Anatomy of the Heart - External & Internal Structures

Summary

This educational video script delves into the anatomy of the heart, starting with blood circulation and moving on to the external and internal structures of the organ. It explains the pulmonary and systemic circulations, the heart's chambers, and the valves that regulate blood flow. The script also covers the heart's surfaces, sulci, and septa, providing a comprehensive understanding of the heart's function and structure.

Takeaways

• 💓 The heart has four chambers: right and left atrium, and right and left ventricle.
• 🔄 Blood circulation involves two main pathways: Pulmonary Circulation (heart to lungs and back) and Systemic Circulation (heart to body and back).
• 🔵 Deoxygenated blood enters the heart through the superior and inferior vena cava into the right atrium, represented in blue.
• 🔴 Oxygenated blood returns to the heart through the pulmonary veins into the left atrium, represented in red.
• 🫀 The right ventricle pumps blood to the lungs via the pulmonary valve and artery for oxygenation.
• 📍 The heart is located in the mediastinum, between the lungs, and has an apex directed forward and downwards to the left, and a base directed backward and to the right.
• 🏗️ The heart's external structure includes the Coronary Sulcus, which separates the atria from the ventricles, and the Anterior and Posterior Interventricular Sulci, which separate the ventricles.
• 🔍 The heart's internal structure includes the Interventricular Septum and Interatrial Septum, which divide the ventricles and atria, respectively.
• 🛡️ Valves such as the tricuspid, bicuspid (mitral), and aortic valves are crucial for preventing blood backflow and ensuring unidirectional flow.
• 💪 The right ventricle has a rough inner layer called Trabeculae carneae, which helps prevent blood from swirling and forming air bubbles.
• 🔑 The heart's anatomy can be understood by recognizing its external features such as the Coronary Sulcus and the sulci that separate the chambers.

Q & A

What is the primary focus of the video script?

The video script primarily focuses on explaining the anatomy of the heart, including its external and internal structures, and the blood circulation within the body.

What are the two main types of blood circulation discussed in the script?

The two main types of blood circulation discussed in the script are Pulmonary Circulation and Systemic Circulation.

How does the deoxygenated blood enter the heart according to the script?

The deoxygenated blood enters the heart through the superior and inferior vena cava into the right atrium.

What is the function of the tricuspid valve?

The tricuspid valve allows blood to flow from the right atrium to the right ventricle and prevents backflow of blood.

What is the significance of the Interventricular Septum?

The Interventricular Septum separates the two ventricles and is crucial for preventing the mixing of oxygenated and deoxygenated blood.

What is the role of the papillary muscles in the heart?

The papillary muscles are connected to the tendinous chords, which in turn attach to the valve cusps, helping to control the opening and closure of the valves.

What is the difference between the right and left ventricles in terms of their function in the blood circulation?

The right ventricle pumps blood through the pulmonary valve into the pulmonary artery for oxygenation in the lungs, while the left ventricle pumps oxygenated blood through the aortic valve into the aorta and then to the rest of the body.

What is the term used for the inner layer of the heart that helps prevent blood from swirling and forming air bubbles?

The inner layer that prevents blood from swirling and forming air bubbles is called the Trabeculae carneae.

What are the three surfaces of the heart mentioned in the script?

The three surfaces of the heart mentioned in the script are the Pulmonary Surface, the Sternocostal Surface, and the Diaphragmatic Surface.

What is the function of the sinuses in the heart?

The sinuses in the heart, such as the sinus of the pulmonary trunk, are spaces formed by the semilunar valves that help in the tight closure of the valves and prevent backflow of blood.

What is the term for the opening between the right atrium and the right ventricle, and what guards this opening?

The term for the opening between the right atrium and the right ventricle is the Right Atrioventricular Orifice, and it is guarded by the tricuspid valve.

Outlines

00:00

🧡 Introduction to Heart Anatomy and Blood Circulation

This paragraph introduces the topic of heart anatomy and sets the stage for a detailed exploration. Meditay begins by explaining the purpose of the video, which is to discuss the heart's anatomy, starting with blood circulation and moving on to external and internal structures. The heart's position in the mediastinum is highlighted, and the importance of understanding blood circulation for grasping heart anatomy is emphasized. The paragraph concludes with an overview of the two types of blood in the body: deoxygenated and oxygenated, and how they enter and exit the heart through specific chambers and valves.

