff so we're going to go through a lot more active potentials tomorrow how EKGs are formed and whatnot so I'll see you guys tomorrow you