Components of the Heart – Anatomy of the Heart

00:00 right chest, little bit upper left chest, lower right chest and lower left chest.

00:01 So, let’s talk a little bit about the parts of the heart. The heart, of course, is a muscle pump. So, that’s the most important part but that’s not the only part. Of course, you have to have valves to keep the blood flowing in the right direction. If in fact, you didn’t have valves, all the blood would just slosh back and forth within the heart.

00:22 You have to have the valves to keep the blood flowing in the right direction. You also have electrical wiring, we are going to talk a lot more about this, but in fact, what triggers the contraction of the heart is an electrical signal that starts high in the right atrium of the heart with a little automatic pacemaker and passes right down through the heart muscle and results in contraction of the heart muscle when the electrical signal gets there. Of course, you also have to have arteries to supply the heart with oxygen and nutrients so it can work. In other words, the fuel line for the heart to put the fuel into the heart cells so that they can contract. The veins are also important because they carry the tired blood- the blood that’s lost its oxygen and some of its nutrients and is carrying waste products, it returns to the right atrium along with the superior and inferior vena cava to be circulated again from the right ventricle into the lungs to gain oxygenation and to give up its carbon dioxide. And then, of course, the entire heart is contained in a membrane, a very tough membrane called the pericardium that protects the heart, particularly, for example, from infections in the lungs, should they occur and it also keeps the heart in a nice shape so that it doesn’t expand too much when it’s working.

01:39 The important lesson here in anatomy is that the heart is a muscle pump, that it’s going to continue to pump blood in a continuous circle through the body and that it is meticulously and beautifully adapted to do this. We will be talking about more detail of the various ways that the heart does this. So, here is the diagram again that you saw before, once more to reiterate, venous blood comes back to the right atrium through the tricuspid valve to the right ventricle, out the pulmonary artery, back. Oxygenated blood comes back to the left atrium through the pulmonary veins through the mitral valve and then pumped out the aortic valve to the body.

02:24 Well, let’s look in a little more detail inside these various chambers. Here you see a diagram inside the right ventricle and you can see… of course, it shows you the blood is blue, that’s the deoxygenated blood. You can see the right atrium above the right ventricle and you can see the pulmonary artery and the pulmonary valve below it. There are a variety of abnormalities that the heart can be found in… in infants. For example, the pulmonary valve can be stenotic or closed, has to be fixed at the… early in life, there can be holes in the heart, for example, a connection between the right and left ventricle where there should be none. All of these are the area of the pediatric cardiologist who can make those diagnoses very early in life and often these days, infants are operated on and have these abnormalities corrected. But, the normal right ventricle, remember, will be separated from the left ventricle with a muscle septum that will prevent blood from the right side from getting on to the left side. When blood from the right side gets onto the left side, the patient actually has a faintly bluish tinge to themselves and you… we will talk about that when we talk about physiology and diagnosis.

03:46 Here we see a diagram of the right ventricle contracting and as I said before, the right ventricle is working like a bellows, you will see in the diagram on the left, that’s the contracted right ventricle and then on the right, you can see the filling right ventricle.

04:01 It looks like a bellows, right? Just like the blacksmith’s bellows that’s used to… to heat up the fire beneath the horseshoes that the blacksmith is working on. The right ventricle again, is thin walled and much thinner walled than the left ventricle because it pumps at a much lower pressure than the left ventricle.

04:22 Here we see a diagram of blood that is passing through the heart and the different pressures in the different chambers. We are going to be talking a lot more about this when we come to the physiology component, but its important to see right here on the left hand side of the diagram, low pressure in the right atrium, then periodic high pressure followed by low pressure in the right ventricle. Then we see in the pulmonary artery, high pressure followed by not such low blood pressure, and then the pulmonary capillaries which are a reflection of left atrial pressure, also a low pressure about the same as the minimal pressure in the pulmonary artery. We see that the blood passes through the heart starting at a very low pressure in the right atrium, the tricuspid valve opens, blood flows into the right ventricle and it squeezes and then you see the pressure going up for the right ventricle. And then when the… the pulmonary valve closes, the pressure falls again down to the baseline where the righ-… the tricuspid valve opens again and the blood flows into the right ventricle.

05:31 Out in the pulmonary artery, when the pulmonary valve closes, the pressure no longer falls anymore and you see a… a sort of baseline pulmonary artery pressure that’s transmitted across to the pulmonary capillaries and eventually, to the pulmonary veins and the left atrium.