Lecture 5: Cardiac Cycle and Sound

Question 1

What is systole and what phases occur during it?

Answer 1

Systole–> ventricular contraction

-Isovolumentric ventricular contraction and ventricular ejection

Question 2

What is diastole and what phases occur during it?

Answer 2

Diatole–> ventricular relaxation

Isovolumetric ventricular relaxation

Ventricular filling

Question 3

Aortic pressure

Answer 3

120/80

Question 4

Ventricular pressure

Answer 4

120/0

Question 5

Ventricular volume

Answer 5

120/~50

Thus, the volume of the ventricle is never at 0.

Question 6

Atrial pressure

Answer 6

15/4

Question 7

What is atrial systole?

Answer 7

Atrial systole is the contraction of of the atria.

Contraction of the atria is initated by the firing of the SA node, causing it to depolarize first.

As a result, they are the first to contract, increasing pressure in the atria.

When RA pressure > RV pressure: AV valves open–> [blood]–> RV.

Filling of the ventricle SLIGHTLY increases ventricular pressure.

Question 8

When the RA pressure > RV pressure; what occurs?

Answer 8

Ventricular filling.

Blood moves from the atria –> ventricle.

Question 9

What is represented by the P wave?

Answer 9

Atrial depolarization and contraction.

Question 10

What is ventricular systole?

Answer 10

Contraction of the ventricles, causing an increase in pressure.

Question 11

What occurs when peak systolic pressure is reached?

Answer 11

It begins to fall even though the ventricle is still contracting, because blood is still leaving.

Question 12

Why do we see atrial pressure increase during ventricular systole?

Answer 12

Filling of the atria with blood because blood is returning to the heart, but cannot move into the ventricule bc RA<rv.>
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Question 13

What is ventricular diastole?

Answer 13

Relaxation of the ventricles, causing a decrease in ventricular pressure

Question 14

Where does ventricular diastole occur on the ECG and on the AP?

Answer 14

T-wave (ventricular repolarization)

Phase 3

Question 15

What ion is inside the myocyte to cause contraction?

Answer 15

Ca2+

Question 16

Where can we see a ventricular systolic pressure of 120 on the EKG?

Answer 16

ST segment

Question 17

What does a ventricular diastolic pressure of 0 mean?

Answer 17

Atrial pressure> ventricular pressure.

Thus, ventricular pressure will begin to increase as soon as blood begins to flow in.

Question 18

Systole/diastole: atrial pressure >ventricular pressure

Answer 18

Diastole

Question 19

Systole/diastole: ventricular pressure > atrial pressure

Answer 19

Ventricular pressure

Question 20

How does contraction affect pressure?

Answer 20

Contraction will increase pressure.

Question 21

Describe the process of ventricular filling (ventricular diastole=relaxation)

Answer 21

1. Atrial systole is occuring–> atria is contracting, which is initiated by the firing of the SA node. Atria depolarizes first and then contracts; causing an increase in atrial pressure
2. When [atrial pressure > ventricular pressure]: AV valves open–> [blood]–> ventricule
3. Ventricular filling causes a slight increase in ventricular pressure.
4. Ventricle relaxes to accommadate blood.
5. At the end of diastole, atrial kick forces the last bit of blood out before systole begins. Thus, the last bit of blood moves out d/t contraction, not the pressure gradient.

In this stage, semilunar valves are closed because the pulmonary artery/aorta pressure > ventricular pressure.

Question 22

Describe the process of isvolumetric ventricular contraction (ventricular systole)

Answer 22

Now that the the ventricle is full of blood, we have to increase pressure in the ventricle so it is greater than pressure in the outflow tracts.

-AV valves and the semilunar valves are BOTH closed.

Ventricular pressure > atrial pressure: AV valves closed.

Pulmonary artery/aortic pressure> ventricular pressure: Semilunar valves are closed.

Ventricular muscle begins to contract, so that we can build up pressure. However, there is no change in volume.

Phase ends when ventricular pressure > outflow pressure.

Question 23

Describe the process of ventricular ejection (ventricular systole)

Answer 23

1. Ventricular pressure > Outflow pressure: semilunar valves open–> [blood]–> outflow.
2. Ventricular pressure increases as contraction occurs, keeping the AV valves closed.
3. Atrial pressure increases slightly because they are begining to fill with blood.
4. As blood goes into the outflow tract, aortic pressure increases.
5. Eventually, ventricular volume decreases, ventricular pressure decreases and aortic pressure decreases, even though blood is still being pumped into it as ejection slows down.
6. When outflow pressure > ventricular pressure; semilunar valves close
7. Aortic and ventricular pressures diverge rapidly.

Question 24

What is the dicrotic notch?

Answer 24

Dicrotic notch is produced when the ventricular pressure drops below that of the aortic (outflow) pressure and the aortic valves CLOSE.

Ventricle begins to relax.

Here, the two pressures will begin to diverge rapidly

Atrial pressure shows a similar wiggle because now that the ventricle is begining to relax, the force on the AV valve (Which kept it closed) is released.

