The cardiovascular system consists of the heart and blood vessels.

The heart consists of three layers: Epicardium (the outer layer), Myocardium (the middle muscular layer), Endocardium (the inner layer).

Hello, how are you my dear? How are you all? Happy new year.

God willing, today we will start the first lectures of the semester, hopefully the topic will be easy and simple.

We will start with the first system called the Cardiovascular System.

Which is the circulatory system consisting of the heart and blood vessels.

Okay, let's see together the first thing regarding the Structure.

The Histological Structure of the Heart.

Okay, first thing, the Heart is what? The Heart is the قلب.

Okay? So we will talk about the structure of the heart.

We know that the cardiovascular system is what?

It consists of the heart and the blood vessels responsible for pumping blood.

Okay, let's see what the shape of the heart is.

Okay, first this is the shape of the heart here.

When we take a section and look at it with the naked eye, its shape.

The histological structure from outside consists of 3 layers.

The word layer means layer, we know what the word layer means?

It means layer.

Or its other Latin name is what?

Tonica.

Its name is layer or what? Tonica.

So let's see together.

The structure of the heart.

It consists of 3 layers.

What are their names?

3 tonica.

So the word tonica means layer.

Okay, let's look together at these layers.

Here are the 3 layers.

Here is the outermost layer.

And the middle layer.

And the inner layer.

Okay, let's imagine we have a heart.

Surely you have seen the heart before of any animal or a frog.

Of any living creature we have seen.

Okay, what is it made of?

It consists of the outermost layer.

The middle layer Myocardium is a thick muscular layer responsible for heart contraction and pumping blood.

The inner layer Endocardium consists of endothelium and connective tissue and contains structures like trabeculae carneae.

The outer layer of the heart is called Epicardium and consists of two layers: simple squamous epithelium and loose connective tissue.

Which is called around or something like that, called epi.

The word epi means above.

So the word epicardium.

The word heart means what?

Cardio.

Like the word cardiovascular system.

So we find the first layer is called what?

Epicardium.

Then the whole heart is made of muscles so it can contract and pump blood.

So the second layer is called mayo meaning muscle.

Myocardium means the muscle of the heart.

And then the inner layer is always called endo.

So the inner layer is called endocardium.

Let's look again, so what is our heart?

When I look at it from outside to inside, the first outer layer is called what?

Epi means around, Cardium means around the heart.

Around the heart is called Epicardium.

Look at the second layer, what is it called?

Myocardium which is this muscle we are pointing at, which is called what?

Myocardium.

And the innermost layer is called what?

Endocardium.

Its name is Endocardium.

So Epi, Mayo, Endo again.

Epi, Mayo, Endo Cardium.

Let's look at the epicardium, it consists of two layers.

It consists of layers.

We will explain everything on this figure.

Because later there will be many things we will encounter in the slides.

We will just flip it like this.

And we will understand the first thing.

Meaning when it repeats with us we will memorize it.

So again, let's go.

The outer layer is epicardium.

The next one is called myocardium.

The one beneath it is called endocardium.

Of course, I want you to be smart and look at the epicardium.

Here is the epicardium, I will draw a circle on it like this.

Tell me, do you see the epicardium.

Is it all one layer or is there a red color.

Above and below is yellow color.

Do you see two layers in a line from above.

The red line is completely red and below its color.

Yellow, the red line is called what? Epithelium.

Its name is epithelium, type simple squamous.

Simple squamous means very thin epithelium, a layer as we see here.

What is beneath it? Beneath it is connective tissue.

Loose connective tissue.

So let's explain again.

How many layers do we have in the heart? 3.

3 layers means what? Tonica, so it consists of 3 tonica.

The outer one is called what? Epicardium.

The next one is called myocardium.

And the inner one is called what? Endocardium.

Let's see, is this layer one? No, it is two layers.

The other line is called simple squamous epithelium.

Beneath it is connective tissue called loose connective tissue.

This muscle is called myocardium.

This is myocardium.

This is myocardium.

And this is endocardium.

It shows trabeculae.

Meaning folds like this.

Okay.

Let's see the myocardium.

Look at the layers and tell me which is the thickest layer in the heart.

Of course from the muscles.

Because the heart will do conduction.

And pump blood, so naturally we.

Need the muscles to be.

Thick and able.

To do conduction.

And at the same time do conduction.

So that the blood reaches the rest of the body.

All good, so what are these.

The three we said, come on who can say their names with me?

Epicardium, myocardium, endocardium. Okay? And the cardiac.

That we said. Is there anything else? Yes. There is something called.

Fibers. Who are the fibers? Tell me, when I contract each.

Cell contracts alone or must when I contract all act as one unit.

So all the blood comes out at once. Right? Logical, what will it do? It will act as.

The fibers responsible for conducting electrical signals in the heart are called Purkinje fibers and help coordinate the heart's contraction as a single unit.

The heart contains valves that allow blood to pass from one part to another without backflow.

One unit, so there are fibers that talk to each other as if, for example, we all want in one class.

Okay, here is the class which is the cardiac muscle fibers.

We all want to stand up at the same time, so we organize together.

I tell the one next to me and the one next to him tells the next, and we all coordinate that we all say come on guys let's stand up at the same time.

So I need to talk to the one next to me, so I talk to him through fibers called what?

The Purkinje fibers, these are cells responsible for conduction, as if I reach the neighbor and gently pinch him, I talk to him on the phone, I send him a message, so these are the Purkinje fibers, okay?

Is there something called valve? What is the valve called? Dead? So now I have the heart which is what? This is the heart here.

Okay.

The upper part is called the atrium.

And the lower ones are called ventricles.

The atrium is called what?

Atrium.

And the lower is called what?

Ventricle.

And the lower is called what? Ventricle.

Blood is transferred from here.

To here normally or must it pass through.

Valves.

Let's continue.

We said what? This is the shape.

Of the heart here.

And we said the upper atrium is called what? Atrium and the upper is called what? Ventricle.

Is it possible to transfer blood from top to bottom or must it pass through valves? The valves are called what? Valve.

So again, let's say together the heart has three layers called epicardium, then myocardium, then endocardium.

To talk to each other we talk through fibers called what? Purkinje fibers.

