and we'll be able to start yeah the the first part of this is actually going to review some of the stuff that was uh from uh that youtube video that i did send you on introducing the heart i went over the basic chambers of the heart and structures and in lab you got more detail of the structures and individual characteristics of the heart and functions of each of the parts so with that all under your belt uh the first part of this is just an introduction that uh if you don't mind me reading along uh it says the heart is a muscular organ responsible pumping blood through the blood vessels by repeated rhythmic contractions the average human heart beats about 72 times per minute every book is different on that number i mean some books will say 75 some books will say 70 it varies but 72 is generally agreed as the normal average uh and will beat approximately 2.5 billion times in a lifetime it is a vital organ and animals circulating oxygenated blood to the body to feed the requirements of the cells etc etc we already know the function of the blood that that is uh that is the main substance that is carried by this pumping organ so we we said that the the function of the heart is main function is to pump blood it generates the force for the flow of blood um it further uh emphasizes the the the critical nature of the heart uh by saying in fact a condition where the heart stops beating known as cardiac arrest is a serious emergency death can occur within minutes of cardiac arrest because the brain requires a continuous supply of oxygen it cannot survive if the supply is cut off all right and um and there are many diseases that are related to the heart and as we know it is the leading cause of death in the united states today okay so uh you know there is a huge area of uh cardiovascular medicine that is uh that is out there and uh and i am one of their personal patients as as uh as i get older and older and older i discover that my social calendar has gone from two or three times a week of outdoor dancing and music to uh two or three times a week doctor's appointments but it's uh it just goes with the flow okay uh structure of the heart okay so here's our little review of the heart we know that the heart is a double pump okay we mentioned that it's a double pump and remember there was uh two circuits of the heart i'm going to give you the opportunity to uh to show off a little bit okay so when we talk about the structure of the heart we remember that the structured heart is involved in two circuits and the two circuits would be what systemic and pulmonary yep systemic and pulmonary you guys rehearsed that very well i heard two different voices out there okay these systemic and and circulatory uh uh systemic and pulmonary circuits uh are the two major cycles that the heart is involved in so that's why we call it a double pump we can look at the right side of the heart as receiving the deoxygenated blood and sending it to the pulmonary circuit so the right side is predominantly the pump for the pulmonary circuit where the left side very very dramatically with the thick wall around it demonstrates its its need for force for the systemic circuit okay so in this little grid here that might be there is is just a little review you don't have to fill anything in there unless you know you want to review for yourself but we know that the heart is split into two halves the left side receives oxygenated blood from the lungs so that would probably go in this box if you were filling in the boxes with the notes that are here you would say the left side receives oxygenated blood from the lungs pumps the blood to the rest of the body excuse me and that would be the the function of the left ventricle okay the right side it says receives deoxygenated blood from the body so that would be here okay and uh and pumps blood to the lungs and that would be the function of the right ventricles in the little video i had sent you through um through youtube i mentioned the basic structures that are involved for example what are the two blood vessels that bring blood deoxygenated blood to the right atrium two main ones superior and inferior yeah very good you've got the superior and inferior vena cava or vena cava if you prefer all right however is that the only two blood vessels that bring blood to the right atrium was there another yes yes okay what was it i don't know if i'm going to say it right it's hard yes very good coronary coronary like coronary thrombosis coronary circulation coronary referring to the heart yeah behind the heart in the rear of the heart there is a blood vessel that we discovered in in lab the coronary sinus is the third vessel that brings blood to the right atrium and you discovered it in lab as being a tiny little opening that's in here somewhere so i'll just put it right here okay that little dot that i just made in our diagram there is the excuse me the opening that we see here of the coronary sinus so it looks like a little dark hole on our models so those are the three vessels that bring the deoxygenated blood to the the coronary sinus okay then the blood remember has to go into the right ventricle because this is only the receiving chamber okay and to get into the right ventricle it has to pass through a certain valve what is that special atrioventricular valve called right question i tried the triposted yeah that's a tricuspid valve okay that's the one that we see right here mentioned also in the little uh illustration the tricuspid valve uh brings the blood into the right ventricle and when the right ventricle goes to pump then the blood is going to go to the lungs and to exit the lungs it has to leave through another valve and this valve here on this side is called the pulmonary valve on this diagram it's also called the pulmonary valve but i remind you that you've got a picky professor that wants you to remember another word and that word was my customer semi lunar that's right it's structure don't don't just give me its directional name but also a structural name it's a semi-lunar valve okay semi-lunar because of its structure having the three sort of half moons that seem to make up its structure that we saw last time okay and then it leaves through the pulmonary trunk which is the big blue vessel that leaves that will separate into the pulmonary arteries okay remember pulmonary arteries normally are uh blue or in certain models they use the lavender color to represent the pulmonary type of circulation once it gets oxygen everything returns to the um the left atrium okay and so you've got your pulmonary i'm sorry i just made you know i'm trying to make things color coordinated here okay so the blood that comes back into the left atrium obviously is going to return through these red vessels but even though they're red they're called what arteries they're arteries that's right they are pulmonary oh wait a minute wait a minute let's get this