welcome to this discussion over the heart uh this will be coming from blossom mostly section 19.1 and just a small bit from 19.2 uh you will not be responsible for the majority of 19.2 through the end of the chapter this is the beginning of material 4 exam 4. exam 4 is heavily weighted on the cardiovascular system however there is also information included on the endocrine system the lymphatic system and the digestive system so be looking for notes about those other body systems as i begin this conversation you should be expecting some connection questions about how the cardiovascular system is connected to other systems so be listening for some of those or imagining some of your own connections and be formulating those ideas for exam number four so let's take a look at the heart it is an amazing organ i know i say that about everything but the brain is amazing the heart is amazing and we're going to see other amazing organs as we continue through this uh this semester but man the heart is amazing you'll also be doing two uh labs labs eight and nine are both on the cardiovascular system and they are coming up and um you will be getting instructions about those uh in the in the upcoming labs so let's take a look at the heart okay here is a beautiful picture a beautiful artist's rendition of the heart and you will before we're done here uh be introduced to all of the great vessels that come and go in and out of the heart you'll be introduced to the vessels that bring blood to the heart and the vessels that take blood away from the heart muscle itself you will also understand how the heart is involved in two different sets of circulations of the blood and everything that's carried in the blood so let's get going uh as we move through this section 19.1 now you learned in the nervous system that the brain is not made up of two equal halves right the left hemisphere and the right hemisphere of the brain are not equivalent recall that for example wernicke's and broca's area are typically found on the left side they're not found on the right side when they are occasionally found on the right side they also are not found on the left so there's also specialized regions within the two hemispheres same thing is true with the heart you're going to be seeing that the heart is oftentimes referred to as a double pump you have the left heart and the right heart and i will use that terminology as well and so basically what you have are two pumps side by side they're slightly different in shape and in size and in function if you've ever played with a pump you know that a pump if you think about like for a pool pump a pool pump is designed to push the water right through the filter and so there is definitely a pushing function of a pump but there is also a sucking function of the pump so the pump is sucking the water back toward it and then it's pushing it out so the human heart is the same way it is both sucking blood back toward it and it is pushing blood out away from it so we'll see how all that works together so let's take a look at the heart anatomy and this will be really really super important for the next exam you'll be studying this rather extensively in the lab as well i'm going to give you some numbers here these numbers are really for you just to go wow right to go wow so on average if you took all the people around the world young and old you would say that the average heart rate is 75 contractions per minute right so the heart beats 75 times a minute again that's an average if you're younger your heart probably beats a little bit slower than that and if you're older your heart probably really beats a little bit higher than that and now keeping keep in mind this number is at rest right this is you're sitting there right now in your chair listening to this presentation that means 75 times a minute that your heart is beating about a hundred and eight thousand times a day i'm not going to highlight that because it's not a number that i want you to memorize but it is just amazing and that means in a year about 39 million times right and if you look at the average life span we're talking about the heart beating roughly 3 billion times in an average lifespan pretty amazing okay now here is another number and this one's a little bit more important i'm gonna go ahead and highlight this one each time that your heart beats it is ejecting or pushing out about 70 milliliters of blood that's not a lot right it's a fair amount but it's not a huge amount of blood so every time your heart beats it's pushing out 70 mils of blood again this isn't a resting adult if we were exercising the heart would be beating faster and harder and would be pushing more blood to supply the muscles with the necessary blood but this is at rest now if you are uh if your heart is beating 75 times a minute and each time it is pushing 70 mils of blood out that means that about every minute and this is another number i want you to appreciate that your heart is pushing about five and a quarter liters of blood right about five and a quarter liters of blood per minute are being pumped by your heart let's stop for a second how much blood do you have in your body we'll discuss this when we get to the blood chapter coming up in this unit but let me just tell you now you have between four and six liters of blood so a large person a male a larger person might have the higher end six liters of blood a smaller more petite person would have closer to the four to five liters of blood so essentially another way of thinking about this your entire blood volume is circulated around essentially right just ish every minute now if we're pumping five and a quarter liters of blood every minute that's 14 000 liters per day that is 10 million liters in a year which is 2.6 million gallons of blood sent through your heart okay and what is even more amazing and we'll see this again when we get to the blood vessels also a significant part of this exam that you have in your body roughly 60 000 miles of blood vessels and to be honest i've seen some books say up to a hundred thousand miles of blood vessels amazing right that within your body you have that many miles miles friends miles of blood vessels remember every cell in your body or most every cell in your body is in direct connection with a blood supply remember we know the exceptions you know that epithelial tissues don't have blood supply directly nearby though and you know that for example cartilage is a vascular but the rest of all of the trillions of cells in your body have a direct connection to blood flow so when you think about that complexity 60 000 miles uh well it kind of blows the mind is not an unreasonable number now make sure that you are definitely watching the videos as you go through the blossom textbook the cardiovascular system i think is a very visual system and it will take a little bit of mental gymnastics to understand the flow of blood through the heart let me tell you now that is a huge learning outcome for this chapter okay for this unit for this exam if you understand the flow of blood through the heart then you understand the chambers and the valves and you understand so much in lab you'll also be working through how the blood flows to the heart so you're gonna be seeing this in multiple angles critical critical critical now as this diagram shows and as you'll read watch as you watch this video we can talk about two circuits there is a pulmonary circuit and the pulmonary circuit is are the blood vessels that the heart pumps over to and from the lungs to and from the lungs from the pulmonary system or the or the respiratory system and then there's the systemic circuit and that's the blood that's sent to and from all of your other systems this is the vast majority of the circuitry through which your heart sends blood so where is the heart located i think we all appreciate that the heart is located in the mediastinum we learned about the mediastinum back in lab one remember the mediastinum is that region essentially between the lungs found in the center of the thoracic cavity so we find not only is the heart in the mediastinum but so are a number of other things for example the trachea right that passes down and brings air to the lungs is also located within the mediastinum the esophagus which is behind the trachea that travels down to the stomach that's not shown here it is also traveling down through the mediastinum and then finally there are the great vessels for example the aorta shown here the aorta is the great artery leaving out of the heart and also you see here the superior vena cava and the inferior vena cava coming up from the abdominal abdomen those are also passing through a portion of the stylum so mediastinum the middle region behind the sternum in the thoracic cavity it is the home to the heart one more thing that's in the mediastinum not shown here but on top of the heart on the superior border of the heart there is a small gland called the thymus and the thymus is an endocrine gland and you'll see that it's associated with the heart and so it too is in the mediastinum we learned back in lab one that the heart is surrounded by the pericardium so the pericardium is shown here remember that's a double layered membrane around the heart the layer that is shrink wrapped to the surface of the heart would be the visceral pericardium and then you can see how the author has pulled away and shown the outer layer around and that would be the parietal pericardium and in between in that thin layer there's going to be some serous fluid which is going to help lubricate and protect the heart so in between the uh pericardial membranes between the visceral and the parietal layer is the pericardial sac if you well and in there that pericardial cavity like i just mentioned full of serous fluid allows the heart to beat multiple times a day as we know and not build up