We must have valves called what? Valves.

Okay, these are the objectives we must know by the end of the semester at the end of this lecture.

And we will review together these things again.

Okay, again, who can tell me what the word tonica means?

Tonica means layer, right? Tonica means what?

Tonica means layer and how many layers do I have in the heart? 3.

What are their names? Endocardium.

And myocardium and epicardium.

Come on, who remembers and tells me.

Who is the most outer one?

Who is the outermost, the Epi or the Endo?

The epicardium is the outermost.

So when I arrange them from outside.

The first one is the Epi.

Who is the middle one? Myocardium.

And who is the innermost? Endo.

Endo, I remember that Endo is.

The innermost.

Okay, we want to see the cardiac muscle.

By Electron and Light Microscope.

Who else can tell me who are the Purkinje fibers?

They are the fibers responsible for us talking to each other.

We are all sitting in the same class.

And I want.

To tell the whole group, come on guys.

Let's stand up at the same time, so what will we do?

We will do signals.

Who are our signals? Which fibers carry the message?

The Purkinje fibers.

We will all give signals.

That everyone will act at the same time.

Purkinje fibers

We will all give signals

That it will all work at the same time

These are called Purkinje fibers

And the cardiac muscle injury

We will also talk about it

And we will talk about the valves

What are these valves? Which means what? The word valve means semilunar valve

The word valve means the semilunar valves when I transfer blood

From one place to another, it's not open to the sea

I must pass through a gate, what is the gate?

What is its name? Its name is the valve or the semilunar valves

Okay, let's start together

With the orientation

Of the heart and cardiovascular system

Let's go

The cardiovascular system is

What is it made of? Who will say with me?

The cardiovascular system is

The circulatory system which consists

Of the heart and blood vessels

What does heart mean? The word heart

Means heart, right?

And the blood vessels are

The blood vessels. So what are the blood vessels?

They are the arteries and veins

And the capillaries. The arteries

Are the arteries

The veins are the veins

And the capillaries are the capillaries

Arteries, veins, and capillaries

Okay, how many layers does the heart have, my dear?

3 layers

Or what is the other name?

Tunica

How many tunics? Come on, tell me

3

The outermost tunic is called Epi or Endo?

Epi

That's right, so

Epi is the very first one from outside

Do you know what the intron people tell you?

Pericardium

Pericardium is the thin transparent layer that covers the heart from above

So pericardium or part of it is called pericardium

Do you remember the epicardium was two layers, a red line, simple squamous epithelium and under it loose connective tissue

Okay, who will enter for me the epi or the mayo or the endo?

Myo to endo. The mayo is the muscles. I want to contract or squeeze to push the blood from the atrium to the ventricle

Okay, who is the innermost called? Endocardium

What does the word valve mean? It means semilunar valves or gates

I will not transfer from one place to another except by passing through the gate

Okay, and there is the conductive system which is the system by which I transfer through a group of points, like gathering points

Come on guys, let's move from place to place and we explain it in detail

Okay, now we have explained this picture, of course people should answer for themselves

The outer layer Epicardium is also known as the Visceral pericardium and contains adipose tissue.

The inner layer Endocardium contains blood vessels and nerves in addition to Purkinje fibers that transmit electrical signals.

This is the body, it consists of three tunics

The other tunics are called

Epicardium chatrine

And the other is mayo

And the other is called endo

Anteriorly, also

These are the other uses

Under it mayo

And under it endo

From above, it consists of

The other uses

Called visceral pericardium

From below, the red full of muscles

Mayo

And the other is called

Endocardium

You see it shows lobes, right?

Okay, look at the epicardium and tell me how many layers?

Two, the red color on top is called simple squamous epithelium

And under it the yellow is loose connective tissue

Let's read, come on now no one stands still

So the epi is the one that goes outward, it is the outer

Who is in the middle? The mayo

And this is a thick middle layer

And who is underneath? The endo is the most inner, it lines the cavity

Is that correct?

Okay, who will tell me what the epi consists of?

2 layers here

Epithelium called simple squamous epithelium

Simple squamous epithelium under it connective tissue which is the loose connective tissue

Why is it yellow?

What is yellow in our body?

Fat

There is adipose tissue in the epicardium

And this is the place where fat is

There is no fat in the middle layer to contract

There is no fat here

Fat is present in the epicardium

Okay?

The trabeculae carneae come from which layer of the endocardium?

Come again quickly

The layer means tunica

I have three tunics

Epicardium, myocardium, and endocardium

The epi 2

Simple squamous epithelium under rose connective tissue

The myocardium is this layer

And the endocardium is the layer under which the trabeculae carneae come out

Come on, give the tunics of the heart, what are their names?

Epi, myo, endo

Okay, quick questions: which is the most outer one called?

It is called epicardium or visceral pericardium

Okay, which is the inner layer called?

Myocardium

Okay, which is the innermost called?

So it is epi, myo, endocardium. I think it's very simple, right?

Let's explain together, tell me number three, what is its name? Epi

Not peri nor endo? Its name is what from its name?

Like this? It is endothelium. It is endothelium, meaning endo

And it places endocardium also under the endocardium

And it places endocardium also under the endocardium

Any connective tissue will have blood vessels and nerves

Blood vessels and nerves

There are fibers very very important called Purkinje fibers

They are called Purkinje fibers

Secondly, we said I have three layers

Epicardium, myo, and endo

This is endocardium here

Endocardium consists of endothelium and under it connective tissue

Endothelium is simple squamous and under it connective tissue

The stuff here will be inside blood vessels and nerves and

Fibers called what?

Purkinje fibers. Do you remember the Purkinje fibers while we were sitting in class?

And we all agreed to stand at the same time, so we brought fibers

Called Purkinje fibers and we told them, come on dear, connect the message, transfer

From me to you, to you. So what are the Purkinje fibers? They are conductive

What does conductive mean? It means the ones that transfer the message, meaning the ones that will tell

They will tell us, guys, transfer from place to place

They will transfer the signal from place to place

So endocardium consists of endothelium under it connective tissue

And there are very important fibers in the endocardium

Fibers, fibers, Purkinje fibers, Purkinje fibers, Purkinje fibers

Do you see them surrounded by a capsule or sheath?