let's try to get our head straight it's blood coming back to the heart so as soon as we say there's blood coming back to the heart we have to say what word veins and even though they're red they're still what the oxygenated no no no no even though they're red they're still pulmonary veins right even though they're red even though they're red they're still veins okay that's what we have to remember okay so so i jokingly might have said in the uh in that little video that you know if you think of like uh arteries are red and veins of blue that's true except when they're pulmonary okay when they're pulmonary they're always going to be the opposite so always slow down slow down your brain slow down your thinking whenever you're talking about pulmonary you have to focus because it's too easy for your brain to do what just happened that when you heard the word red your brain says artery okay as soon as i say well but these things are still red so they're pulmonary and then you know somebody jumped in and said arteries because red you associate with arteries but not when it's pulmonary okay so just remember that okay so these pulmonary veins which again i'm not quite sure why these colors are the way they are they use an assortment of weird colors over here and i think the artist might have made a big mistake uh but anyway the the oxygenated blood comes into the left atrium it then goes into the left ventricle through the valve somebody mentioned before the valve we're talking about now on the left side is the bicuspid or vitro valve for some reason i'm seeing mitral valve used more and more often but remember it is a bicuspid valve either name works now remember these valves are not semilunar okay those valves the bicuspid and tricuspid valves are classified by location they are atrioventricular valves okay so what's an atrial ventricular valve it's a valve that's between the atria and the ventricles okay so that's just a classification name for your uh for your tricuspid valves and your and your bicuspid valves it's just a classification name okay but blood has to leave so when the ventricle contracts it contracts and goes out through which is hidden on our textbook diagram but we sort very clear in the models okay but hiding underneath there is an aortic valve okay and i think it's mentioned over here aortic valve but once again we have to remember that it's not just an aortic valve it's a nature semi-learner okay so i don't know why cat locks went on my fat fingers is that okay semi luna bell okay any question about the basic structures of the heart okay now to just finish this introduction obviously when the blood leaves the semilunar valve it's got a big journey it's going to go into the expressway of the body and that is the aorta and we already introduced the fact that the order is divided to segments depending on where it's going it's ascending so it's called the ascending aorta then it makes a u-turn so that's called the arch of the aorta or just aortic arch and then it descends behind the heart to go through the thoracic cavity hence the name descending thoracic aorta and once it gets through the diaphragm then it's the division is called the descending abdominal aorta and that's coming up that's coming up um possibly this wednesday when we start our introduction to the blood vessel chapter in lab okay so now that we've got a quick review of the heart and its motion of blood flow any questions on that okay so that our introductory lecture was basically on all this introductory stuff that you see here on the first uh the first page okay all right so how does the heart work well that's the question we have to answer and this is the little part of the lab that we didn't get to but we did talk about the valves of the heart and the structures that support the valves the chordae tendineae and the papillary muscles in lab we extensively looked at the structure of the heart and saw its anatomical differences between the left and and right ventricles and chambers uh we we spoke of the the valves and how the vowels are associated with heart sounds and that's going to come up again okay now you get a better view on the right side here of the bicuspid and tricuspid or atrial ventricular valves versus the exiting valves the semilunar valves what they look like when they're closed and how they appear when they're open okay and we found out that it's the actual closing of the vowels that make that classic love dub sound okay we had a little opportunity to look at coronary circulation the names of the different blood vessels that supply blood to and from the heart muscle itself this was the section of the lab on coronary circulation okay but now we're looking and going to dwell on the actual functioning of the heart all right and the way the heart actually functions is by the specialized muscles that allow it to literally beat on its own that was some unique characteristic of cardiac muscle okay that little system that the heart is built with actually controls what we call a cardiac cycle so these are the two things we're going to explore right now all right on the left side is an introduction to the conduction system okay you actually see the conduction system hiding under here and we'll talk about that in a moment and it's relationship to the e k g or e c g depending on how you want to spell it okay so let's take a look at the conduction system okay now here's a picture from the textbook and here's the silly little picture that came with the workbook but first of all what is the conduction system if you read it tells you an electrical conduction system in the heart controls the rhythm of the heart main components of the conduction system are well let's elaborate on that a little bit more okay so in the space that you have on your handout or in your notebook whatever you prefer okay let's write a little bit more about what this conduction system is okay conduction conduction system it is a system of specialized cardiac muscle cells that act like nerves okay by generating action potentials oops which regulate the basic heartbeat okay so what you i'm about to label right now are going to sound like they're nerves but again i stress the fact they're not nerves at all these are specialized muscle cells that are found inside the heart and they were arranged in a internal networking of fibers muscle fibers that is uh that actually act like nerves uh in fact their names they don't have a specific name but the these cells are sometimes referred to as conducting myo fibers okay conducting myofibers myo remember refers to muscle okay myofibers myofibrils uh that were part of the structure of muscle especially striated muscle but these are conducting myofibrils so those are the uh specialized cardiac muscle cells that that we're referring to before okay so where does it all start well let me just give you a little historical background okay many many years ago