The heart consists of two atria and two ventricles separated by a septum, and it works as a pump to pump blood in the body.

Oxygenated blood moves from the heart to the tissues through the aorta, and deoxygenated blood returns to the heart then to the lungs to get oxygen.

God willing, I will be with you in explaining the physiology material, but of course before I start,

just to love, what? That we know before I enter, just uh

to understand some basic information to build upon the talk that will be about

flooding and see what is the stabilizer of the heart.

Replace the opposite today and the stabilizer.

From the echo diagram, we will aim for you and the values from the right atrium to the left ventricle by buying the physiology.

If I give you the heart of the right atrium.

The right atrium heart consists of two atria and a ventricle and the septum, same thing.

The sky element brings to the sky you have a right atrium that helps in the heart's function.

It is connected to the artificial heart greatly.

It consists of two ventricles separated by what? A septum. Okay, what is the function

of the heart? The function of the heart. The heart works as a pump. Pump of what? The heart

now, suppose there is blood here in the tricuspid. What does this do?

Just for understanding, guys. Uh, what does this blood do in what? Oxygen as you

see here in what? Oxygen. It takes this blood and moves in

the aorta to move, move, move to go to the tissue. Your cells.

The cells then receive oxygen from your cells. Here the cells

take oxygen and give it what? Carbon dioxide CO2.

CO2 is carried as we know. It goes out in what?

It goes out in what? In. It moves in. And the superior vena cava blood that is in

the head and neck area gathers here in this area which

is the right atrium. The right atrium will drop the blood to the right

ventricle. And the right ventricle, this blood is what, guys? It is not loaded

with oxygen. It does not have what? It does not have oxygen. So where does it go? It goes

through the pulmonary artery. And it goes where? To the lungs. Because the lungs are

the ones that will put on it what? Oxygen. And after the lungs put oxygen,

they will return the oxygenated blood to whom through the pulmonary

they will return it to the left atrium.

And the left atrium drops it to the left ventricle.

Because the left ventricle, let's repeat the cycle again.

And it sends it to your tissues.

And the tissues take oxygen and give you carbon dioxide.

This is the whole story in short.

I don't want you to memorize, I want you to understand only.

Each chamber in the heart is separated by a valve that prevents backflow of blood and allows it to pass in one direction, such as the tricuspid valve between the right atrium and right ventricle and the mitral valve between the left atrium and left ventricle.

The heart contains an electrical conduction system starting from the sinoatrial node (SA node) called the pacemaker, and the electricity passes through the atrioventricular node (AV node) then the bundle and bundle branches and Purkinje fibers.

The heart beats spontaneously without the need for external nerves because of the presence of pacemaker cells that generate electricity by themselves.

The sympathetic and parasympathetic nervous systems regulate only the heart rate and do not initiate electricity.

And I want you to know that between each chamber in the heart there is a valve.

For example, between the right atrium and the right ventricle,

there is a tricuspid valve separating them.

Tricuspid valve, we call it tricuspid valve.

As you see, it has 3 cusps approximately.

Also, there is a valve separating

between the right

left atrium and left ventricle.

And here between the two there is a valve

called the mitral valve.

What is the function of these valves, doctor?

The valves' function

is that they prevent

and allow the blood to

move in one direction, in one direction.

They do not let the blood go back in the opposite

or different

direction.

So they allow the blood to move in what? In one direction.

Okay, this is the first information we learned that the heart is the pumping system, it is the pump

and the vascular system, meaning the blood vessels I have, the pulmonary artery and the aorta.

And of course the blood returns to the heart through 3 pulmonary veins, through 3 what? 3 pulmonary veins where?

4 pulmonary veins where? Sorry.

Okay, and then as you understood, it contracts.

Okay, now let's come to the conduction system.

The heart's electricity, the heart of course has electricity.

This electricity is what makes the heart contract.

It makes the heart what? Contract.

Okay, what produces this electricity?

Or what stimulates the electricity?

As you have

to light a lamp,

you need what? To connect electricity.

The heart to contract,

needs to be connected to electricity.

So the electricity that will come out of the heart is

we want to know its source.

And how it moves.

First, its source.

Something called the SA node.

And this SA node, guys, they call it

the pacemaker. The pace what? The pacemaker. Which is what? Our boss

that produces the electricity. This is the SA node. It produces

electricity and goes to another area called. Another station called. So

the electricity went from it. And moves through something called. And then

branches to the right bundle branch and left bundle branch. So it came out of what?

Meaning it moved in something called the bundle and branched to a right branch called right

bundle branch and left bundle branch. And what? And each branch is what? Wrapped around

its wall, meaning it wraps around to make a reflection on it and comes out of it

what is called Purkinje fibers. Meaning there are fibers that come out to electrify

the heart to electrify all the heart muscles. Its name is what? Let's call it this. This is

the money I want you to know from the beginning. It moved and is located where?

Located in the right atrium. And the AV node is located where? Also in the right atrium.

Then it moved through the bundle and branched and moved in

small fibers called. So you find me telling you here that the heart has

meaning what? The heart does not need nerves to start beating. The heart, God

meaning if you take my heart, yes, my heart like this and take it out of the body, it will beat by itself.

It does not need any nerves because there is what? The name that produces it, it is the one that

beats automatically. This is called. Okay, guys, okay, this is the story that

I want to tell you. But you say, doctor, so it does not need nerves?

But the nerves you drew above,

you drew here the sympathetic and here the parasympathetic.

Which is the vagus nerve.

I drew them to tell you

that they regulate

them, the sympathetic and parasympathetic.

They regulate what?

They regulate

your heart rate. If your heartbeats are fast, they slow them down.

If your heartbeats are slow, they increase them.

So they are regulators,

just organizers for the movement.

Okay, but your SA node

produces like

it is called the initiator.

Initiator, its abbreviation is what?

Sinoatrial node.

Sino what? Sinoatrial node.

The initiator means it starts the electricity.

Okay, so how

does the whole heart contract?

Meaning all of it.

As one unit, all as muscle.

One unit because the heart

between muscle and muscle,

meaning this is cardiac muscle and this is cardiac muscle.

And this is cardiac muscle.

You studied that there is something called

gap junction.

Between the heart muscles, there is something called gap junction.

Meaning once this muscle is electrified,

this muscle receives the electricity,

and this receives the electricity

through the gap junction

between the muscles.

So the gap junction makes the heart

contract as one unit.

As one single unit.

Okay, I told you

that to light a lamp,

you need electricity.

So you turn on the electricity

first, then

the lamp gives you the light. Same thing. You produce electricity first,

then the AP gives you contraction. And so on, based on

this, we divided the action into two types. Or the action what? Two types.

Types in the muscles, which is in the muscle related to the muscle

and present in the fiber which is in

the SA node. So based on that you have two electrical things in

the first, then muscle contraction. So you have two types of

action potentials. Present in the SA node and AV node.

These are the primary and these are the secondary. Okay? And this is the shape of

the SA node and AV node. Either action potential

which is related to muscle contraction,

and this we call what?

This is its shape.

This is it.

Each one of these we will study in detail.

This is called fast response.

This is called slow response.

So this is fast response.

And this is slow response.

Don't rush, each type of these comes in detail.

Let's start, in the name of God,

and understand what we want to say.

First, a note

says that the Cardiovascular system is a closed system.

Closed system as I explained to you, it is a closed system of tubes.

Tube meaning the vessels, which is a water base.

As you saw, the heart sent out the aorta going to the tissue.

And the tissue gives you the blood that goes from the inferior vena cava.

From the Inferior vena cava to the Right atrium

From the Right atrium to the Right ventricle

Then to the Lung

And the Lung returns again, making it feel like a closed system

closed system

Okay?

Inside which blood circulates, the blood circulates

continuously

by the pumping action

of the heart

And what is the heart?

The blood moves in one direction

If I ask you why, you say because

of the valves, doctor

The valves are what prevent the blood

from going in two directions; it goes in one direction

Okay

So what does the heart consist of?

As we have seen, the heart consists of

the cardiovascular system

It consists of

the heart, which is the pumping that moves the blood

and blood vessels, which are containers through which circulation occurs

And this is where circulation happens, as you saw

Where the oxygenated blood goes and where the deoxygenated blood goes

And this is the story of the cardiovascular system overall

The cardiac muscle is a striated involuntary muscle, characterized by the syncytium property that allows the heart to contract as one unit due to the presence of gap junctions between cells.

The heart consists of two types of muscle cells: contractile cells that contract and represent 98% and non-contractile cells that generate electricity and represent 2%, which are the pacemaker cells.

Now let's look at the properties of cardiac muscle

Cardiac muscle has properties

What are the properties of cardiac muscle?

Of course, cardiac muscle is striated muscle

First, it is somewhat like skeletal muscle which you have studied

Skeletal muscle is striated

And cardiac muscle is striated

They differ from each other

They differ in that skeletal muscle

is voluntary

They differ in that

cardiac muscle is involuntary

What does involuntary mean?

It means it contracts without your will

You control skeletal muscle

You can contract your biceps and triceps

But you cannot contract the heart muscle voluntarily

Also, it has a property called syncytium

Syncytium or syncytium

What is this syncytium property, doctor?

