Cardiac Cycle And Sounds

Question 1

When do the electrical events in the heart occur?

Answer 1

Before the mechanical event (contraction)

Question 2

What is an electrocardiogram?

Answer 2

A recording of electrical events in the heart associated with the heartbeat

Question 3

What is the P wave associated with?

Answer 3

Atrial depolarization and is usually initiated by the SA node

Question 4

What is the PR interval?

Answer 4

The conduction velocity in the AV node is slow so there is a pause b/w the depolarization of the atria and that of the ventricles leading to this interval

Question 5

What does the QRS complex represent?

Answer 5

Ventricular depolarization

Question 6

What does the ST segment represent?

Answer 6

The time that the entire ventricle is in the plateau phase of the AP

Question 7

What does the T wave indicate?

Answer 7

Ventricular repolarization and occurs before the actual relaxation of the ventricle

Question 8

What are the different waves for the jugular pressure wave?

Answer 8

A, c and v waves

Question 9

What is the a wave?

Answer 9

The pressure wave created by atrial contraction

Since there is no valve between the atria and great veins the pressure is reflected backwards

Question 10

What is the c wave?

Answer 10

A pressure wave created by isovolumetric contraction of the ventricles
The AV valves which are closed bulge back into the atria creating an increase in pressure that is reflected backwards

Question 11

What is the v wave?

Answer 11

A pressure wave created by blood returning back to the atria
Because the AV valves are closed the blood fills the atria and increases the atrial pressure

Question 12

What is the first heart sound associated with?

Answer 12

Closure of the AV valves

Question 13

What makes the first heart sound?

Answer 13

The sound is a result of blood in the atria hitting the closed valves as it tries to enter the ventricle
That impact creates vibration in the cardiac tissue that can be heard

Question 14

What is the second heart sound associated with?

Answer 14

Closing of the pulmonary and aortic valves

Produces when the blood in the aorta/pulmonary A back flows and bounces off the closed valves

Question 15

What creates the third heart sound?

Answer 15

The blood rushing into the ventricle during the rapid filling phase
Normal in children but may not be heard in normal adults unless conditions are right

Question 16

Describe the 4th heart sound

Answer 16

May be heard during atrial contraction
It is the result of that last little bit of blood being squeezed into the ventricle
Normal in children but not generally heard in a normal adult

Question 17

The four normal heart sounds are the result of what?

Answer 17

Blood moving in the expected directions

Question 18

A murmur can be heard when either what occurs?

Answer 18

Blood is moving in a direction it shouldn’t be moving (regurgitation)
Blood is having a hard time moving in the direction it should be moving in (stenosis)
May be heard in systole or diastole

Question 19

What is mitral regurgitation?

Answer 19

Regurgitation of blood back into the atria

Question 20

What can cause a systolic murmur?

Answer 20

Mitral regurgitation

Stenosis of the aorta/pulmonary A not allowing blood to enter

Question 21

What causes a diastolic murmur?

Answer 21

Aortic regurgitation

Blood not being able to move into the ventricles due to stenosis

Question 22

What is aortic regurgitation?

Answer 22

Regurgitation of blood back from the aorta or pulmonary A into the ventricle

Question 23

Review

Answer 23

Cardiac cycle