Yes, so the Purkinje fibers are a group of fibers

Surrounded together by a capsule or connective tissue sheath

Grouped together by a capsule or connective tissue sheath

Let's focus the image after that

The muscle cells in the atrium are called Atrial myocytes and secrete the hormone Atrial Natriuretic Factor (ANF) which regulates blood pressure by affecting sodium reabsorption in the kidneys.

ANF works to regulate blood pressure by controlling sodium and water in the body through the kidneys.

The muscles in the Myocardium are organized in an interwoven manner to allow strong and efficient contraction for pumping blood.

Secondly, what are the uses of the myocardium?

Can you tell me a word about it? Is the myocardium a thick layer or a thick layer?

It is a thick layer, it is the inner layer in the heart and one of the most needed for us to do contraction

So I must put many muscles, so the myocardium is the middle layer

It is the thick layer, the thickest layer of the heart

Okay, it is in the middle between the outer? The epicardium and the inner? The endocardium

So the myocardium is the cardiac muscle fibers

The cells of the myocardium as we said

The one above is called what? What is atrium?

Which is the atrium

The one below is called what? Ventricle

Which is the ventricle

The one in the middle between them is called what? It is called valve

Atrium

Ventricle and there is a valve between them or called moot

The cell here is called atrial myocytes

And the cell here is called ventricular myocytes

Meaning there are cells here that contract to push the blood here

There are cells here that contract to push blood to the whole body

Right? Okay

The cell in the atrium is called atrial myocytes

Myo means muscle

Cyte means cell

The cell in the atrium produces a substance called atrial

From its name natriuretic factor

Very important

Atrial natriuretic factor

ANF

ANF is a very important hormone that regulates our blood pressure

Blood pressure by doing

Sodium reabsorption

Sodium works on sodium reabsorption

So we remember from its name

ANF

Atrial natriuretic factor

It works on the Kidney

Regarding the Sodium which is NA

Okay?

That's why it's called

Atrial Natriuretic Factor

It works on the sodium which is

the NA present in

the body

So again

The myocardium is the thickest layer

It is the layer present in the middle

The cells of the atrium are called atrial myocytes

And those of the ventricle are called ventricle myocytes

These fibers

secrete a substance called atrial

natriuretic factor

This atrial natriuretic factor regulates

blood pressure by

acting on sodium

Look at the shape of the cells

and tell me

Do you want the myocardium to be

a thick layer or a thin layer?

We said it should be a thick layer, why? Because it's a thick layer

to start doing what?

to pump blood

So the first information is that it is

the conductor

Secondly, do you want this conductor

to be arranged in an organized way

or do you want it to be tangled in multiple directions

to give

meaning, do you want it to be all

in one direction

or do you want it to be tangled in multiple directions?

Naturally, it should be tangled

Why do I want it to be tangled?

So it can make a powerful contraction

and pump blood to the whole body

Right?

Okay, there are certain fibers I mentioned

present in the endocardium

and I said they are very important for conduction, transmitting the signal

that will transmit the signal from one place to another

What are they called?

So when I describe the conductor

Don't forget there are certain fibers

called what?

So again

The atrial natriuretic factor (ANF) is a substance secreted by myocytes in the atrium and works to regulate blood pressure by controlling sodium and water secretion from the kidneys.

The heart contains three main layers: epicardium on the outside, myocardium in the middle, and endocardium on the inside, where the epicardium contains simple squamous epithelium and loose connective tissue with adipose tissue that gives it a yellow color.

Come on, who can tell me the atrial natriuretic factor?

Who remembers which cells it comes from? From its name, atrial, atrial, huh?

So it comes from where? From the atrium, from the atrial myocytes

What does it work on starting with the letter N, huh?

It works on sodium through the kidney, it controls sodium through the kidney to regulate blood pressure

So this natriuretic factor is produced by the atrial myocytes

which are the atrial muscle fibers, it regulates blood pressure through the kidney

It works on what starting with the letter N, yes

It works on sodium and water

And it is secreted from the atrium, not from the ventricle

It is secreted from the atrium, not from the ventricle

Okay again, my dear, we said we have how many layers? Three

The outermost is called epicardium

The one in the middle is called myocardium

The innermost is called endocardium

Outside the epicardium was composed of

simple squamous epithelium

and beneath it loose connective tissue

The conductor was very thick

In the atrium, a substance called ANF is secreted

atrial natriuretic factor

Don't forget it works on the kidney

It regulates blood pressure

by regulating sodium and water

It causes their excretion

So it controls the volume

How is pressure regulated through the kidney, sodium, and water?

Excretion means it throws them into the urine

Okay, what is the outer layer called?

Epicardium is the outer layer

Epicardium or its other name

visceral pericardium and this is the outermost

Okay, let's summarize how we described it

You should hear it now

It consists of an outer layer called

simple squamous epithelium and beneath it

loose connective tissue

simple squamous epithelium and loose connective tissue

Who can tell me why its color is yellow?

Because it contains

adipose tissue

What does the word adipose tissue mean?

It means fat

The word adipose tissue means fat or

healthy fat

So it is loose connective tissue

Of course, it contains collagen fibers

It contains simple squamous epithelium

It carries blood vessels and nerves

And its color is yellow because of adipose tissue

Okay

Now look at this picture quickly

Look at it quickly with me

The outer tunica is called

epicardium, beneath it is called

myocardium, and the innermost

is called endocardium

The epicardium has two layers of simple squamous

epithelium and loose connective tissue beneath it

Its color is yellow because it contains fat

Beneath it is the myocardium

Is it thin or thick? Thick layer

Okay, these conductors in the atrium secrete a substance called

atrial natriuretic factor

It moves water through sodium and the endocardium

It contains somas and the endocardium contains water cream

It contains epithelium or endothelium and contains water cream

Okay, now let's see the three tunics present which are the epicardium, myocardium, and endocardium

The epicardium is the outermost and consists of simple squamous epithelium and beneath it loose connective tissue with blood vessels and nerves, its color is yellow because of adipose tissue

The myocardium is the muscle present in the atrium called Atrial Natriuretic Factor which produces EMF

The endocardium is the innermost and consists of endothelium and beneath it connective tissue

Don't forget there are very important fibers called Purkinje fibers

The Purkinje fibers are special fibers in the heart that transmit electrical signals between cells to make the heart contract as one unit.