05:04

🔍 Dissecting the Heart's Chambers and External Features

This section delves into the heart's external features and the chambers within. It describes the heart's position, with its apex pointing downwards and forwards, and the base connected to major vessels. The heart's surfaces are outlined, including the pulmonary surface, sternocostal surface, and diaphragmatic surface, with a note on the variability in the number of surfaces described by different sources. The paragraph also discusses the significance of external sulci in locating internal chambers and the importance of the septum in separating oxygenated and deoxygenated blood within the heart.

10:09

🔬 Detailed Examination of the Right Atrium and Ventricle

The focus shifts to the right side of the heart, detailing the anatomy of the right atrium and ventricle. The right atrium's walls are explored, including the anterior wall with the right auricle, the superior wall with the opening for the superior vena cava, the posterior wall with the inferior vena cava opening and sinus venarum, and the medial wall featuring the interatrial septum and oval fossa. The right ventricle's triangular shape is described, along with its internal structures like the tricuspid valve, papillary muscles, and trabeculae carneae. The paragraph also explains the function of the pulmonary valve and the sinuses of the pulmonary trunk.

15:10

🌐 Left Atrium and Ventricle: The Oxygenated Side of the Heart

The narrative moves to the left side of the heart, examining the left atrium and ventricle. The left atrium is characterized by its smooth walls, the interatrial septum, and the openings for the pulmonary veins. The left ventricle is described with its base featuring the left atrioventricular opening guarded by the bicuspid (mitral) valve and the aortic opening leading to the aorta. The paragraph explains the function of the mitral valve, the structure of the left ventricle, including the papillary muscles and tendinous chords, and the aortic valve's composition of three semilunar cusps. The summary concludes with an overview of the systemic and pulmonary circulation, emphasizing the heart's role in oxygenating the body's blood.

Keywords

💡Anatomy of the heart

The term 'anatomy of the heart' refers to the structural makeup and arrangement of the heart's components. In the video, this concept is central as it provides the foundation for understanding how the heart functions within the body. The script delves into the external and internal structures of the heart, including its chambers and valves, to explain the blood circulation process.

💡Blood circulation

Blood circulation is the process by which blood travels through the body, delivering oxygen and nutrients while removing carbon dioxide and waste. The script explains two types of circulation: pulmonary and systemic. It is integral to the video's theme, as it describes how deoxygenated blood returns to the heart and how oxygenated blood is distributed to the body.

💡Chambers

The heart has four chambers: the right atrium, left atrium, right ventricle, and left ventricle. The script describes each chamber's role in the circulation process. For example, the right atrium receives deoxygenated blood from the body, while the left ventricle pumps oxygenated blood to the body.

💡Valves

Valves in the heart are crucial for ensuring one-way blood flow. The script mentions several valves, such as the tricuspid, bicuspid (mitral), pulmonary, and aortic valves, each with a specific function and location within the heart's chambers. They prevent backflow and maintain the directionality of blood circulation.

💡Pulmonary Circulation

Pulmonary circulation is the pathway by which deoxygenated blood travels from the heart to the lungs to receive oxygen. The script explains that this circulation is 'small' because it is a self-contained circuit, involving the right side of the heart and the lungs. It is a key part of the overall blood circulation process described in the video.

💡Systemic Circulation

Systemic circulation is the process where oxygenated blood is pumped from the heart to the rest of the body and then returns deoxygenated to the heart. The script describes this as the 'major circulation' and contrasts it with pulmonary circulation, highlighting the difference in the types of blood contained in arteries and veins during this process.

💡Septum

The septum of the heart is a wall that separates the right and left sides of the heart. The script explains the importance of the septum in preventing the mixing of oxygenated and deoxygenated blood. It also differentiates between the interventricular and interatrial septa, which separate the ventricles and atria, respectively.

💡Pectinate Muscle

Pectinate muscles are found in the atria of the heart and are characterized by their striated muscle fibers. The script mentions these muscles in the context of the right atrium, explaining their role in contracting to push blood towards the ventricles, which is essential for the atrial function in circulation.

💡Trabeculae carneae

Trabeculae carneae are internal structures within the ventricles that help prevent blood from swirling and forming air bubbles. The script describes these as essential for maintaining efficient blood flow and preventing potential air embolisms when blood enters the heart with high velocity.