when these early physiologists were studying the human body you know they did a lot of animal experimentation right and what they discovered was when they took an animal heart i'll make one up let's say frog heart turtle heart it doesn't really matter okay but they they took a heart and what they discovered was something amazing and that was when they took the heart out of the body of the organism okay it continued to beat they would put it in a in a little cultured dish filled with ringer solution that was bubbling oxygen and as long as that tiny heart was surrounded with oxygenated fluid that heart continued to beat on its own so they said isn't that amazing it almost looks like science fiction that this massive flesh that was taken out of the body of the frog turtle or whatever was still beating and pulsating even though it was disconnected from the body so of course these scientists were looking at the heart in amazement and of course they were looking at the heart as a as if it was a living being itself you know this is where religion and science sort of crisscross paths where they said well then the heart must be where the soul of a person exists because look at this heart still beating when it's removed from the body so in their curiosity they took a scalpel and cut the heart in a couple of pieces and wanted to see what would happen and when they took the pieces of the heart okay let's say uh it doesn't matter if i have the exact number that i cut it into but let's say the heart originally was beating at oh i'll just come up with the number 80. all right let's say it was beating at 80 beats per minute when they cut the heart apart they discovered that the heart was actually beating at a random rate each piece was beating at a different rate one was beating at 40 one was beating at 50 one was beating at 80. one was beating at uh 65 uh one was beating at 30. uh one was beating at 45 and i'm just making up the numbers as i went along okay and they found imagine sitting in the petri dish and these pieces of flesh were pulsating and individual types of rates all on their own and then just out of curiosity they pushed the pieces back together again so they would touch one another and suddenly this massive pulsating flesh kept beating erratically for a few minutes and then after less than a minute it's suddenly all the pieces started beating in unison again and guess what number they started following when they were beating in unison again somebody want to guess 80 80 yeah yep it went back to 80. so they were all curious gee how come when they're separate they beat their own rates but when they're all together they seem to follow the one that's beating the fastest so they started exploring that part of the heart that would always beat the fastest and sure enough that part of the heart was discovered to be right here that part of the heart was always in the upper right atrium and so that's why that part of the heart is known as the pacemaker of course now we learn that we give these things more anatomical names this is a sinoatrial node okay so the conduction system begins with the sinoatrial node the pacemaker part the special group of cells in the right atria that initiate the contraction all right now again if they looked at this they found that the pacemaker had somewhere and you know what i had this written down and every book is different um okay i'll double check but the conduction system the cyanoatrial node may have a rhythm rate of somewhere between and again i'm just trying to use my memory on this i think it was 80 to 120 is it 120 okay i was going to say 100 but it's 82. that's per your video ah thank you beats per minute okay all right it has uh that i mentioned that in my video i'm sure i took notes okay you took notes so then you would know okay 80 to 120 beats per minute okay that is the sinoatria node it depolarizes at that rate and not that the heart beats that often but that's the potential that the sinoatrial node can actually beat at so this would be uh beats per minute or or depolarizations per minute okay and if you remember from nerves and muscle depolarization generate action potential all right so there's a lot of overlapping depolarization if you remember was when the the sodium gates opened and the sodium ions went into the muscle cells and that caused a change in the voltage across the membrane but if you don't remember that uh then uh that that's okay it's just the the the depolarizations uh actually are the things that generate the action potentials okay all right so that's a sign that you know the pacemaker now what happens when the sinoatrial node does depolarize well as you can see here okay there are these so-called intranodal pathways these internal pathways basically radiate out the the the depolarizations so if i draw lines like this okay these lines are showing you the radiation of the depolarizations and the depolarizations radiate across both atria and the result is the atria contract okay so that's the result of the sinoatrial node the pacemaker it it sends out this depolarization across the atria and it causes the atria to contract ultimately all right then somewhere down here okay somewhere in this lower area here is another mass known as the atrial ventricular node that's number two on our list the atrial ventricular node is like the secondary pacemaker it's almost like the sinoatrial node is in a relay race and it runs the first leg of the race and makes the atria contract then it passes the baton to the av node the atrial ventricular node the atrioventricular node on the handout is defined as the electrical gateway to the ventricles located near the tricuspid valve so it's in the floor and you and you'll see this on wednesday when we review this in lab that this is the little green splotch that's that's in the floor of the um of the right atrium uh right near the tricuspid valve all right now because the ventricles have to contract from the bottom up these this this node does not radiate its messages or depolarizations outward instead it relays its depolarization through a series of constructed pathways the first is the atrioventricular bundle okay or it used to be called the bundle of hiss all right now the bundle of his sometimes i used to pronounce and bundled his and then i got i wanted to be politically correct and i was saying the bundle of his and hers but that didn't go over very well so i just started pronouncing it hiss instead the bundle is or you could just call it the the atrioventricular bundle okay but the atrial ventricular bundle atrial ventricular always refers to between the atria and ventricles so there's that word again av atrial atrioventricular the atrial ventricular pathway a bundle rather bundle bundle it's the pathway for the electrical signals as it leaves the av node and what it does is directs the message right to the septum okay so there you go and that leads to