significant heat where is the heart located you can read the specifics here i should say uh as i introduce this and as you read through this it's referring to the base of the heart and to the uh the base of the heart is introduced here as is the apex of the heart so the base of the heart base i'll go ahead and just highlight that the base and the apex the apex is the tip the pointed tip that points inferiorly on the heart the base is actually the superior surface of the heart so it's kind of upside down isn't it so when you think of the word base you would think it's on the bottom but in fact in the heart the superior surface the top surface is the base the bottom pointy region is the apex and you'll see that is here the apex pointing down into the left okay and then the base would be the superior border of the heart the base is where the aorta and the superior vena cava enter and leave the the heart uh also notice that the part is shifted just a little bit over to the left side it is protected by the sternum okay largely but not completely it's also protected by the rib cage and you can see that it's actually directly behind that costal cartilage so that cartilage that connects the ribs to the sternum it's right back there so when person's doing cpr and they're doing compressions you're actually pushing on that costal cartilage which of course is more flexible than bone and that is going to allow the actual chest compressions to squeeze or to push on the surface of the heart now it is possible when people do cpr to be a little overzealous and to fracture ribs but that's the price of keeping that person alive uh doing those chest compressions there is a inbox here about cpr i am not expecting you to know this uh you will most of you if you go into allied health fields will become cpr certified and i will leave that for that time but just appreciate the location of the heart and this is a really excellent inset and it just reminds you of the hand placement over the particular ribs when you're doing the chest compressions so the heart itself just introduced it it's it's sort of about the size of your fist okay that is a good estimation of the size of your heart so a bigger person bigger fist bigger heart and um the the heart the weight of it don't worry about the numbers but you can see that uh the female heart again on average is a little bit smaller than the average male heart male hearts 11 to 12 ounces guys it's not even a pound right so we're not talking about a heavy organ uh the heart is hollow right there are four hollow chambers within the heart now a well-trained athlete can have a larger heart now larger heart here i want to make sure i will appreciate this later on and tell you about this a larger heart is oftentimes considered a diseased heart so the largeness here is overall just the the muscularity of the heart uh but it's also possible to learn the heart to enlarge over time we'll talk about that later and that is actually a sign of a weakened heart now remember that the heart is the home of cardiac muscle and we will finish today's presentation reviewing cardiac muscle in section 19.2 recall that cardiac muscle is involuntary is regulated by your autonomic nervous system remember the sympathetic division can turn up your heart rate and the parasympathetic system can turn down your heart rate it is possible though like i said a well-trained heart can be slightly enlarged but what we don't want is a condition called hypertrophic cardiomyopathy this is a condition that we hear about every man it seems like every season we hear about a highly tuned athlete who dies on the basketball court or on the football field and when they go to do the autopsy they realize that this person had this pathology this disease of the heart hypertrophic it becomes very enlarged and we'll see that an enlarged heart muscle is not a healthy heart okay so if the heart gets large it can't pump as efficiently and unfortunately this is one of those things that does not routinely get screened in health and physicals sports physicals it wasn't that long ago my son was going through a sports physical season right like a lot of football players have to get their physical in in the summer before they can play contact practice in the fall and there was and there usually is every year some medical clinic somewhere who is doing a more thorough screening of hearts is not necessarily part of the physical exam required for sports physicals but wow how important it is and it really should be every person who's been cleared for athletic activity really should have their heart checked to make sure they don't have this underlying condition which is undiagnosed completely misdiagnosed and can result in sudden death so let's take a look at the chambers of the heart you're probably full aware the human heart has four chambers uh there is a left side and a right side the left heart and the right heart each side has an atrium you know from your vocabulary that atrium means entry way homes you may refer to as having an atrium or a church or a business has an atrium an entryway we'll see that the atria plural are the chambers that first receive blood so they're the entryway into the heart they are the more superior of the chambers and then each side has a ventricle the ventricle are the more muscular we'll see that in a moment and they are the more inferior chamber on each side so one atrium two atria one ventricle two ventricles make sure we're using that terminology properly i mentioned already that we have two circuits and these are quite distinct there is the pulmonary circuit so pulmonary circuit is transporting blood to and from the lungs the primary job of that is done by the right heart and then we have the systemic circuit that's transporting blood to all the other tissues of your body and returning it as well and that's the systemic circuit okay the systemic circuit so these videos are excellent make sure you're watching these make sure you're also of course reading and looking at these fill in the blank and the questions throughout this chapter let's take a look at some of the major arteries and veins and vessels that are associated with the heart so the right ventricle the right heart the ventricle and the right side of the heart is going to pump deoxygenated blood let me just pause there if you are watching this video first then let me make sure you understand this idea of deoxygenated blood and oxygenated blood deoxygenated blood is sort of a misnomer this is not blood that is completely lacking in oxygen although the name suggests that it is without oxygen this blood however does have less oxygen in it and this is going to be colored blue if you don't already have a blue pencil and a red pencil get one um it could be a blue highlighter a blue and red marker pencil something like that but as you are in lab and as you are labeling parts of the heart red and blue are significant very important now if you don't have red and blue and you only have purple and green that's okay but be consistent with your coloring of the heart and you'll see as we go through lab and through this presentation the consistency of the colors so the right ventricle pumps blue blood deoxygenated blood in fact i'm going to go ahead and just um say that over here i was going to highlight it blue but remember that blue is sort of my color code for things that we're going to delete so i don't want to do that but i'm just going to put over here that deoxygenated blood right is blue blood and it's gonna be first pumped into the pulmonary trunk now it tells us two things here pulmonary this is part of the pulmonary circuit this blood is going to the lungs trunk like a tree trunk is a big vessel and tree trunks just like tree branches are going to branch into smaller branches so we're going to see the pulmonary trunk is going to bifurcate or split into the right and left pulmonary arteries let me just pause for a second really quick to make sure as well that you appreciate the arteries are always arteries are always never an exception going away from the heart okay always always always arteries are going away from the heart veins are always going toward the heart okay so that that is a never false statement always always always okay so when you see pulmonary arteries and down here pulmonary veins it tells you the direction of the vessel the direction that it is carrying blood arteries always away a a away from the heart veins always back toward the heart also everything in the pulmonary trunk and all the blood in the pulmonary arteries heading over to the lung this is blue blood it is carrying that deoxygenated blood over to the lungs where gas exchange will occur as gas exchange occurs carbon dioxide co2 is going to leave you're going to blow that off through your respiratory system and oxygen is going to enter when that oxygen enters we're going to understand this better between this chapter and more in the blood chapter but when the oxygen enters it changes the color of the blood and the blood will now turn from being sort of blue blood to red blood okay so that red blood is then this highly oxygenated blood is then going to return back from the lungs to the pulmonary veins so the pulmonary veins are carrying red blood okay they're carrying red blood highly oxygenated blood back toward the heart and it turns out that the pulmonary veins are now sending blood into the left atrium so remember this blood left from the right ventricle has gone to the lungs and is now entering back to the left side of the heart into the upper chamber the left atrium the left atrium blood is now going to pump down to the left ventricle and now the left ventricle is going to pump with great force blood out through the aorta to all of the systemic circuit so you're going to see this over and over and over this may be the first time that you're hearing