Anatomy 1352 Ross College this is unit three part two welcome back as we talk about the heart so we're going to briefly talk about arteries and veins because the heart is getting blood from somewhere veins pumping it out into arteries and as we talk about circulatory C circuits we have to have a few things established about arteries and veins we will go into much greater detail about arteries and veins in unit four so let's have at it first thing arteries arteries uh always always always always carry blood away from the heart so when blood is pumped from the ventricles pumped out through those semi lunar valves the blood enters arteries period no exceptions now we usually think of arteries as carrying oxygenated or oxygen-rich blood this is true for the aorta and all the arteries that come after the aorta pulmonary arteries are different they have oxygen poor blood why well you're still going to the lungs to get oxygen that's why so most arteries oxygen rich exception pulmonary arteries now blood coming out of the heart is under significant pressure arteries have thicker walls than veins why more pressure so and that's what we you need to know that now as you get further and further from the heart and pressure drops the arteries become thinner as they simply have less total pressure in them so vein veins always without exception always return blood back to the heart so the veins from the entire body are carrying back deoxygenated or oxygen poor blood remember there's still oxygen in that blood you're just down around 75% saturation and you can't get any more oxygen out of the blood so that's why I like the term oxygen Poe better than deoxy ated but be able to use both terms interchangeably now veins being towards the end of the circuit coming back pressure keeps dropping pressure keeps dropping as blood flows veins are exposed to much lower pressure in some cases almost zero pressure I emphasize almost there's always a tiny bit to help keep the blood moving so veins much lower pressure therefore they don't need thick walls they have a much thinner wall and as we'll talk about more when we do veins in unit four veins have valves because of that very low pressure they need valves to help maintain blood flow in the correct direction always back to the heart now most veins oxygen pour blood deoxygenated blood what's the exception excuse me the exception is pulmonary veins remember we took blood to the lungs to get more oxygen in it so blood returning to the heart from through pulmonary veins is oxygen rich but then again it's going to go through the left side and get pumped right out to the rest of the body that needs that oxygen so when you think about arteries oxygen rich vein Ms oxygen po except for pulmonary where they're backwards so so let's now look at the individual major arteries major veins so on the left side of the heart the one and only artery coming off that left side is the aorta the aorta the largest single artery in the body um it's got different portions to it we'll talk about that in unit four coming off of the right side of the heart leading to the lungs the very first thing you have is a short pulmonary trunk which then splits into the left and right pulmonary arteries frequently pulmonary just gets sometimes trunk gets skipped and we just refer to the pulmonary arteries but realize it's there and then then the third set of very important arteries are the coronary arteries now the coronary arteries actually come off of the aorta in the very first inch of the aorta the coronary arteries because of some unusual characteristics mostly the contraction of the heart muscle there's a little bit of different properties there coronary arteries fold back and feed oxygen-rich blood into the heart muscle we'll talk talk about that later now the major veins there's a few more of them than what we've discussed for arteries uh veins returning to the heart on the right side of the heart we have two large veins called the vena these are the superior coming from basically everywhere above the heart and the inferior everything below the heart vnea both enter into the right atrium on the left side of the heart there's four veins coming from the lungs two left two right these are the four pulmonary veins all four pulmonary veins enter into the left atrium now again there are specialized blood vessels around the heart coronary arteries delivered blood into the heart muscle on the back of the heart posterior side there's a wide oval vein called the coronary sinus all the blood coming out of the small coronary veins collects in the coronary sinus before being returned to the right atrium so it also empties into the right atrium so the heart's own circulation coming off of the orta returns separately to the heart right beside the superior vnea so those are your major vessels know all of them but of course we're going to cover these in much more detail when we do unit four so now the only reason to really get those major arteries and veins right now is to talk about our um circuits of um blood flow or circulatory paths remember we got two sides of the heart pumping blood out there are actually two circulatory routes one going to the entire body that's systemic circuit or systemic circulation um this is out through the aorta all throughout the bodies returns through the vnea the systemic circulation well starts at the aorta it starts from comes out of the left ventricle distributes oxygen to the whole body returns to the right atrium remember anytime a little old blood cell is wandering around the body it goes through both sides of the heart before repeating anything now we return that blood to the right atrium