Lecture 10: Cardiac Cycle and Heart Sounds

Question 1

Describe the P wave.

Answer 1

Start of cardiac cycle: Atrial depolarization

-initiated by SA node

Question 2

Describe the PR interval.

Answer 2

Pause between atrial and ventricular depolarization

-imp so ventricles can be filled w/ blood before ejection

Question 3

How are ventricles depolarized?

Answer 3

First the septum to the apex of the heart. Then it goes back up along the side of the ventricular walls.

• Most efficient way to eject blood into pulmonary artery or aorta
• depolarization done by bundle branches and purkinje fibers

Question 4

Describe the QRS complex.

Answer 4

Ventricular depolarization

-takes time for ventricular pressure to increase and ventricles to begin contraction

Question 5

Describe the T wave.

Answer 5

Ventricular repolarization

Question 6

Between the QRS complex and T wave, what is the state of the ventricular myocytes?

Answer 6

Ventricular myocytes are depolarized

Question 7

When does the mitral valve open?

Answer 7

When atrial pressure is higher then ventricular pressure

Question 8

When does the aortic valve open?

Answer 8

When ventricular pressure is higher then aortic pressure

Question 9

What is systole?

Answer 9

Phase of cardiac cycle when the heart contracts and pumps blood from the ventricles into the aorta
–isovolumetric contraction to beginning of isovolumetric relaxation

Question 10

What is diastole?

Answer 10

Phase of the cardiac cycle when the heart muscle relaxes and allows the chambers to fill with blood

Question 11

What does jugular pressure measure?

Answer 11

Pressure in internal jugular vein that indirectly can tell the pressure of the right atrium

Question 12

Describe the a wave in the jugular pressure wave.

Answer 12

Atrial contraction

Question 13

Describe the c wave in the jugular pressure wave.

Answer 13

Isovolumetric contraction in ventricles

• all valves are closed
• pressure building in ventricles

Question 14

Describe the v wave in the jugular pressure wave.

Answer 14

Ventricular contraction

• AV valve is closed
• blood filling atria

Question 15

Why is atrial pressure increasing during ventricular systole?

Answer 15

Atria is filling while AV valves are closed, causing atrial pressure to increase

Question 16

What is the dicrotic notch?

Answer 16

After the aortic valve closes, there is a notch in the aortic pressure wave that looks like a wiggle. It signifies the closing of the valve.

Question 17

What is the first heart sound ‘lub’ associated with?

Answer 17

Closure of AV valves

-sound is from blood entering atria and hitting closed valve trying to get to ventricle

Question 18

What is the second heart sound ‘dub’ associated with?

Answer 18

Closing of semilunar (aortic and pulmonary) valves

-sound is from blood in aorta and pulmonary artery trying to go backward and hitting closed valve

Question 19

What is the third heart sound associated with?

Answer 19

Rapid filling of ventricles

• normally heard in children
• normal in adults but not common

Question 20

What is the fourth heart sound associated with?

Answer 20

Topping of ventricle during atrial contraction

-normally heard in children

Question 21

What can cause a murmur?

Answer 21

Blood moving in the wrong direction

Blood having a hard time moving in the right direction

Question 22

What can cause a systolic murmur?

Answer 22

Blood moving back into atria from ventricles

Blood cannot get into aorta or pulmonary artery due to stenosis

Question 23

What can cause a diastolic murmur?

Answer 23

Blood moving back into ventricle from aorta or pulmonary artery
Blood cannot get into ventricle due to stenosis