this i know it sounds confusing that's why the videos are so important and why paying attention in lab and labeling things will be so critical to your success in this unit so those um that's how the blood gets to and from the lungs pulmonary arteries and pulmonary veins now how does the blood get back from the body to the right side of the heart and there are two major veins there's a superior vena cava the superior vena cava is going to bring blood back from every place essentially above the heart think head neck and arms and the inferior vena cava which is going to bring blood back from everything below the heart think abdominal abdomen uh and length okay and we'll see that all that blood is going to dump back into the right atrium okay and that blood coming back from the body is going to be that blue blood right so once we're in the right atrium the blood is then going to be blue it's already been delivered oxygen to the tissues co2 has been accumulated and the right atrium pumps down to the right ventricle and then we're back to where we started so you're going to see this is a big cycle a big cycle and i'll show this to you in multiple ways as you learn about the flow of blood through the heart so watch that video on the being a cava and then you should be able to maybe not at this very first moment but you should soon be able to appreciate this diagram and sort of trace it with your finger what's going on here so we see the heart here and let me follow the same sort of presentation as a paragraph above so we're going to leave out of the right side this big old vessel leaving the heart here is the pulmonary trunk the pulmonary trunk is going to split into the right and left pulmonary arteries these are heading off to the lungs this set of vessels represents sort of the lung over here on the left and right we see that the blood going to the lungs is blue it's deoxygenated you see here in the middle a little hint of purple that purple whenever you see purple in this unit purple is going to represent where gas exchange is happening where red and blue blood mix so whenever you see purple it's telling you something that is where there is gas exchange going on once that gas exchange occurs the blood now is a bright red the blood's going to return to the heart through the pulmonary veins again and there are two of them so there's two pulmonary veins on either side one pulmonary artery two pulmonary veins they're bringing blood back to the left side the left side is then gonna pump the blood out the aorta here some of that blood is going to go up to the brain some of that blood's going to go down and go to the rest of your body again this is just a simplified overview of how this works that red blood that is being pumped out is carrying oxygen you see a hint of purple representing gas exchange in the capillaries then we come back through a series of veins the veins from below the heart are going to dump back up into the inferior vena cava the veins coming back from the head and the neck are going to come through the superior vena cava and these two major veins are going to merge back not really merge but both dump into the right atrium so soon you'll be able to trace this with very great confidence [Music] so taking a look at this anatomically correct diagram of the heart the heart here has been cut open in a frontal or coronal section and there are two things about this diagram that are critical one it shows the color of the blood and it shows the directionality of the flow so again let me go through this with you so we see blood coming down this is the superior vena cava coming from the body specifically from the neck the head the arms this blood is coming down it has already delivered his oxygen it's coming back as blue deoxygenated blood simultaneously there's blood coming up i wish there was a an upward arrow right here so you could see this but up from the body again this is the inferior vena cava bringing blood back up from the core from the abdominal region and from the legs that blood all merges and dumps into here the right atrium we'll talk about the valves in a minute but from the right atrium the blood's going to go down into the right ventricle then up and through another valve into here is the pulmonary trunk the pulmonary trunk is the thicker wider uh combined region if you will and then we see the pulmonary trunk split right and left pulmonary arteries now it's not showing it going over here but it would continue over here and go over to the right lung over here and the left lung over here remember when i just said right and left that we're looking into a person's body right and so we have to think about anatomic position the apex down here is pointing to the left so this is the left side of the heart left side of the body left lung over here this is the right side okay this is the right side this is the right heart that is showing the blue blood so the blood is going to go off to the lungs it's going to come back through those pulmonary veins two veins shown here draining into the left atrium now the same thing is happening over here we just can't see it coming into the left atrium down through the valve that we'll discuss down into the left ventricle and then up and out into the aorta okay and the aorta is going to branch off from the top and go to the brain and the arms and what we don't see here the aorta continues behind the heart and then would appear here inferiorly traveling to the abdominal region and down to the legs so what's great about this image is it shows you the color and it shows you the directionality of the flow let's talk about the outside of the heart and then we'll go back inside the heart you know from the introduction today as well as from lap one long ago that there is the serous membrane that is wrapped around the heart again the pericardial layers the pericardial sac this video goes through that for you as a review and you can see here even the two layers that are associated with around the heart remember that the pericardium like the other serous membranes the peritoneum and the pleura all it is remember it is nothing more than a simple squamous epithelium so the visceral layer and the parietal layer are just that now there is however another part to the pericardium unlike the other serous membranes and that is around the heart there's an additional outer layer called the fibrous pericardium you'll see this coming up in a video and you'll see it coming up for some diagrams so the fibrous pericardium is a third outer layer of the pericardium and this fibrous pericardium unlike this the serous layers unlike the visceral or the parietal layers is made up of a dense connective tissue and this fibrous pericardium is going to make sure that the heart is better protected also helps to maintain its its position and this fibrous pericardium is partly attached to think about it attached to the sternum holding the heart in place it's also attached down to the diaphragm so the heart is being held in place by this tough connective tissue sac called the fibrous pericardium and that sac is attached to the sternum into the diaphragm now another term is uh to learn you've learned about the visceral pericardium you know that that's the shrink wrapped layer to the surface of the heart that layer has another name so it's also called the epicardium so these two are the same visceral pericardium aka the epicardium and um these are these are synonymous terms okay i think this is again being that fused or shrink wrapped layer to the surface it's very thin in lab you're going to get to dissect a heart uh some of you will have fresh hearts some of you will have preserved hearts regardless when you have what you think is just the heart in your hands there is a very thin layer all around it remember it's just simple squamous it's something you're not going to be able to visualize okay just know that it's there so think of the shiny surface of the heart as being the visceral pericardium aka the epicardium let's take a look at that a little bit more completely and here we see again the double layer so the fist zero pericardium aka the epicardium is that thin layer shrink wrap to the surface of the heart and then there is the parietal pericardium that layer is the outer layer and in between is that pericardial sac where there's fluid right that pericardial fluid that lubricating fluid what this diagram is not showing is that even around the outside of this there would be that that fibrous pericardium the fibrous pericardium would be external to the parietal pericardium another name for the serous membranes is mesothelium mesothelium so if you hear about the mesothelium that means that it is derived from remember the mesothelium right is derived from the mesoderm so the mesoderm is that middle layer of the early embryo the mesothelium is derived from that layer and again it is simply a simple squamous epithelium okay um so that's the that's what we already know about we already know about this right we look at the heart muscle here and we see again keep we're going to kill this until you know it well but here is the visceral pericardium shrink wrap to the surface of the heart itself this is the heart muscle you know that if we zoom into this we're going to see in fact let's do that even in this artist's rendition you can see that this is cardiac muscle you can see those intercalated discs you can see the branching right you see the branching that occurs of this of this type and you can also see the striation so even in this artist's rendition you can see that you can also see there are lots of blood vessels right that are going down into and around the heart muscle supplying the ever needed oxygen to create the atp to keep the heart pumping then here is that parietal pericardium okay again simple squamous this purple layer simple squamous epithelium and that