💡Sinus

In the context of the heart, sinus refers to a dilation or a space that forms part of the cardiac structure. The script mentions the sinus of the pulmonary trunk and the aortic sinuses, which are spaces behind the semilunar valves of the pulmonary and aortic valves, respectively. These sinuses are important for the functioning of the heart valves.

💡Endocardium

The endocardium is the innermost layer of the heart, lining the chambers and covering the valves. The script mentions that the cusps of the heart valves, such as the mitral and aortic valves, are formed by a double layer of endocardium, which is crucial for the valves' structure and function.

Highlights

Introduction to the anatomy of the heart and its importance for understanding blood circulation.

Explanation of the heart's location in the mediastinum and its connection to the great vessels.

Overview of the blood circulation pathways, distinguishing between deoxygenated and oxygenated blood.

Description of the Pulmonary Circulation, detailing the process of oxygen exchange in the lungs.

Clarification of the Systemic Circulation, explaining how blood is pumped from the heart to the body and back.

Unique feature of pulmonary circulation where arteries carry deoxygenated blood and veins carry oxygenated blood.

Identification of the heart's apex and base, and their respective positions and connections.

Discussion on the heart's surfaces, including the Pulmonary Surface, Sternocostal Surface, and Diaphragmatic Surface.

Importance of the Coronary Sulcus in distinguishing between the ventricles and atria.

Exploration of the Interventricular and Interatrial Septa, their roles in separating heart chambers.

Detailed anatomy of the right atrium, including its walls and the function of the pectinate muscles.

Description of the right atrium's medial wall, featuring the oval fossa and the coronary sinus.

Explanation of the tricuspid valve's structure and function in preventing backflow of blood.

Anatomy of the right ventricle, highlighting the trabeculae carneae and their role in blood flow.

Function of the pulmonary valve and its similarity to the aortic valve in structure.

Introduction to the left atrium, its position, and the significance of the pulmonary veins.

Detailed look at the left ventricle, including the mitral valve and aortic valve.

Concluding remarks and anticipation for the next video covering the heart wall layers and conducting system.

Transcripts

Hey, What's up. Meditay here. Let's talk  about the anatomy of the heart. In this video,  

We're first going to look at how  the blood circulates in the body.  

After that, we're going to cover the different  external structures you'll find on the surface  

of the heart. Then we're going to open up the  heart and go through the internal structures of  

each chamber, which include the right and  left atrium and the right and left ventricles. 

Then in the next video, we'll talk  about the layers of the heart's wall,  

the conducting system, and then the topography. Now, let's start with the circulation. 

So here is see the anterior  view of the thorax, right? 

If you remove the sternum and the rib  cartilage, you'll be able to see the heart  

right here. The heart lies between the pleura of  the lungs in an area called the mediastinum. Now,  

let’s go ahead and pull the heart out. So  before we talk about the heart's anatomy,  

I wanna first take you through the general  layout of the blood circulation in the body.  

Once you understand the concept of how the blood  circulates in the body, you'll be able to learn  

the anatomy of the heart much more efficiently. Ok. Throughout your body, your blood will either  

be deoxygenated, meaning it lacks oxygen.  And Oxygenated blood that has oxygen. 

We’re going to start with the heart receiving  deoxygenated blood from the body. So the body  

has collected the oxygen, and it's sending the  blood back towards the heart. The blood will  

enter the heart through the superior and  inferior vena cava into the first chamber  

which is the right atrium. So the color  blue will represent deoxygenated blood. 

The blood is then going to go through the  tricuspid valve into the right ventricle. The  

right ventricle is then going to pump the blood  through the pulmonary valve and then into the  

pulmonary artery, which is then going to pump the  blood to the lungs to exchange CO2 with Oxygen. 

And when this is done, blood will come back into  the heart with oxygen, so the blood is oxygenated,  

now represented in red. And they will come back  through the pulmonary veins into the left atrium. 

The circulation where the blood goes  from the heart to the lungs and back  

is called Pulmonary Circulation or the small  circulation since it’s a circuit on its own. 

Now, the left atrium will send the blood through  the bicuspid valve towards the left ventricle. And  

when the left ventricle pump, it'll send the blood  through the aortic valve where it's eventually  

going in end up in the aorta and then back to the  body again. So the circulation in which the left  

ventricle pumps blood to the body, and the body  sends the blood back into the heart is called the  

Systemic Circulation, or the major circulation. And notice that in the pulmonary circulation,  

Arteries contain blood without oxygen, and veins  contain blood with oxygen. Opposite from the  

systemic circulation, where arteries contain blood  with oxygen and veins contain deoxygenated blood. 