the left and right bundle branches now whether you call them the left and right bundle branches whether you call them the av bundle branches it doesn't matter to me i mean as long as you remember the atrial ventricular bundle or bundle of his relays to them so that would be number three uh number four on the list the right and left bundle branches okay you see them right here okay the bundle branches are mentioned right there okay there's two of them obviously they're going to go down the septum and when they go down the septum they get to the apex and when they get to the apex they make a u-turn and when they make a u-turn they create these little muscle cells that look like nerve endings and these are known as the purkinje fibers and that's number five on the list purkinje fibers fibers that branch the left and right ventricles and coordinate the contraction of the ventricles these are like and i keep saying like like nerve endings but they're not nerves remember so these muscle fibers these purkinje fibers at the very end here actually radiate the signals to the muscles and this is what makes the ventricles contract so ventricular contraction happens here okay where atrial contraction happens up here okay so atrial contraction is happening up here ventricular contraction is happening down here okay so this is the structure of the conduction system and what it's doing oh by the way the av node uh it contracts a little bit slower okay uh was that remind me 40 to 60 yes 40 to 60. 40 to 60 beats per minute okay and uh and you're going to see the significance of that in a minute in fact uh that minute is coming up right now because obviously this conduction system of the of the heart is the conduction system that generates a very very specific signal throughout the body and this can be recorded as your ekg so this conduction system is recorded and not that you need to know the numbers specifically okay but you just need to know the deflections so i'm going to try my best to to draw these deflections on here so you can see them and hopefully not lose everything all right but here we go okay so here is the voltage maybe the voltage is minus 30. i said you didn't need to know it but i believe the resting voltage is minus 30. all right what creates that minus 30 is remember the sodium ions are on the outside and the potassium ions are on the inside and the potassium ions also have chloride ions on the inside so if you add up the positives and negatives there's a net negative charge um but we're not going to worry about where these numbers come from we're just going to look at what happens so here is the heart at rest at 30. and then what happens is the sa node depolarizes when the sa node depolarizes it causes a depolarization that causes a deflection that looks like this and then it goes back down okay and as it goes back down this generates what we call the p deflection so the p deflection is a mirror of what's going on with the sa node okay the p deflection is caused by the depolarization of the sa node and it's an indication of how functional uh your sa node is all right i'll get back to that in a minute after that what happens well the av node now is gonna fire okay it's going to relay its signal to the bundle of his that's going to go to the right left bundle branches and eventually it's going to get to the purkinje fibers and that's going to make the ventricles contract well obviously this is going to take a little bit longer okay if we were actually measuring this right here this literally takes one tenth of a second one tenth of a second is for the sa node to depolarize what happens at after the p is as you can see from the diagram here i'm going to try to draw it as best as i can there's a drop slight drop and there's a huge peak and it comes back down again a little bit lower and then it slowly returns to normal again okay these three spikes right here or the part of the ekg known as the q r s the qrs is reflective of all of this the qrs is reflective of the atrioventricular node depolarizing and sending its signal to the purkinje fibers to make the ventricles contract so when you look at this nice sharp qrs you're looking at an indicator for ventricular contraction how well are your ventricles contracting then after that there's a little bump that ends the cycle of ekg and this is the t deflection or t wave now because the qrs takes longer okay uh the qrs is approximately i think to this point right here uh might be about 0.4 seconds so from here to here okay that's uh three tenths of a second just for the qrs okay and then the rest of this is to end it is about 0.8 seconds but the whole thing the whole thing is 0.8 seconds sorry about that i'm almost afraid to go to print and lose the whole screen that's why i'm trying to do that actually it's a beetle i don't know why try let me do it the old-fashioned figure eight way there we go that's safer harder to do that with a rolling mouse okay remember this is all in seconds okay so 0.8 seconds all right and um and that's an ekg okay and that that's what the ekg is reflective of okay so it's reflecting the health of your conduction system and it's also reflecting the rhythm of your heartbeat okay so when they're doing an ekg on you uh they hook up your your chest and sometimes your ankles and the side of your body and i've had leads on my legs and things like that i don't know they every ekg system does things different but they're recording the electrical conduction going through your body and by looking at this ekg they're looking at the health of your conduction system as well as the health of your heart all right now that you know that okay now that you know that see a little ekg knowledge now so if you were looking at an ekg of a patient and you saw their ekg doing this okay as best as i could the first thing you would notice is okay how come i'm not getting a p there's no p wave there i'm getting a wiggle i'm getting a wiggle but then i'm getting a sharp q r s t but i'm not getting the p okay if you're not getting a p deflection that's an indication of possibly atrial fibrillation okay that's what they would see okay because obviously the atria are not contracting properly the sa node is not firing properly and so the atria are spasming okay the atria are fibrillating that's what they call it so that's why it looks like a flutter but as long as the qrs is strong that's okay okay lots of time you see patients sitting in bed with little flippy flops as their atria are fibrillating but as long as the qrs is strong the qrs can keep the person alive because remember that's the ventricles contracting and they're pumping the blood out it might not be pumping the blood out effectively because it doesn't have that support from the atria but you have you you have the bulk of the blood actually being ejected out by the strength of the ventricle ventricular contraction that's going on all right