is the second layer of the serous membrane and then outside of that outside of that would be that fibrous pericardium when we get to the respiratory system i will describe pleurisy pleurisy is when there's a fluid buildup between the serous membrane between the pleural layers around the lungs and that fluid buildup makes it difficult for the lungs to expand it makes it difficult for the person to breathe likewise it's possible for fluid to build up in the pericardial space i think this picture really gives us an idea of what that might look like and this extra fluid of course is going to create pressure make the heart work harder and this is just an example of how fluid can build up in this area it can be serious fluid it could also be more often times blood that can accumulate in there but again that just makes it harder for the heart to do its work [Music] this is one of those conditions that can lead to death if it is not surgically corrected typically by puncturing the the pericardial membrane and just draining that fluid out now let's take a look at the external features of the heart okay this is one of those pictures or likenesses thereof you're going to be labeling multiple times in lab in your online homework and i definitely recommend that you also take a look in your hebrew lab atlas and take a close look at the models that are given in the atlas for the heart all labeled up for you beautiful presentations so let's go over this there's a couple things here i've already introduced let me just point out let's get our orientation here's the apex of the heart okay that's the pointy the conical end of the heart this is pointing to the left side if i were to take a scalpel and puncture into the apex i am in the left ventricle so keep that in mind the apex is uh a portion of the left ventricle the base of the heart is up here where i'm pointing this is basically the top of the heart it is where we see the pulmonary trunk leave it's where we are yeah leave with where we see the aorta leave the heart it's also where we see the superior vena cava and sneaking up from behind the inferior vena cava all sort of merge so these four what's called the great vessels the four great vessels two of them are veins the vena cava two of them are arteries the pulmonary trunk and the aorta they are all essentially associated with the base of the heart so it's important you know the four great vessels let's take a look at another surface feature and that is the article the article now you've seen the term article before remember the flappy portion of your ear is called the article okay the flappy portion of your ear so the ear just like the ear has two articles or the body has two articles two ears there are these two oracles these two flappy regions on the surface of the heart now it's pretty easy remember the apex is on the left side so the article on the same side is gonna be the left article the left article is a continuation with the left atrium below or deep to that and then the other article that you'll see over more closely associated with the vena cava this is the right article again it is deep to the right article is the right atrium so i have just given you the surface features for three of the four chambers if you were to take a scalpel and go deep to the right article you'd be in the right atrium go deep to the left article you'd be in the left atrium go deep to the apex you're in the left ventricle over here the one region we haven't looked at this would be the right ventricle over on this side on the surface of the heart you can see that there are vessels these are the coronary arteries and the cardiac veins these vessels will see them in a moment more detail but they are the vessels that are carrying blood to the heart muscle that would be the red colored coronary arteries the blue cardiac veins are returning that deoxygenated blood back toward the heart to be recycled there are a couple of sulci remember on the brain a sulcus was a shallow groove so too on the surface of the heart there are a couple of sulci for you to know one is the coronary sulcus it essentially goes around the heart okay it goes around the heart it's called the coronary sulcus the other name for this sulcus the other name for the sulcus is the atrioventricular sulcus so i'm going to go ahead and find where that is listed um yes so the coronary sulcus is also called aka the atrio ventricular and you're going to see this word atrial ventricular a lot and all it means right it's the groove the sulcus that is in between the atria on the top and the ventricles down below so this is that coronary sulcus okay aka the atrioventricular because it's separating think about it it's separating the atria externally from the ventricles now there's another sulcus to actually two other sulci uh one is down the front of the heart and it's called don't make this hard the anterior interventricular sulcus anterior in the front enter between ventricles there's a groove right anterior intraventricular sulcus so right here where these coronary arteries are sort of on the outside of the heart they are sitting in this groove protected in part and so if i were to take a labeling marker right i would say everything on this side right everything over here is the left ventricle everything on this side is the right ventricle again inter means between so that sulcus is between the ventricles so again externally all of these external landmarks or clues tell you more about what's going on inside the heart this is an anterior view on the top on the bottom we have a posterior view or more of a bottom view so now we can clearly see the inferior vena cava coming up and going into the right atrium here's the superior vena cava coming down dumping also into the right atrium we don't see the right article it's hiding on the other side here we do get a glimpse of the left article right here remember i have no problem remembering this is the left article because there's the apex which is on the left side of the heart so that's always going to give you your orientation here if we were to flip this around think about it the pulmonary trunk comes up and splits into the left and right pulmonary arteries those are heading off to their respective lungs that blood then goes back through the respective pulmonary veins two pulmonary veins on the right two pulmonary veins on the left and they are merging into the left atrium can't see it here but deep to this is the left atrium which is deep to that left article coming around the backside and only on the back side there is a very large vein this vein has the name coronary sinus sinus recall is a large space right and the brain we saw the dural sinuses or you also saw even more specifically like the superior sagittal sinus remember those were the blood filling regions of the brain they were filled with blue blood weren't they filled with blue blood so same way here all of these cardiac veins that we see on the surface of the heart are going to drain up and fill into this coronary sinus also not to confuse you but the coronary sinus is in the groove called the coronary sulcus okay so the coronary sinus is the vessel and it is sitting partly protected in that groove called the coronary sulcus so there is the front and the back external features anatomy of the heart oh didn't say it back here on the back side there is a posterior interventricular sulcus so this is the groove on the back side of the heart between the ventricles on one side we have the left side the apex associated side on the other side and up around will be the right ventricle over on this side here there is a three-dimensional model that you can interact with to study more about the heart and now let's take a look at the layers of the heart itself three layers not equal at all in their shape but this video goes through those three layers let me describe them to you from superficial to deep there's the epicardium we've already seen that word that's the outer layer right also called the visceral pericardium then there is the myocardium you have enough vocabulary knowledge to know that this is the muscle layer myo muscle of the heart myocardium and then the inside layer is the endocardium endo means within so the endocardium is essentially the layer that comes in contact with the blood the endocardium is the inside of both the ventricles and the atria and you can think of it as being in contact with the blood again the myocardium is the muscle layer it is the thickest of these three layers and it's made up exclusively of cardiac muscle cells and you know what cardiac muscle looks like under the microscope we'll review it briefly here today but that is making up the myocardium great video to watch to give you a better look at this and yet another video that goes through the layers of the heart this will go through the epicardium the myocardium the endocardium as well as will go through uh i think i just did that backwards so out here we have the the serous membrane so here is your parietal pericardium here's that space the parietal so the pericardial cavity here is the visceral pericardium aka the epicardium here is the very thick layer of myocardium and then on the inside there is the endocardium and if we were in the heart right here where i'm touching this would be blood filled in the chambers [Music] you don't really get to appreciate this by looking at the heart although even when you look up at previous drawings of the heart if i look up here sorry for going back up but notice the author has tried to include the directionality of the fibers remember fibers in this conversation muscle fibers are muscle cells and you can see that there's a grain to the muscle or there is a directionality of the muscle fibers and that directionality changes as you look over here so this diagram down here i really like this one it does a nice job not to