Awesome. Let's finally start  with the actual anatomy. 

So if we turn this picture to  the side, you’ll be able to see  

a pointy end called the Apex of the Heart, Which  is directed forward and downwards to the left. 

And then if we turn the heart around and look  at the backside. We can see the heart's base,  

or basis cordis, directed backward and a little  to the right. The base is connected with the  

great vessels you see here. So an apex and a base. Now the heart has three surfaces; it has Pulmonary  

Surface, towards the left lung, as you see here. And then, we also have the Sternocostal Surface  

directed towards the inner surface of  the ribs and the perfectly drawn sternum. 

And then, we have the Diaphragmatic Surface  towards the central tendinous part of the  

diaphragm. Some sources say there are  5 surfaces on the heart. Counting the  

right pulmonary surface and the base as  two other surfaces, so sources may vary. 

Let's now take a closer look at the  surface. The only margin that the heart has  

is the right margin or the right border,  which lies between the Sternocostal Surface  

and the Diaphragmatic Surface. One cool thing in knowing the  

external structures of the heart is that you’re  actually able to know exactly where the inner  

chambers are based on the external structures. And I’ll show you how. First, we have the Coronary  

Sulcus, which separates the ventricles from the  Atria. This sulcus goes around, and here you  

see the posterior aspect of the heart again. The  Coronary Sulcus goes all the way around like this  

separating the right and left atrium  from the right and left ventricles. 

Another sulcus you’ll be able to see is  the Anterior Interventricular Sulcus.  

This sulcus continues posteriorly as  the posterior interventricular sulcus,  

and it separates the right ventricle  from the left ventricles externally. 

Now. Let’s take the heart and give it a  good slice, then remove the upper half,  

and look at it from this perspective.  You’ll see that it looks like this. 

So we have this wall called the Septum of the  Heart separating the right side of the heart  

from the heart's left side. And it's crucial to  have this wall because remember the right side of  

the heart contains blood without oxygen, while the  left side of the heart contains blood with oxygen,  

and you really don't mix those up,  so it’s good to have this wall. 

Alright, so we divide this wall into two parts.  We first have the Interventricular Septum,  

separating the two ventricles. And we have the  Interatrial Septum, separating the two atria. 

Now the Interventricular septum can be further  subdivided into two parts. We have the muscularis  

part down here since, in this area, the muscles  are packed together. And up here is the membranous  

part, since this is the area where the valves are. So that's mainly the general structures we have  

on the external heart. Now, let's look  detailed into the different chambers. 

We'll start with the right atrium. So here you  see the anterior lateral view of the heart.  

And the right atrium is located right about here  inside this area. In order to understand the full  

anatomy of the right atrium, we need to go through  all six walls of it. So let’s work our way through  

this list, starting with the Anterior Wall. So the Anterior Wall is right here,  

and it consists of the Right Auricle. The  Right Auricle is a small muscle pouch,  

and this is where the Anterior and Lateral Wall  has something in common. Both have this muscle  

layer called Pectinate Muscle. As you see here,  the pectinate muscle consists of striated muscle  

fibers, which help contract the right atrium to  push the blood further into the right ventricle. 

That's the anterior and lateral  walls so let's check them. 

Now, let’s go ahead and remove the lateral  and the anterior wall to look inside the  

right atrium. Here we can see a little bit of  pectinate muscle we mentioned earlier. Now,  

if you look at the superior wall, the superior  wall has an opening for the Superior Vena cava.  

So That's mainly the superior wall. On the posterior wall,  

we can find the opening for the inferior vena  cava. Remember, the heart is tilted forward,  

and because it’s tilted forward, the inferior  vena cava becomes part of the posterior wall. 

Another thing you’ll find  in the posterior wall is,  

You know, anteriorly, you have the rough  pectinati muscle, right? But posteriorly,  

between the opening for the superior and inferior  vena cava, we have a wall called the Sinus of Vena  

Cava or the sinus venarum. This had a function  during embryonic development, but now it forms the  

area for the SA node, for the conductive system. Now, there's a line that separates the pectinate  

muscle and the sinus venarum. If we look  at the outside of the lateral wall again,  

we have a crest called the terminal crest  that separates the transition between the  

pectinate muscle and the sinus venarum. So that's mainly how we can distinguish  

where the sinus venarum is and  where the pectinate muscle ends. 