down to the right ventricle well the right ventricle pumps into the pulmonary circuit or pulmonary circulation so out through the pulmonary trunk and arteries to the lungs back through the pulmonary veins pulmonary begins at the right vein ventricle right side of the heart but when the blood returns it returns to the left atrium see make a little picture for yourself it does help all right now the book or at least my pictures your book has some slightly different ones I always hate these pictures um I think they're a little too confusing just they're busy your best thing you can do right now is draw a big circle start in one of the four chambers of the heart on that Circle go through the whole flow until you eventually get back to where you began so we can start that Circle here with the right atrium or right ventricle whatever makes you happy and start pumping into pulmonary circuit so if we start with the right atrium here blood flows from the right atrium through the tricuspid valve into the right ventricle now when that ventricle contracts blood flows from the right ventricle out through the pulmonary valve into the pulmonary trunk and arteries into pulmonary circulation which means from there it goes to the lungs picks up oxygen gets rid of CO2 and then returns by way of the pulmonary veins remember it's going on on both sides simultaneously so as we're continuing around that pathway our oxygen rich blood returns to the left atrium over here well from the left atrium we're going to go through the mitro valve into the left ventricle then the left ventricle is going to pump out and by the way it's behind this vessel the left ventricle is going to pump out through the aortic valve into the aorta from there delivered throughout the body returning by way of the superior and inferior venne CA returning us back to our right atrium where we initially began please please please please draw this out just use words and arrows to make a big circle and get back to where you started include all four chambers include all four valves include the major arteries and veins all of them aorta vnea pulmonary arteries pulmonary veins and then put lungs and systemic circulation SL body for the other part include all of those things once you've got that down and really committed to memory it really does help with having all your factors of blood flow through the heart and basics of circulation organize correctly in your mind so that's that now this pict picture kind of does show all that but it's n necessarily busy um all the bits and pieces though are there see right atrium tricuspid right ventricle pulmonary trunk pulmonary arteries to the lungs pulmonary veins left atrium bicuspid valve or mitro valve left ventricle aortic valve aorta all through the body and then the vne AV back to the right atrium get this usually I find simplifying the picture a little bit does help quite a bit so all righty plus remember what the two functions of the circulatory routes are systemic circulation here on the bottom deliver oxygen to the tissues pick up carbon dioxide return it to the heart to get rid of it remember what's going on in pulmonary at the top deliver carbon dioxide to the lungs to get rid of it pick up oxygen and return it back to the heart as you go around that circuit so and that brings us now into already questions four and notice what the very bottom says be able to follow that flow of blood through the heart very very critical so now we're going to cover a few other conditions going on some other uh disease States before we start talking about uh electrical flow and initiation and regulation of heart contraction so there are some different disease States you will have to consider um we've already mentioned uh atrial and ventricular septal defects um we're also going to look at some other ones here coarctation of the aorta is one of them in this condition you have a narrow opening to the aorta that's going to put extra pressure on the left ventricle it's going to create higher pressure in the left ventricle over time with it harder pumping you can get enlargement of that ventricle and that's never good and then there's a very very serious condition tetrology of phow now phow is a French doctor that first described this this is Tetra 4 four rolled together defects in the heart this is very very very critical situation this is an infant going from um the birthing Suite within hours or days into fetal open heart or into newborn open heart surgery to get blood flow working properly uh if not corrected this is always going to be fatal so our defects what do we have the we have an interventricular septile defect so big opening between the two ventricles in fact the aorta is actually coming off of both ventricles so it's coming off at the point of the hole instead of just the left ventricle now because of that slightly twisted and slightly Offset you get stenosis of the P pulmonary valve so narrowed pulmonary valve so you get less flow to the lungs and you also end up with an enlargement of the right ventricle um none of this is good because it makes it very hard to get oxygen rich blood very hard to get blood to the lungs in order to get even oxygen rich blood blood back to the heart so this is a difficulty that does not emerge until after birth because pulmonary circulation is basically irrelevant until birth When baby starts breathing we'll cover that in unit four though so the immediate effect of this is immediate cyanosis and immediate medical tension needed so I want want you to get the general idea what tetrology of phow is we're I'm not going to ask you to go through each individual defect kind of know the end result