memorize this but what you see is that the fibers around the heart are not just in one direction what this does is that when the heart squeezes when the ventricles squeeze it doesn't just squeeze the heart but it twists the heart imagine when you're mopping right you got an old-fashioned mop and you twist that water out of the fibers of the of the mop same idea so when the heart contracts it's twisting up the muscles of this of the myocardium the muscle cells and that is causing the blood to leave the heart with greater force and more completion remember i used number earlier about 70 milliliters of blood get pumped out with each contraction of the heart now another significant difference between the left heart and the right heart is nicely illustrated in this artistic rendition and what you see is that the right side of the heart and the left side of the heart are quite different in their muscularity specifically the left ventricle is much much thicker much much thicker than the right ventricle okay you also see the left ventricle is smaller than the right ventricle the right ventricle has a larger space the left ventricle is smaller and tighter now why is this the reason is the right ventricle doesn't have to be very strong it only has to pump the blood with enough force right the right ventricle only has to pump the blood with enough force to get it over to the lungs right the pulmonary circuit's not very large the lungs are not very far away so it doesn't need a lot of force therefore it also doesn't need as much muscularity however the left side oh my goodness this is the real workhorse of the heart the left side must be very thick and it must be very muscular so that it can pump the blood up toward the brain through the aorta as well as send blood down all the way to your big toe so it's the left ventricle that does all the work now but the majority of the hard work of the heart is here in the left ventricle because it must pump blood up and out of the heart against gravity push that blood up through your vessels to your brain as well as push the blood out with enough force to perfuse that's a fancy word that just basically means bringing blood to the organs so you have to get adequate blood flow to your liver to your kidneys to your all your other organs right need adequate blood flow and your big toe needs blood too so we've got to have a lot of force of the blood leaving the left ventricle now let me ask this question now we see that the right ventricle is larger in size and i've told you that it pumps under less pressure the left ventricle is smaller in size and pumps out with greater pressure but tell me about the volume of blood what volume of blood is pumped out of the right side of the heart versus the left side of the heart do you think there is more blood out of the right side more blood out of the left side what do you think and a lot of students fall for this they think oh the right side is bigger so it must be pumping more blood or they think the left side is having to send blood to the brain so it must be pumping more blood in reality though the left and right sides of the heart work in concert so the amount of blood being pumped from the right side matches the amount of blood from the left side now that's in a healthy heart in a healthy heart the two sides are pumping the same volume think about it for a second if one side was pumping more or less blood there'd be a backup or an overflow of blood somewhere in the body that's not what we want so in a healthy cardiovascular system the left and right heart even though they're pumping under different pressures they're pumping the same volume okay they're pumping the same volume continue with your reading about the endocardium and the endocardium is lined also with a layer of simple squamous epithelium this is nicknamed the endothelium okay now we're going to be seeing the word endothelium quite a bit remember we have seen epithelium right we know about epithelium that is what's covering uh your body if you think about the stratified squamous keratinized we have stratified squamous non-keratized epithelium in our mouth down the esophagus anus and vagina we've seen mesothelioma right mesothelium again was aka your serous membranes and now we have endothelium well guess what guys it is derived from the endoderm right derived from the inner layer of your early embryo and this is the name of the simple squamous simple squamous epithelium that lines your blood vessels and your heart chambers okay so the endothelium it's just a code word for the simple squamous epithelium that is lining your blood vessels and your chambers of the heart the endothelium or the endocardium remember we have 60 000 plus miles of blood vessels they're all lined by simple squamous epithelium wow right you really start to get a sense of the complexity and the awesomeness of this system now your heart is constantly beating as we know but we learned back in the autonomic nervous system that not all organs are getting the same blood flow 24 7. remember we talked about the sympathetic nervous system and when you are in a fight or flight moment more blood is being pumped to your muscles remember what happens to your skin right when you're scared you go white what's going on blood from your dermis is not completely but is largely shuttled to the inside of your body to your muscles in preparation of fighting remember too that in a sympathetic nervous system uh surge your digestive system your your urinary system your reproductive organs they also lose not all but more blood is shunted away from those organs to your muscles your brain is going to receive the same amount of blood all the time that the brain receives the same amount of blood i don't care if you're scared or relaxing the brain must have a constant 24 7 supply of blood remember too that in parasympathetic that some organs get more blood during parasympathetic rest and digest your muscles have less blood but your digestive your urinary your reproductive organs and your skin have more blood flow so my point is this there must be a way that the heart pumps the blood but then some organs receive more blood and some organs receive less blood and that is going to be the magic we'll talk about that when we get to the blood vessels in another presentation but there's vasoconstriction vasodilation opening and closing of different blood vessels going to different organs that allows for certain organs to receive more blood or less blood based upon the homeostatic needs of the body so let's now travel inside the heart we've talked about the external structures uh the layers around the heart now let's head inside inside the heart remember there's four chambers those four chambers must be separated and they are separated by septa just like you have a nasal septum you have septa inside your heart which are separating the chambers one from another these are physical if you will separators between the two atria is the inter atrial septum don't make this difficult we know inter means between so between the atria there's a divider a septum and in the we'll see the same thing to be true down in the ventricles between the two ventricles there's another septum called the interventricular symptom now of note in the interatrial septum there is an oval-shaped depression called the fossa ovalis the fossa ovalis now you're going to see this in all the adult heart models okay and what is the fossa ovalis we know what it is the fossa we know is an indented region and it's oval in shape as a fetus before you were born your heart had a hole called the foramen ovale okay we know foramen means hole or opening it was an oval shaped opening between the atria so as a fetus you have a foramen ovale after you're born and as an adult you have a fossa ovalis so i remember this ovalis what is now right so the fossa ovalis is what is now the foramen was the opening found in the fetus you'll learn a little bit more about that coming up you'll also see this in the lab and what you'll see is that the foramen ovale allows for blood to jump directly from the right atrium over to the left atrium thereby much of the blood bypasses the pulmonary circuit and you'll appreciate that more as we go through this go through lab as well as start to understand the circulation of the blood through the heart better so within seconds after birth a flap of tissue called the septum primary just a little flap begins to close down that foramen and begins to create the fossa avalas again we'll look at this in more detail definitely take a look at this video that describes for you and visually shows you the septum in addition to the septa that separate there are also four valves and these four valves are going to separate the chambers and the outflowing vessels and uh these valves are going to assure that blood only moves in one direction through the heart two of these valves are called atrioventricular valves they're abbreviated the av valves it tells you exactly where they are they're between the atrium and the ventricle so on the right side there's the right atrioventricular valve on the left side there's the left atrioventricular valve again you believe on all of this the other two valves are referred to as the semi-lunar valves semi-lunar valves and one of these semilunar valves goes up into the aorta and one of these semilunar valves goes up into the pulmonary trunk also while i'm here i'll tell you that the atrioventricular valves are also and probably more commonly referred to as the bicuspid valve and the tricuspid valve so you'll see that word quite a bit i will say now and i'll show you in a moment in the heart you try it before you buy it so the tricuspid valve we're going to see comes before the bicuspid try it before you buy it tricuspid before the bicuspid all of these septa help to create what's referred to as the cardiac skeleton