The intercalated discs are ladder-like structures that connect cardiac muscle cells together to allow rapid transmission of electrical signals, making the heart work as a synchronized unit (syncytium).

Who can tell me what these Purkinje fibers are?

They transmit the signal

They transmit to me and to my neighbor and to the neighbor next to us all so that we contract as one unit

Now let's see what cardiac muscle fibers look like under the light microscope and electron microscope

And the discs present which is very important, I want to tell you now

I am now part of the heart

And I am one cell and I am another cell

Do you want each one to contract alone or do we contract as one unit to give a powerful contraction?

We said we contract all together at the same time as one unit to give a powerful contraction

So we said we communicate by signal, right?

And that's why I had important fibers called what? These fibers are

called Purkinje Fibers

So when I describe, I can't not describe

the Purkinje Fibers, right?

So I need the Purkinje Fibers

Okay, there is also something else, yes

There is a ladder

The intercalated disc is like a ladder

Quickly, quickly transmit the signal from one to another

I transmit

This intercalated disc is a ladder

I want the ladder

To transmit from one cell to another

So this is called the intercalated disc

It makes the heart

contract as one unit

as one unit

One

One

It makes a network called

sensitive

It makes a network called sensitive

Okay again

So when I look here

At this slide only

I will explain to you the units

The intercalated disc

The ladder

The intercalated disc

Or this ladder consists of what?

That all the cells

communicate with each other by signal

So that

I and they all contract as one unit

So I communicate with each other through the ladder

Which you call the intercalated disc

It makes the heart work as one unit

The word one unit or unit by unit

Or as if we are holding hands together

What is this called?

Syncytium or network

What is it called?

Syncytium

They come together but I like to open the explanation like this

Let's go

Cardiac muscle is involuntary, short, cylindrical, branched, and the nuclei are central and can be single or double.

Cardiac muscle shows transverse striations and contains intercalated discs that connect the cells together.

Cardiac muscle contains important cellular components such as mitochondria for energy supply, glycogen as an energy reserve, lipids, rough endoplasmic reticulum (RER), Golgi, and lipofuscin pigment that accumulates with aging.

Let's describe the cardiac conductor

We said we will describe it

Any histology has two microscopes

One is called light microscope and the other is EM

There is nothing that says histological structure

does not have LM and EM

The word LM means light microscope

The microscope we have in our labs

And electron microscope is the image from the electron microscope

That shows me the details

First thing, sitting like you in Egypt

Is it voluntary or involuntary?

Meaning, can I stop the heart now while sitting?

Or I can't control it?

So this word is called involuntary muscle

So involuntary means not voluntary

Not voluntary

I can't control it

I can't control the muscle

So cardiac muscle is involuntary

It is present in any layer in the middle layer

Which is called myocardium

Didn't I have three?

Myocardium and endo

Where were the muscles present? In the myocardium

Right? Can I control it or not?

I can't

So this is called involuntary muscle

Involuntary muscle

Right? Okay

Let's describe it

What do we describe it with, how many microscopes?

With two types of microscopes.

And with the electron microscope.

Since the image is colored like this, my dear,

then what is this? Light microscope.

A colored image by the light microscope.

It describes the details of the muscle for us.

First thing, these muscles look like a cylinder.

A cylinder like a cylinder like this.

This is called a cylinder structure.

Cylinder structure.

And short muscle.

And branched, meaning it branches.

Why do I want it to branch?

Because the more it branches, the more it interlocks.

So it is short.

Branched slender involuntary.

Again, short.

Slender.

Branched.

And involuntary.

We said what does the word involuntary mean?

It means I cannot control it.

Now, an important word.

These cells are held together.

In a way like a ladder.

What is the name of this ladder?

Intercalated disk.

Held together by a ladder, what is it called?

Intercalated disk.

What is the function of this ladder?

That I want to contract all

Together, so I make one unit.

Or a word called syncytia.

Syncytia.

Okay.

It has lines, it is striated.

Like this or not, striated?

It has transverse lines.

Okay?

Transverse line.

Again.

Let's go.

While I describe the heart.

Cardiac muscle.

Which layer is it?

The one in the middle.

What is its name?

Myocardium.

Its shape.

Short.

Slender.

Branched.

Involuntary.

Short.

Slender.

Branched.

Involuntary.

Held together.

By a disk like a ladder.

Its name.

Intercalated disc.

And in the middle it has.

Striations.

Its name.

Transverse.

Striations.

Are all muscles.

The same shape?

Or is there a part specialized that talks to the one next to it and tells it to contract? Are they all like this? No, there is another part called Purkinje fibers. Let's remember together the Purkinje fibers. So while I describe the heart, don't forget that there are important fibers called Purkinje fibers. Let's describe the rest of the heart.

Here.

Let's go.

The muscle.

Short, cylinder.

What else?

Branched, involuntary.

Four words.

Short, cylinder.

Branched.

Involuntary.

Is that correct?

In the middle, what are these lines?

What is the name of this disk?

Intercalated disc.

Intercalated disc is like a ladder.

It allows me to make syncytia.

Look at the nuclei.

Here is its nucleolus or nucleoli.

Here are the nucleoli when it is.

Mono or bi nucleated.

One or two.

It has nucleoli in the middle.

So it is called central nucleoli.

Central nucleoli.

Let's describe quickly again.

The cardiac muscle.

Short cylinder.

Branched involuntary.

Let's say short cylinder.

Branched involuntary.

In the middle it has lines called Intercalated Disc.

Intercalated Disc.

How is the nucleus?

Central.

The nucleus is in the middle, so it is called central, meaning in the middle of the muscle.

In the middle of the muscle, central, vesicular, oval.

So again, what is the muscle itself?

Short Cylinder Branched Involuntary.

What are these lines called?

Intercalated Disc.

The nucleus is either single or binucleated.

Central, vesicular.

What does vesicular mean? It means active nucleus.

Here it is.

Let's describe again with the light microscope.

In longitudinal section.

What does longitudinal section mean? It means lengthwise.

It means the muscles are lengthwise like this.