On the posterior wall, we can also see a  valve. And this valve is called the valve  

for the inferior vena cava. It’s considered  an embryonic valve that, during fetal life,  

the blood went directly from the inferior vena  cava to a hole on the medial wall, which is now  

called the Oval Fossa. The blood went directly  from the right atrium to the left atrium since the  

fetus doesn’t need pulmonary circulation because  they get their oxygen through the placenta. But in  

adults, the valve remains, it’s still there, but  it remains as small folds on the posterior medial  

wall, which is that ridge you see here. So that is the posterior wall.  

Now let’s do the medial wall. Remember, the  medial wall is made up of the septum between  

the right and left atria. Called the Interatrial  Septum. On this septum, that’s where you'll find  

the oval fossa. And Around the oval fossa,  you’ll see that it’s bordered by an elevation  

called border of oval fossa, also  referred to as the limbus of oval fossa. 

Another thing you’ll find here is an opening  for the coronary sinus, which lies between the  

medial and posterior wall. This is the opening  of the main vein draining blood from the heart. 

And this opening is guarded by a valve  called The Valve for the coronary sinus.  

Which is really just a fold covering it. So on the medial wall of the heart,  

you will also find very small openings returning  blood directly from the layers of the heart's wall  

called the openings of the smallest cardiac veins. So that's mainly the structures on the medial  

wall. Now lastly, we have an inferior wall. And  to see this one, we need to slightly change the  

angle, as you see here. Now you’re able to see an  opening called the right atrioventricular orifice  

or opening. That's the opening between the right  atrium and the right ventricle. And this opening  

is guarded by a tricuspid valve, which prevents  the backflow of the blood. It's called a tricuspid  

valve because it has three cusps or three  leaflets. So if we zoom in on it, you'll see three  

cusps right here—just a quick way to remember  that the tricuspid valve lies on the right side.  

The name tricuspid valve has the letters "R" "I,"  which resembles the word right, so the tricuspid  

valve is on the right side. And it consists of  the anterior, posterior, and the septal cusps 

So that is the inferior wall. Now, let's look  at the right ventricle. So the right ventricle  

has a triangle shape, as you see here.  Now on the base of the right ventricle,  

you'll find the Right Atrioventricular Opening,  which is the opening between the right atrium  

and ventricle. Another opening you'll find  is the Opening for the Pulmonary Trunk. 

Now, If you look within the actual ventricle,  you'll see a rough inner layer, right? 

And most of that rough inner layer is called  Trabeculae carneae. The Trabeculae are essential  

because they prevent the blood from swirling  around cuz remember, when the blood enters  

the heart, it enters with high velocity.  And by having this rough inner layer,  

you actually prevent the blood from getting  air bubbles as they reach a sudden break  

which could cause a potential air embolism And here, you can also find papillary muscles,  

just like in the atria. Their function is  connected to the tricuspid valve. So this  

valve again guards the right atrioventricular  opening and has three cusps or leaflets, as I  

mentioned earlier. It has the anterior cusp right  here, and it has a posterior cusp and has a septal  

cusp towards the ventricular septum. That's a  septum that divides the right and left ventricle. 

These cusps, including all other cusps, are  formed by the endocardium. We’ll talk more about  

that in the next video but keep that in mind. The opening is also surrounded by a fibrous ring  

that supports the valve and functions as  an attachment point for these three cusps. 

So each cusp has 3 margins. One margin of  each cusp is attached to the fibrous ring.  

And the other two margins are attached to the  Tendinous Chords, which are cords of fibers  

that attach the cusps to the papillary muscles,  which control the valves' opening and closure.  

And then up here, we have something called the  pulmonary valve, which has 3 semilunar cusps. 

And these, just like the tricuspid  valve, are formed by a double layer  

of the endocardium. If you’re unsure what  endocardium is, that's no problem. For now,  

just know that the endocardium form these cusps. The pulmonary valve also has a fibrous ring around  

where the base of the semilunar cusps are attached  to. While the free margins are directed upwards  

into the pulmonary artery, as you see here. The pulmonary cusps have a free margin,  

as you see here, so they differ from the tricuspid  valve. There’s a nodule in the center of the free  

borders called Nodules of the semilunar valve,  which provides a tight closure of the valves. 

And so here we can see another structure  Between the semilunar valves and the walls of  

the pulmonary artery. We can see the sinuses  called the sinus of the pulmonary trunk.  

