1 00:00:02,132 --> 00:00:04,826 I really like this picture that I found. It actually 2 00:00:04,826 --> 00:00:08,465 shows you really neatly where the heart sits in our body 3 00:00:08,465 --> 00:00:12,543 so you can see the heart is surrounded, on both sides, by ribs, right? 4 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 5 00:00:16,200 --> 00:00:20,080 lungs would be. This is the right lung 6 00:00:20,080 --> 00:00:23,464 and on this side you'd have the left lung. So this is where 7 00:00:23,464 --> 00:00:27,543 your heart sits: between two lungs. And I'm saying 8 00:00:27,543 --> 00:00:31,424 left and right from the perspective of the the person who owns this 9 00:00:31,424 --> 00:00:35,700 heart. So this is their left and right, which is the opposite 10 00:00:35,700 --> 00:00:39,328 of us if we're looking at it. The heart is actually sitting between the two 11 00:00:39,328 --> 00:00:42,952 lungs within this protective casing that 12 00:00:42,952 --> 00:00:47,072 the ribs are basically there to keep all these important organs 13 00:00:47,072 --> 00:00:51,108 safe. And then below them, so if you draw 14 00:00:51,108 --> 00:00:55,529 this here. Or if I draw it, you can 15 00:00:55,529 --> 00:00:58,606 see now that below all this stuff is 16 00:00:58,606 --> 00:01:02,865 a really really important muscle. So this muscle 17 00:01:02,865 --> 00:01:07,309 people don't talk about this muscle, or this is not the kind of muscle 18 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. 19 00:01:10,847 --> 00:01:15,113 So your diaphragm muscle 20 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 21 00:01:22,841 --> 00:01:25,686 ceiling and the walls of this space. 22 00:01:25,686 --> 00:01:30,188 And if you look at the contents of this space, you'd have your lung 23 00:01:30,188 --> 00:01:33,770 and you'd have your heart. So, this entire space then 24 00:01:33,770 --> 00:01:38,856 is called your thorax. 25 00:01:38,856 --> 00:01:42,267 So what exactly does the heart do? Let's actually make a little bit of 26 00:01:42,267 --> 00:01:45,836 space now, and bring up a 27 00:01:45,836 --> 00:01:47,770 zoomed in version of the heart. 28 00:01:47,770 --> 00:01:53,969 Let me start by orienting you to the heart. This is our right lung 29 00:01:53,969 --> 00:01:58,035 and on the other side we have our left lung. And all this would be 30 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 31 00:02:01,375 --> 00:02:05,498 make it harder to see the heart itself. So to think 32 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 33 00:02:09,732 --> 00:02:13,434 to actually imagine that you're a cell. So put yourself in the perspective 34 00:02:13,434 --> 00:02:17,361 of a cell, and let's say you're a cell hanging out 35 00:02:17,361 --> 00:02:21,195 over here. This is you. And you can 36 00:02:21,195 --> 00:02:25,013 think about any part of the body that you could be. Let's say a little 37 00:02:25,013 --> 00:02:27,977 toe cell. So let's say you're a toe cell 38 00:02:27,977 --> 00:02:32,737 and your job, of course, is to live and be happy,and you've got 39 00:02:32,737 --> 00:02:36,834 near by, a little blood vessel. And in fact, every cell in our body 40 00:02:36,834 --> 00:02:40,791 has a little blood vessel that's near by. And this toe cell 41 00:02:40,791 --> 00:02:44,209 is just trying to make a living. And toe 42 00:02:44,209 --> 00:02:48,914 cells need certain things, right? They need, for example, let's say oxygen. 43 00:02:48,914 --> 00:02:52,815 I'll write it in white so it's very clear. They need oxygen 44 00:02:52,815 --> 00:02:56,589 and they need nutrients, right? 45 00:02:56,589 --> 00:03:00,429 So cells need certain things to live and be happy. 46 00:03:00,429 --> 00:03:03,938 And on the flip-side, they also make waste. They're in 47 00:03:03,938 --> 00:03:08,269 a sense just like us, they make waste. And that waste could be 48 00:03:08,269 --> 00:03:12,525 all sorts of things, and one that kind of jumps to mind is 49 00:03:12,525 --> 00:03:15,197 carbon dioxide (CO2). So carbon dioxide is waste 50 00:03:15,197 --> 00:03:19,394 for this cell. So it's making some 51 00:03:19,394 --> 00:03:23,494 waste and for the moment let's imagine that there's no blood flow. 52 00:03:23,494 --> 00:03:26,044 So, even though there's a blood vessel near by, 53 00:03:26,044 --> 00:03:29,905 really, no flow is happening, so I'll just write "no flow". 