This syncytium property means the heart can contract

as one unit

I tell you the heart contracts as one unit

And I told you it is because of the gap junction

He is telling you these two words

He tells you that syncytium means that cardiac muscle

the heart muscle cells

contract or are able to excite

contract

and contract as one unit

As a single unit

Why, doctor? Because of the gap junction

The gap junction is the connection

When muscles connect, each muscle is connected to the one next to it

Meaning there is communication between one muscle and the adjacent muscle

He says the two atria we drew were like this and that, there was this and that, he says what now? He says

You have the two atria above, they have what?

All of these are connected between them, meaning what do you benefit from these two words?

I benefit that the two atria above contract together, the ones above

So I named them because the two above contract together. But the two ventricles

contract too, so I named them and you understood from this. And this matter is completely separate

Meaning the two are separate from each other. Separate

Yes, doctor. Separate by the valves I told you about. Meaning

Here, as I told you, you are separated by a valve called the

Right ventricle and right atrium are separated by a valve called the tricuspid valve, right?

Around every valve there is fibrous tissue

fibers

A ring called the fibrous ring

A V-Ring

Atria Ventricular Ring

So the two are separated by a valve, a normal valve, but you add that the valve is surrounded by fibrous tissue

Surrounded by fibrous tissue

Okay

What is this then?

This was a note directly transmitted

And therefore the contraction

or the impulse

cannot move

from one syncytium

to the other, meaning it cannot

You don't find the two atria contracting

and at the same time the two ventricles contracting

No, the two atria contract together

And after a while, God willing, the two ventricles

contract as well

Okay, why is that?

Because of the AV ring

The fibrous AV ring that is present in the valves

In the valves. Okay, the myocardium

of the heart. The myocardium of the heart consists of what? Two types

Of cardiac muscle. Didn't I just tell you that you have two types of

cardiac muscle? Yes, but indirectly. I told you you need what?

To light a bulb you need electricity. I named that electricity what? I named

it the heart's electricity, right? The one that produces electricity is the one, but the main one is what?

The main one you say if the heart is working, this is a type of cells

And the other type I told you when this produces electricity, the heart is in

You have cells called cardiac muscle cells that contract with this electricity

One type is contractile

Called contractile muscle cells

They represent 98%

of the cardiac muscle

Okay

And the action potential

Was called

Did it happen or not? And what did it look like? It looked like this. Not exactly like this, but

Let's say when we connect it, it looks like this, this, this, right?

Right or not? So you have two types. This is the contractile type.

And this one has, and its function is pumping that

It is contractile to push forward the rest of the body's organs. And the other type

And the second type, surely you guessed, the second type which does not do pumping, doctor

Is the pacemaker and its name is what?

So it represents about 2%, which are represented in what? If you are asked, you say in the

Right, so these are the cells that represent what?

Their function is electrical conduction and their function is what?

And their name is what? I hope what? We gathered all this in

the two pages we mentioned above. Now let's go to the beginning of the lecture.

God willing, we will cover everything in detail

Cardiac muscle, the heart muscle, has 4 properties

4 properties

So it has 4 properties

What are the 4 properties, guys?

The 4 properties are that you have

The cardiac muscle has four main properties: rhythmicity, excitability, contractility, and conductivity.

The property of rhythmicity means that the heart contracts spontaneously and regularly (spontaneous and rhythmic contraction) without external stimulus, and this property results from pacemaker cells.

Pacemaker cells are non-contractile cells but capable of generating electricity by themselves (self-exciting) and are called myogenic origin because the contraction originates from the muscle itself.

Meaning the heart muscle has 4 what?

4 properties

What are the 4 properties?

A property called rhythmicity

A property called excitability

A property called contractility

And a property called conductivity

Let's take each one separately, come on

Let's take the first property, which is rhythmicity

This rhythmicity property is what, guys?

Rhythmicity means the heart

contracts spontaneously

I just want you to know that the heart

contracts, it contracts

spontaneously, automatically

Plus it contracts

rhythmically

Rhythmically means what? It means regularly

So the property of rhythmicity means the heart contracts spontaneously

Spontaneously means what? Without a stimulus

When I told you, I drew the heart above and told you it needs nerves to be electrically activated to start contracting

I told you no, I told you even if I drew it with two nerves, the sympathetic and parasympathetic nerves

I told you these are regulatory only, but don't think they are responsible for the heart contracting

No, if I take the heart out, it will contract

This is called spontaneous

And this is represented in the property

called rhythmicity

The second thing, rhythmically

Rhythmically means what?

Rhythmically means contracting regularly

Meaning every beat of your heart

Or every electrical impulse from the heart

Comes out with a fixed time between each one

Okay?

So we must differentiate rhythmicity

The property rhythmicity is the ability of the heart

The heart's ability

to initiate

to start its own contraction

Its own contraction

Independent of external stimuli

Without depending on an external stimulus

So it means

Rhythmicity means

This is the property of automaticity

Which is

Didn't I tell you rhythmicity means two things?

Spontaneous

Which equals automaticity

That the heart contracts spontaneously without an external influence

The second thing, the word rhythmicity

Means the heart contracts

regularly

Every beat after the other

With a fixed time between them

Okay, now it says that

Spontaneous rhythmicity and

automaticity of the cardiac muscle

Is due to what?

Due to the pacemaker

Right or not?

The property that it contracts spontaneously

And regularly is due to the pacemaker

Is due to what result?

What result? The result of the pacemaker.

Right or not?

The property that it contracts spontaneously.

And regularly as a result of the pacemaker.

What we explained at the beginning

The SA node and the AV node

And how electricity comes out

And from which external influence it comes out

So this is what the result tells you

due to excitatory conductive system

Everything I drew for you when I said this is the SA node

And electricity goes to the AV node

And then to the bundle of His

And from the bundle of His it branches to the right bundle branch

And the left bundle branch

And then comes something called Purkinje fibers

All of this is called the conductive system

Okay?

So what are we?

All of this is the conductive system

Okay

So it tells you here

Here it is

Excitatory

As a result of the conductive system

Which is composed

Of cells

Self-exciting

Meaning it can generate electricity by itself

Electricity

Non-contractile, it does not contract

Because they divided it

They divided it into contractile and non-contractile types

This is the non-contractile type

So it is indeed self-exciting

It can start

The excitation or contraction of the heart by itself

And non-contractile, it does not contract

Because it

Is not meant to contract

It is meant to generate electricity

And these cells we call

The pacemaker cells

Rhythmic

Is myogenic

In origin

Meaning the contraction of the heart

That the contraction

Is

Rhythmic

Meaning regular

It tells you what?

Myogenic in origin

Meaning it comes from where?

From the conduction system itself

The muscles themselves

The muscles themselves

The autonomic nervous system, such as sympathetic and parasympathetic, regulates only the heart rate and does not initiate electricity or contraction.

Heart rate in the heart is controlled by the sympathetic and parasympathetic nervous systems, but they do not start the electricity in the heart; they only increase or decrease the heart rate.

The sinoatrial (SA) node is the main pacemaker because it has the highest rhythmicity rate and initiates the electricity that spreads in the heart.

The pacemaker is a part of the heart characterized by high rhythmicity; it starts the electricity in the heart and determines its rhythm, and the rest of the heart parts follow its rhythm.

The SA node is the primary pacemaker because it has the highest rhythmicity and generates electricity at a rate of about 100-110 beats per minute, compared to other parts like the AV node and Purkinje fibers which generate electricity more slowly.

Independent

Here, independent

Meaning not dependent

On autonomic nerve supply

But the autonomic nerve supply

Which is sympathetic

And parasympathetic

What do they do?

Control the heart rate

Only

As I told you, they can increase heartbeats

Or increase the heart rate

Or decrease, but they

Don't initiate

They never start the electricity

As I told you, who is the initiator that starts the electricity?

You say the pacemaker

Is it the sympathetic or the parasympathetic?

Or what is called the autonomic nervous system

Can it start

The heart electricity or excitation?

Meaning no, but what it does is

Regulatory, meaning it increases

The heart rate or decreases the heart rate

Okay, let's talk a bit about the pacemaker

Come on

Pacemaker means that this

Is a part of the heart

A part of the heart

Has high automaticity

It has high automaticity

And the whole other part of the heart

Follow its rhythm

Why?

Why is it the pacemaker?

It is what we call it

Even though we had what, guys?

We had here

As we drew here

We had the SA node

The SA node

And I had the AV node

And then electricity

Goes like this and then goes

To something called bundle of His

In the right bundle branch

And left bundle branch and Purkinje fibers

As long as I have the SA node

And AV node, why the pacemaker?

I have the big boss

The SA node, honestly first

Because it produces the largest

Meaning it has

The highest automaticity

It has the highest automaticity

Meaning what? It is

The one that produces the most, what does that mean? The electricity that comes out

The pacemaker is the fastest in the heart and thus determines the heart rhythm; the rest of the heart parts respond to it and no part can start electricity independently from the pacemaker.