or also called the fibrous skeleton of the heart just like your body has a bony skeleton right that gives its shape so too the heart has a fibrous skeleton not made of bone but made of connective tissue and this fibrous uh skeleton we're going to see wraps around the valves and helps to separate the atria from the ventricles and this cardiac skeleton also creates an important divider between the atria and the ventricles when it comes to the electrical conduction the electrical signal that passes through the heart now the electrical signal of the heart will be a discussion for the physiology part of the cardiovascular system next semester so next semester in lab you will be experiencing how to read ekgs learning more about blood pressure how to take blood pressure how to listen to heart sounds um also again learn how to read about eight or nine common uh ekg patterns and some arrhythmias of the heart so this semester will introduce all of the pieces and parts next semester you'll better understand the physiology so now let's take a look at this coronally cut part and this one does a couple nice things it does show us the directionality of the blood flow and the arrows represent the color of the blood in that section and this chamber or this particular view also shows us the valves so let's get the valves figured out right now now there are two valves between the atria and the ventricle so here's the right atrium here's the the right ventricle blood leaves the right atrium passes down through this valve into the right ventricle this is the tricuspid tricuspid this is also the right atrioventricular valve right so the tricuspid aka the right av valve atrioventricular valve then over here here's the left atrium here's the left ventricle blood is going to go from the left atrium down through this valve this valve is three names for this valve guys three names for this valve and you need to know all of them so let me find where it's mentioned right here so the the the bi-custard valve okay the bicuspid i'm going to change the colors of that the bicuspid valve is also called the mitral valve which is also called the left i'm just going to abbreviate it the left b valve okay the left atrioventricular valve so these are all referring to the same valve you need to learn all three names likewise the tricuspid put it all right here the tricuspid is also called the right atrial valve the right atrioventricular valve okay so make sure you know these equivalent terms so in this diagram they're referring they're labeling this valve as the mitral valve aka the bicuspid aka the left atrioventricular valve remember i told you in the heart we try it tricuspid before we buy it by cusp i'll say it now let's introduce you in a moment these atrioventricular valve have string like structures coming down from them these are tendonous cords from the latin the chordae tendony and these chordae tendineae come down and anchor the valve and they anchor the valve down to muscles called the papillary muscles now the papillary muscles are only found in the ventricles you know from previous experience that papillary refers to nipple-shaped so you can see these are nipple-shaped muscles they're protruding from the wall of the ventricle the right side of the heart because it's the tricuspid will have three papillary muscles are not all shown in this particular diagram but there are three papillary muscles attached to the three portions of the valve remember cusp means points so the tricuspid valve has three parts to it the bicuspid valve you kind of get the idea only goes down to two papillary muscles okay two papillary muscles on the left side for the bicuspid or mitral valve the other two valves shown here this valve is blocking the entryway to the pulmonary trunk so this is the pulmonary valve this valve here is blocking the entrance to the aorta this is the aortic valve now note that the aorta flips back behind the pulmonary trunk and this is why in lab i introduce to you quote a square heart it's just a whole lot easier to draw as you are first learning about the heart structures but you will need to eventually be able to appreciate the complexities of the criss-crossing of the vessels here in the anatomically correct heart i think there's a couple things i that are labeled here that i did not introduce uh let me just mention them now get this a little bit larger uh trabeculae carnet if you look at the ventricle and only in the ventricle remember that word trabeculae we've seen it a couple of times spudgy bone is also called trabecular bone and spongy bone kind of looks like this right so what you have is along the bottom of the right and left ventricles this arrangement of the tissue is called the trabeculae carnae um man when i hear that word i think some sort of carne asada right so carne just means you know meat right so trabeculae carne is just the this trabecular looking muscle or meat that we find here in the ventricles this diagram also labels the interatrial septum i mean that's tough in a cut like this but the inter atrial septum does divide the left atrium from the right atrium and then down here is the interventricular septum it divides this is much easier to see it's dividing the left ventricle from the right ventricle here's another video that you can interact with oh i just went past it a little video or a little 3d model you can interact with and has everything labeled for you okay so let's get past this and let's now sort of travel through the heart here is the right atrium so let's go through the four chambers so the right atrium it is i mean the blood going through the heart is sort of a cycle if you will and we can start anywhere but by convention this book in the lab book and my discussions we're going to start the blood flow coming into the heart in the right atrium okay and this is the receiving blood uh this is the blue blood the systemic blood the deoxygenated blood that's coming in from both the superior and the inferior vena cava now there's a third place by which blood comes into the right atrium i introduced this in the pre-lab video as well and that is that coronary sinus remember the coronary sinus was that blue vessel that collected all of the blood coming back from the cardiac muscle right from the cardiac veins so there's three ways by which blood gets to the right atrium superior vena cava inferior vena cava and the cs the coronary sinus that blood is going to come in okay come into the right atrium again the superior vena cava is bringing blood back from the superior regions the head the neck the upper limbs and the thoracic region whereas the inferior vena cava is draining blood back from everything below the diaphragm below the heart and that is the lower limbs and the abdominal pelvic region when blood comes into the right atrium the internal surface of the right atrium and the left atrium is smooth we'll see that fossa ovalis and within the right atrium and you'll see this in some of the diagrams there are some ridges of muscle referred to as the pectinate muscles okay the right article has pectinate muscles the left atrium um has a little bit of the pectinate muscles as well in the article and i'll show this to you in a picture but just in case i forget um pectin the what the pectinate muscle looks like to me and when you're peeling an orange right the white stuff uh part of that white stuff that makes up the peel and that white stuff is called pectin that's just the name of the stuff that makes up that sort of that white membrane that goes around the orange and so that's kind of what i look when i see this in pictures the pectinate muscles kind of look like that pectin layer sort of that ridgey sort of stuff that goes around an orange when we're now we're going to go down to the right ventricle again the right ventricle is receiving blood from the right atrium everything on the right side continues down to the right side the blood is going to go down through the right atrioventricular valve or that tricuspid valve that tricuspid valve is held on by those chordae tendineae okay or quote your heart strings we've all heard about the heart strings pulling on your heart strings literally in your heart you've got these heart strings right they are 80 collagen not something you would want to eat so when people do eat heart uh they have to get rid of these collagenous fibers they're a little bit stretchy a little bit of elastic but mostly very very strong collagen fibers and again i've told this earlier but here it is in words those chordae tendineae go down to the papillary muscles that go down to the ventricular wall three of these papillary muscles are in the right ventricle and we'll see that on the left side there are only two of these here are those chordae tendineae you'll get to see this when you dissect your heart here are the papillary muscles to which those chordae tendineae attach and we can also see the trabeculae carnae sort of that trabecular structure that we find on the ventricular wall when the left sorry when the right ventricle contracts blood will be ejected into the pulmonary trunk to get there it had to go through the pulmonary valve or the pulmonary semilunar valve okay so all that's detailed here once the blood has gone to the lungs and comes back through those pulmonary veins we're now going to come back into there are four of those pulmonary veins two on the left two on the right and that blood is going to enter into the left atrium now the left atrium um the left atrium is in everything on the left side it's going to be red blood this is blood that's coming back from the lungs it's been highly oxygenated when blood is oxygenated it is bright red you've all cut yourself and you know that blood as it comes out of your vessels uh is bright red and if you've ever given blood you know that when they give when you give blood they take blood from