WEBVTT 00:00:02.132 --> 00:00:04.826 I really like this picture that I found. It actually 00:00:04.826 --> 00:00:08.465 shows you really neatly where the heart sits in our body 00:00:08.465 --> 00:00:12.543 so you can see the heart is surrounded, on both sides, by ribs, right? 00:00:12.543 --> 00:00:16.200 And in fact, I didn't draw it in yet, but let me show you where the 00:00:16.200 --> 00:00:20.080 lungs would be. This is the right lung 00:00:20.080 --> 00:00:23.464 and on this side you'd have the left lung. So this is where 00:00:23.464 --> 00:00:27.543 your heart sits: between two lungs. And I'm saying 00:00:27.543 --> 00:00:31.424 left and right from the perspective of the the person who owns this 00:00:31.424 --> 00:00:35.700 heart. So this is their left and right, which is the opposite 00:00:35.700 --> 00:00:39.328 of us if we're looking at it. The heart is actually sitting between the two 00:00:39.328 --> 00:00:42.952 lungs within this protective casing that 00:00:42.952 --> 00:00:47.072 the ribs are basically there to keep all these important organs 00:00:47.072 --> 00:00:51.108 safe. And then below them, so if you draw 00:00:51.108 --> 00:00:55.529 this here. Or if I draw it, you can 00:00:55.529 --> 00:00:58.606 see now that below all this stuff is 00:00:58.606 --> 00:01:02.865 a really really important muscle. So this muscle 00:01:02.865 --> 00:01:07.309 people don't talk about this muscle, or this is not the kind of muscle 00:01:07.309 --> 00:01:10.847 that you usually see people working on at the gym, but this muscle is called the diaphragm. 00:01:10.847 --> 00:01:15.113 So your diaphragm muscle 00:01:15.113 --> 00:01:22.841 and your ribs are enclosing a space, right? The diaphragm becomes the floor, and the ribs are kind of the 00:01:22.841 --> 00:01:25.686 ceiling and the walls of this space. 00:01:25.686 --> 00:01:30.188 And if you look at the contents of this space, you'd have your lung 00:01:30.188 --> 00:01:33.770 and you'd have your heart. So, this entire space then 00:01:33.770 --> 00:01:38.856 is called your thorax. 00:01:38.856 --> 00:01:42.267 So what exactly does the heart do? Let's actually make a little bit of 00:01:42.267 --> 00:01:45.836 space now, and bring up a 00:01:45.836 --> 00:01:47.770 zoomed in version of the heart. 00:01:47.770 --> 00:01:53.969 Let me start by orienting you to the heart. This is our right lung 00:01:53.969 --> 00:01:58.035 and on the other side we have our left lung. And all this would be 00:01:58.035 --> 00:02:01.375 inside of the rib cage, but I'm not going to draw that now, because that would 00:02:01.375 --> 00:02:05.498 make it harder to see the heart itself. So to think 00:02:05.498 --> 00:02:09.732 about exactly what the heart does, I think one, kind of neat way to do it is 00:02:09.732 --> 00:02:13.434 to actually imagine that you're a cell. So put yourself in the perspective 00:02:13.434 --> 00:02:17.361 of a cell, and let's say you're a cell hanging out 00:02:17.361 --> 00:02:21.195 over here. This is you. And you can 00:02:21.195 --> 00:02:25.013 think about any part of the body that you could be. Let's say a little 00:02:25.013 --> 00:02:27.977 toe cell. So let's say you're a toe cell 00:02:27.977 --> 00:02:32.737 and your job, of course, is to live and be happy,and you've got 00:02:32.737 --> 00:02:36.834 near by, a little blood vessel. And in fact, every cell in our body 00:02:36.834 --> 00:02:40.791 has a little blood vessel that's near by. And this toe cell 00:02:40.791 --> 00:02:44.209 is just trying to make a living. And toe 00:02:44.209 --> 00:02:48.914 cells need certain things, right? They need, for example, let's say oxygen. 00:02:48.914 --> 00:02:52.815 I'll write it in white so it's very clear. They need oxygen 00:02:52.815 --> 00:02:56.589 and they need nutrients, right? 00:02:56.589 --> 00:03:00.429 So cells need certain things to live and be happy. 00:03:00.429 --> 00:03:03.938 And on the flip-side, they also make waste. They're in 00:03:03.938 --> 00:03:08.269 a sense just like us, they make waste. And that waste could be 00:03:08.269 --> 00:03:12.525 all sorts of things, and one that kind of jumps to mind is 00:03:12.525 --> 00:03:15.197 carbon dioxide (CO2). So carbon dioxide is waste 00:03:15.197 --> 00:03:19.394 for this cell. So it's making some 00:03:19.394 --> 00:03:23.494 waste and for the moment let's imagine that there's no blood flow. 00:03:23.494 --> 00:03:26.044 So, even though there's a blood vessel near by, 00:03:26.044 --> 00:03:29.905 really, no flow is happening, so I'll just write "no flow". 