Cardiovascular System 1, Heart, Structure and Function

Well, welcome to today's video where we are going to consider the

heart

and

heart

s as a hollow muscular organ located in the thoracic cavity and we need to learn the basic anatomical terminology and the basic anatomical

structure

s of the heart before we continue, so this is kind of introductory session to cover that basic anatomy. Now, of course, in anatomy you remember that you're always looking at someone else's, so it's like you're looking at my heart, so this is my left hand here, so the right one is on the left. side of the board and right on this side of the board so we don't get confused now I will start drawing the image of the heart that you can frame in the trees whenever you want and draw your own so here we see the main lower chambers in The heart and these The lower chambers are called ventricles, so we have a left ventricle on this side and the right ventricle on the other side, and the left ventricle in particular has a thick muscular wall, so here we see the thick muscular wall of the left ventricle and Of course, the right ventricle also has a muscle wall, but it is much thinner now.

Why does the left ventricle have a thick muscle wall and the right ventricle has a thin muscle wall? Well, as we will see, it is the left ventricle that pumps blood. around the body into the

system

ic circulation, so the blood that is pumped from the left ventricle goes to the ears, the toes and the brain, absolutely everywhere in the body, the entire

system

ic circulation, so you need to generate a fairly high pumping pressure with a large muscle mass on the left side while as we will see the right ventricle only pumps blood to the lungs, if the heart is here then the lungs are alone so there is no so much distance to pump the blood, so the pressure doesn't have to increase. be so tall so the amount of muscle mass required is less now the key about the heart is that it is in these four chambers now first of all we need to remove some arteries that come out of the heart now this valve here protects the aorta which is the Vessel big one coming out of the left ventricle and the valve points up and then between the ventricle at the bottom of the upper chamber there is another valve and that one points down, so here we see the left ventricle with a valve. there and a valve there, now the upper chambers of the heart of a much thinner muscle wall, so the muscle becomes thinner at that point and you can probably see here we're starting to draw an additional chamber, one of the chambers superior, the atria and draining into the atria are four large veins in humans.

I think in this diagram today I'm only going to draw two, so here we see two large veins draining blood into the upper chamber, the left atrium. Remember there are actually four in humans, so now we see. we have the left ventricle and here we can see clearly now there is an additional chamber, the left atrium, so the left ventricle, the left atrium pointing down, the valve pointing the way and this valve between the atria and the ventricles below It is called the atrioventricular valve. between the atria and the ventricles, so it is the atrioventricular valve or atrioventricular valve and this particular valve has two cusps, it opens like this, the left atrioventricular valve only has two cusps, so it is sometimes called a bicuspid valve because It has two cusps, but it is adequate.

The name is mitral valve, so the left atrial ventricular valve is the mitral valve and it has two cusps, the valve between the left ventricle and the aorta, which is the aortic valve and they are sometimes known as semilunar valves because They look a bit alike. crescent, then, the aortic arterial valve or the aortic semilunar valve, which is the one that points upward, as we have said, this vessel is the aorta, the large vessel that leaves the left ventricle and carries blood to the entire systemic circulation and these bean veins here. Remember that we said that there were four veins that carried blood to the left atrium.

There, the pulmonary veins, of course, pulmonary means having to do with the lungs and the terminology is very simple. An artery is any vessel that carries blood from the heart, while a vein is any vessel that carries blood. blood to the heart, so since these are veins, we know that they carry blood to the heart because their pulmonary veins we can know that these are the veins that carry blood to the heart from the lungs, they are the pulmonary veins, now we move. on the right side of the heart and in the same way here there is a valve that points upward and this connects to a large arterial vessel that quickly divides in two a branch of this vessel goes to each lung because this The large vessel that leaves the right atrium is the pulmonary artery.

We know that pulmonary means that it has to do with the lungs. We know that an artery is any vessel that carries blood from the heart, therefore, the pulmonary artery is the artery that carries blood from the heart to the lungs. and we also notice that this valve points upward and this is the pulmonary valve, which is the pulmonary arterial valve, also sometimes called the semilunar valve of the pulmonary artery, so both valves are sometimes described as semilunar valves. Now here we have a valve that points downward. This way and the valve, the left atrioventricular valve, had two cusps, this one has three cusps, so I can't do this, it only has two hands, but it would be one there, one there and one under the three cusps, so is called. the tricuspid valve, so the right atrial ventricular valve is called the tricuspid valve, but out of curiosity, we can note that the aortic semilunar valve and the pulmonary semilunar valve also have three cusps, but it is this one that we call the tricuspid valve, now what?

