HRR: Cardiodynamics I

Question 1

What initiates the electrical activation of the heart?

Answer 1

The SA node

The SA node is known as the natural pacemaker of the heart.

Question 2

What occurs after the impulse spreads to the AV node?

Answer 2

The impulse waits, generating the PR segment

This delay allows the atria to fully depolarize and contract before the ventricles.

Question 3

What does the QRS complex represent?

Answer 3

Depolarization of the ventricles

The QRS complex is typically narrow in healthy individuals.

Question 4

What is the first area to depolarize in the ventricles?

Answer 4

Endocardium and papillary muscles

This helps the chordae tendineae maintain valve closure during pressure changes.

Question 5

Which heart chambers are significant when referring to systole and diastole?

Answer 5

Ventricles

Systole refers to contraction, while diastole refers to relaxation.

Question 6

How is blood flow from the vena cava and pulmonary veins characterized?

Answer 6

Continuous

There is no pulsatility associated with this flow.

Question 7

What is end diastolic volume?

Answer 7

The volume in the ventricle just before contraction

This is the maximum volume of blood in the ventricle during the cardiac cycle.

Question 8

What is end systolic volume?

Answer 8

The volume in the ventricle just after contraction

This represents the minimum volume of blood remaining in the ventricle.

Question 9

Define stroke volume.

Answer 9

The amount of blood ejected in one cycle

Stroke volume is a key indicator of heart function.

Question 10

What is the ejection fraction?

Answer 10

The percentage of blood emptied during a beat

Ejection fraction is an important measure of cardiac efficiency.

Question 11

How do valves in the heart work?

Answer 11

They rely on pressure differences

Valves open when proximal pressure exceeds distal pressure.

Question 12

Where is resistance higher when a valve is closed?

Answer 12

Proximal side

This is due to the pressure differential across the valve.

Question 13

What is the typical pressure in the right atrium?

Answer 13

4 mmHg

This pressure is crucial for understanding cardiac function.

Question 14

What is the typical pressure in the right atrium?

Answer 14

4 mmHg

The right atrium typically experiences low pressure compared to other chambers of the heart.

Question 15

What is the typical pressure in the right ventricle?

Answer 15

21/4 mmHg

The right ventricle has a low pressure compared to the left ventricle, as it pumps blood to the lungs.

Question 16

What is the trial pressure in the pulmonary artery?

Answer 16

21/10 mmHg

This pressure reflects the resistance the right ventricle faces when pumping blood into the pulmonary circulation.

Question 17

What is the typical pressure in the left ventricle?

Answer 17

120/8 mmHg

The left ventricle generates higher pressure to pump blood into the systemic circulation.

Question 18

What is the typical pressure in the aorta?

Answer 18

120/80 mmHg

This pressure represents the systolic and diastolic pressures in the aorta during the cardiac cycle.

Question 19

What does the Wiggers diagram represent?

Answer 19

The relationship between cardiac pressures, volumes, and ECG waveforms

It illustrates the phases of the cardiac cycle and the corresponding pressures in different heart chambers.

Question 20

Fill in the blank: The pressure in the right atrium is typically _____ mmHg.

Answer 20

8

Question 21

Fill in the blank: The pressure in the aorta is typically _____ mmHg.

Answer 21

120/80

Question 22

True or False: The pressure in the left ventricle is lower than in the right ventricle.

Answer 22

False

The left ventricle has a much higher pressure due to its role in systemic circulation.

Question 23

What is the significance of the pressure in the pulmonary artery?

Answer 23

It indicates the pressure the right ventricle must overcome to pump blood to the lungs

Elevated pressures in the pulmonary artery can indicate pulmonary hypertension.

Question 24

What is the normal pressure range in the right ventricle?

Answer 24

21/4 mmHg

This low pressure is necessary for the function of the right ventricle as it pumps blood into the pulmonary artery.