From the heart is about 100 or 105 or 110. Or

105 is not a problem. How much electricity does the AV node produce? It produces about 45 to 60. 45 to 60. And the Purkinje fibers

Produce how much? About 25, those are 25 to 40, so

Who is the fastest among us? The fastest is the SA node because the heart muscles

Listen to the fastest, so the fastest or the one that has it is the SA node

Therefore, the definition of the pacemaker is the fastest, it is the part of the heart that has

And all the other parts of the heart listen to its rhythm, meaning no part can go here for example and produce

Electricity and the AV node listens to it? No, the AV node or the heart muscles

Listen to the fastest, so we will come to a disease, God willing

You can imagine the heart contracting 400 or 500 times, definitely some hearts

Have one faster producing 400 or 500. So you leave it aside. But by the mercy of God, the 400 or 500 go down to the atria at a lower number, we will understand why later. So it is

The highest automaticity. It means that a part of the heart

Has it and all the heart and all parts of the heart listen to it. So let's

Take the pacemaker, how many are there? There was, right? Which is 90 to 110

Which is, as I told you, about 110, it's 90 to 110.

And we call it the primary pacemaker. This rhythm is called what?

The rhythm that comes out, we call it sinus rhythm. Okay?

There are secondary pacemakers such as the AV node which generates electricity at a rate of 45-60 beats per minute and works if there is a complete block in the pacemaker.

Sinus rhythm. The secondary is represented by who, guys? Represented by the secondary pacemaker represented by the electricity from the bundle fibers from 45 to 60 per minute. This works

If some damage happens or it stops, it will work instead. This rhythm here we call it what? Above you

I call it here the nodal rhythm. It comes from here, here, here, here, here, here, so we call it. This is it. It produces about 25 to 40, 25 to 40. And it works when, if it also has

Complete block. This rhythm we call idioventricular rhythm. Okay?

Okay. Let's take the channels in the heart. I have in the heart several channels.

Channels. Several channels. The channels I have, in my opinion, are

Let's take what happens first. And we say the channels that exist. Okay, come on, let's say what's on it so we can go back and see it.

And it becomes easy as we took the two pictures at the beginning like this

And the topic became a bit easier. Now we said we have two, right?

One happens in the right atrium. Yes, one sorry

Happens in the contractile cells, one happens in, right or not? Okay. Now

We will take what happens in, when we talk about, okay let's draw a sketch for our AP that we used to call the pacemaker or what we call the slow response. Okay guys? Okay. This

We will draw a line like this. Then a line like this. Then a rising line like this.

Then what? Then a falling line like this. Okay? This is what happens. What

Happens? What makes it produce electricity first? We will just put here

What? The name here is phase four here.

Nasty.

Come here now, this is phase four and this phase we call phase zero and this like this

Phase three. Let's see what happens. First we are in phase

Four because this is what we will talk about what happens in

The pacemaker cells.

The resulting eighth from the eighth year, so it's constant.

People do not think about the word ecomoters.

The pacemaker has an action potential called slow response which consists of several phases starting with phase 4 that represents the preparation for electricity where sodium ions enter through the funny channel raising the voltage from -60 mV to -50 mV.

After phase 4, the transient calcium channel opens allowing calcium to enter and raising the voltage quickly to -40 mV, leading to rapid generation of electricity.

Phase zero is characterized by calcium entry through the long-lasting calcium channel which opens for a longer period causing relatively slow depolarization, hence it is called slow response.

Phase 3 is the repolarization phase where potassium exits the cell through a special channel (delayed rectifier potassium channel) restoring the voltage to the resting state.

We have a course, topinian enemies.

I will present the visa equal.

Meaning not the previous day you stayed.

Although the message we will push in it means what it relates

To itself if you send the node.

Where or from the exit of the special Emirates with him.

This is called what? Preparatory. Meaning what? Meaning before electricity happens.

So this is to prepare for the electricity to come out.

What happens? Ions enter. Okay, the ions that

Will enter are? The first ion that enters is sodium ion. Sodium ion

Enters through what? Through a channel called funny channel, let's call it an abbreviation.

Sodium enters through the funny channel which raises the voltage.

When sodium enters, it raises the voltage from minus 60 mV up to

Minus 50. Then another channel opens, what channel?

A channel related to calcium. Calcium enters.

Calcium enters through a channel called T-type, meaning it opens for a limited time then closes. This raises the voltage to what?

By itself if you send T note.

Where or from the exit of its special Emirates.

What is this called? Preparatory. What does it mean? It means before before.

The electricity that will happen. So this is to prepare for the electricity to come out.

What happens? Ions enter. Okay, the ions that.

Will enter, what are they? The first ion to enter is the sodium ion. The sodium ion.

Enters through what? Through something called the funny channel, I know it like this, some abbreviation.

Entered now, entered now, the sodium entered and what is called.

And match, so sodium entered through the funny channel, raising the voltage.

When sodium enters, it raises the voltage from minus sixty millivolts up to.

It reaches minus fifty. Then another channel opens, what channel?

A channel related to calcium. Calcium enters. Calcium enters through a channel called what, we will write it here below named T, meaning delayed.

It will close, meaning it will open for a delayed time and close. This raises the voltage to what?

Exactly? And of course, there are things we said about the pacemaker normally because there are things we will still talk about. And this pumps three out, which we all know.

To minus forty. To minus what? Minus forty. Did you notice something?

The voltage difference after that will start to do what? It rises to electricity. Did you notice

that the voltage difference between minus sixty to minus forty is not much. Only minus twenty.

As we will explain, the difference is big. This indicates that

God made the difference small here so it happens quickly. So you are close to

meaning close to, right? So as soon as you reach from minus sixty to minus forty, electricity rises.

It doesn't take time. So what? The difference between minus sixty

and minus forty is not much. Okay. This was done by the entry of two things.

Through and calcium through. Okay, this period is spontaneous. Not

I said, does it come from an external stimulus that makes it? No, spontaneous. So this period

is spontaneous. When does it happen? It happens in in what? In systole.

Systole, which is what? The contraction of the heart. Now we are not preparing

for the heart to contract. Meaning we are in the phase before which is

which is. Okay, now let's come to phase zero. In phase zero, what happens?

Phase zero starts calcium entry. Ah sorry yes,

calcium. But this time calcium enters through another channel. What is

the name of the channel? It is no longer calcium. Which is what?

What do we call it? What? Okay, thank God it happened. So this phase

was called what? Or we call it or transition from the resting state. But what?

Between it and a small difference. Then electricity rises. Which is

called what? Which is and then what happens? Repolarization.

Repolarization here should release ions. Repolarization

releases what? It releases potassium. It releases potassium. It releases

potassium through a channel called the delayed rectifier potassium channel (I_K). Okay? We will learn all this

and all these. So this is the story and here you have

then start another phase. Which is what? You start again

and rise like this and finish the same idea. Okay? So this is what?

No, it means it should be what?

We draw it like this, yes.

And then it rises like this and like this.

And so we repeat the same idea again.

Okay guys, so this is what?

This is the pacemaker.

The action potential, to light the lamp,

you needed what? You needed electricity.

And for the heart to contract, you need what?

Electricity. So you must start by electrifying the pacemaker.

Okay?

Which is the action potential of the pacemaker.

The slow response so that then what happens? The second electricity happens. The second action potential. Which is what? What happens in I want to explain something here but the next talk will avoid it. Notice that I

talked about this part a bit and told you it is four from what? Minus

sixty close to minus forty. Now if I draw it again like this, sorry.

And I said what? I don't know how to draw, I told you. Here. This is called the

slope. You see it rises like what? Like a slope. So this is called

slope. I told you it was approximately at minus forty to minus sixty here.

And as soon as it reaches minus forty, it happens, meaning you are close to. So the more it was

the faster you reach the firing, right or not? So

the more it was, the faster you reach firing. Right or not?

So this means the more it was, the faster you reach firing. Right or not?

So this means the more it was, the faster you reach firing. Right or not?

So what do you think if

it was like this? Long. We call it. So the more it was, the more it was

less. So here you find the heartbeats are what? Less. Because what happened?

The electricity that came out was slower. So the more it was, the more it was what?

The higher. The more it was, the more it was less. Right or not? Because here you

took a longer time and so it comes out a bit late. Right or not?

The speed of electricity generation in the pacemaker depends on the slope of phase 4; the faster the sodium and calcium entry, the steeper the slope and thus the faster the heart rate.

The sympathetic nervous system increases heart rate by increasing sodium and calcium entry through beta-1 receptors in the heart, which increases the slope of phase 4 and makes depolarization faster.

Increased temperature raises heart rate because heat increases the slope of phase 4.

Potassium deficiency in the extracellular fluid increases heart rate because it allows greater sodium entry into the cells.

The parasympathetic nervous system decreases heart rate by releasing acetylcholine which inhibits the funny channel (If) reducing sodium entry and decreasing the slope of phase 4, thus reducing the speed of electricity generation.

Increased potassium in the extracellular fluid decreases heart rate because it opposes the effect of sodium and slows electricity generation; high doses of potassium may stop the heart.

Okay. Now if I tell you, if I tell you what things increase heart contraction and what things decrease it? First I will tell you

the sympathetic. The sympathetic, doctor, is what increases heart rate.

The sympathetic works on beta-1 in the heart.

And what does it do? It increases sodium entry. So it increases sodium entry through what?

Right, hello. So when sodium enters quickly and also increases calcium by the way.

So what happens in the slope, guys?

Does it increase or does it become slow slope?

No, you will increase the slope.

Meaning fast.

Or more slope.

Meaning it becomes like this.

You will reach depolarization

faster.

So here it becomes more slope.

What else increases heart rate?

Temperature.

Isn't it if you come to someone who is hot,

has a fever, you find his heart rate

faster.

So temperature

increases heart rate.

What else?

Low potassium

in the extracellular space.