Let's say short, slender, branched, involuntary.

Short, slender, branched, involuntary.

What are these lines called?

Intercalated disc.

Intercalated.

Do you see the branches? Are they branched or not branched?

Are they branched or not? Branched.

So it is called short, slender, branched, involuntary.

What about the nucleus?

Here it is central, vesicular, single, or binucleated.

Okay?

What are these lines called?

Intercalated disc.

Between them collagen fibers.

Fibroblast blood vessels blood vessels blood vessels fibers Fibroblast Blood Vessels Blood Vessels BV Blood Vessels Blood Vessels.

Or are there specialized fibers?

There are different fibers.

Every now and then we say it in every slide.

They are called Purkinje fibers.

There are other fibers called Purkinje fibers.

Okay.

Let's quickly point to the fibers again.

They are Short Slender Branched.

Involuntary nucleus single nucleus.

These lines are called intercalated disk.

Here in transverse section, meaning cross-section.

What does that mean? Here the muscles lengthwise like this.

I will call it section, it will be cross-section like this, what is it called?

Transverse section.

Transverse section means as if the muscle.

I took a piece of meat and cut it crosswise like this, circles.

Right? So it will appear as a rounded profile.

Explain to me the location of the nucleus.

Central nucleus.

Central nucleus.

Central nucleus.

Let's quickly describe with the light microscope.

Short slender involuntary.

Branched nucleus central.

Intercalated disc.

Six words with the light microscope.

Short branched involuntary.

Slender.

Okay.

Intercalated disc central nucleus.

Okay, this is with the light microscope.

Now let's see.

What are the things.

The organelles present in it.

With the electron microscope, I want to describe its details.

And everything present, why it is present.

Now.

The heart works.

Does it need energy or not?

Of course it needs energy.

So what must be present?

First thing, there will be.

Mitochondria.

They are responsible for.

Responsible for.

The components and also mitochondria.

To help you with the components.

The second is glycogen.

I told you first about the stored thing.

With the yellow documents.

With the layer that gives mitochondria.

And the glycogen store.

What does it show? The degree.

The second to make sure of its exposures.

Are the cells?

The exposed material.

For example, the exposed material to us.

Material more than accuracy.

By God.

That's why I originally have a pigment called lipofuscin pigment.

What is lipofuscin pigment? It is a pigment with aging.

What does that mean? It means now my cells, when I am 20 years old.

These cells do oxidation and release materials and leave them.

And when I am 40 years old, the accumulation increased.

And when I am 60 years old, the accumulated materials increased.

So I have a pigment or dye that accumulates in cells that do not regenerate.

And it is called lipofuscin pigment.

And lipofuscin pigment means aging pigment.

It is something that accumulates with age.

Where do I find it more? In the heart?

And who ages with it?

And it is more in the nerve.

Because they do not regenerate.

So the pigment accumulates with age, it accumulates.

Among the pigment, it is called lipofuscin pigment and Golgi.

Among the pigment, it is called lipofuscin pigment.

For these large cells.

So with the light microscope, we said six words, what are they?

Short, branched, involuntary.

Slender, intercalated disc, central vesicular nucleus.

With the electron microscope, three energy things.

Mitochondria, glycogen, lipid.

One related to age, lipofuscin pigment.

Rough endoplasmic reticulum and Golgi, six things in one.

Now let's see.

Cardiac muscle contains a special structure called dyad consisting of a T-tubule and a terminal cistern of the sarcoplasmic reticulum; these two structures are important for rapid electrical signal transmission and contraction stimulation.

Intercalated discs consist of three types of junctions: fascia adherens, macula adherens, and gap junctions; these junctions allow cardiac cells to connect and coordinate contraction as one network (syncytium).

The dyad and intercalated disc consist of 3 junctions: fascia adherence, macula adherence, and gap junctions that form a junctional complex between two adjacent cells.

Gap junctions open a channel between two cells allowing electrical signals to pass, making the two cells function as one cell (syncytium).

The intercalated disc contains 3 junctions: fascia adherence, macula adherence, and gap junctions that allow communication between cells.

Purkinje fibers are located in the endocardium layer beneath the subendocardium and are specialized fibers responsible for conduction, not contraction.

Purkinje fibers are larger and lighter in color than regular cardiomyocytes, contain glycogen and eccentric nuclei, and do not have intercalated discs or transverse striations.

Regular cardiomyocytes are small, short, branched, contain intercalated discs and transverse striations, have central nuclei, and are responsible for contraction.

Purkinje fibers do not contain striations or intercalated discs, while cardiomyocytes contain both.

Purkinje fibers are light in color due to glycogen content, and their nuclei are eccentric, meaning off-center rather than central.

Purkinje fibers are responsible for conduction (transmitting electrical signals) while cardiomyocytes are responsible for contraction.

When ischemia or a heart attack occurs and heart cells die, these cells do not regenerate because there are no satellite cells and because they are specialized non-renewable cells.

The lack of regeneration of heart cells leads to their replacement by fibrous tissue which reduces the heart's efficiency in contraction.

Heart valves are protrusions of the endocardium that prevent backflow of blood and consist of three layers: endothelium on both sides and connective tissue in the middle.

The conduction pathway in the heart starts from the sinoatrial (SA) node in the atrium, then the AV node, then the AV bundle, then the bundle branches, and finally Purkinje fibers that transmit signals to the heart muscle.

The SA node and AV node are connected by the internodal pathway, which is a path between nodes for transmitting electrical signals.

Purkinje fibers are large, light-colored fibers that contain glycogen and eccentric nuclei, and are part of the heart's conduction system.

The endocardium contains Purkinje fibers and valves that prevent backflow of blood and consist of endothelium and elastic fiber connective tissue.

Cardiac muscle contains a dyad, a structure consisting of a T-tubule and terminal cisternae located at the Z-line, which is very important for conduction.

The intercalated disc consists of 3 junctions: fascia adherence, macula adherence, and gap junctions that allow ionic continuity between cells.

Lipofuscin pigment is responsible for aging in heart cells and indicates the cells' inability to regenerate.

The first thing present in the Cardiac Muscle Fibers.

A very very important word.

This slide.

Very very important.

Everyone, focus very much.

This slide is very very important.

What is present in it?