a vein and that blood in that tube is not very bread right the blood that you donate comes out of your veins that is called blue blood and it is a much darker bricky sort of bricky burgundy color so uh left atrium is receiving red blood oxygenated blood okay and this blood is then going to travel from the left atrium it's going to go down through the mitral valve aka the bicuspid aka the left atrioventricular valve down into the left ventricle again the same amount of blood is going to come down from the left side and the right side the difference is the left side is much more muscular so it is going to contract under greater force remember on the left side we only have two papillary muscles for the bicuspid valve when the blood is pumping out of the left ventricle under high power is going to be going up into the aortic valve into the aorta and off to the systemic circuit so just reminder about those heart valves right the right atrioventricular is also the tricuspid right three flaps three parts three papillary muscles on the right side on the left side we instead have the mitral bicuspid or the left av valve with only two parts and only two papillary muscles the other two valves are the pulmonary valve and the aortic valve the aortic valve is also referred to as the pulmonary semilunar valve you'll hear it pronounced also pulmonic right change the syllables around so pulmonary valve for the pulmonic valve and this one has three little flaps um that um are allowing blood to go up into the pulmonary trunk and then finally there is the aortic valve this one is in all these valves are preventing backflow you do not want backflow if you have backflow coming through your heart valves that means that blood that makes sense but if blood is going backwards that mean not as much blood is pushing forward and if your heart is not pushing blood out in adequate volumes then your body is not getting the necessary oxygen and blood flow and your heart is having to work much more hard to get the blood to your body now when these valves open and close when these valves open and close there's a sound okay love dub lub dub lub dub so when a doctor or nurse is listening to your heart and they are putting the stethoscope on your chest the next time you get an evaluation notice they're having you breathe and they're moving that stethoscope to four places why are they moving that stethoscope to four places because they are positioning the stethoscope to hear the opening and closing of the four valves so four locations four valves okay also we'll talk about this a little bit more but when the tricuspid valve is open so too is the bicuspid valve so the two av valves open and close together and the two semilunar valves the aortic and pulmonary valves they're going to open and close also in a coordinated way so that's for the love and dub the what's called the sound one or the sound two s1 s2 so when you listen again love dub lub dub lub dub those are the valves open actually the the sound is the percussive closing of the valve and not only is the valve closing but there's also blood that is immediately stopped and so the combination of the closing of the valve and the blood that kind of bumps up against that closed door is what creates the heart sounds okay so i what i just said is is here in these two pictures and that is these valves open and close in a coordinated way the right side working in concert with the left side now can things go wrong absolutely can a valve be faulty one of the four valves be faulty absolutely and um let's think about that for just a second which valve which of the four valves do you think is the one that has to work the hardest and is more often the one that is going to go bad so if a person's going to have a bad bowel and have to have a valve replacement which valve do you think is the one working the hardest remember the valves open to allow blood to pass but when they close they're also preventing backflow they're working against that back pressure keeping blood from going backwards so i hope you're thinking and imagining that the mitral valve is the one that is more commonly going to get damaged or show some sort of leakage think about it when the left ventricle contracts it is contracting under tremendous force that blood is being pushed up and out through the aortic valve but at that point the mitral valve is closed and it is having to resist that pressure of the left ventricle so that blood does not go back up into the left atrium and so for that reason the mitral valve is the one that is really being worked the most and the one that is more likely to fail again that's all described here for you in words now this chapter does a beautiful job describing heart valves different heart valve conditions uh also goes through surgical replacement of the valves it's very very well done i'm not going to hold you to this though um i just but i think you could appreciate that here is a valve right and this is the mitral valve you see these chordae tendineae coming down and this is just referring to infections uh there are some infections streptococcus infection scarlet fever which can actually cause damage to the valves okay so that's one reason why valves can become sick or dysfunctional uh there are there's endocarditis right inflammation of the inner layer and not only is the endothelium coded by the endo or the endocardium not only is the endocardium lined by the endothelium that same endothelium lines your valves so infection of that endothelium can cause valvular damage when there is a weak valve literally with the stethoscope you can hear regurgitation you can hear back flow a leaky valve you'll hear it referred to in two ways one regurgitation but you'll also hear referred to as a murmur so if you hear about someone who has a heart murmur it's code for they have a valve that is not closing all the way down and for whatever reason right disease genetics some sort of congenital deformity that valve is not closing all the way down leading to blood going backwards if that backflow of blood is sufficient such that the heart is not getting blood moving out with enough force then that valve may need to be replaced if the leakage is minimal it won't need to be replaced doctor just watch that murmur listen for it each and every year and uh make sure that it's not getting worse so in this section it goes through this it shows you a couple of the different types of artificial valves that are being replaced uh some people get uh pig valves uh pig hearts are very similar to human hearts we can take vowels from pigs we can make bowels from human donors right now this is not a a donor like giving up a kidney but from cadavers and from when a person is an organ donor one part of that organ donor that can be donated is the valves for someone whose heart valves are deficient or we can have different types of mechanical valves as well so i'm not going to go through any of these procedures but it's very interesting and you may have a family member who has been through a situation like this let's talk about this the coronary circulation for a moment that is what are the coronary arteries on the outside of the heart there are four of these actually six vessels altogether that i'm going to introduce you to you'll also see them in the lab so i will use this diagram first as soon as blood comes up from the left ventricle goes through the aortic valve and comes up into the aorta immediately there are two coronary arteries there's one off to the right and there's one that comes off the left so that's the right coronary artery and the left coronary artery now the right coronary artery artery has two most often two main branches okay the the right coronary artery goes on to become the marginal artery what the names speak to you it runs along the margin along the edge of the heart okay the marginal artery and we'll see in a moment that it also is going to go to the back of the heart and go to the posterior interventricular so it's here in words right typically the right coronary artery splits into the marginal artery and the posterior interventricular artery okay so those you'll see in the diagrams and the left coronary artery splits into the circumflex i think of it it flexes it bends circum around circumflex kind of wraps up around the left article and into the anterior interventricular artery okay so that's that those facts are down here okay or is it up here let me find it somewhere up here it's up here uh there it is the left the left coronary arteries which are the circumflex and the anterior interventricular okay now your heart in my heart if we were to do an angiogram which would be a visual visualization of the vessels of the heart you would see that your circulation of your heart's almost like a fingerprint everyone's got slightly different arrangements of branches so no two heart vessels have exactly the same but these branches these two major branches of each of the right and left coronary arteries are pretty consistently found in most individuals okay so that is shown here here's your front view here's your posterior view and here is that marginal artery kind of runs along the margin of the heart and also that posterior interventricular artery again these are branches of the right coronary artery there's also a series of cardiac veins that you see traveling back from the heart muscle and they all again are going to merge onto that coronary sinus which is only present on the posterior surface when you look at your heart sample your your specimen you will be clearly able to see the coronary sinus it will it'll be very obvious to you going back up there's a great video here on these coronary arteries so definitely take this to appreciate the anatomy here now if a person let me go here these coronary arteries are the very vessels they get blocked in a heart attack okay so let me point