so that's if you've ever heard of somebody having a fib or they're diagnosed with afib that's what they probably saw on their ekg okay they may give them they might prescribe a beta blocker for them they may prescribe a change in diet or something but usually they can give medication to correct that all right unfortunately if they see something like this well now the person is having what i'm a heart attack yeah yeah they're having cardiac arrest or maybe not cardiac arrest yet but they're definitely having a heart attack they're in total fibrillation and that's why now you might get it why that machine that they have now in hallways of major buildings where you've definitely seen them on medical shows okay they're called a defibrillator because if the heart is doing this this is not good that means the entire heart now is spasming the whole heart is fibrillating so what do you try to do with that defibrillator you try to shock it you know you like i said if you've never you know seen one i'm sure you've seen it on tv where they have these little paddles and they and they put a little gel on them they rub them together and they tell everybody to stand clear and what they're hoping will happen will be this while the heart is fibrillating when they shock the heart the heart will do this the heart will contract and then the hope is that when the heart relaxes it gets back into its rhythm that we we shocked the heart to get out of that fibrillating stage of course in many of the doctor shows it doesn't happen on the first time so they i don't know if they increase the voltage a little bit some of you may have had more experience with it than i uh but i remember having uh an emt worker in the classroom and this was years ago and back then this was years ago and back then uh they they said that they would actually try to jumpstart the heart three times and they would increase the voltage each time and after the third try they would stop trying anymore because they were told that if they try to do it any more than three times it was just going to fry the heart today that's not the case anymore i've been told that today you tell me if i'm right or wrong you're supposed to keep on trying and you you're supposed to do you know various forms of cpr in between uh anything you have up until 30 minutes 30 minutes yeah okay all right and so uh so now you you see why this ekg is so critical in terms of diagnosing you know potential problems with the heart okay now i'll share a little personal story with you and just this past thursday i went in for a procedure because my last ekg my last stress test i was diagnosed with a depressed st now i didn't know what that meant initially i had to look it up myself but a depressed st refers to the fact that the st was actually a little bit lower than it should have been okay it was depressed and what that usually means is while i was on the treadmill my ventricles were not getting enough oxygen this is an indication that possibly those coronary arteries that we learned may have been occluded may have been clogged may have had you know that you know the fatty deposits in it that cause hypertension so i had to go through a procedure on thursday and i picked thursday because i figured i would have the whole weekend to recover and what they had to do was they had to put a catheter a cardio cardio catheterization it's called uh and uh they they went through my wrist okay normally they go through the groin through the femoral arteries up your aorta but uh because of another condition i've got they went through my wrist instead and they went through my right wrist and they went all the way up my arm into my heart and they inject dye and it's like an angiogram that's what an angiogram is they inject dye and they look at the dye going through those arteries then after they look at the dye going through the arteries if they find the clog since they're already in there if they find a an occlusion or an artery that's pinched in they will immediately do an angioplasty okay so look at all these words i'm throwing at you okay so an angiogram is looking okay that's looking that's that's using the dye okay just look at the uh inside of the heart to see what's going on okay if they find a clog they might do an angioplasty that's when they'll insert a balloon in the catheter and they'll inflate the balloon to widen the artery and then in that widened artery they'll then put in a stent and depending on how many clogs and depending on how many clogs they may find they'll put in one stent two stents three stents for the major arteries depending on which one they were okay i'm here pleased to announce that they found no occlusions no blockages no clogs and there was no need to put in any stents but i'm now left with a depressed st when i'm running a treadmill and trying to find out why okay so that there must be some other medical reasons so that's uh that's that's the next exploration but i'm happy to report that at least the blood vessels around my heart are not occluded and not clogged and i guess i stopped eating french fries and mcdonald's hamburgers early enough where it didn't cause that much clogging of my arteries even though i do have slight hypertension so i was a living example of this unit that that you're studying right now but thank goodness everything came out well okay now on that happy note let's continue any questions on the ekg how it's related to the conduction system uh professor i have a quick question sure um the the t wave that that represents the ventricular depolarization right no you i'm glad you asked me that question because that's something i forgot to tell you okay i mentioned that the t p was the depolarization and contraction of the atria okay qrs was a depolarization of the ventricles and the ventricles contracting the t is actually the repolarization of the ventrals because remember after depolarization is repolarization okay that's what the t is which raises another interesting question if the p [Music] is the depolarization of the vent of the atria and the contraction of the atria if the qrs is the depolarization of the ventricles and the contraction of the ventricles and the t is a separate deflection for the repolarization of the ventricles then where's the repolarization of the atria it's within the qrs complex right very good yes it's happening somewhere in here someplace yeah because of the severity of the magnitude of the qrs the the repolarization the atria are hidden within the qrs of the ventricles all right so it happens somewhere in here so the interesting thing is when you look at this time wave okay when you look at this time wave right here you know and again thank you for asking that question because you helped me put a closure to our discussion on ekg when you look at this timeline one second one tenth of a second for the p uh three more tenths of a second for the qrs what is the heart