Low potassium

outside the cells

increases heart rate.

Because it gives

when potassium is low

outside the cells,

it gives a better chance for sodium

to undergo inward influx

into the cells.

If I ask you

what decreases heart rate,

you will tell me the opposite.

Parasympathetic.

I say yes, parasympathetic.

This is one.

What does parasympathetic do? It releases

acetylcholine, right?

Sympathetic releases catecholamines,

which is norepinephrine.

While parasympathetic releases catecholamine that does what?

It inhibits the f

which is the If

which is the funny channel.

Therefore sodium will not enter,

and thus will not reach the firing level.

Therefore, decrease in the slope

your slope that I drew will decrease and will be like this.

It will no longer be what? Where is the slope?

Upwards? No, our slope

became almost flat.

So decrease in the slope.

Correct. What else?

I told you above, you said what?

Increase in potassium extracellular.

Because when potassium

increases outside, it causes

an opposing action, meaning it opposes

the action of sodium.

By the way, some people

in America,

there is something called

the lethal injection with potassium.

They give a potassium injection

in a large amount. So when potassium increases,

what does it do to the heart? It decreases heart rate.

But this time not just decreases, I tell you

they give large doses and stop the heart

completely. So they kill the person

with a potassium injection.

Okay.

What else?

Of course, there are things like

drugs that block calcium

channels.

We won't say sodium enters and calcium enters.

At first, there are also things like that.

There are many factors we will see in the playoffs but

these are the most important.

Okay, let's go

to see what the talk is.

Let's see

the ionic channels in the heart.

The first ion I told you is the T-type.

Transient calcium.

Transient calcium, we said it is what? Present

There are different ion channels in the heart such as the transient calcium channel found only in the pacemaker, the long-lasting calcium channel found in the pacemaker and contractile cells, and the fast sodium channels found in cardiac muscle cells.

The pacemaker works automatically and regularly due to the properties of ion channels that allow slow and regular generation of action potentials, which determines the basic heart rhythm.

The electrical concentration of potassium controls the opening and closing of ion channels in cardiac cells, where potassium starts to exit gradually as the voltage approaches -60 mV.

The electrical pulse in the heart may reach 110 beats per minute, but the actual heart rate is lower due to the effect of the parasympathetic nervous system which reduces the pulse rate.

The vagus nerve (parasympathetic system) supplies the cardiac muscle and reduces heart rate by inhibiting the SA node from 110 to about 75 beats per minute.

The vagus nerve supplies the entire heart muscle except the ventricles, which protects the ventricles from excessive stimulation effects that may cause cardiac arrest.

Excessive stimulation of the vagus nerve may lead to a severe decrease in heart rate, but the ventricles are protected from this effect thanks to the vagal escape phenomenon.

Factors affecting heart rate include the effects of the sympathetic and parasympathetic nervous systems, where acetylcholine decreases heart rate while norepinephrine increases it.

Acetylcholine decreases heart rate by stimulating certain receptors that increase potassium outside the cell, which reduces the pulse speed.

Norepinephrine increases heart rate by stimulating beta-1 receptors that increase sodium and calcium entry into cardiac cells.

Thyroxine hormone increases heart rate by increasing metabolism and the sensitivity of adrenergic receptors.

Ion effects on the heart include sodium which initiates depolarization, and potassium which affects pulse speed where its deficiency causes tachycardia and its excess causes bradycardia.

Increased extracellular potassium (hyperkalemia) causes bradycardia and may lead to cardiac arrest at high doses.

Calcium helps in cardiac muscle contraction; excessive calcium causes continuous contraction of the heart leading to cardiac arrest.

Calcium channel blocker drugs like verapamil work by closing calcium channels which reduces heart rate and are used to treat hypertension.

Oxygen deficiency and increased acidity reduce cardiac cell energy and negatively affect their functions.

Increased body temperature raises heart rate by about 10 beats per minute for each degree Celsius increase due to acceleration of enzymatic reactions.

Decreased body temperature reduces heart rate due to slowing enzymatic reactions and severe hypothermia may lead to cardiac arrest.

The heart has excitability which enables it to respond to appropriate stimuli either by mechanical contraction or by an electrical signal (action potential).

The action potential in the heart has two types: slow in pacemaker cells and fast in contractile muscle fibers.

Phase 0 of the action potential is the rapid depolarization phase due to sodium entry through fast voltage-gated channels.

Phase 1 involves potassium exit from the cell through special channels which slightly reduces the electrical voltage after rapid depolarization.

Phase 2 or the plateau phase is a balance between calcium entry and potassium exit, which is important for cardiac muscle contraction.

In muscle contraction, calcium enters the cell and potassium exits; this exchange is important for contraction to occur.

Calcium entering the cell goes to calcium stores inside the muscles and is released from them to stimulate muscle contraction.

The muscle passes through a refractory period during which it does not respond to any stimulus to prevent two contractions at the same time.

Phase 3 is the phase where a large amount of potassium exits, restoring the electrical voltage to the original negative state (-90 mV).

At a certain phase, calcium channels close and potassium exits in large amounts to restore the cell's electrical voltage to -90 mV.

The potassium-sodium pump works to redistribute ions to their normal places inside and outside the cell after contraction.

The heart has the ability to respond to sufficient stimuli, and this response is either through the cardiac conduction system which generates electrical signals by itself or through electrical conduction via specialized fibers.

The electrical potential in the cell starts from -90 mV and reaches +20 mV due to the entry of sodium and calcium, with a plateau phase due to the balance of calcium entry and potassium exit.

The plateau is a slow phase in the membrane potential lasting about 200 milliseconds due to ion balance.

After the plateau phase, the calcium channel closes and the potassium channel fully opens to allow potassium to exit rapidly, starting the restoration of the cell's negative potential.

The absolute refractory period is a phase during which the muscle does not respond to any stimulus to prevent repeated and spasmodic contractions in the heart.

The absolute refractory period includes phases zero, one, two, and the first part of three, extending until the potential reaches -50 mV.

The relative refractory period starts after the absolute phase, where the cell begins to return to normal potential and requires a strong stimulus to respond.

In the relative refractory period, a new electrical impulse can occur if there is a strong stimulus; this phase is called the supernormal phase and is a critical phase.

Abnormal electrical impulses arising outside the normal pacemaker are called ectopic focus, which may cause arrhythmias such as extrasystole.

The abnormal impulse appearing in extrasystole replaces the normal impulse that occurs during the absolute refractory period, leading to cancellation of the normal impulse.

After extrasystole occurs, the patient feels a strong heartbeat due to the increased amount of blood accumulated during the short cardiac pause.

Extrasystole is an early abnormal electrical impulse that appears before the normal impulse and occurs during diastole when the heart is filling.

Extrasystole is an abnormal ectopic impulse arising outside the normal pacemaker, called premature because it appears early.

Extrasystole occurs due to increased excitability above normal and usually happens after the end of the relative refractory period.

Extrasystole appears in the supernormal phase, which follows the relative refractory period; this period is called the vulnerable period.

Ectopic foci can appear in different locations such as the atrium, atrioventricular node, or ventricle, causing abnormal impulses.

Extrasystole can arise from three locations: atrium (Atrial Extrasystole), atrioventricular node (AV node Extrasystole), or ventricle (Ventricular Extrasystole).

Causes leading to ectopic foci include nervous tension, heavy smoking, psychological stress, as well as heart diseases like arteriosclerosis and infarctions.

Natural causes of extrasystole include nervousness, heavy smoking, emotional stress, and heart problems such as arteriosclerosis or infarction.

Ventricular extrasystole leads to a phase called post extrasystolic potentiation where the next beat is stronger due to increased ventricular filling with blood.

The compensation phase is the waiting period for the third beat which comes late, allowing greater ventricular filling and thus a stronger beat.

The compensatory pause resembles a short cardiac arrest leading to delayed arrival of the next normal beat due to the absolute refractory period.

The normal beat that was supposed to come second appears during the absolute refractory period and thus does not appear, causing the patient to feel that a beat has occurred.

The third beat is strong due to increased calcium released from the sarcoplasmic reticulum and increased ventricular filling with blood.

The delay in contraction onset occurs about 0.2 seconds after the start of phase zero in the action potential and takes longer than one and a half times the duration of the action potential due to calcium entry.

Diastole starts in phase 3 and ends in phase 4, where the cell fully relaxes at the end of diastole.

The absolute refractory period includes phase zero, phase one, phase two, and the early part of phase three in the action potential, during which a new impulse cannot be excited.

only in the pacemaker

cell during pacemaker and this is the one that allows calcium entry, okay?

They are rapidly inactivated producing transient calcium influx.

Calcium influx enters. But then it is transient, why? Because

it undergoes inactivation immediately. There is another type called L-type, okay, its name is

long-lasting L-type and this is present in both.

It is present in contractile as we will explain,

which is the contractile type.

And present in the pacemaker which I just explained, right or not? And these close

late, so it is called that. The third type, the third type is called

the calcium channel type 3 and it can work

depending on membrane voltage, whether the ions inside are more or outside are more.

We said it depends on voltage and ion concentration.

Okay? And of course there are things we said about the pacemaker normally because there are

things we will talk about later. And it pumps three out, which we all

know like a medical student. It brings in two and pumps out three. It

also pumps out three and brings in two. So I hope you

Like a medical student. It inputs two pieces of information and outputs three. It also outputs three, three and inputs what? Two. So I don't wish that you.

