Welcome, my name is Dr. Warrick Bishop. I'm a cardiologist, an author and a keynote speaker. I'm CEO of the Healthy Heart Network. I'm all about trying to help people live as well as possible for as long as possible. Heart disease is huge in Australia. Every 20 minutes someone suffers a heart attack. Most of these could probably have been avoided if only we knew what to do. This podcast is all about helping you understand blood pressure, weight, cholesterol for better health. If you enjoy this podcast, I would be honoured for a five-star review. You can share it with your family and friends. It may well save someone you love. Hi, I'm Warrick Bishop and welcome to my podcast and videocast station. I hope you're well. Today I'd like to talk about heart anatomy and heart function. Well, I've done several hundred podcasts to date and covered the heart and associated health-related issues and lots of bits and pieces, but it's always good to go back to basics and remind ourselves of exactly what goes on when we think about that wonderful pump that lives in our chest. What's the heart there for? To a large degree, cardiologists would say it's the most important organ in the body because that's what we focus on. But from a practical perspective, it would be quite reasonable to say that the heart is simply there to ensure oxygen gets moved out to the tissues and carbon dioxide moved back from the tissues. Oxygen is important for every cell in the body because it allows that cell to metabolize and keep alive. So without oxygen, our cells will perish. Well, carbon dioxide is the waste or byproduct from what we call respiration. Respiration being that process of metabolism of oxygen for energy. So without moving blood out to the tissues and then back, to the lungs to exchange oxygen and carbon dioxide, then we would die. So the heart is supportive of that process. When we think of blood moving around the body, it's possibly easiest to think of the blood coming back to the heart in the first instance. That blood comes back through the veins and those veins... get larger and larger, like big tributaries or big roads leading into a city perhaps. Those large tributaries that run into the heart are called the superior vena cava and the inferior vena cava. The superior vena cava drains all the blood from the upper body. The inferior vena cava, the blood from the lower part of the body. Now that blood is drained into what we could quite easily call the right side of the heart. It moves through the atria, which if you like are a pre-pumping chamber, into the right ventricle. The right ventricle then gives that blood a more forceful squeeze, squeezing it into the lungs. In the lungs, gas exchange occurs and then blood flows. From the lungs into the left atrium, the receiving chamber of the left side of the heart. That chamber then gives the blood a squeeze, pushing it through the mitral valve into the left ventricle. The left ventricle is the powerful compression chamber of the heart. And the left ventricle squeezes hard. Blood flows out through the aortic valve and into the aorta. and then is distributed through the arterial system out to the tissues. So you can think of the heart as a pump in two parts. The right pump, which receives blood from the venous system and pumps blood to the lungs, and then the left heart, which receives blood from the lungs and pumps blood out into the body. As we think about the entire heart, it's actually all wrapped around each other. So although we think of it as two hearts, it really is, if you like, all closely approximated when it comes down to looking at the heart as a single organ. For each of those sides of the heart, though, there is an atria and a ventricle. The atria is the receiving chamber. If you had a house or you went to a function event, you might collect in the atrium of that function event. That's the receiving chamber of that place. The atria are thin walled structures. On the right hand side, the atria gives the blood a little squeeze. That blood is then pushed through the tricuspid valve. so named because of its shape, as the blood passes through the tricuspid valve, it is then squeezed by the right ventricle at a lowish pressure, much lower than the systolic or systemic pressure that we'd measure at the arm. That blood is then squeezed from the right side of the heart into the lungs through the pulmonary valve, which stops blood regurgitating back the tricuspid and pulmonary valves. point so that the blood goes forward if you like forward towards the lungs and doesn't go backwards back towards whence it came the legs the arms wherever. As the blood filters through the lungs our breathing helps that pumping process and then as that blood is The gas exchange occurs with that blood. It then, through respiration, the assistance of respiration and pressures within the heart, drains into the left atrium, which again is not the main pumping chamber of the heart, but closely related to the right atrium in an anatomical way. The left atrium squeezes the blood through the mitral valve. Again named because it looks like a mitre hat of a religious person. The blood in the left ventricle is then squeezed. And this is the main heartbeat that we tend to feel in our chest. If we ever feel our heart beating it's... generally the left ventricle, the left ventricle squeezes out through the aortic valve, which again is a one-way valve, just like the mitral valve, so the blood flows forward and out into the body. Well, of course, the blood has the muscular components that we've just talked about, the engine block, if you like, and that makes up the right atrium, right ventricle, left atrium, left ventricle, so they're the... compression chambers. It has those valves that ensure that the blood flows in one direction. The tricuspid valve between the right atrium, right ventricle, the pulmonary valve preventing blood coming back into the right ventricle, the mitral valve receiving or allowing flow from the left atrium to the left ventricle and then the aortic valve. And then we've got an electrical system for the heart. So that electrical system is a timing mechanism. And from a fascinating perspective, it turns out that every cell in the heart has an ability for what is called automaticity, which means it can generate its own electrical charge or impulse. And that's because the cells in the heart... have a leaky membrane and that leaky membrane allows ions like calcium and sodium to drift across that membrane until the charge across that membrane gets to a point where it triggers an electrical action potential. So remarkably if you were able to take every cell in a living heart and spread them out on a table you would see each of those individual cells which sounds incredibly creepy but also is spectacularly fascinating at the same time. So the electrical function of the heart tends to be driven by the cells that depolarize or beat the fastest. And these cells tend to live in the atria, specifically in the right atrium. So the right atrium electrical signal tends to be the first electrical signal that then passes through both atria. and then through a special conduction node into the ventricle, distributed by these amazing cells, which literally act like copper wires, making sure that that electrical signal gets to the lateral and furthest parts of the ventricles, so that they squeeze from the far end, squeezing blood out, rather than squeezing from the near end, squeezing in on themselves. The timing in the electrical system is just exquisite. If we think of the heart and we think of an analogy, it's a wonderful analogy to think of our car engine. The electrical system being the timing system. We think of the atria and the ventricles as the pistons, if you like. And I've described to you the valves. Altogether, an amazing system, which... I've already spoken so much about in previous podcasts and look forward to sharing even more about with you into the future. I'm going to wrap up on heart structure and function and I hope you've enjoyed it. For now, I'm going to wish you the very best. If you have any queries or questions, drop us a note at info at drWarrickbishop.online. Take care and bye for now. Join the Healthy Heart Network and become part of our growing community. If you're interested in your heart health and risk of heart attack, then join the Healthy Heart Network for only $5 as a lifetime member. This represents $55 worth of value. We offer and help people understand their present state of heart health. what their current level of risk is and the positive steps they can take to improve their risk of heart attack in the future. Go to www.healthyheartnetwork.com.au and click the join the family button.