The pulmonary trunk is just another name for the  pulmonary artery, and this sinus is basically just  

a space here that the cusps form. Here's another  picture just to visualize it. You can see the 3  

semilunar cusp down here, and you have a nodule  in the middle which helps with the tight closure,  

and the space or the depression behind  it's called the pulmonary sinus. 

So that was the anatomy of the right side of the  heart. Here again, you get the blood coming from  

the body into the right atrium. From the right  atrium, blood goes through the tricuspid valve,  

as you see here, into the right ventricle. Then  the blood continues up through the pulmonary  

valve into the pulmonary artery. Which goes to  the lungs, where it gets oxygenated, and then  

the oxygenated blood goes into the left atrium. So now, let's have a look at the walls of  

the left atrium. Remember, the left atrium  lies on the other side of the right atrium. 

Let’s repeat something first. So here  you see an anterior view of the heart,  

where you’ll be able to see the right atrium  again. Remember, the anterior wall of the  

right atrium consists of the right auricle. But  if you turn the heart so that we're looking at  

the posterior lateral surface. We can see that the  anterior wall here is made up of the left auricle,  

which remember is a muscle pouch  containing pectinate muscle.  

And back here, we can find 4 blood vessels  on the posterior wall where oxygenated blood  

from the lungs comes in. These blood vessels  are called Pulmonary veins. So the posterior  

wall of the left atrium has four openings,  called the Openings of the Pulmonary Veins. 

Alright, so let's open up the walls and look at  the inside. You can see that the medial wall is  

the Interatrial Septum, which, as you know,  separates both Atria. And then, anteriorly,  

you'll find the opening, which leads into the  left ventricle, The Left Atrioventricular Opening. 

And this opening is also guarded by a valve called  the bicuspid valve, or you can also use the term  

mitral valve. So that was all for the left  atrium, now. Let's look at the left ventricle. 

Here you see the left ventricle with the mitral  valve. And if we tilt it a little bit in this  

direction, you will see one more valve. So let's  now talk about the base of the left ventricle.  

From these two angles, we're able to  see the Left Atrioventricular Opening,  

where blood from the left atrium comes in, and  the Aortic Opening, which leads into the aorta.  

Let's now do the Left Atrioventricular opening  first and then do the Aortic Opening. Here you see  

the Left Atrioventricular Opening again, and it's  guarded by the bicuspid valve or the mitral valve. 

And you know, just like the other valves, it  has a fibrous ring around that the cusps are  

attached to. Now since it’s called Bicuspid valve,  it means that this valve consists of two leaflets.  

One is called the Anterior Cusp,  and one is called Posterior Cusp.  

But regardless of the name, there're actually  several small cusps located in between them. 

So here we have the bicuspid valve. Here's  the anterior cusp and here the posterior cusp.  

And these small cusps right here, these are  called commissural cusps, Which are very small  

cusps that support the valve. Now If you look  closely at the surface of the left ventricle,  

you'll notice that it more or less has the  same structures as the right ventricle. 

There's the Trabecula Carneae for the blood  flow. And here we have Papillary Muscles,  

which remember are attached to the Tendinous  Chords. So the Tendinous Chords bind the  

cusps of the mitral valve onto the papillary  muscles. So when the papillary muscles contract,  

they open up the mitral valve. Now, let’s turn the heart in this direction so  

that we can see the aortic opening. This region  that leads into the aortic opening is called  

the Aortic Vestibule inside the left ventricle. So this opening is guarded by the Aortic Valva,  

which is made up of three semilunar cusps, very  similar to the pulmonary valve. Here we’ll find  

three semilunar cusps, but this time, they’re  called the Right semilunar cusp, the posterior  

semilunar cusp, and the Left semilunar cusp.  So right posterior left. They also have  

nodules that help close the valve tightly. We  also have 3 aortic sinuses here on the top,  

which remember are just a depression  formed by the semilunar valve. 

Awesome. So now we have gone  through the pulmonary circulation,  

which pumps oxygenated blood into the left atrium.  The left atrium will now pump the blood through  

the bicuspid valve into the left ventricle,  which will pump blood through the aortic valve  

into the Aorta. And then to the rest of the body. I really hope you found this video helpful. If it  

did, please like, comment, share. Now in the next  video, we'll look at the layers of the heart wall,  

the conducting system, and then  the topography of the heart.