I have with the electron microscope something called sarcoplasmic reticulum.

What is the sarcoplasmic reticulum and the T-tubules?

Sarcoplasmic reticulum and the T-tubules.

What does it mean?

Now, this is the sarcoplasmic reticulum which is less than the skeletal muscle.

Now, what is the sarcoplasmic reticulum?

It is the smooth endoplasmic reticulum.

It is present in the heart.

And it looks like a ball.

A ball like this.

Okay, what about in the skeletal muscle?

In the heart, you will have one ball.

Then I walk with the cell and then something makes a T shape.

Do you know the T shape? Here it is.

Just like this, the T shape.

But it goes down, so what is it called?

T-Tubule.

T-Tubule, the T shape.

So I have two things together.

T-Tubule which is.

An invagination like this.

And next to it a piece of ending.

The end of the sarcoplasmic reticulum.

The one called Terminal, which is this circle

What is its name?

Terminal Cistern

What is its name? Terminal Cistern

TC

So ADC TPU the letter T

And next to it a circle, what's its name?

Terminal Cistern

Terminal Cistern

One

Two

When something is made between two things, it's called

Dyad

Meaning two

Tri means three

Mono means one

So dyad means two

What are the two things? This is very important

The T-tubule and the terminal cisternae

of sarcoplasmic reticulum

These two make something called

Dyad

What's the purpose of this?

The heart wants a signal link

It wants a signal quickly

Like fast nerve signals

To contract

So it speeds up through the T-tubule

And at the same time responsible for contraction

Because of the calcium of

That is present in the sarcoplasmic reticulum

So now the heart has a very important part

Called dyad

The word 'dya' means 2

Who forms it then?

This is very important, it tells you what the two are and who forms them?

The terminal cisternae

Terminal cisternae

Even the T tubule

Terminal cisternae

Sarcoplasmic endoplasmic reticulum

Or sarcoplasmic reticulum

Plus T-tubule

Both together

Make something called?

Dyad

This dyad is located at the Z line

Located at the Z line

So the word dyad

And this is our highlight now

That the word dyad equals

One T-tubule and one sarcoplasmic

cistern

terminal cistern

Located at the Z-line

So I have two

So I have

In the heart muscle there are

Dyads, so the word dyad means

Two, one terminal cistern

One T-tubule

One terminal cistern

One T-tubule

The terminal cistern is the end of

The sarcoplasmic reticulum

If I ask you now

By light microscope, six words

Short, branched, cylinder

Involuntary, central nucleus

And intercalated disc

Six words by electron microscope

Three energy

Mitochondria, glycogen, lipid

And RER

And that is

Golgi

And the pigment of the year

Which is called lipofuscin pigment

So the word dyad means the two T-tubule and terminal cistern

The T-tubule and cistern

So who can tell me what the intercalated disc is?

Which is the ladder, remember the ladder

This ladder made me create what? Syncytium

This ladder made me create syncytium

So this is a junctional complex, a group of junctions between two cells

Junctional complex between two adjacent cells

Remember it as sum

Remember it as sum like the other

I, the dyad

And the intercalated disk

Sum of the dyad and intercalated disk

Okay, it consists of

Three junctions, remember them as sum

Fascia adherence, macula adherence

Gap junctions

Fascia adherence, macula adherence

And gap junctions

These three together make something called

Junctional complex

Fascia adherence, macula adherence

And gap junctions

These three are between

Two adjacent cells

They make the two cells work

As if they are one

They communicate with each other

How do I give one cell

And give another cell

No, I glue them together and open a channel between them

This channel makes what happens here happen here

And this channel makes what happens here happen here

And so on

Three junctions

Fascia adherence, macula adherence, gap junctions

Fascia adherence, macula adherence, gap junctions

These make me work as a syncytium

So exactly

From gap junction to syncytium

So the intercalated disk has three junctions

Let's say them

Fascia adherence, macula adherence, gap

Fascia adherence, macula adherence, gap

The gap is between the two cells

It creates continuity as if they are one cell

And it connects it to the other cell

So this is called gap junction

Gap means space

You know what gap means? It means space

So this gap makes the signal

Pass from one cell to another

Makes me work as a network

Called syncytium

So what do gap junctions do?

Syncytium. So my two most important words

I said so far the word dyad

And I said it consists of

Terminal cistern

And T-tubule

And the second important word

Is that we talked about

The intercalated with three junctions

Fascia adherence, macula adherence

And gap junction

And this makes syncytium

Who are the Purkinje fibers?

Every now and then I say Purkinje fibers

Who can tell me?

Purkinje fibers are in which layer?

Epi, myo,

Or endo?

They are in the endocardium

They are in the endocardium

And is this

One of the fibers

Responsible for

Contraction

As we described it

Or is it responsible for conduction?

It is responsible for the conducting system

This is the specialized fiber for conduction

Second

I have a part of specialized fibers in the camel, opposite Purkinje

We see the cat

Purkinje in the camel is around the windows

In the endocardium

I use the endocardium

The endocardium is endothelium

And beneath it, beneath it, beneath it, beneath it

Beneath it, beneath it

In its middle

There are specialized fibers

Called Purkinje fibers

So when we said they are surrounded

Alone or

Surrounded by sheath

Look at their shape

Are they similar or bigger?

Or large?

Purkinje fibers are different from regular fibers

They are specialized fibers

Specialized, responsible for

Conduction

Good

Responsible for conduction

So they are specialized fibers

Responsible for conduction

Their shape is larger and lighter, big

Large fibers surrounded by sheath

Large fibers surrounded by sheath

Above them from the endocardium

And subendocardium connective tissue

Different from

Cardiac muscle fibers

Not like them, different

So again, Purkinje fibers

Are specialized fibers

Responsible for conduction

Located in which layer?

In the endocardium

Under the subendocardium

Their features

Larger, lighter

Their color is lighter

And surrounded by connective tissue

So now I have three things

Larger

Because we said regular cardiac fibers are small

No, these are large now

Larger, lighter, and surrounded by something

So now I give Purkinje fibers

And the regular cardiac myocytes

From big Purkinje, larger, lighter

This is the reference excel which is small

Cardiomyocyte

Short, slender, involuntary

What else?