this out so let's say you have a blockage right here right a complete blockage here that means that this portion of the heart would not receive oxygen just like the brain the heart is very very sensitive to a lack of oxygen and quickly after a lack of oxygen the heart muscle cells die and sort of like neurons cardiac muscle does not regenerate very well at all so once cardiac muscle dies it is dead forever it is replaced by scar tissue and no longer contributes to the pumping strength of the heart so if you have a small vessel blockage and you have a small region of the heart that is dyed right from the heart attack you're going to survive that heart attack a small part of the heart has been damaged the heart's a little bit weaker but this person is going to survive this fully however what if that blockage is up here right and if that blockage is up here and all of your basically your marginal artery and your posterior interventricular and essentially half of the heart circulation is cut off that would be considered a massive coronary and that is not a heart attack that a person can survive they might survive for a day or two right they get into the hospital they stabilize them but they realize that the heart muscle is absolutely unable to sustain life and those are the massive coronaries they hear people dying they drop and they're dead or they have a massive heart attack and they're dead a day or two later when the extent of the heart damage is realized and the heart cannot sustain itself by itself so those are massive deadly heart attacks another name for a heart attack is a myocardial infarction okay a myocardial infarction an mi that's just the fancy word for a heart attack a heart attack is more often times caused by a build up of plaque in the coronary arteries and on this exam you can certainly expect a case study that will be focused around a heart attack and you can see here right that the fatty deposits within the arteries block the blood flow and that can be a slow gradual blood flow blockage but when it is a complete blockage the person has complete blockage that is going to be a full-blown heart attack and again depending upon which vessel and how big that branch is and how much muscle tissue there is distal to the blockage is really indicating how much of the muscle is damaged and the outcome of that heart attack so definitely re read through this and we've talked about referred pain before the classic although not always um i mean up to up to 60 of mis present without the symptoms that i'm describing here but there are a number of individuals uh who will feel um that radiating pain in their left pectoral region and down their left arm some people feel faint some people start getting sweaty they get nauseous or vomiting they have a shortness of breath these are all signs of a heart attack so don't only re don't only think about the left side i just had a college friend host on facebook that he was laying in bed felt this little weird discomfort in his left going down his left arm he thought maybe he had slept on it funny he moved around um and it wasn't going away he played a mental game with himself you know how about how foolish he would feel if he went to the emergency room and it wasn't an actual heart attack he has no history of a heart attack no other indications this was his first experience he gets to the emergency room and they say it appears that um you have not yet had a heart attack they said you have not yet heard a heart attack because ekg was still normal uh but he was still having this discomfort and they left him there for observation for a couple of hours in the in the emergency room well within two hours he was having a full-blown heart attack and thankfully he was in the er when it happened and they were able to quickly put in three stints so what's a stent a stent is basically when the blood flow is blocked and they go in and they do one of two things let me go down to a picture of it oh let me say this before i go on this area here do not worry about this section um yeah we're not going to worry about this i'm going to color this in blue right for one paragraph at a time so this section blue come on john don't worry about this okay don't worry about this video that follows here okay and this is just good to know uh right after a person is having an mi right you want to give that person oxygen uh you want to give them aspirin merch works to break up the clot and nitroglycerin is a chemical that's given uh typically to help with this the blood flow vasodilates the vessels of the heart okay and and then if a person continues to have blood clots they might give them uh agents that help dissolve the clot uh tpa is one you may have heard about i'm not going to test you on that but let's take a look at what a stint is going down and again um yeah read through this this is important and what causes an mi not completely linked but we know that cholesterol levels are a major player in this and your lbls right your you want your low your ldl cholesterol to be uh low your lows will be lows and this is your bad cholesterol so people with higher levels of ldl are more prone to heart disease and you want high levels of the hdl you want high levels of the high of the hdl and that's your good cholesterol which is actually thought to be heart protective so when you have your blood work done you want low lows and high highs we'll get to that pictureless tint in a moment read through this on the coronary veins they're also referred to as cardiac veins these are the veins that are bringing blood back from the heart muscle all dumping into that coronary sinus so all of these cardiac veins drain back into the coronary sinus recall the coronary sinus is also a way by which blood gets into the right atrium so here's an angiogram it's a visualization of the heart and you can see the blood flow through the heart and notice there are two they're pointing them out and i wouldn't ask you to identify this but you can see two constrictions right where blood flow is restricted and that is uh where there is significant buildup of the plaque that build of a plaque can lead to chest pain and when that completely blocks that would be a complete mi and what they do here it is here's what they do they put in some chicken wire that's my words but they put in a mesh up into the vessel that mesh is then expanded it pushes that plaque off to the sides of the vessel and restores blood flow so when you hear about something having a double bypass or having two or three stints put in right they've actually had this mesh put into their vessel and if a person has you know three or four stents what it means is that they have three or four vessels that have significant narrowing and thankfully we have the technology now to go in and open up those vessels so you can see examples of that here they'll go in and do balloon angioplasty bring a balloon in expand that vessel and then sometimes also bring up the mesh into that vessel again if you have a single double triple quad doesn't matter it's just referring to the number of these procedures that are done at one particular time so that brings us to the end of 19.1 do make sure you answer all of these questions at the end take a look at these labeling activities down here as well and of course don't forget about the vocabulary checkup we have just a little tiny bit left and it's very very little and it's about cardiac muscle and we're only going this far okay you're not you're going to stop here we're not going beyond conduction system of the heart so all this is a quick review i'm not going to spend any time on this right now we've already seen this same diagram back in the the histology unit and remembering that cardiac muscle cells you see the interpolated discs the cells are still striated you know that the striations are evidence of actin and myosin overlapping sarcomeres and heart muscle cells or cardiomyocytes still have a lot of mitochondria we need to make a lot of atp right to run the pumping of the heart and that an interpolated disc is really a combination of a desmosome and we talked about desmosomes long enough they're like those snaps or those rivets and jeans places where they need some extra adhesive properties and gap junctions which are basically channels that allow molecules to move through and these gap junctions are critical for the electrical activity that runs from one cell to the next that's all i'm going to say about that we'll learn more about how the muscle cells work in physiology as you learn about the physiology the last thing is to remember the heart is autorhythmic this means you can disconnect the heart from the brain the brain is not sending a direct signal for your heart to contract instead in your heart there are clusters of cells called the pacemaker cells you'll learn a lot about these next semester i'm not going to have you worry about them now but these pacemaker cells set the rhythm of the heart remember the autonomic nervous system the sympathetic division turns up the heart rate the parasympathetic turns down the heart rate but the central nervous system does not initiate the heart rate the heart itself initiates it if a person's pacemaker is natural pacemaker is deficient we now have the ability of putting in an external pacemaker and that external pacemaker is now manually right electrically stimulating the for it to contract each and every time so that brings us to the end of everything for chapter 19. again just a quick reminder about cardiac muscle and stop here at conduction system of the heart uh the only let me just check the only question that skip all this ekg stuff this will be next semester you can answer the first question at the end of 19 only worry about the first question the other questions do not worry about they're not content that you'll be responsible for for this example