Cardiac Cycle & Control of Cardiac Output - Quiz 3

Question 1

Ventricular Systole

Answer 1

Phase 2: Isovolumic Contraction

Phase 3: Rapid Ejection

Phase 4: Reduced Ejection

Question 2

Ventricular Diastole

Answer 2

Phase 5: Isovolumic Relaxation

Phase 6: Rapid Filling

Phase 7: Diastasis

Phase 1: Atrial Systole

Question 3

Atrial contraction is ____ essentatial for ventricular filling.

Answer 3

NOT Essential

More important for faster heart rates

Accounts for 10% of LV filling

Question 4

When does most of ventricular filling occur?

Answer 4

Phase 6: Rapid Ventricular Filling

• AV valves open, Aortic and Pulmonic Vavles Close
• Passive filling

Question 5

Opening of AV Valve produces what sound?

Answer 5

• No heart sounds opening of any normal valves
• S3 may be present and normal in children during rapid filling d/t tensing of chordae tendinae and AV ring.
• Not normal in adults = Ventricular Dilation

Question 6

Closure of Aortic and Pulmonic Valve produces what sound?

Answer 6

Produce S2

Question 7

Closure of AV Valves produce what sound?

Answer 7

Produce S1

Question 8

What does the incisura or dicrotic notch of aortic pressure tracings mark the beginning of ?

Answer 8

Diastole

Aortic and Pulmonic Valve Closure

Question 9

During what cardiac phase does the Mitral and Aortic valve both close?

Answer 9

Phase 2: Isovolumic Contraction

All valves are close

QRS = ventricular depolarization

Phase 5: Isovolumic Relaxation

• All valves closed
• Ventricular volumes constant

Question 10

Various Waves of CVP

Answer 10

a: atrial contraction
c: ventricle contraction
v: slow atrial filling, AV valves close

x descent: base of the atria are pulled downward decreasing initial atrial pressures/

y descent: opening of the AV valve that causes a massive fall in pressure

Question 11

What signifies the first heart sound?

Answer 11

Closure of the AV Valves

(Triscuspid and Mitral)

Question 12

What signifies the second heart sounds?

Answer 12

Closure of Aortic and Pulmonic Valves

Question 13

When does the majority of blood ejection from the LV happen?

Answer 13

Phase 3: Rapid Ejection

• Aortic and Pulmonic valves open, AV valves stay closed
• About 70% ejected

Question 14

How much does Atrial Kick contribute to Ventricular Filling?

Answer 14

About 10%

• At Higher HR, atrial kick up to 40%
• In A-Fib, atrial kick is 0%

Question 15

4 Major Determinants of Cardiac Output

Answer 15

Heart Rate, Contractility, Preload, and Afterload

CO = HR x SV

SV = EDV - ESV

EF = SV
EDV

Question 16

How can Stroke Volume normally be increased?

Answer 16

Increase End Diastolic Volume (EDV)

OR

Decrease End Systolic Volume (ESV)

Question 17

What is the Bowditch Effect?

Answer 17

Autoregulation - Increase in heart rate will cause Positive Intropy

AKA: Treppe Effect/Staircase Phenomenon

Due to Na/K ATP pump unable to keep up with influx of NA at higher rates –> more intracellular calcium.

Question 18

Why do extremely high heart rates result in decreased Cardiac Output?

Answer 18

Decreased Stroke Volume due to decrease filling time –> decreases End Diastolic Volume

Question 19

The name of the phenomenon where Preload increases and Cardiac Output increases

Answer 19

Frank-Starling Mechanism - Upward curve shift

Question 20

As PRELOAD decreases, CARDIAC OUTPUT decreases. This is called?

Answer 20

Frank-Starling Mechanism - Downward curve shift

Question 21

What keeps the CARDIAC OUTPUT of the ventricle matched with venous return?

Answer 21

Frank-Starling Relationship - Stretching of the ventricle results in increased force of contraction

Question 22

What keeps the CARDIAC OUTPUT of the right and left ventricles matched?

Answer 22

Frank-Starling Mechanism

Question 23

Factors that Affect Ventricular Preload (7)

Answer 23

• Venous BP
• Venous Volume
• Filling Time (HR)
• Ventricular Compliance
• Atrial Contraction
• Inflow/Outlfow Resistance
• Ventricular Systolic Failure

Question 24

What is the Frank-Starling Relationship?

Answer 24

Increases venous return, ventricular filling, and preload leads to increased stroke volume

Question 25

What is the Y-Axis of the Starling Curve?

Answer 25

Stroke Volume

Question 26

What is the X-Axis on the Starling Curve

Answer 26

Left Ventricule End Diastolic Pressure (LVEDP)

Question 27

Factors that Cause Increased Afterload

Answer 27

Aortic Pressure Increased SVR Aortic Stenosis Ventricular Dilation

Question 28

How does After Load effect Cardiac Output

Answer 28

Increase in Afterload decreases Cardiac Output

Question 29

Does ventricular wall hypertrophy have more of less wall stress?

Answer 29

⇣wall stress/afterload on individual fibers because there are more parallel fibers to share the stress. Think of it as an adaptive mechanism, by which the ventricle is able to offset the ⇡ in wall stress that is associated with ⇡ ventricular systolic pressures or ventricular dilation.

Question 30

Wall stress can be used to help understand what determinant of Cardiac Output

Answer 30

Afterload \> a more exact definition is wall stress during LV ejection Bigger left ventricle the greater its radius, the more wall stress At any given radius (LV size) the greater the pressure developed by the left ventricle, the greater the wall stress

Question 31

What is Contractility?

Answer 31

Capacity of myocardium to contract independently of changes in afterload or preload

Question 32

What is another name for Contractility?

Answer 32

Inotropy

Question 33

What is the Anrep Effect?

Answer 33

Modest increase in inotropy after an abrupt increase in afterload

Question 34

When are S4 heart sounds produced?

Answer 34

Sometimes heard during atrial contraction - vibration of ventricular wall with reduced compliance

Question 35

Phase 2: Isovolumic Contraction

Answer 35

All Valves Closed QRS - Ventricular Depolarization Rise in Ventricular pressure, but volumes stays the same

Question 36

Phase 4: Reduced Ejection

Answer 36

T Wave - Ventricular Repolarization

Question 37

When would an S3 sound be produced?

Answer 37

Not normal. May happen during Rapid refilling - tensing of chordae, tendinae and AV ring. also known as the “ventricular gallop,” occurs **just after S2 when the mitral valve opens**, allowing passive filling of the left ventricle. The sound is actually produced by the large amount of blood striking a very compliant left ventricle.

Question 38

Phase 7: Diastasis

Answer 38

Reducing Ventricular Filling

Question 39

What is the most important mechanism regulating inotropy?

Answer 39

Autonomic Nerves * Sympathetic nerves have big role in intropic regulation. * Parasympathetic have big **negative** inotropic effects in atria, but little in ventricles.

Question 40

What valve closes at the dicrotic notch?

Answer 40

Aortic Valve