Question 25

What causes the atrial wiggle in the atrial pressure that we see at the dicrotic notch, when the ventricular pressure \< aortic (outflow pressure)?

Answer 25

Now that the ventricle has ejected all of the blood, it is relaxing, decreasing the force that held the the AV valve shut.

Question 26

Describe the processes of **isovolumetric ventricular relaxation (ventricular diastole)**.

Answer 26

In this stage, **all the valves are shut** and there is **no change in the volume of the ventricle.** 1. Aortic (outflow) pressure \> ventricular pressure because the aortic pressure is being controlled by peripheral run-off: semilunar valves closed ---but--- Ventricular pressure \> atrial pressure: AV valves closed. 2. Ventricles continue to relax 3. Decrease in ventricular pressure 4. Ventricular pressue \< atrial pressure 5. AV valves open, marking the begining of ventricular filling.

Question 27

**During diastole**, the **aortic pressure continues to drop** (and will continue to do so thoughout, why?

Answer 27

Blood is leaving the aorta and flowing into smaller vessels in the periphery. The rate of the peripheral run off is determined by the resistance to blood flow.

Question 28

What pressure does the **L and R ventricle** have to be at for the blood to enter FROM the atria?

Answer 28

Ventricular pressure has to be the **LOWEST of all pressure during diastole** for blood to enter the ventricle

Question 29

When the AV valve opens, what is the ventricular pressure and volume? What is the affect of this?

Answer 29

Ventricular volume and pressure are both **very low.** Thus, **blood** will **flow** into the ventricles **rapidly**.

Question 30

What are the three waves on the jugular pressure wave?

Answer 30

A wave C wave V wave

Question 31

Describe the jugular pressure wave.

Answer 31

**A wave**--\> caused by the contraction of the atria, pushing back on the jugular vein **C wave--**\> due to isovolumentric contraction of the ventricles, causing the atria to bulge backwarfs **V wave**--\> pressure wave created as blood goes back to the heart, but cannot enter the ventricles.

Question 32

What comes first: contraction of electrical activity?

Answer 32

Electrical activity--\> contraction

Question 33

What ECG wave occurs when Na+ influx is occuring in the atrial myocytes? Compared to the increase in atrial pressure, when does it begin?

Answer 33

**P wave.** **P wave will begin right before the increase in atrial pressure.**

Question 34

What does the difference in time represent from the P wave onset and the increase in atrial pressure?

Answer 34

**The time it takes for the atria to contract.**

Question 35

What is the PR interval?

Answer 35

The pause between the depolarization of the atria and ventricles, caused by the slow conduction velocity of the AV node.

Question 36

What happens once the AV node transmits the AP to the ventricles?

Answer 36

Bundle branches and purkinje fibers transmit the AP to the ventricle, depolarizing the septum and free wall of the both ventricles from the apex, up.

Question 37

On the ECG, ventricular depolarization is represented by what?

Answer 37

QRS complex.

Question 38

What comes first: QRS complex or the increase in ventricular pressure?

Answer 38

**QRS complex.**

Question 39

Does ventricular contraction occur through the QT interval and ST segment?

Answer 39

**Yes**

Question 40

What phase is the ST segment?

Answer 40

Phase 2

Question 41

What is the T wave?

Answer 41

T wave- start of ventricular repolarization. It begins before relaxation of the ventricle. Ventricular pressure starts to fall as blood is ejected out of hte ventricle because there is less blood to push out, so there is a decrease in pressure--\> [relaxation].

Question 42

What are the 4 heart sounds?

Answer 42

S1- AV valves close S2- Semilunar valves close S3- rapid filling of the ventricles (mostly seen in kids) S4- Atrial contraction (last bit of blood squeezing into the ventricle)

Question 43

S1

Answer 43

Lub- caused by AV valves closing. The sound is due to blood in the atria hitting the closed valve as it tries to enter the ventricle, causing cardiac tissue to vibrate.

Question 44

S2

Answer 44

Semilunar valve closing. Blood in the outflow tracts backflow and bounce off the close valve.

Question 45

S2 Dubà Semilunar valves closingà blood in the aorta and pulmonary artery backflow and bounces off of the closed valves. ## Footnote **Why does the blood backflow?**

Answer 45

**Gravity pulls the blood down when the valves close.**

Question 46

What are the 4 heart sounds a result of?

Answer 46

Blood moving in the right direction.

Question 47

When do we hear a murmur?

Answer 47

1. Blood is moving a direction is shoulding 2. Blood is having a hard time moving in a direction that it should

Question 48

Murmurs can be heard in **_systole, diastole, or both_**

Answer 48

**BOTH**

Question 49

What causes a systolic murmur?

Answer 49

* Blood is moving back into the atria, due to regurgitation (mitral regurgitation) * Blood cannot get into the aorta/pulmonary artery d/t stenosis.

Question 50

What causes a diastolic murmur?

Answer 50

* Blood is moving back into the aorta or pulmonary artery due to aortic regurgitation. * Blood cannot get into the ventricle due to stenosis.