If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Main content
Current time:0:00Total duration:5:34

Video transcript

so I want to talk about non cyanotic heart disease but before I do that let's do a quick review of blood flow through the heart so blood is coming back from the rest of the body and as it's coming back it is going to be deoxygenated because you know the body was using up all the oxygen and now it's sending the blood back to the heart and it hardly has any oxygenate its it actually is deoxygenated so this is going to be coming back to the right side of the heart and from that right side as the heart is beating it is going to send the blood the deoxygenated blood via these vessels and they're gonna go to the lungs and it's a good thing that they're going to the lungs because here's what's happening in the lungs as it's passing through these little vessels that we call pulmonary capillaries as it's passing through those capillaries it's gonna pick up something that's very important and the thing that it's gonna pick up is oxygen and as it picks up that oxygen you'll see that it kind of becomes a brighter red color a brightest red color before it was very dark but as it's picking up that oxygen it is it is it is changing color to where it's kind of bright red and then that blood is gonna come back to the left side of the heart and it's gonna go through the left side of the heart and as the heart beats it's gonna send that oxygenated blood now throughout the rest of the body so this is that blood it's going through all of these vessels and it's going throughout the body which makes sense it's delivering the oxygen to the body now here's the thing you want to have this separation you want the the right side to have your deoxygenated blood so that it can go to the lungs and then come back for your this left side so that that can then go in it's oxygenated form to the body now in individuals that are born with non cyanotic heart disease there is some kind of a defect and I'm showing a defect here where there's a hole in the heart and that defect allows for of course blood is going to pass through that hole even though that's not you want the blood to pass if the hole is there and the heart is beating the the muscle is contracting its gonna send blood through that opening but the question is which direction is the blood going to flow and to answer that question let's just think logically about what's happening here on the right side this side of the heart is beating when the heart is beating this side is sending blood it's not going far distance it's going right next door to the lungs to come back to the left side but when the left side contracts when that beats it's sending blood all throughout the body it's going to the head it's going to the neck it's going to the arms and the and the legs and all throughout the body and this has to do significantly more work you can see here that the muscle here is significantly thicker on the left side than we have on the right side and as a result of their as a result of that we're going to have significantly more pressure over here and if you have more pressure over here that is gonna squeeze the blood through that opening and it's gonna go from the left side to the right side and that's exactly what we have with non cyanotic heart defect it's a congenital disease and congenital just means that that individual is born with it that causes blood to shunt from left to right okay so what's what's the problem here okay so we have blood that's shunting from left to right because we have a hole in the heart and you often hear about a hole in the heart and you wonder maybe okay that must be bad right well let's think about what's happening let's get back to that color that we were using before what kind of blood do we have over here on the left well it's oxygenated blood and if some of that squeeze squeezes through that little opening and gets into the left side okay yeah that that oxygenated blood is gonna go back to the lungs and and as it goes back to the lungs with the rest of the blood they're gonna be picking up oxygen and and and then that's gonna go back to the the right side of the heart as we expect it to go and then it's gonna go to the body some of it might go back through is that a real problem well yeah usually when we have individuals with a small hole in the heart its asymptomatic because what we're doing is we're just sending oxygenated blood back to the lungs that is not efficient this is not an efficient system but it's still functional the oxygen levels are going to be adequate for normal function and of course the the body needs oxygen in order to to do all of the things that need to be done so that you can have the energy that it needs and with this oxygenated blood that's going back yeah if we still end up with normal levels of oxygenation on this right side so it's going to be asymptomatic and it doesn't matter if the hole is down here or up here or up here the fact is you have higher pressure on the right on the left side sorry and that is going to always overpower the lower pressure on the right side so you will always have that left to right shunting and that is in non cyanotic heart disease