00:03:29.905 --> 00:03:34.306 So as the little cell 00:03:34.306 --> 00:03:38.949 makes waste. That waste, let's draw a little ball right here, 00:03:38.949 --> 00:03:42.078 it's going to start accumulating, you're going to start collecting more and more of it 00:03:42.078 --> 00:03:45.462 since the blood is not really flowing. And it might kind of 00:03:45.462 --> 00:03:50.435 end up getting all the way around our toe cell. So our toe cell is getting 00:03:50.435 --> 00:03:54.100 swamped, literally getting kind of covered by its own waste. 00:03:54.100 --> 00:03:58.759 And on the flip-side, is it getting oxygen or nutrients? No. 00:03:58.759 --> 00:04:01.945 It's not getting either of these things. So, before very 00:04:01.945 --> 00:04:06.133 long, I would say within minutes, our toe cell 00:04:06.133 --> 00:04:09.637 is thinking, "Well this is not a very happy way to live!" this is 00:04:09.637 --> 00:04:13.245 actually really very sad, this is awful. And if this continues 00:04:13.245 --> 00:04:17.418 the toe cell would die. So, what a toe 00:04:17.418 --> 00:04:20.630 cell needs, and what every cell needs, and that could be a finger cell or a 00:04:20.630 --> 00:04:25.199 skin cell, or really any cell that's living, needs 00:04:25.199 --> 00:04:29.349 flow. Right? It needs this blood to be flowing nicely 00:04:29.349 --> 00:04:31.623 and smoothly. And if there is flow 00:04:31.623 --> 00:04:36.244 then you get a very different picture, right? If there's flow then all the sudden all the 00:04:36.244 --> 00:04:39.564 waste product is actually now lifted and taken away. 00:04:39.564 --> 00:04:43.182 It's flowing away, and it's a little bit like having 00:04:43.182 --> 00:04:48.294 someone come by and pick up the trash, then you don't have trash all over the house. 00:04:48.294 --> 00:04:51.289 So then you have nice flow, and 00:04:51.289 --> 00:04:56.135 in return, oxygen and nutrients are delivered. So this stuff 00:04:56.135 --> 00:04:59.613 gets delivered as well. So, all of the sudden the cell is going to be 00:04:59.613 --> 00:05:03.606 very, very happy, and is going to be living just fine. 00:05:03.606 --> 00:05:06.977 So, really if you want all of the cells in your body to be living just fine 00:05:06.977 --> 00:05:11.414 like this cell here, you really want good flow throughout the 00:05:11.414 --> 00:05:15.100 body. And so this is really point number one. Is that you really 00:05:15.100 --> 00:05:19.068 need, somehow, to have blood flow moving and pushing 00:05:19.068 --> 00:05:22.117 blood constantly throught the body. So, 00:05:22.117 --> 00:05:27.741 to do this for billions and billions of cells you would need a pretty powerful 00:05:27.741 --> 00:05:31.034 pump, right? Something that's going to be able to pull 00:05:31.034 --> 00:05:35.281 in all the blood from the body, and then push it back out. And that's what the heart 00:05:35.281 --> 00:05:39.223 is. I mean at its core, that's exactly what the heart is doing. 00:05:39.223 --> 00:05:42.910 It's an amazing pump, pushing blood, so that 00:05:42.910 --> 00:05:45.540 you have good blood flow. And so I'm 00:05:45.540 --> 00:05:49.524 going to write that on the side as kind of job number one. These are the jobs of the heart. 00:05:49.524 --> 00:05:53.479 So jobs, and number one, would be 00:05:53.479 --> 00:05:56.045 blood flow. And I'll write systemic 00:05:56.045 --> 00:06:01.049 flow. Systemic flow. And all 00:06:01.049 --> 00:06:05.043 that systemic means is that I'm refering to the entire body. So systemic 00:06:05.043 --> 00:06:08.782 when I say that word, I just mean the entire body. All the cells 00:06:08.782 --> 00:06:12.861 in the body. Now, exactly how that happens actually 00:06:12.861 --> 00:06:16.508 you can see on this picture. So, here you have a giant 00:06:16.508 --> 00:06:20.656 vein, this is a vein, and you have an artery. 00:06:20.656 --> 00:06:23.602 This is an artery. 00:06:23.602 --> 00:06:28.698 And blood is actually going through the artery, that way. 00:06:28.698 --> 00:06:32.938 And it's actually coming into two veins, the one 00:06:32.938 --> 00:06:36.820 at the top, this is called the superior, superior just kind of means 00:06:36.820 --> 00:06:40.490 at the top. Superior vena cava. That's the 00:06:40.490 --> 00:06:44.382 name of the vein. And at the bottom here, you can't see it because 00:06:44.382 --> 00:06:48.496 it's on the other side of the heart, but there's another vein called the inferior vena cava. 00:06:48.496 --> 00:06:51.522 And these two veins, this is also a vein, 00:06:51.522 --> 00:06:57.533 these two veins are actually dragging blood in from all over the body, 00:06:57.533 --> 00:06:59.406 into the heart. 