Understanding How the Human Heart Works – APC

In this micro-lecture, APC Hon. Snr. Lecturer Sam Willis talks about the Heart.

In today’s micro lecture, we’re going to talk about the heart. Now whenever I teach anything to do with the heart, I’m still fascinated about how the heart continuously beats day in, day out without any conscious effort whatsoever. I mean obviously without it, we wouldn’t be alive. So it’s a pretty important organ in this highly sophisticated. So let’s talk through the basics in this short micro lecture.

So blood enters the right atrium via the superior vena cava, so that’s this large venous circulation. So this is carrying deoxygenated blood back from the rest of the body as well as the inferior vena cava enters this right atrium from carrying blood from the bottom of the body and the superior is from the top. Once the blood hits here, into the right atrium, but when both atria contract together, the blood on this right side get pushed into this right ventricle. Then when both ventricles contract, it gets pushed into the pulmonary artery. Now this is the only place in the body whereby a vein is called an artery, in other words it’s the only artery in the body that actually contracts and carries deoxygenated blood to be oxygenated, ’cause as you know, veins carry deoxygenated blood, and arteries carry oxygenated blood.

So once the atria have contracted and pushed blood into the ventricle, the right ventricle, it gets pushed up into the pulmonary circulation and it goes to the lungs. So anything with the word pulmonary mean lungs. Then the oxygenated blood, the now oxygenated blood enters through the pulmonary veins and likewise these are the only veins in the body that carry oxygenated blood and enters this left atria, then the atrium contracts it pushes it down into the ventricles. So two things that happening at the same time, as the atria contracts, this one’s pushing it into the ventricles, the ventricle here, and it’s still got deoxygenated blood. Then when this one contracts, it’s the oxygenated blood and it pushes it down into the ventricle to be pushed out into the rest of the body. Then when the ventricles contract, as you know on this side, the ventricle pushes blood, the right ventricle pushes blood into the lungs and the left ventricle pushes blood into the aorta and around the rest of the body.

Just notice how here, the left ventricle is really, really muscular, and of course it has to be muscular because it’s pushing blood all the way around the body. Also notice these things called chordae tendineae, which are your basic, your muscles within the actual ventricles themselves. You’ve also got the different types of valves of the pulmonary semilunar valve. You’ve also got the left atrioventricular valve, and the right atrioventricular valve, they all have slightly different names depending on which text you read.

So that’s a micro lecture on the heart.

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