Branched, right?

Has intercalated disc

And has

Intercalated disc as we said and has dyads

Okay

Who has intercalated disc?

Regular cardiomyocytes have it

But Purkinje does not

Why? Purkinje is responsible

For conduction but these are responsible

For contraction

What surrounds them?

Purkinje

Purkinje is surrounded by sheath

Here there is no sheath around them

Then which one has striations?

Cardiomyocytes have striations

But Purkinje does not have striations

So the most important thing

Is the striations and intercalated disc

So again

Purkinje is larger

Surrounded by sheath

Does not have

No striations

No intercalated disc

And no striations

So Purkinje is larger and lighter, no intercalated disc, no striations

Okay, let's continue comparing Purkinje fibers and cardiomyocytes

We said Purkinje, four very important words

Larger, lighter, no intercalated, no transverse striations

Remember, Purkinje fibers, larger, lighter, no intercalated, no transverse striations

Large and light color, no striations, no intercalated disc

Okay, so what is their color?

Pale, lighter pale, vacuolated, acidophilic cytoplasm

Full of glycogen

Full of glycogen

We know that glycogen is for energy

Do they have transverse striations? No, they do not

Do they have intercalated discs? No, they do not

Who has them?

Regular cardiomyocytes

It has intercalated discs and transverse striations.

That's right, it has striations.

From the one whose nucleus we said is central, right?

And in the middle, it is a central nucleus.

But this one has an eccentric nucleus.

Eccentric means on the edge.

Exactly.

Glycogen, glycogen larger.

Purkinje large lighter.

It doesn't have transverse striations.

It doesn't have intercalated discs.

Its color is light because it is full of what?

Glycogen, its nucleus.

Exactly, this word is called.

Eccentric nucleus.

The cardiomyocytes are the opposite.

Short, slender, branched.

They have intercalated discs.

They have striations.

Exactly, their nucleus is in the middle.

Central located nucleus.

The light color of the Purkinje is because it is full of.

Glycogen.

Who wants to tell me about Purkinje fibers?

They are responsible for conduction.

They are responsible for conduction.

But.

The cardiomyocytes are responsible for.

Contraction, these are the ones that contract.

So these are responsible for conduction.

But these are responsible for contraction.

Conduction means transmission.

Contraction means contraction.

Again.

The Purkinje fibers.

Is it these or these?

This big opening.

This is the Purkinje.

These are the regular cardiomyocytes.

Look at the colors.

From the large.

Larger and lighter.

The Purkinje.

Larger.

This one is large.

Larger and lighter.

Why is its color light?

We said because it is full of.

Glycogen.

Does it have transverse striations? No, it doesn't have transverse striations.

Does it have intercalated discs? No, it doesn't have intercalated discs.

It is pale, vacuolated, full of glycogen, right?

Larger, lighter.

Does it have transverse striations? No, it doesn't.

Does it have intercalated discs? No, it doesn't.

And its fibers are peripheral fibers.

And another thing is, what about its nucleus?

Eccentric nucleus.

Eccentric means on the edge.

Look here, here it is, look at the nucleus.

Is it in the middle here in this part?

Or on the edge?

On the edge, so this word is called what?

Eccentric nucleus.

Okay.

Someone tell me now.

Now, God forbid, if someone has ischemia.

What does that mean?

It means now the blood is not reaching the heart.

You know, people in old age, God protect me.

That someone might have a stroke in the heart.

What does that mean?

It means the blood didn't reach the heart well.

Right?

So a part of the heart didn't get blood in this area and died.

These cells died.

Do you think these cells can regenerate again?

Or since these cells died.

They will be.

And they won't contract again.

What do you think?

Do you think this area can regenerate?

Or will it be.

Of course, it won't regenerate.

And it will form.

And there won't be new muscles in its place.

And this is a very important question.

Very very important that it won't be able to regenerate and then in its place.

It won't contract, so the efficiency of the heart decreases. So imagine if someone now.

God forbid, had a problem that the blood didn't reach the heart and this area died.

So nothing will form in its place, these cells won't regenerate, so.

There will be.

So if it happens, what happens when no blood reaches this area?

What happens?

If it happens, like an infarction or a clot or blood didn't reach.

What happens when this happens? Do these cells regenerate or not?

Do you know the evidence that they don't regenerate? The stain called.

What? Didn't we say this stain means the cells don't regenerate?

Okay, are there cells that can regenerate? No, I don't have.

No satellite cells and it heals.

So it will be scar tissue and it won't be able to contract again and this area will be like.

Because it is not, so regeneration is by whom? We will answer fibrocytes not by.

New cardiac muscle because first, they are specialized cells.

Specialized cells, non-renewable. Second, are there satellite cells that regenerate?

No, there are no satellite cells, so these cells won't.

Regenerate, so the cells will die and won't come back again.

So why don't the cells regenerate?

Why? Because they are specialized cells.

Non-renewable, they don't regenerate.

Evidence is the stain.

They also don't have satellite cells.

This is opposite to whom? Opposite to skeletal muscle.

Meaning the muscles of our body.

The muscles of our arms, the muscles of our legs.

Thank God, if they get any injury.

They can regenerate.

Because they have satellite cells.

As long as I don't have satellite cells.

Which are the cells that regenerate.

As long as I don't have the cells, which are my satellite cells.

Then it won't regenerate again, so the heart won't regenerate.

So if anyone has MI myocardial infarction.

Or loss of the blood supply.

It will heal by fibroestichio.

So the important question is why will it heal by fibroestichio?

Because I don't have satellite cells.

And because they are non-renewable cells.

So no satellite cells, healing by fibrous tissue.

And therefore non-renewable cells.

Fibrous tissue will form in their place.

The last thing is the heart valves.

What are these valves?

We said if I have an atrium.

And a ventricle.

I won't let the blood move from here to there.

Without it passing through valves.

Or moving from here to there without passing through valves.

These valves are present in any layer, they are present in the endocardium.

There are two important things present in the endocardium.

The smart one who can tell me.

Specific fibers we described in detail called Purkinje fibers.

And very important valves, these two things.

The valves which are the valves.

There are two things present in the endocardium.

The valves called valves and the Purkinje fibers.

So these valves are.