Thyroxine hormone.

Thyroid gland hormone.

The metabolism process, energy production also happens what to it?

This pump keeps working the same way, it takes in two pieces of information and outputs three.

What we just said is present in this, it does the funny thing, what the funny thing

We said it takes in what? It takes in sodium. Okay? It tells you and it takes in

Also what? It tells you. Okay, in the fasting sodium. What did we say

That there is something like this, where is it present? We will say it soon. Huh? The fasting sodium

Where will we say it? In the plasma, Sally. This does not split sodium. Don't rush like that.

I will draw you a diagram like it. And the potassium channel, and these are many types. But

All of them do what? All of them let potassium out, and this is what does the

We explained it in what? Which is here. Here. The exit of what? Potassium.

He told you the mechanism that I explained about the pacemaker cell.

What does the pacemaker do? It means it spontaneously fires by itself, and it was

Also regularly, it's the same, the same, the same, the one that fires, it is responsible for, I mean,

What means that it fires spontaneously by itself, which is firing regularly.

As I drew it like this, it is from what I explained and they call it

Because what? Because it is what? That was our start. Then it was

What? Then.

Okay? Here. Here, here. This is our diagram. I had phase four.

I told you it represents what? And it is about minus sixty millivolts, all that, yes. Yes.

It depends on what? For the funny channel to let in what? Sodium and what? Potassium.

This adds with us this thing.

But who is the main for sodium?

The important thing, as he said normally, potassium channel.

Sodium and potassium enter.

The potential difference and as soon as it reaches, as I told you, minus 50.

It opens another channel called the transient one.

To let in what? Calcium. Okay? And what happens? After that happens.

A cell reaches you how much? I told you it reaches a cell at forty. Then from the cell.

At forty, we enter phase zero. What happens in phase zero?

Okay? I told you it opens another channel called what? The long-lasting one. Calcium enters.

Because of calcium movement through inside the cell. It is not

Not what? The entry is not fast.

He says here that because of calcium entry.

Because of calcium movement through this channel.

Okay, inside the cell, it is not fast, okay.

Therefore, the rate of depolarization is what? It is slower a bit.

therefore

the action potential of pacemaker

That is why we call it slow response.

And so what did we call it at first?

I told you pacemaker action potential.

I call it slow response.

Phase 4.

The repolarization was caused by.

Calcium entry.

As a result of what?

Opening of potassium channel.

Or outward potassium.

Along the concentration and electrical.

Gradient, I mean with the concentration gradient.

I mean from higher concentration to lower concentration.

Of course, you didn't start opening, so close the one above, exactly that.

What happens? You close and open what? And potassium goes out and closes.

The one that was what? That was entering. Here.

It stops what? Entering. It continues until we reach back to the original.

To about minus sixty, we return to minus sixty. Or toward, then what? After that.

As we approach minus sixty gradually, potassium starts. And then it starts.

The opposite, wasn't the start that it was entering? Yes, now it starts to open the gate.

What? Sodium, which is to what? We return again to phase four and so on. And this.

This is the drawing I drew, he repeats it again. Okay, what do we notice?

Now? We notice some notes, all we said at first. Which is that.

It fires 110. 110 what? 110, I mean beats.

Per minute. But doctor, my pulse is not 110. My pulse is between.

Sixty to ninety or sixty to one hundred. How is it 110 and my pulse simply.

I tell you that your regulator is what? Your regulator is the parasympathetic.

And the sympathetic, they control the heart rate. And you respond to it.

You tell me doctor, actually I have in the vagal tone the parasympathetic.

What connects? What makes 110 not appear on my heartbeats.

And it appears as if it is seventy-five or sixty or ninety because of the vagal tone.

Parasympathetic. Okay? Now, duto continuous inhibitory is a result of.

Where does it come from? From what is represented in what? In the parasympathetic. Which.

Goes to the SA node and reduces its rhythm from 110 to 75.

The vagus nerve supplies the whole cardiac muscle.

But he made a mistake.

The doctor asks you, does it build.

Vagus nerve.

Be regulatory, be control.

The atrium only.

I mean here.

There was SA node and AV node.

I don't know what and so on.

Correct, and Purkinje fibers.

And what we said.

You are asked and you say, and they say the sympathetic and parasympathetic do regulation for the SA node.

Which are the ones that regulate the atrium and the ventricle also.

And you say, no, be careful now, the ventricle has no relation to the vagus nerve.

Here, the vagus nerve supplies the whole cardiac muscle except the ventricle, and this is a blessing from God.

And this is called the vagal escape phenomenon.

This phenomenon.

Protects the ventricle from abnormally high.

Vagal stimulation.

Which can cause cardiac arrest.

Imagine with me if you.

The vagus worked.

What would happen to it?

Strong stimulation.

And therefore your heartbeats dropped a lot.

Reached for example.

Forty or something.

So if you want.

Your heartbeats or the atrium.

Not affected, no problem.

But the ventricle which pumps blood.

Is affected and becomes forty or less, you are in trouble. You might enter.

If heartbeats are for example thirty or twenty, then the blood that goes.

Because I told you the ventricle pumps blood to the tissue. So the blood that goes.

To the tissue will be enough for them. No. That is very slow, what do you fill with? Heartbeats.

Slow. So all the tissue will die while you every now and then.

Send it a little blood. A little blood. Suppose the rate reaches that what? Heartbeats.

That is what I see the factors that affect it and we can divide them.

If we divide them, I mean, okay, we divide them into those that affect what I told you.

The dialogue, I mean in the end what increases it and what decreases it, okay guys.

Let's see the first thing. The first thing I have are factors related to what like.

Deja just said it works through and decreases, it does what? I mean what? It decreases how?

Through stimulation, it binds to its receptor.

Old term called O, and it does what? Didn't I tell you it makes what.

Was entering and does for it, and I told you based on that, what do you think about.

The slope will decrease. And therefore it will decrease. I mean in the end what will happen? It will decrease.

He tells you in addition to that what? Yes, yes, also not only that.

O goes and stimulates something called, it makes potassium when, didn't I tell you if potassium outside extracellular is higher, this decreases.

Heart rate, right? So acetylcholine closes and increases potassium outside. Okay?

And this also decreases. Okay, second thing, O works through norepinephrine and acts on beta of that, I mean it increases.

Heart rate. The mechanism stimulates beta one. It binds to.

Beta one and works on it. And of course it works how? By increasing.

A second messenger called cyclic AMP. The important thing in the end doctor.

It does what? It goes to the funny channel and increases sodium. So.

You expected. And not only sodium. And calcium. So you expected.

The slope, what do you think about it? What happened to the slope? It increased the slope. While.

Here the slope decreased, so it will take time, how? It will take time until it happens but.

Here the slope increased, so from minus sixty we reached minus forty immediately, so it happened.

While here he said it will take time until it reaches minus forty.

Third thing and the chemical factors. Chemical.

Factors, let's see adrenaline. First thing adrenaline does what?

Increases the rhythm.

And we just said.

And acetylcholine decreases the rhythm.

And we just said that.

Thyroxine.

Thyroid hormone.

Hormone of the thyroid glands.

It stops. Temperature has a certain level. So what happened? If.

And I said below fifteen, also what happens? The heart beat stops. Okay, after.

If I asked you what you think about a thyroid patient

who has hyperthyroidism

meaning they have an increase in thyroid hormones

meaning they have overactive glands

what do you think about their heart rate?

Don't you find their heart rate is fast?

See, their heart rate is fast like this

because of what? Because of thyroxine

Thyroxine has the property

of increasing metabolism

it increases burning so it produces energy

So this thyroid patient you find them what?

warm, warm because

they have a fast metabolic rate or

fast metabolism and energy is released

in the form of heat. The same thing

Thyroxine has what effect on the pacemaker? It increases metabolism

of the pacemaker

so this increases the rate

of energy production inside, so it works faster and what signals does it produce?

Also, there is something else here maybe not written that

thyroxine goes to the receptors that it acts on

who? The ones adrenaline acts on, and it increases their number and increases

the sensitivity of adrenaline to them. Okay? Now, effects of ions.

Effects of ions, we have sodium, potassium, and calcium. Let's

see what the effects of these ions are. What is the effect of sodium?

It is the one that starts the what? Sodium is the one that starts, isn't it?

It was working on it and starting it, right? But it couldn't stimulate it. Why?

I told you it goes from minus sixty to minus fifty only and says goodbye and opens another channel called, so it can't stimulate

what? It needs someone to complete it. What about potassium ion? Didn't I say

that hypokalemia, what happens? Meaning potassium deficiency does what?

And hyperkalemia does what? Hypokalemia increases during it

Let's stay first. Yes, an increase in potassium deficiency is fast. Potassium deficiency

what happens? Potassium deficiency, if you want to know the mechanism,

it comes to the pacemaker and does what? It makes potassium channels what?

close quickly. And when they close quickly, what does that do? It increases the

automaticity causing tachycardia. As for hyperkalemia,

then hypokalemia causes what?

The concentration difference here of potassium

means hypokalemia

potassium goes out

and so what is more outside?

Okay

when hyperkalemia occurs,

hyperkalemia causes bradycardia, right?

It decreases heart rate

That's why I told you when they inject

potassium

the lethal injection

the American one they do

it stops the heart muscle how?