which is the bottom bit right there so now the coronary vessels are some Oddities they're just a little bit of differences to them so now you would think well doesn't the heart get out oxygen from the blow blood in the heart well remember the right side has oxygen poor blood so it can't but on the left side where there's oxygen rich blood that oxygen only goes a short distance into the tissue only a few cell layers so the vast majority of the muscle has to rely on the coronary arteries in order to get oxygen and nutrients to those cells so myocardium needs the coronary circulation so now it's kind of funky coronary circulation is not continuous it's a start stop because when the ventricles contract those coronary arteries get compressed and collapsed so blood is not moving continuous as soon as those chambers begin to ra relax blood rushes into the coronary circuit so it's not a continuous smooth flow it's very start and stop very jerky so but it does continue to keep flowing in the proper direction and it is corrected for by having larger vessels to overcompensate for the start stop flow so when the blood is Flowing lots of blood is Flowing so all righty let's go on from there now the coronary vessels do come off of the aorta they come off in the very first inch of the aorta Blood come enters coronary circuit before it even branches off to the brain because it really doesn't matter how much blood your brain gets if your heart's not pumping because it can't get enough blood so blood to the heart is even before blood to the brain so there are two major vessels we call them the left and right coronary arteries that come off of the aorta and they Branch then into a total of five smaller vessels so I'm not going to ask you the names of any of the individual coronary vessels just know them collectively as the coronary realize there's more than one now that blood is then going around the outside of the heart and then penetrating in through the much smaller arteries and capillary beds into the muscle and then coming back out collected on the back side of the heart into the coronary sinus we'll get there in a minute now we do know we have a lot of problems associated with blood flow through the heart in some of our patients if you get partial blockage in any of these coronary arteries you may develop what we call angina pectoris angina pain pectoris chest chest pain why not enough oxygen to the heart muscle why not enough oxygen um the coronary vessels are plugged up com part way if not more some patients may experience intense pain Others May experience very minimal pain even if they have equal amounts of blockage there is no Rhyme or Reason really to just know it occurs now if you get total blockage of any of those vessels no oxygen is going to get to the muscle beyond the blockage and then you get a myocardial infarction as we said earlier infarction death of The myocardium heart muscle death of the heart muscle that's an MI or heart attack so and that we have now we'll come back to addressing that in a little bit now let's look at the back side of the heart so we're looking at the back of the heart here you see in red you see the uh left atrium in blue over to the right edge of the screen right atrium you can tell the left is the left because you've got four vessels entering two pulmonary from each side easy peasy now wrapping around the midsection of the heart um roughly between the Atria and the ventricles you have the coronary sinus it's a wide kind of flat it's almost like it's an oval shaped vein that is collecting all the blood that comes out of the heart muscle that was taken in by the coronary arteries comes out through the coronary veins collects into the coronary sinus coronary sinus directs that blood around and the coronary sinus empties into the right atrium so in reality coronary circulation is really part of systemic circulation it's just a specialized part of it so and due to the severe importance of the heart this is why we're talking about it separately now so that's that one now we're on to coronary artery disease we're going to then go back to why are we getting that an pectoris and why are we getting that myocardial infarction well coronary artery disease or CAD this is leading cause of death in men and women heart attacks so um and that's what it is literally leading cause of death in the US for both genders why we have a buildup of what we call that atherosclerotic plaque in the coronary arteries reduced blood flow to The myocardium what's the reduced blood flow going to cause in many individuals chest pain angina pectoris although be warned some people have little to no detectable pain and if that disease State um progresses far enough you're going to get little to no flow through one or more major coronary arteries resulting in heart attack your myocardial infarction so what are our risk factors for CAD well number one top of the list smoking nothing good comes out of smoking ever you can look at virtually any disease state in the body and smoking always makes it worse if you smoke knock that off moving on high blood pressure can cause damage to those vessels diabetes why diabetes causes a hardening of those vessels resulting in less stretchability and diminished blood flow because the can't stretch of those uh flow through there high cholesterol is a major issue why the higher the cholesterol is the faster you're going to build up atherosclerotic plaque period obesity is an issue causing more stress and more work on the heart uh high stress personality stress uh type a sedentary lifestyle sitting around nothing and then of course family history of CAD those are all contributing