doing the rest of the time relaxing it's relaxing and here's where we start introducing a couple of new words whenever the heart is beating whenever we say the atria is contracting the ventricles are contracting we end up introducing these two terms systole which is contraction and diastole which is relaxation now these words are a little bit confusing because you might have heard those already when you talk about blood pressure when someone says standard blood pressure is is 120 over 80. okay the 120 is systolic pressure so systole as an i guess adjective is pronounced systolic you drop the e you put ic so the 120 would be systolic pressure and the 80 would be diastolic pressure when the heart is relaxing okay we're going to get more into that when we do the unit on blood vessels but just to give you an introduction to those vocabulary words before we get into the uh the cardiac cycle okay so from now on any time we say during atrial contraction we can also call that atrial systole so if i was labeling the ekg we would label the ekg the timeline of ekg is that the first tenth of the second would be atrial systole okay and what would the atria be doing the rest of this time if this first tenth of a second is atrial systole what would the atria be doing for the rest of this time relaxing it would be relaxing relaxing and filling up with blood okay so this long long line here that i just drew this would represent atrial diastole okay now i cringe every time i go to change color because i that that's usually when everything disappears okay all right good it didn't happen okay if we look up here of course i change color and color goes back okay if we look at the qrs right here right where i'm putting the double arrows there okay the qrs this represents uh 0.3 seconds okay and this is when the ventricles are contracting so this would be ventricular systole so then what is the heart doing the rest of this time here and prior okay yeah that's when the ventricles are relaxing the only reason why i went through the trouble of of doing this is because it just goes to show something that's very unique about the heart we talk about the heart as being beating it's actually beating it begins to beat somewhere around the sixth to tenth week of fetal development and here's an organ that has to beat and function for a lifetime all right literally and and and so as it's beating the whole lifetime you tend to think wow the heart is a very very uh hard working organ it's beating for a whole lifetime it's constantly beating it doesn't have a chance to rest but in reality if you look at the design of the heartbeat okay if you were in atria okay if you were in atria take a look you beat for one tenth of a second and then for the remaining seven tenths of a second of the cycle you're relaxing what a wonderful work week imagine working one hour a day and having a seven hour break and then you work one hour you have a seven hour break that's the job of an atria so when we think of the heart working so hard in reality the design of the heart's physiology is such where it's actually spending more time relaxing and recovering than it is actually functioning now of course that might be you know sort of downplaying the importance of the heart because obviously when you're exercising when you're running your heart has to be faster and faster and faster and faster but even in that cycle one out of .8 seconds the atria is contracting and if you pick a ventricle well the ventricle has a different hourly schedule three tenths of a second it's contracting the other five tenths of a second in that cycle the other five tenths of a second it's relaxing so that would be like having a three hour work day and a five hour break okay not too shabby all right so again we're impressed with the the efficiency of the heart and its ability to beat all those years and yet the design of it is such where it does be effectively and efficiently according to its its its timeline its timetable and this effective type of cycle that we see here is actually what this is leading into next and that's what we call the cardiac cycle okay so if there's no questions here oh let me undo that okay any questions on this um sometimes you're probably confused with what you just explained okay i'm gonna i'm gonna explain it again i'm gonna make a timeline later when you see the conduction system i mean uh the cardiac cycle okay yeah this is just showing you a time scale but i'm gonna go over that again okay and it's coming up right now okay so after we understand the conduction system we now look at this and this is just explaining everything i just said okay what happens during the cycle okay and we said the cells of the sa node trigger an action potential electrical signal then generates by nerves uh which is i i hate this it says electro signal generated by nerve cells but these are not nerve cells remember that they're not nerve cells okay action potential moves through the two atria causing the atrial contraction natural systole the action potential then depolarizes the av node the action potential then gets propagated to the bundle of his the action potentials propagated through the ventricles and causes the contraction of the ventricles and then mentioned the left and right bundle branches okay oh one little more side note in lab i did mention something called the moderator band this conduction system okay favors the left ventricle and left ventricle has more fibers it's going to conduct and contract a lot harder but you see this little fiber right here notice that this little fiber is like taking a shortcut okay this little fiber right here is taking a shortcut it's not labeled but that's the area of the moderator band okay and i described the moderator band as being it's like a little shortcut notice it comes off the septum before you reach the apex there are some purkinje fibers that cut across here okay so the moderator band is an electrical shortcut that allows the right ventricle to contract in harmony i guess that's a good word to use with the left ventricle and if you can't see that that well because i'm using a bad color you might be able to see it better now that's the moderator band now of course if you look up moderator band it in in your textbook it's a much more elaborate definition but that's the functional definition of what the moderator band is and it makes sense when you look at the thinness of the right ventricle and the thickness of the left ventricle that the right ventricle would actually fall behind if it didn't get that little head start right there okay so what is the next page all right now the next page describes the cardiac cycle in words all right so this is almost like a script but in reality you heard the script already because we just did the conduction system so let's do this one step at a time and you highlight the parts that you feel are necessary to highlight okay