00:06:59.406 --> 00:07:02.906 And then, when the heart is ready to pump it back out, it goes into this 00:07:02.906 --> 00:07:07.256 artery, and the name of it is the aorta. 00:07:07.256 --> 00:07:10.827 So if you've heard of the aorta, this is the artery that people 00:07:10.827 --> 00:07:14.856 are talking about. So this is how blood comes and gets pumped 00:07:14.856 --> 00:07:18.775 around. But this isn't actually the only job of the heart. The job, 00:07:18.775 --> 00:07:22.465 the second job of the heart, is actually 00:07:22.465 --> 00:07:26.536 also in this picture, and it's called pulmonary flow. 00:07:26.536 --> 00:07:30.517 Pulmonary flow. So, what does that 00:07:30.517 --> 00:07:34.116 mean? Well, we know that cells are expecting 00:07:34.116 --> 00:07:39.079 oxygen, right? We know this. And that they have a lot of carbon dioxide 00:07:39.079 --> 00:07:42.322 waste. Well, it's good to move things around. It's good 00:07:42.322 --> 00:07:45.399 to move blood around. But if you actually never got rid of that carbon dioxide 00:07:45.399 --> 00:07:49.786 or brought in new oxygen, then a cell is not going to be very happy either. 00:07:49.786 --> 00:07:53.107 I mean, you can have blood flow, but at some point it's also going to want some oxygen. 00:07:53.107 --> 00:07:57.271 And it's going to want to get rid of that carbon dioxide. So, that's where the 00:07:57.271 --> 00:08:00.911 lungs come in. So what happens is that the heart, before 00:08:00.911 --> 00:08:05.436 sending blood out the aorta, before just dishing it out back into the body, 00:08:05.436 --> 00:08:09.411 it actually sends the blood over to the 00:08:09.411 --> 00:08:12.895 lungs. And it goes over to the left lung, and over to the right lung. 00:08:12.895 --> 00:08:17.186 And the blood comes back from the right lung 00:08:17.186 --> 00:08:21.280 and the left lung, and gets pushed back into 00:08:21.280 --> 00:08:24.629 the heart, and then gets squeezed through the aorta. So there's this 00:08:24.629 --> 00:08:28.223 actual extra little step here, where blood is going to 00:08:28.223 --> 00:08:32.528 and from the lungs, and that's the pulmonary flow. 00:08:32.528 --> 00:08:36.813 So the final thing you'll notice, if you look at this picture it's hard not to notice, 00:08:36.813 --> 00:08:40.196 is that there are these, kind of wriggly looking little 00:08:40.196 --> 00:08:44.344 blood vessels all over the heart. And what are these 00:08:44.344 --> 00:08:47.030 exactly? I mean, you've got red ones, and blue ones, and 00:08:47.030 --> 00:08:50.356 the blue ones are the veins, and the red ones are the arteries 00:08:50.356 --> 00:08:55.270 but are they part of the systemic flow, or pulmonary flow, or something else? 00:08:55.270 --> 00:08:58.476 Well, these vessels, all of them, 00:08:58.476 --> 00:09:01.943 together are called coronary vessels. 00:09:01.943 --> 00:09:06.929 And so specifically you might hear about 00:09:06.929 --> 00:09:10.720 a coronary artery, or a coronary vein, but together you can call them 00:09:10.720 --> 00:09:14.450 coronary blood vessels. I'll add the word blood here. So these 00:09:14.450 --> 00:09:18.109 coronary blood vessels are actually serving the heart muscle 00:09:18.109 --> 00:09:20.715 itself. I mean remember, the heart 00:09:20.715 --> 00:09:24.724 is made up of thousands and thousands, actually tens of thousands of cells 00:09:24.724 --> 00:09:29.948 and those cells, just like our toe cell that we drew, 00:09:29.948 --> 00:09:33.636 they also need oxygen, nutrients, and have waste. 00:09:33.636 --> 00:09:37.223 So, those cells are going to need blood vessels supplying 00:09:37.223 --> 00:09:40.319 them as well. So, that's what the coronary blood vessels are. They're literally 00:09:40.319 --> 00:09:43.835 the blood vessels that go to and serve 00:09:43.835 --> 00:09:47.735 the heart. So these are the ones that serve the heart. 00:09:47.735 --> 00:09:51.059 Now, if they're serving the heart muscles 00:09:51.059 --> 00:09:55.616 and the heart cells, then, think about it, would they fit under 00:09:55.616 --> 00:09:59.304 the systemic flow, or pulmonary flow? Well if the 00:09:59.304 --> 00:10:03.411 main job is to serve the needs of cells, then 00:10:03.411 --> 00:10:08.167 the coronary vessels fall under the systmic flow.