Because potassium causes bradycardia

if you give it in high doses, it stops the heart. Okay? So it stops

the heart. Of course, because potassium when it increases outside the cell

above the concentration of what? From inside, I told you it does what? It

opposes the action or function of what? Sodium that was entering through

So this is the story of sodium and potassium. It says

it can stop the heart. What about calcium? What does calcium do?

Calcium helps in systole. If calcium enters inside the cells, what does it do?

It goes to or causes cardiac systole. Also, hypercalcemia is responsible

for contraction, meaning for contraction. But if it increases greatly,

greatly, it makes the heart muscle in a contracted state

meaning it keeps the heart muscle contracted continuously

and relaxation does not occur in it.

Therefore, it starts to enter what?

a state of contraction

the heart muscle remains contracted, contracted, contracted

you enter a state of continuous contraction

this makes the heart muscle what? Stop

cardiac arrest

Okay

Regarding drugs now,

there are drugs called calcium channel blockers

calcium channel blockers like drugs called verapamil, you will study them in pharma

these go to the gates of what? The calcium channel and close calcium channels

which are the ones that open with activation

So when they do that, calcium does not enter inside

and therefore causes bradycardia

and so this is a treatment used for people who also have

by the way, it is also used in treating hypertension, yes

Okay, calcium shots are dangerous and never give calcium injection quickly. The calcium injection has something called calcium

gluconate, you should know it, it must be taken properly so it doesn't cause death.

Okay, effects of blood gases like what? We have oxygen deficiency and increased hydrogen or increased all that

all that simply decreases because these cells need

oxygen. So when it decreases or acidity increases,

all this reduces energy and affects the enzymes working inside

these cells. So in the end, it reduces. Now give me drugs. Drugs

so drugs that do not work like sympathetic will increase the rhythm

while parasympathetic mimetic drugs will decrease the rhythm

There is a famous drug called digitalis

this drug increases contractility very well in systole, it increases the muscle, makes the heart muscle contract

very well but it makes the sinus node and causes it to be inhibited, closing it

so we used it to cause what? Bradycardia

we used it as if it increases the contractility, we used it in treating heart failure where the heart muscle can't contract

and also since it causes inhibition, I can reduce the heart rate by using what? Using

Okay, now let's come to the effect of toxins

First, there are toxins like diphtheria and typhoid

diphtheria and typhoid are toxin poisons and they affect pacemaker cells causing inhibition

they destroy the enzymes of the pacemaker, so they are inhibited, so in the end the rhythm decreases

Now, the third thing we said is chemical, which we just mentioned, and nervous

and finally physical

Physical factors like what? Like warming

warming, meaning a patient who is warm and their temperature is

a bit high, not just what? No, have you ever seen a patient with high temperature

and slow heart rate? No, high temperature increases, increases, increases because

and every degree of temperature you increase your body temperature

the heart rate increases by ten beats per minute.

When you increase temperature, if your temperature was 37 and became

38, if at 37 your heart rate was 70, when it becomes 38 your heart rate will be 80.

Every degree of temperature you increase increases heart rate by ten beats per minute.

Meaning simply, it increases by ten, like I gave you the example, 70 becomes 80. Okay?

This is what? Because simply it speeds up reactions inside, you know these enzymes?

Temperature increases enzyme activity. So this is not difficult for you now.

Cooling, meaning if temperature is low, what happens?

It decreases, it decreases because it affects what?

It affects and decreases what comes out of it. But be careful if

the temperature is very high above 40, what does this do? It can do what?

It destroys cells, yes, it stops completely because enzymes, guys, enzymes

are present in all cells and enzymes depend on temperature. When

you increase temperature above 45, you break and denature

enzymes and proteins inside cells, so they die

and their function stops. Okay? Now, guys, let's come to or also

high temperature and I meant by cold below 15 also

stops because enzymes that depend on

metabolism and energy production also stop. Temperatures have a certain range.

So what happens if

it goes below 15? Also, what happens? The heart rate stops. Okay, after

that, we have the second property of the heart. Something we said, the heart has four

properties. The first property we took a while ago, right? The second property now, guys

That, we have the second property of the heart. Something we said the heart has four.

Properties. We took the first property a little while ago, right? The second property now, guys.

Which is, right? That potassium starts what? To go out. Then the plateau. And this is what? It is slow. And the membrane is almost.

Stable at how much? I told you zero. Almost two hundred milliseconds.

Because of balance. I told you because of the balance of ions. Which is the exit and entry.

The what? Let's also understand like we did and then go back

to the PDF. First, excitability. Excitability.

What does it mean? It means the heart's ability or the heart's capacity

to respond to a stimulus. That it receives, it receives, it receives a stimulus.

adequate stimuli

Okay, a sufficient stimulus.

So what happens to it?

It makes a response.

Now, the response it will make

will be in two forms.

Well, this response can be

in the form of mechanical contraction

or it can be

in the form of an action potential,

electrical, I mean.

The electrical

the action potential.

But you know

the Action Potential had two forms.

It was Slow

and Fast.

Slow Action Potential.

Right or not, which was represented in whom?

In the Pacemaker.

And you knew there was Fast

Action Potential.

That was represented in whom?

In the Muscle.

The Contractile Muscle Fiber.

The Contractile Muscle Fiber.

Now,

we want to see

how the heart muscle, that is, how does the response happen, the electrical response?

The response of whom? Didn't it turn out to be electricity?

How does the muscle respond to this electricity? That it, what? We want to see

what makes the muscle. Let's draw the diagram, what? The diagram of

the what? What happens in the myocardium. Here.

This diagram here. We will draw here minus ninety millivolts, and here, for example,

zero millivolts, and here twenty millivolts. Let's see what

happens. First, I want a number. How many do I have first? These and these I have.

Let me draw a little above. And I have what we call

the plateau. The plateau in. The plateau. Okay? And I have what is. Now let's

take phase 0, which is depolarization.

So phase 0 is rapid depolarization.

If you ask what causes rapid depolarization,

what causes rapid depolarization? First, what happens? Calcium enters.

Calcium entry opens voltage gated fast channels.

We call it fast sodium channel.

So sodium enters.

It enters through what?

It enters, so we call it fast, so we call it. And the potential goes from minus ninety millivolts

to how much? To twenty millivolts, which is up to here. The potential reached

from minus ninety to minus, to minus twenty millivolts. Okay.

Not minus, sorry, yes, plus one hundred and,

because it's not minus since we passed zero.

Okay, plus one hundred plus twenty millivolts. This is due to what, guys? This

is due to calcium entry. This is phase zero. Then

what happens? Phase one. Phase one, which we call because this is

the part where what happens? Because of closing, what happens? You will start

to close the previous phase. Close the previous one. So you close

what is called gate and open what? Open a gate for potassium here and potassium exits.

Like this. Potassium what? Exits potassium.

So here what happened?

Potassium efflux through gates called

potassium efflux. Potassium comes out like this.

Okay. The result here is what? The potential decreased, what? It reached

twenty millivolts. The potential reached twenty millivolts. This is called

but at the beginning. Let's continue. We have in the myocardium three phases. The first,

second, and third. All of them. The second we call the plateau phase.

And note that the plateau phase was not present in any of the action potentials nor in

the plateau. Okay, let's see what happens in the plateau and I'll tell you why it's not

present. The plateau, which is phase two, happens in what? Here,

the plateau has a balance between ions. Therefore, note that it is present

at zero, so here there is an ionic balance. If

something enters and something exits. And this is what really happens in the plateau

phase. Because calcium enters and potassium exits.

Calcium enters and potassium exits.

So there is calcium influx and potassium efflux. Okay? So this is what? The exit

of potassium and entry of calcium. Now the importance of calcium

in the plateau phase is what? Because the calcium here, guys, is

what will do, what is important in the contraction process. It will go

to calcium stores. Okay? Inside the cells. Okay? Inside

the muscles. And it releases calcium and does what? Okay? Does what? Does

contraction. Yes, and therefore what? Therefore, in this phase, what happens

from the beginning, the process starts especially in the process. And therefore here in

it happens that the muscle cannot feel any stimulus.

The muscle cannot receive another stimulus. Why? Doctor, here I tell you

can two happen at the same time? No. So

here it happens, but it cannot happen while we started, it cannot happen that the muscle contracts again. Okay? So this is the benefit.

What happens in it? And calcium entry which is important in contraction.

In muscle contraction. Okay, what else happens? But this is what

happens in. Let's continue to the third phase which is what happens

also? Potassium exits again. But this time potassium

exits in large amounts. Okay? Potassium exits in large amounts. So this is

called repolarization. Here we closed the calcium channels. Okay.

I told you when you start phase, close the old channels you left behind.

And potassium starts to exit in large amounts. Potassium exits

in large amounts. Okay? The result here is what happened? We restored

our potential and returned to minus ninety. We reached minus ninety. We reached

minus ninety. Then we enter phase four. So this is

phase what? The phase above. Which is this phase where you need to return

and complete, that is, return the ions to their normal place. Which

is to operate your pump called because potassium should not

be outside. It should be inside. So this pump here is a pump that takes

potassium in and pumps sodium out to restore the normal distribution

that God created in the ions. Okay? Now, what else?

And also it works even sodium calcium pump.

So that also to restore the cell's natural ions.

Okay, so this is the action potential that happens at the muscle level.