Outgrowths from the endocardium.

And they prevent.

The backflow of the blood.

They prevent the blood from moving in the opposite direction.

They act like a guard.

You are entering where and going where, going from where.

I have a certain direction I will go in.

If you try to go backward and go in the opposite direction.

No, sorry, this is your direction.

So the valves will stop you.

So the valves or the valves are.

What prevent the backflow of the blood.

And they consist of what?

Connective tissue.

Elastic connective tissue fibers covered by endothelium on both sides. So endothelium.

From here, and endothelium from here, and in the middle connective tissue. So it is three.

Layers. Remember that these are three layers. Endothelium from here, okay?

Endothelium from here. Okay. And the other side here also endothelium. And.

In the middle, what is there? Connective tissue. So endothelium on both sides and in the middle there is.

Connective tissue.

Okay, so what we explained is here. Okay. Present in which.

Not in the myocardium, but present in, it is made of, from above and.

Below and in the middle fibrous tissue and it is present in and made of.

Endothelium from above and endothelium from below and elastic connective tissue in the middle.

So how does the valve work? It comes from where? From the endocardium, it is made of endothelium on both sides and connective tissue in the middle.

I want you to say what? It must be tight, it prevents the blood from moving in the opposite direction. I want you to go from above from the atrium to the ventricle.

It is not allowed to go from the ventricle to the atrium, so I prevent the backflow of blood.

Okay, the conducting system now, how do we transmit the impulses correctly?

So now I have two types of heart cells.

One type called conductive, which transmit, called Purkinje.

And the contractile which do contraction, which do the contractions we described.

Right, so we have to see what the conducting system transmits through.

So impulse conduction, now where is the impulse first located?

It is located in the atrium, the impulses which are the signals, which are the contractions.

They will start with something called the Sinoatrial node.

Called SA node.

Called the SE node

And in actual physiology, they share with us something big

SA node is the site located here

It is the first site of impulse conduction called SA node

It is called Sinoatrial node

After we go to SA node

We want to reach the next point called AV node

Atrial

Ventricular node

AV node

Remains SA node

AV node

To connect between them

I connect through

internodal pathway

inter

Means between

nodes

internodal pathway

Means between

nodes

Between this

And between this

Okay

So

The SA node

Here is the first one

SA node

Which is

sinoatrial node

The next one is called

AV node

I will walk between them

In a pathway

Called

internodal pathway

internodal pathway

Okay

From the AV Nodes I reach a bundle called AV Bundle or Bundle of His

Then from the AV Bundle this bundle branches called Bundle Branches

Then I reach the last fibers called Purkinje Fibers

So again I have a pathway I will walk the impulses from one path to another

Like for example at station number 1 I reach station number 2, 3, 4, 5

SA node to AV node, AV bundle, bundle branch, Purkinje fibers

Again SA node, AV node, AV bundle, bundle branches, Purkinje fibers

So the last one is the Purkinje fibers located where? In the endocardium

So this pathway is specialized for stimulation so I can make contraction

So this is my pathway

Where is the SA node located?

Located in the atrium here

And the ventricles

SA node, AV node

AV bundle

Bundle branches

And Purkinje fibers

These are the stations

SA node

AV node

Between them there is a pathway called

internodal pathway

internodal pathway

After the AV node

I reach the AV bundle

To the bundle branches

To the Purkinje fibers

Again

SA node, AV node, AV bundle

Bundle branches, Purkinje fibers

Between these and these there is a pathway

Called internodal

Means between the nodes

The pathway between the nodes

So come look with me

Who is the excellent smart one

Who will tell me what are the rounded fibers

The big pale ones

These are the conducting system of

The Purkinje fibers

Which are called larger, lighter

Because they are full of

Right?

They have

They have

So

They have

And full of

Okay, remember

Their nucleus is in the middle

Or eccentric

We said their nucleus

Is not in the middle

Their nucleus is on the side

Here is something very important

Take home messages

Take home messages are very important

We want to know quickly

Which is let's summarize our lesson

Now the heart has 3 tunics

Or 3 layers called

Epi, myo, endocardium

The epi, myo, and endocardium

Important with me are the valves

And the conductive pathway

The epicardium is the most outer one

It consists of epithelium and connective tissue and is yellow because it contains adipose tissue

The myocardium is the conductor

Don't forget the Atrial Natriuretic Factor

Which is secreted from the atrium to regulate blood pressure through the letter N which is Sodium

The endocardium which is the most inner one

Which consists of endothelium and endothelial connective tissue in blood vessels and nerves

Don't forget it contains Purkinje fibers and don't forget what else?

The valves

The cardiac muscle quickly

Short, slender, branched, central nucleus,

Intercalated disc, dyad

Located at the Z-line

Dyad is very important located at the Z-line

Okay, answer

The junctions between them make

Sensitium can it do

Healing? No, it cannot do healing

Because there are no satellite cells

Purkinje fibers, pale,

Large, contain glycogen

Contain eccentric nucleus

To compare them with cardiomyocytes

They are responsible for conduction

The valves have 2 endothelium layers and in between

Fibroelastic connective tissue which is responsible for conduction

And prevents back flow of blood

Look this is very very very important

The dyad is 1 t-tubule and 1 sarcoplasmic reticulum

Terminal cistern located at the Z-line

So cardiac muscle has dyad

Has dyad

The t-tubule with the terminal cistern are less than the skeletal muscle but very important for conduction

The intercalated disc consists of 3 junctions

Fascia adherens, macula adherens, gap junction

And the gap junction makes ionic continuity as if we are connected in a circle reaching the next circle

Lipofuscin pigment is responsible for aging process

It is present because the cells do not regenerate

Atrial natriuretic factor

This factor controls sodium

And water excretion and regulates

Blood pressure

Purkinje fibers are larger, lighter

They have no striations, no intercalated discs

They have eccentric nucleus

No satellite cells

Therefore they cannot regenerate

The valves arise from which layer?

From the endocardium

And it consists of endothelium

On both sides and in the middle connective tissue

The heart can contract without innervations

And it is modified cardiac myocytes not nerves

Good luck, God willing

Introduction and definition of the circulatory system

Detailing the layers of the heart: Epicardium, Myocardium, Endocardium