now i decided to start off with phase one at the end of the last heartbeat so this is late ventricular diastole okay so let's let's write this down okay what do we already know about late ventricular diastole well read the first bullet this is when both the atria and the ventricles are both relaxed okay so this is relaxation soon as you see diastole anytime you see the word diastole okay just just to get into a habit of writing relaxation okay so in late ventricular diastole the ventricles are relaxed the atria relaxed everything is relaxed so what is the heart doing when everything is relaxed well let me move the diagram on the right side is it filling with blood yes that's exactly what it's doing okay oh i guess i could use this oh okay i hate those blackouts and that's okay i'm glad it happened now okay so in late ventricular diastole okay the heart is relaxing and as the heart is relaxing what's happening is blood is coming back from the body and it's filling up the that's filling up the atria here okay blood from vessels flow to the atria av valve into the ventricles there's no pressure in the ventricles so the av valves are open so the av valves are open and so the blood is going to go in here and fill up this side and i should do this okay so the blood is just going in okay this is and and again i i added certain words to the original book definitions the heart now is filling with passive blood flow this is blood just pouring in no force the heart is not contracting the heart is in diastole okay the heart is relaxing and so this is the passive blood flow the heart fills with this passive blood flow from the bottom up so it actually i should have started down here and say the heart's filling up filling up filling up filling up filling up okay and the other side was doing the same thing once filled the relaxed ventricles are at eighty percent capacity the heart is said to be in a special state called diastasis okay so when it can't fill with any blood anymore so filled with blood in a relaxed state okay that's what we call diastasis but notice something very unusual it's said i know i'm repeating exactly what's written okay but notice it said this state of diastasis is not filled to 100 percent yet the ventricles are only filled to 80 percent capacity now i know that sounds like a contradiction how do you say it's full but it's only 80 capacity and the only analogy i can come up with is it's like one of those musical concerts where you find out oh yeah it it's sold out okay and then all of a sudden three days before the concert they said hey we just opened up 200 more seats well wait a minute wait a minute i thought it was sold out where did these 200 seats come from well obviously they did not sell out to capacity they opened up some more sections maybe slightly behind the stage they decided they wanted to make more money uh and so now they open up you know or maybe they put some chairs in in an area that was an open area so they increased the the capacity of that particular venue well the heart's a little different than that see we can fill up the heart with blood but we know the heart can hold more blood because muscles are elastic muscles can stretch and that's what we're ready to deal with now so step one picture this in your head the heart is relaxed and all it's doing is filling up with blood until it reaches what point what's that little fancy word is that diastasis got it so that's step one step two well step two you already heard of already but let's go through it again step two phase two atrial systole what word do we write every time we see the word systole contract extraction contraction and we get used to that we get into a habit so it becomes part of your normal vocabulary okay what happens in atrial systole well at this point you should be able to tell me but we can just read together cyanoatrial node depolarizes and causes the atria to contract no surprise is it no but when the atria contract what's happening in the heart more blood is forced into the ventricles causing the ventricles to stretch to a hundred percent capacity ah now it makes sense these atria just contracted and pushed that other 20 of the blood into the ventricles and the ventricles swelled up okay so that forced the excess blood that other 20 so that explains why we just went from 80 to 20 percent because the atria just contracted because the atria contracted what would you expect the pressure in the ventricles to do right now we just squeezed blood into there yeah right ventricular pressure is going to go up well sure enough what does it say pressure in the ventricles increases due to the increased volume of blood and forces the av valves to close there's your first heart sound okay right at the end of phase two so the atria contract ventricles expand and you hear the first love sound the first heart sound the closure of these av valves so let's see what that looks like if i can slide the side up okay there we see the sa node depolarizing the purple's representing the the wave of the action potential is the av node doing nothing yet now the atria are contracting forcing the blood into the ventricles there's something wrong with this picture i don't see the av valves closed okay so uh the atria oh this is atrial contraction okay the impulses travel from the av bundle the moderator band okay here we go all right that was just before it okay got it okay so here's the atria finishing their contraction and now the pressure is building up in here and that's makes these valves close okay all right now notice we're ready for phase three now that the ventricles are filled now we have ventricular systole but notice ventricular systole is in two parts and you'll understand why in a moment ventricular systole early ventricular systole to keep our routine going we write contraction next to systole okay atria repolarize and relax diastole and begin refilling with blood so that's sort of like an afterthought so these atria are going to relax and gonna fill up with blood meanwhile the av node depolarizes and relays the stimulus to the puking fibers ventricles depolarize and begin to contract systole pressure increases in the ventricles oh but this is an important line right here look at this ventricles depolarize and begin to contract pressure in the ventricles increases even more now but no blood is ejected yet no blood is ejected yet why because this diastolic pressure in the aorta and pulmonary artery are still greater than the ventricles ah so in other words pressure in here pressure in here and here or building up remember when the heart was filling up pressure was zero okay and now the atria contract and now don't worry about this graph you're going to see it later the atria contracted and now the ventricles are contracting and the ventricles are contracting ventricles contracting ventricles contracting but the blood is not leaving yet because we haven't