54 00:03:29,905 --> 00:03:34,306 So as the little cell 55 00:03:34,306 --> 00:03:38,949 makes waste. That waste, let's draw a little ball right here, 56 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 57 00:03:42,078 --> 00:03:45,462 since the blood is not really flowing. And it might kind of 58 00:03:45,462 --> 00:03:50,435 end up getting all the way around our toe cell. So our toe cell is getting 59 00:03:50,435 --> 00:03:54,100 swamped, literally getting kind of covered by its own waste. 60 00:03:54,100 --> 00:03:58,759 And on the flip-side, is it getting oxygen or nutrients? No. 61 00:03:58,759 --> 00:04:01,945 It's not getting either of these things. So, before very 62 00:04:01,945 --> 00:04:06,133 long, I would say within minutes, our toe cell 63 00:04:06,133 --> 00:04:09,637 is thinking, "Well this is not a very happy way to live!" this is 64 00:04:09,637 --> 00:04:13,245 actually really very sad, this is awful. And if this continues 65 00:04:13,245 --> 00:04:17,418 the toe cell would die. So, what a toe 66 00:04:17,418 --> 00:04:20,630 cell needs, and what every cell needs, and that could be a finger cell or a 67 00:04:20,630 --> 00:04:25,199 skin cell, or really any cell that's living, needs 68 00:04:25,199 --> 00:04:29,349 flow. Right? It needs this blood to be flowing nicely 69 00:04:29,349 --> 00:04:31,623 and smoothly. And if there is flow 70 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 71 00:04:36,244 --> 00:04:39,564 waste product is actually now lifted and taken away. 72 00:04:39,564 --> 00:04:43,182 It's flowing away, and it's a little bit like having 73 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. 74 00:04:48,294 --> 00:04:51,289 So then you have nice flow, and 75 00:04:51,289 --> 00:04:56,135 in return, oxygen and nutrients are delivered. So this stuff 76 00:04:56,135 --> 00:04:59,613 gets delivered as well. So, all of the sudden the cell is going to be 77 00:04:59,613 --> 00:05:03,606 very, very happy, and is going to be living just fine. 78 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 79 00:05:06,977 --> 00:05:11,414 like this cell here, you really want good flow throughout the 80 00:05:11,414 --> 00:05:15,100 body. And so this is really point number one. Is that you really 81 00:05:15,100 --> 00:05:19,068 need, somehow, to have blood flow moving and pushing 82 00:05:19,068 --> 00:05:22,117 blood constantly through the body. So, 83 00:05:22,117 --> 00:05:27,741 to do this for billions and billions of cells you would need a pretty powerful 84 00:05:27,741 --> 00:05:31,034 pump, right? Something that's going to be able to pull 85 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 86 00:05:35,281 --> 00:05:39,223 is. I mean at its core, that's exactly what the heart is doing. 87 00:05:39,223 --> 00:05:42,910 It's an amazing pump, pushing blood, so that 88 00:05:42,910 --> 00:05:45,540 you have good blood flow. And so I'm 89 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. 90 00:05:49,524 --> 00:05:53,479 So jobs, and number one, would be 91 00:05:53,479 --> 00:05:56,045 blood flow. And I'll write systemic 92 00:05:56,045 --> 00:06:01,049 flow. Systemic flow. And all 93 00:06:01,049 --> 00:06:05,043 that systemic means is that I'm refering to the entire body. So systemic 94 00:06:05,043 --> 00:06:08,782 when I say that word, I just mean the entire body. All the cells 95 00:06:08,782 --> 00:06:12,861 in the body. Now, exactly how that happens actually 96 00:06:12,861 --> 00:06:16,508 you can see on this picture. So, here you have a giant 97 00:06:16,508 --> 00:06:20,656 vein, this is a vein, and you have an artery. 98 00:06:20,656 --> 00:06:23,602 This is an artery. 99 00:06:23,602 --> 00:06:28,698 And blood is actually going through the artery, that way. 100 00:06:28,698 --> 00:06:32,938 And it's actually coming into two veins, the one 101 00:06:32,938 --> 00:06:36,820 at the top, this is called the superior, superior just kind of means 102 00:06:36,820 --> 00:06:40,490 at the top. Superior vena cava. That's the 103 00:06:40,490 --> 00:06:44,382 name of the vein. And at the bottom here, you can't see it because 104 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. 105 00:06:48,496 --> 00:06:51,522 And these two veins, this is also a vein, 106 00:06:51,522 --> 00:06:57,533 these two veins are actually dragging blood in from all over the body, 107 00:06:57,533 --> 00:06:59,406 into the heart. 