factors I want you to definitely know the top five on that list so then the stress and sedentary those should be pretty obvious so as well as family history now no one single one of these is the major contributor it's usually a blend of several that lead to coronary artery disease in people and historically males are more likely to have coronary artery disease at a younger age however by about age 70 women have caught up to men in coronary artery disease yay that's one category you want to be last in so uh yes so we tend to think more about this in males but in your elderly female population it is as important as it is in male population so how do you diagnose this how do you treat EK uh coronary artery disease well you need to do an EKG an electrocardiogram this is measuring Electric electrical activity of the heart we'll talk about it more later however when the heart is not under stress it may appear normal so you have to do an EKG along with a stress test that usually means our treadmill to make the body work harder make the heart have to pump harder under those conditions it's much much easier to detect CAD as you start seeing small abnormalities in EKG and depending where in EKG it is you can narrow it down to what parts of the heart are at the problem so you can narrow it down to the major or first branches of all those coronary arteries then how do you go from there to detect it you can also do a cardiac cathet catheterization or cardiac cath here you're going to go in either through an artery or a vein uh it's easiest to go in through an artery on the um in the legs and go sorry it's easier to yeah it's easier to go through an artery in the legs thread your Way backwards to the aorta uh and then into the coronary arteries and now in that catheter is a little tiny camera and you can look for narrowings partial blockages in those larger coronary arteries if you went in through a vein you'd have to weave your way through the heart and then you're going to go out through the um pulmonary arteries and that's better left for looking at the pulmonary arteries than looking at the coronary arteries so then what can we do well you find a blockage what do you do you need to do a bypass surgery this is a coronary artery bypass grafting so you take a vessel and you bypass or connect around the blockage Point usually what's used is a vein and we'll get into the details of that in unit four um now that involves opening up the chest and doing major surgery for a younger patient that's going to be the best possible option for an older patient they may not be able to handle the surgery you may need to do some of the other things listed here before you can get to bypass grafting or if your patient is significantly old enough uh one of these other functions may be plenty good enough so then there's an anoplasty and stance now an angioplasty in one of those cardiac caths instead of using a camera or in addition to using a camera you thread in a very tiny tiny balloon and that balloon is used to rapidly inflate and rapidly stretch the narrowed part of the artery in doing so you tend to squish and compress that atherosclerotic plaque that helps that crushed and squished plaque actually gets even harder because of the squishing and helps hold hold the vessel open angioplasty can be a way to improve patient Health on a short-term basis getting them them to a healthier state in order to survive bypass surgery or depending on their very very Advanced age um it can be useful for several years if you've got a 92y old patient that be all you really need uh they may die of something else in just a matter of a few years so you have to think about that in addition that angioplasty is far less difficult on the patient begin they're going to be under a mild anesthetic and you're not cracking the chest open and then a stent is a modification of the anoplasty here you take a compressed wire tube around that balloon when you blow the balloon up you stretch out that wire screen and you make a little tube to help hold that artery open after the angioplasty is finished that stent can last much longer than the angioplasty Sten are assumed to automatically last at least five years and in many cases upwards of 10 years so you know you got an 85y old patient the angioplasty alone may not be long enough but the stent probably is so and again it's no more invasive than the angioplasty itself because really it's just a modification of the angioplastic so now as far as if you've heard someone go in for a double bypass triple bypass that's how many bypasses they have to make and remember two major coronary arteries that one branches into two branches the other has three three branches so it's a total of five branches the usually the highest number of U bypasses is five and if you've ever heard someone go in for a double bypass and then they come out they had a triple byass um be aware that one of those branches is around the back of the heart and it's very very difficult to assess how healthy it is until literally in the chest so surgeons always prepare to have enough round and are prepared to check that back artery and are expecting to have to fix it also and then just happy as can be when it turns out it's in pretty good shape and they don't have to so that's why that factor changes in patients all right on to more questions here's question five and then we're going to go into the cardiac muscle which has the beginnings of and all the way through talking about the conduction the signals to contract this is a major change in Gears this is a good time to bring to a close part two this is where we'll start for part three thank you very much