What we need to place now is the final chamber of the heart, which is the right atrium, so here we have the right atrium and there are two large vessels that flow into the right atrium, the vessel that comes from above and drains the upper part of the body Is superior. The vessel that drains the lower part of the body here is inferior and both are known as the vena cava, so the vena cava is the largest vein in the body, the superior vena cava drains the upper half of the body and the inferior vein. cava is draining the bottom half of the bubble, both draining blood into the right atrium, so what we can do now is start to describe the flow of blood through the heart, now the blood returning from the lungs will return to the pulmonary system . veins and this blood is oxygenated and if you do an oxygen saturation test yourself you will probably find that your oxygen saturations are about 98 or 99 percent, between 96 and 100% and if you are young and fit, They place an oxygen saturation probe. on your finger you will find that it is 98%, take a few deep breaths and it will increase to 100%, which means that your lungs are completely saturating the blood passing through them with oxygen and this highly oxygenated blood containing oxyhemoglobin will return from the lungs in the four pulmonary veins towards the left atrium from here the blood will pass through the mitral valve towards the left ventricle when the left ventricle contracts that blood will be expelled through the semilunar aortic valve towards the aorta from there towards further arteries small that perfuse the entire arterial circulation system and then, as the blood circulates through the tissues of the body, it gives up some of its oxygen, not all, but some, so that when it returns from the systemic venous circulation from the upper half of the body, it will return through the superior vena cava and from the lower half of the body it will return through the inferior vena cava and this partially deoxygenated blood that traditionally in biology we draw as blue, although it is not blue, it is still tinged red and is drain again. from there the blood will pass through the tricuspid valve into the right ventricle when the right ventricle contracts, that blood will be expelled through the semilunar valve of the pulmonary artery and will go to each lung so that the blood flow through the heart is regulated by the four valves and passes through you from the atria to the ventricles and the body back to the right atrium right ventricle pulmonary artery and out to the lungs and we'll see how this happens in more detail shortly, but just before doing that.

I want to finish the anatomy so let's summarize the basic anatomy that we have so far we have the four pulmonary veins we have the superior and inferior vena cava an otter pulmonary artery left atrium right atrium left ventricle right ventricle the left atrial ventricular valve is the mitral this is the valve aortic valve or the aortic semilunar valve this is the tricuspid valve which is the right atrial ventricular valve this is the pulmonary arterial semilunar valve so that's the essential anatomy we need to know now the valves that I don't want the valves to expand or open too much, so connecting them to the valves there are tendons that are called sensitive cords or sometimes they are known by their Latin name chord e tendon e, but these days we normally call them tendinous. cords and what they are is tissue that supports the valves threads that support the valves and prevent them from returning to the Adria because the whole point of a valve is a

structure

to ensure unidirectional flow, so we want this blood to go from the atria to the ventricle, but not back, that would be regurgitated, which is a pathological situation.

So, Tim, they're very open that way so they don't back off too much and to keep them from backing off too much we have this sensitivity. The cords and these tendon cords are directed towards the wall of the heart through specialized muscles that direct the tendon cords towards the wall of the heart so that the valves cannot expand too much and these muscles that connect the tendon cords to the wall of the heart. are the papillary muscles the papillary muscles so we look at the chambers we look at the vessels we look at the valves the other thing we need to learn when we start learning about the heart is the layers of the heart now Around the outside of the heart that surrounds the whole outside there is a fibrous sinking.

This fibrous sac is very important because it provides physical protection to the heart, as well as the ribs and vertebrae in the sternum. It is made of tough fibrous tissue and it also prevents the heart from expanding too much, so it can expand so much when blood returns to it, but not expand too much, which would damage the heart, and this fibrous sac facilitates that protection and this It is round on the outside, because it is round. on the outside is the pericardium so peri means perimeter is around on the outside car diem is the heart it is the pericardium and it forms a sac in which the heart sits to protect it now it lines the inside of the heart we have a layer of squamous vascular endothelial cells , this is a very thin layer, but it goes all the way around the inside of the heart and this is very important to make sure that we have smooth blood flow because we don't want any turbulence in the blood flow through the heart, so it's a nice surface smooth squamous vascular endothelial cells and this is called endocardium endo means that in the endocardium is the inner layer of the heart and of course, as you will see, the thick muscular layer in the middle and this whole area is omitted. here the thick muscular wall of the left ventricle this part that goes up the middle the wall of the left atrium the wall of the right ventricle and the right atrium all of this contains bands of a specialized muscle called cardiac muscle it is a striated muscle in which it is arranged several bands that allow the heart to contract in the most optimal way possible and this vital muscle, of course, is the myocardium.

Myo means muscle, the heart muscle is the myocardium, so what we see is that the heart is on two sides, the left side and the right side and this structure that separates the two sides now a structure in anatomy that separates them is called septum and of course this is the heart, so that structure in the middle is the cardiac septum cardiac because it is cardiac septum because it is a tissue that divides Here we have the cardiac septum that separates the left heart from the right heart and, to put it in terms Very simply, we see that the left ventricle pumps blood to the body, which is why we very often call the left side of the heart the body's pump. the left side of the heart is the pump of the body, we see that the right ventricle pumps blood to the pulmonary artery that goes to the lungs, so the right side of the heart is the pump of the lungs, so the left is the pump of the body, the right is the lung. pump, so it is the basic anatomical structures of the heart that we need to learn and that is the patternbasic blood flow through the heart.