opened up the semilunar valves yet okay because you've got the heart contracting without ejecting blood is a name for this this is called iso volumetric contraction and the definition of isovolumetric contraction is right here it's when pressure increases in the ventricles but no blood is ejected yet hence the word isovolumetric iso means no change it's the same like in math isosceles triangles two sides were the same isometric exercises versus isotonic exercises maybe you did that in 131 okay but iso refers to stability not changing so what is the heart doing just read it the heart is contracting without losing blood okay and the blood pressure just keeps building up so that's why they call that isovolumetric contraction but eventually you're going to reach a pressure that's going to make the semilunar valves open and that's phase four it's this late ventricular systole the period evjection so soon as you see period of ejection you know that's when the semilunar valves opened okay say so i want you to be able to associate the notes to what's going on period of rejection blood is ejecting all right and that's where exactly it says underneath ventricles fully contracted and systolic pressure forces the pulmonary and aortic semilunar valves to open so let's go back for a second and insert some numbers so back at phase three pressure increases in the ventricles but no blood is ejected because diastolic pressure in the aorta and pulmonary artery are still greater than the ventricles what is diastolic pressure again what's the number we give to dyestock pressure 80 80. remember 80 is the low number okay so as pressure is building up and building up and building up in the ventricles it's building up and building up and building up but it didn't reach 80 yet because you need 80 to open up the valves because on the other side of the semilunar valves that's the diastolic pressure that's the pressure in the arteries when the heart's not beating but the ventricles don't just wait till it gets to 80 no the ventricles contract with a force remember it's three tenths of a second so when the ventricles contract it's going to go past the 80 until it reaches enough systolic pressure to open up the valves and what number should we put here 120 120. yeah well you see systolic pressure forces the pulmonary and aortic valves to open we're talking about 120. by the way the mm stands for millimeters of pressure okay blood pressure is measured by you know pressure of of of the the mercury in a tube or something like that but that's the unit they use for pressure okay so that's the systolic pressure of the aorta and and it makes sense doesn't it now the pressure is big enough to open up the semilunar valves the blood is going to go squirting out blood leaves the ventricles blood from the right ventricle travels through the pulmonary arteries to the lungs meanwhile the blood from the left ventricle travels through the aorta to the rest of the body now there is one more line there i'm going to see if i can stretch this without losing the notes yes perfect okay as you can see the finale of all this is so the blood from the left ventricle travels from the aorta to the rest of the body why did that happen i didn't do anything well i'm glad it happened at the end of the slide but unfortunately i think we lost all the nuts okay so only two-thirds of the blood leaves okay two-thirds of that blood leaves and this is called the stroke volume so there's another vocabulary word how much blood leaves the heart during a heartbeat okay that word is going to come up later also that's called a stroke volume that's 80 milliliters of blood that's going to squirt out but i think you already know something if this blood is going to squirt out because the ventricles just contracted as soon as the ventricles relax what's gonna happen next what are those semilunar valves gonna do they're gonna open but they did open the blood just went squirting out remember but as soon as the ventricles relax they're gonna close yeah they're gonna slam shut right in the face of those ventricles so you just squeeze the blood out okay remember the pressure on the outside of those semilunar valves is 80. so when the ventricle squeezed with 120 those av valves burst open everybody went flying out of the elevator and the door slammed shut right in the face so the atria is still in diastole but that's just another little side note so what are we looking for we're looking for what happens after this and so sure enough it says early ventricular diastole okay it's called a period of rapid filling the ventricles repolarize and relax diastole this drop in pressure causes the semilunar valves to close so there you go there's our second heart sound okay so for a moment not only are the av valves closed they're closed because the ventricles just contracted but the semi-learner valves that are leaving they're closed also okay all four valves are temporarily closed the atria have been filling up with blood causing enough pressure to open the av valves to allow a rapid filling of the blood into the ventricles and the process begins again all right and so that is what's going to happen so soon as the for a second all four vowels are closed okay that means there's no blood coming into the ventricles no blood leaving the ventricles okay so for a second just for a second right here we have iso volumetric relaxation okay no blood going into the ventricles no blood leaving the ventricles we have isolated relaxation diastole okay now once you understand all the words and basically it's almost like you got to repeat the story to each other remember this entire story takes point eight seconds and so whether you study it by way of words or you actually look at the diagrams that come in the book okay there's a little repeated ekg okay there's also a diagram like this in the book that goes through the the cardiac cycle okay so what did we just do the cardiac cycle all the events during a single heartbeat that's what the cardiac cycle is all the events of a single heartbeat and remember that timeline that somebody said they were confused about there you see it in the middle there's the timeline okay it's 0.8 seconds they have things in milliseconds here see it's 800 milliseconds that's eight tenths of a second all right so look atreal systole one tenth of a second the rest of the time it's relaxing diastole now if you don't like a circle timeline you can actually draw it like this if you'd like you could take this timeline and stretch it out okay and let me do this for you try to make it as even as possible it's not perfect but you get the idea one two three four five six seven eight there we go if you want to make this in your notebook you can if you like zero 0.5 let's see if my estimates are right not bad okay so ready okay for the person especially for the person who is a little confused oh no not now okey dokey that must be a sign