Now let's see what? The excitability here

means what? The heart's ability to respond to a sufficient stimulus that makes the muscle respond. This response

is in two forms. Either you have, either it comes out in the form of

cardiac muscle cells self-excited, meaning, of course, we said it is self-excited because

it produces action potentials by itself by the pacemaker, old stuff, and conducts or

transmits this electricity through the AV node, bundle branches, and Purkinje fibers.

Okay? To produce cardiac muscle conduction or what we call fast response.

Because after that it goes to and does what we call.

The interval what? Okay. Then I tell you. We said minus ninety, okay. And then minus

zero which is the response.

Caused by what? From minus ninety I told you it reaches plus twenty as a result of what?

Through what? Or or then the rapid what? Here it is called because you were producing and then what? Show

something simple. It happens and then it closes, right? Show, so we call it what?

Meaning something what? Not not, okay. Simple. As a result of closing the previous channel.

Which is, okay? That potassium starts to exit. Then the plateau. And this is what?

It is slow. And the membrane almost holds steady at how much? I told you at zero. Almost two hundred milliseconds.

Because of its ionic balance. I told you because of the balance of ions. Which is the exit and entry.

Exactly, if you did it twice in a row, when will the heart fill?

So it fills what? It allows enough time for the heart to.

Fill. Now we have something called what? We finished something called.

Phase B. What is this? This phase, what happens in it? This phase.

Calcium. And as a result, the long-lasting channel opens, right? And where was this located? In the D start D that opens even in its readiness for calcium entry.

As soon as it reaches minus forty. As soon as it reaches minus forty, it starts, meaning it remains, what? The channel remains open before what? Before it undergoes what? This is what? This is the calcium channel. Right?

And what else happens? Potassium, what happens to it? It goes out. Then what was it? The one below, which is the result of closing the previous channel, which is the channel, and then the potassium channel opens, maximum activated.

I said potassium goes out with what? Fast, fast potassium flux. And finally, we reach the resting membrane potential. Right?

Then what do I wait for? For it to happen again and we repeat the same idea from the beginning. And this is the drawing we drew together. We made a comparison between what happens in the pacemaker and the slope.

Here it was minus ninety, there it was minus sixty or minus fifty-five step. Here it was there, I told you why God made it to be ready to immediately release electricity, to release it immediately. Right?

Here, ours, which is what? This one, which is represented by sodium entry. But there, the upstroke is a bit slow, which is the sodium entry we explained.

Here, as a result of calcium, we reach how much? We said here plus twenty. There, we said plus ten millivolts. The plateau is present here, but here there is no plateau.

Why, doctor, is there no plateau? I'll tell you, my dear, you want to know? Here, no. The plateau was caused by what? Calcium entry and potassium exit. Calcium was causing in this phase of the plateau.

So, do you need phase one, phase two, and phase three? But there, only.

Then, guys, we talk about something called the absolute refractory period.

What is the absolute refractory period, doctor? I'll tell you now. This is the phase in which you have no response to excitability.

Meaning, here is the phase I explained to you, where I said when it is like this, like this, like this. I told you here or even not only from zero, one, two, and the first part of three, you cannot have here another occurrence.

It cannot happen, meaning the heart cannot feel or respond to any other stimulus. Why, doctor? Because here, something is happening. Two cannot happen together, otherwise the heart will have a problem called the heart being tetanized and it will enter what?

It may die, meaning. Therefore, here, this phase is represented by zero, one, two, and the early part of three.

But if it happens after what? You continue quickly normally, we finished the contraction, thank God. Then you can go out normally and respond.

So you have the absolute refractory period, meaning there is no response. Here it is, what? It says in zero, one, two, and the early part of three and part of three. Right?

Until we reach full minus fifty. Uh, yes, meaning the phase which is zero, one, two, and three represented by what? Represented by, what doctor? Meaning represented by the systole phase.

Meaning if I want to draw the systole for you, the systole is represented like this. Draw it like this. This is the systole, the period in which the heart contracts.

Then, meaning zero, one, two, and three, which is the yellow part going up, this is the systole, the contraction.

Then the diastole. So it tells you here mine is considered to include the systole phase and also part of what? The diastole, which is the period in which the heart undergoes relaxation.

This is the stole, while the systole is the phase in which contraction of the heart and pumping of blood occurs.

The importance of the long acting, which I mean, the absolute refractory period, which is the phase in which the heart does not respond to any stimulus.

Its importance is what? I told you, it prevents something called tetanus or tetanized.

That the heart undergoes tetanus, it spasms from the risk of contraction.

And it prevents cardiac fatigue because if it gets two contractions.

If it happens twice at the same time, the heart will get tired. It allows time for the heart to fill.

Exactly, if you do it twice in a row, when will the heart fill?

So it allows enough time for the heart to fill. Now we have something called, we finished the thing called.

B. What is this? This phase, what happens in it? This phase is supposed to be finished from zero, one, two, and three and started to go down to what?

Started to go down, right? In this period, you start to go down until you reach what? Minus seventy-five.

You kept the last one with me at minus seventy-five millivolts. So here, minus seventy-five millivolts, and you are going down from what? From above, from almost zero, down to minus seventy-five.

Can your body respond to something? No. Here, I mean, to respond to something, you need a strong stimulus.

Because from zero to minus ninety, there is a big voltage difference. So you need a strong stimulus to produce electricity for you.

Therefore, here your body does not respond. Here you start to recover the normal state, meaning you cannot respond to something here, but what?

But why? Because I just tell you if something comes to you, maybe, but yes, the voltage difference from zero to minus ninety is very far, so something making you here is difficult.

So here, it is the same, he said, it is not like the one above. Here, it is impossible for something to affect you, but here, if something strong happens, maybe.

That is why they called it relative. Right? Because you started to return to normal, here it is until you reach minus seventy-five.

And this phase is the remaining because zero, one, two, and three, part of three, which is all the systole, which is the yellow part, and part of what? And part of the rest.

This is the stole represented in the problem we have. There is something strange, guys, listen.

It needs some thinking here. The cell started to go down to what? We started to go down to minus ninety, right?

We said from minus seventy-five to minus ninety, we continue on the relative. We reached minus seventy-five.

You, by the way, minus seventy-five millivolts is close to minus ninety.

Meaning here, it is not possible for something strange to come out alive as a pulse.

Because we are almost close to normal.

So something might have the ability to produce electricity.

And produce electricity and cause a new action potential outside the SA node. You will say, doctor, didn't you tell me the SA node is the one working?

Yes, but in pathological cases, there are pathological cases.

Where something called ectopic focus happens.

And this ectopic focus, doctor, is ectopic, meaning external, and focus means a point.

A point outside the SA node.

It has no relation to the SA node.

It produces electricity, so it takes advantage of the fact that you are close to the voltage.

It became from minus seventy-five close to ninety, close to minus ninety.

It suddenly fires at this phase.

So this is called supernormal.

And this is a dangerous phase, so we call it vulnerable.

Meaning a critical or dangerous phase.

Here, excitability is higher than normal.

Meaning here the cell can be excited faster than normal.

Because here, you are close to minus ninety.

It happens when? In the last part of phase 3.

It follows after the relative until the membrane is fully repolarized.

It happens at the end of diastole.

And this is a dangerous phase.

Right?

Supposedly, you finished, yes, from zero, one.

Then two, three and started to go down to what? Started to return to the normal voltage of.

It started to go down, right? In this period, you start to go down until.

You reach what? Minus seventy-five. I kept the last one at minus seventy-five.

Millivolts. So here minus seventy-five millivolts. And you are going down.

From what? From above, from about zero, down to minus seventy-five.

Can your body respond to something? No. Here I need a strong stimulus.

Because from zero to minus ninety is a big voltage difference.

So you need a strong stimulus to produce what? To produce electricity. So here your body does not respond.

Here you start to restore normality. That is, you cannot respond to something here. But what?

But why? Because I just tell you if you get, maybe. But yes.

The voltage difference from zero to minus ninety is very far. Something does something hard for you here.

So here it is the same, he said, it is not like above. Here.

It is impossible for something here to affect you, but here maybe if something strong.

Maybe. That is why they said relative. Okay? Because you started to return to normal, here it is.

Until you reach minus seventy-five. And this phase which is left because it was.

Taken zero, one, two, and three. Part of three, which is.

All systole, which is in yellow here. And part of what? And part of the rest.

This is systole represented in the problem we have, something strange, guys, you hear.

This needs some thinking here. The cell started what? To go down to what? Started, we started.

To go down to what? Minus ninety, right? We said from minus seventy-five to minus.

Ninety, we continue the what? On the relative. We reached minus seventy-five.

You basically. Isn't minus seventy-five millivolts close to minus ninety?

Meaning here, it is not possible for something strange.

To come out alive as a pulse.

Because we are almost close to normal.

So maybe something has the ability.

To produce electricity.

And do what? Produce electricity and cause.

A new action potential outside of.

The SA node, you will say doctor, didn't you.

Tell me the SA node is the one working, yes, but in pathological cases.

In pathological cases.

Something called.

Ectopic focus.

And this ectopic focus, doctor, is like a cow.

Ectopic means external and focus means cow.

A cow outside the SA node.

It has no relation to the SA node.

It produces electricity, so it exploits that you are close to the voltage.

It became from minus 75.

You got close to ninety, here you got close to minus 90.

Then it produces at this phase.