108 00:06:59,406 --> 00:07:02,906 And then, when the heart is ready to pump it back out, it goes into this 109 00:07:02,906 --> 00:07:07,256 artery, and the name of it is the aorta. 110 00:07:07,256 --> 00:07:10,827 So if you've heard of the aorta, this is the artery that people 111 00:07:10,827 --> 00:07:14,856 are talking about. So this is how blood comes and gets pumped 112 00:07:14,856 --> 00:07:18,775 around. But this isn't actually the only job of the heart. The job, 113 00:07:18,775 --> 00:07:22,465 the second job of the heart, is actually 114 00:07:22,465 --> 00:07:26,536 also in this picture, and it's called pulmonary flow. 115 00:07:26,536 --> 00:07:30,517 Pulmonary flow. So, what does that 116 00:07:30,517 --> 00:07:34,116 mean? Well, we know that cells are expecting 117 00:07:34,116 --> 00:07:39,079 oxygen, right? We know this. And that they have a lot of carbon dioxide 118 00:07:39,079 --> 00:07:42,322 waste. Well, it's good to move things around. It's good 119 00:07:42,322 --> 00:07:45,399 to move blood around. But if you actually never got rid of that carbon dioxide 120 00:07:45,399 --> 00:07:49,786 or brought in new oxygen, then a cell is not going to be very happy either. 121 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. 122 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 123 00:07:57,271 --> 00:08:00,911 lungs come in. So what happens is that the heart, before 124 00:08:00,911 --> 00:08:05,436 sending blood out the aorta, before just dishing it out back into the body, 125 00:08:05,436 --> 00:08:09,411 it actually sends the blood over to the 126 00:08:09,411 --> 00:08:12,895 lungs. And it goes over to the left lung, and over to the right lung. 127 00:08:12,895 --> 00:08:17,186 And the blood comes back from the right lung 128 00:08:17,186 --> 00:08:21,280 and the left lung, and gets pushed back into 129 00:08:21,280 --> 00:08:24,629 the heart, and then gets squeezed through the aorta. So there's this 130 00:08:24,629 --> 00:08:28,223 actual extra little step here, where blood is going to 131 00:08:28,223 --> 00:08:32,528 and from the lungs, and that's the pulmonary flow. 132 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, 133 00:08:36,813 --> 00:08:40,196 is that there are these, kind of wriggly looking little 134 00:08:40,196 --> 00:08:44,344 blood vessels all over the heart. And what are these 135 00:08:44,344 --> 00:08:47,030 exactly? I mean, you've got red ones, and blue ones, and 136 00:08:47,030 --> 00:08:50,356 the blue ones are the veins, and the red ones are the arteries 137 00:08:50,356 --> 00:08:55,270 but are they part of the systemic flow, or pulmonary flow, or something else? 138 00:08:55,270 --> 00:08:58,476 Well, these vessels, all of them, 139 00:08:58,476 --> 00:09:01,943 together are called coronary vessels. 140 00:09:01,943 --> 00:09:06,929 And so specifically you might hear about 141 00:09:06,929 --> 00:09:10,720 a coronary artery, or a coronary vein, but together you can call them 142 00:09:10,720 --> 00:09:14,450 coronary blood vessels. I'll add the word blood here. So these 143 00:09:14,450 --> 00:09:18,109 coronary blood vessels are actually serving the heart muscle 144 00:09:18,109 --> 00:09:20,715 itself. I mean remember, the heart 145 00:09:20,715 --> 00:09:24,724 is made up of thousands and thousands, actually tens of thousands of cells 146 00:09:24,724 --> 00:09:29,948 and those cells, just like our toe cell that we drew, 147 00:09:29,948 --> 00:09:33,636 they also need oxygen, nutrients, and have waste. 148 00:09:33,636 --> 00:09:37,223 So, those cells are going to need blood vessels supplying 149 00:09:37,223 --> 00:09:40,319 them as well. So, that's what the coronary blood vessels are. They're literally 150 00:09:40,319 --> 00:09:43,835 the blood vessels that go to and serve 151 00:09:43,835 --> 00:09:47,735 the heart. So these are the ones that serve the heart. 152 00:09:47,735 --> 00:09:51,059 Now, if they're serving the heart muscles 153 00:09:51,059 --> 00:09:55,616 and the heart cells, then, think about it, would they fit under 154 00:09:55,616 --> 00:09:59,304 the systemic flow, or pulmonary flow? Well if the 155 00:09:59,304 --> 00:10:03,411 main job is to serve the needs of cells, then 156 00:10:03,411 --> 00:10:08,167 the coronary vessels fall under the systemic flow.