Lecture 2: Cardiovascular Review

Question 1

Phase 0 of the myocardial AP is dominated by opening of what channels?

Answer 1

Voltage-gated Na^{<strong>+</strong>} channels

Question 2

What is occurring during phase 1 of the myocardial AP?

Answer 2

• Initial repolarization
• Inactivation of Na⁺ channels
• Voltage-gated K+ channels begin to open; K+ flows out

Question 3

What is occurring during phase 2 (plateau) of the myocardial AP?

Answer 3

Ca²⁺ influx balances K+ efflux

Question 4

What is occurring during phase 3 of the myocardial AP?

Answer 4

• Rapid repolarization
• Massive K+ efflux due to opening of votage-gated slow K+ channels and closure of Ca²⁺ channels

Question 5

What is occurring during phase 4 of the myocardial AP?

Answer 5

High K+ permeability = high K+ conductance

Question 6

What are the 3 phases of the pacemaker AP and the events of each?

Answer 6

• Phase 0 = upstroke - opening of Ca²⁺ channels and closing of K+
• Phase 3 = repolarization - closing of Ca²⁺ channels and opening of K+ channels –> ↑ K+ efflux
• Phase 4 = slow spontaneous diastolic depolarization due to opening of funny voltage-gated Na⁺ channels (I_f )

Question 7

The slope of which phase of the pacemaker AP in the SA node determines HR?

Answer 7

Phase 4

Question 8

At the top of the graph of the cardiac cycle what are the 3 events occurring in order during systole?

Answer 8

1) Isovolumetric contraction
2) Rapid ejection
3) Reduced ejection

Question 9

At the top of the graph of the cardiac cycle what are the 3 events occurring in order during diastole?

Answer 9

1) Isovolumetric relaxation
2) Rapid ventricular filling
3) Reduced ventricular filling

Question 10

Which valves are associted with the S1 and S2 heart sounds?

Answer 10

• S1 = mitral valve closes
• S2 = aortic valve closes

Question 11

Which phase of cardiac cycle is represented by #1?

Answer 11

Isovolumetric contraction

Question 12

Which phase of the cardiac cycle is represented by #2?

Answer 12

Systolic ejection

Question 13

Which phase of the cardiac cycle is represented by #3?

Answer 13

Isovolumetric relaxation

Question 14

Which phase of the cardiac cycle is represented by #4 and #5?

Answer 14

• # 4 = rapid ventricular filling
• # 5 = reduced ventricular filling

Question 15

The QRS complex represents which phase of the AP spreading throughout the ventricles?

Answer 15

Phase 0

Question 16

The T wave represents which phase of the ventricular myocyte AP?

Answer 16

Phase 3 = repolarization

Question 17

The dicrotic notch represents what?

Answer 17

Aortic valve closure

Question 18

The P wave represent which phase of the atrial myocyte AP?

Answer 18

Phase 0

Question 19

At which point is the voltage differences between regions of the ventricles the greatest?

Answer 19

Point 8

Question 20

The start of isovolumetric contractin correlates with what waves on the ECG?

Answer 20

Peak of R wave thru the S wave

Question 21

Afterload is the pressure the heart must overcome to do what?

Answer 21

Open the aortic valve for ejection of blood

Question 22

Which term is used to describe the amount of stretch on the myocardium at the end of diastole (i.e., the volume in the ventricle)?

Answer 22

Preload

Question 23

Answer 23

Point 7

Question 24

The reduced ejection phase of systole is represented by what wave on the ECG?

Answer 24

T wave

Question 25

What conductance changes in the atria are causing the wave in point B?

Answer 25

Ca²⁺ conductance = **phase 2**

Question 26

The dashed line represents dysfunction during which part of the cardiac cycle?

Answer 26

Diastolic dysfunction ## Footnote \*Bottom curve **represents** how well ventricles are relaxing/allowing for filling and when you see it shifting up you should automatically think **diastolic dysf.**

Question 27

How do you calculate pulse pressure?

Answer 27

Systolic - diastolic

Question 28

How do you calculate mean arterial pressure?

Answer 28

Diastolic + (1/3 \* PP)