So this is called supernormal.

And this is a dangerous phase, so we call it.

Vulnerable.

Meaning a critical or dangerous phase.

Here the excitability is higher than normal.

Meaning here the cell can be excited.

Faster than normal.

Because here, because you are close to.

Minus ninety.

It happens when in the last part of phase 3.

It follows after the relative.

Until the membrane is fully.

Repolarized. It happens in the end diastole.

And this is a dangerous phase.

Okay.

Dangerous period in which the excitation.

That the heart is like you made the video pause.

Like you stopped the heart.

As if the heart stopped for half a second more, it says what is this?

Meaning no one came.

Okay, so from them, it became a little more.

wave lead to cardiac arrhythmia

And here unfortunately

it causes something called arrhythmia

like ventricular fibrillation

and I imagine with me I'm telling you that the alb

and it beats one beat and the second and the third. That's normal. I came and told you doctor you have ectopic focus. Honestly this ectopic focus leaves you

fall what happens the first beat the second and then it goes up here count minus five

and seven. And it makes you the fourth beat. As if you were beating one two three

became one two three four. In two beats five and four. The two beats five and four what is their cause? Their cause is that happened in that ectopic focus

and this is what we will explain below

this causes a disease called what now

extrasystole

extrasystole is due to a

strange beat coming from outside

the pacemaker we will explain it to you now

so you understood

the part of the supernormal phase

come now because this part is annoying

and to explain it to you I will give you an example

better to clarify this talk to you

what is this extrasystole

Doctor extrasystole

extrasystole my dear that you have the heart it was

honestly it was working perfectly. One day suddenly here appeared

a cow named also it started to moo. So if I give you an example just

this example that will clarify all this talk. If I give you an example now.

the natural generator in my body what will it produce? Uh three

beats beat and beat and a beat. The first beat will come at the first second.

and the second beat will come to me. Okay? And the third beat

will come to me what at the third second. So I have three beats.

I don't have the disease called yet. And let's suppose that something happened to him.

what will happen? Suddenly at one and a half seconds. Suddenly at

what? At one and a half seconds here like this. A beat appeared here

at one and a half seconds

what will happen doctor

at one and a half seconds

what happened first

the heart contracted normally

it happened

contracted normally

it came at one and a half seconds

and contracted again

it was supposed to contract at the second second

but what happened a strange cow appeared

it appeared so

it appeared at one and a half seconds

we want a bigger drawing but okay

it appeared like this at one and a half seconds

okay

so this is the first beat

and this is the second beat but a strange beat

so where does the normal second beat go doctor?

unfortunately now

the normal second beat comes to

meaning it comes out

you find that the heart is in the absolute

refractory period that we mentioned

so the second beat appears

does not appear because the strange beat

took its place

so the second beat says to it

move aside

the heart tells it move aside

I have a beat working I can't contract

because I told you you have absolute refractory period

so here

the heart took the first beat

okay and took the second beat okay

took the first beat at second

and took the first second beat at one and a half seconds

so what about the absolute refractory period

it will continue for

for example 0.4 seconds

or 0.3

meaning the heart like this unless something happened

meaning the heart like this

remained

okay so the heart now

what happened the heart like this

working from the first second

to the second second

which is one and a half seconds and zero point four

meaning it remains two seconds

and the second second was canceled because we are in

the absolute refractory period right or not?

okay

and the third second

so the second second was canceled so who remains the third second

imagine now you are sitting from the second

from one and a half seconds to the third second

became one and a half seconds this

is a very long time guys

I said between each beat and beat is one second

but you counted one and a half seconds

so the heart took a long time

to reach the third beat

why doctor the second beat was canceled

so it took time

until we reach the third beat

will this cause a problem? It will cause a problem I will tell you about it

okay so you took a pause like this

the heart stopped saying

guys where is the third beat

I am late now by half a second more than my time

and it does not know that because a strange beat came

took the place of the second beat

so the second beat when it came after half a second

did not find its place it found its place in

absolute refractory period

so the third beat came

as I told you after a full one and a half seconds

okay after a full one and a half seconds

meaning the heart

took longer than normal right or not?

and that's why the patient tells you doctor

I felt my heart stopped

all of a sudden like this

I felt a beat dropped from me

the heart stopped all of a sudden because it took

a full one and a half seconds

so there really was a beat dropped from the eye this

okay and after a while

he tells you what and tells you after

they call it post

extrasystole

potentiation he tells you after a while

he tells you when the

third beat came doctor meaning he finally

felt that his heart what stopped a little

but when the beat came after it guys

this patient said what

he told you I felt after my heart

stopped a little a very strong contraction

what is the cause of this contraction guys

if I ask you you will say the heart

stopped one and a half seconds

so it took time to fill

so it filled a lot of blood

so when it contracted

the contraction was loaded with blood

so it made what

a strong beat

I hope it is clear because the topic is what

needs an example like this

okay this extrasystole is a pathological condition in which there is an abnormal impulse a strange beat abnormal coming from ectopic focus outside the normal pacemaker and this is expressed as abnormal systole premature premature means what means it came early so they called it premature second and a half before it comes what happens in the diastole phase in which the heart fills

extrasystole is due to what excitability

above the normal

which usually occur after end of relative

uh when does it happen

this extrasystole happens after the end of the

relative refractory period

okay which is when in the supernormal

phase in the previous phase

and you in the supernormal phase when you were close

to the resting membrane potential

and it appeared that what the beat

okay where does it happen in the supernormal phase

or at the end

at the end of the RRP

or at the beginning of the Supernormal phase

that's why we call it the Vulnerable period

so the Abnormal site of ectopic focus

there are 3 places where this cow can come

the first place is the Atrial

at the Atrium

the Auricle we call it Atrial Extrasystole

or at the AV node

at the AV node we call it AV node Extrasystole

or in the Ventricular

we call it Ventricular Extrasystole

the causes

natural things

that you are nervous

your nature is nervous

Heavy smoker

or emotional

sadness and stress. Things that cause problems at the level of what? The heart. It happens to you.

like for example uh atherosclerosis or heart attack. Uh okay what happens?

there is.

ventricular extrasystole.

called post extra systolic potentiation

the compensation

this compensation phase guys

which is the phase

in which the heart is waiting

for the third beat to come and it was delayed

it took one and a half seconds

so when it was delayed the heart was filling

more blood because it was waiting

so it filled more blood

and the next phase listen to what

post extra

or post systolic potentiation

or post extra systolic potentiation

which is what

when the third beat came it came strong

because it filled more blood

okay

the Explanation now explains why the Compensatory Pause happened

the Compensatory Pause which is what

that the heart as if you made the video pause

as if you stopped the heart

as if the heart stopped for half a second more it says what is this

meaning no one came

so what happened then a little more

it says Arrival of the normal

Due to Arrival of the normal heart beat

It says to you Arrival of the normal.

Due to Arrival of the normal heartbeat.

It's like the heart stopped for an extra half a second, what is this saying?

I mean, no one came.

So from them, it became a bit more, what else?

It tells you Arrival of the normal

Due to Arrival of the normal heart beat

As a result of the Arrival of the normal heart beat

that was supposed to come at the second

appeared in the absolute

refractory period, so what

the heart won't show it, say goodbye to it

what do you call it, Mazed?

Mazed or dropped beat, which is when the patient comes

and tells me that they felt a missed beat

okay, the excitability here

is zero, and we know in the absolute

refractory, but the longest

is the post extrasystolic potentiation

no, here it happened as a result of the large

amount of calcium from

sarcoplasmic reticulum

in addition to increase

ventricular filling

the ventricle was filling with blood when we delayed it

plus calcium also from

inside from sarcoplasmic reticulum came out

this when it created this created

so it created the ventricle to increase

increase the blood volume

and therefore when you do

it becomes strong

and so in the end what happened

the time of

with with with this this means what happened here? what happened in the end?

guys? what happened is that you have uh the time that means there is a time the time of

and the time of okay? and the time became that of the third beat which

only and this is what we explained. Okay, so what do we say now?

the last thing in the file we tell you something called.

what? that here it tells you which is of

it starts. As I told you I drew the systole what? it starts what? after

approximately it starts at zero point two. zero point what? two

seconds what? it takes what? more than approximately one and a half times. one and what?

meaning the start of contraction happens after what? after which is with zero point

two. so contraction happens when? after phase zero at zero point

two seconds. okay? and it is delayed. it is delayed, it takes what? it takes uh

approximately uh one and a half times the action time. why this delay? this delay

is due to the result of calcium entry as I told you and it goes to and acts on

the muscle in the myosin and actin of the muscle so it happens. it reaches

its effect at the end of the plateau. because what happens in calcium entry.

where does diastole start? diastole. it tells you here diastole starts at

phase three. at phase what? three.

and it ends of course and ends at what? at the bottom. so here it tells you

the second half of diastole. okay? which is phase four. here the cell

was completely rested. but what happens at the dead meat

that happens in the sun uh happens in the rapid

rapid phase. this is the start of diastole. or okay? while the end

of the last part of diastole happens where? in phase five and we have reached okay?

okay and so we have explained

here it tells you this is our action potential here

and the absolute refractory period

which we said is what

includes phase zero

and includes two and three

the early part of the stall

and here as I drew for you

the contraction

and then the stall

and the stall

and this is the absolute refractory period phase

and I hope you found the lecture