Cardiac Cycle (w/ diagram) Review

Locate the sound associated with the semi-lunar valve shutting.

Answer explanation

Remember, every time a valve shuts.... it makes a sound. The semi-lunar valves are between the aorta and ventricles.

Tags

HS-LS1

Click on the area in the volume graph identifying ventricular ejection.

Answer explanation

When blood is being ejected, it leaves the heart so blood volume decreases.

Click on the specific point in the pressure graph identifying the beginning of ventricular diastole.

Answer explanation

Ventricular systole ENDS at the point ejection ends, when the semi-lunar valve closes (letter C). At this point, ventricular diastole begins (when the semi-lunar valve closes and isovolumetric relaxation begins)

Click on the specific point in the pressure graph identifying where the Atrioventricular (AV) valves open.

Answer explanation

When ventricular pressure drops below atria pressure, the AV valves open and blood flows into the ventricles.

During isovolumetric contraction, all the valves in the heart are ​ (a)   and the pressure in the ventricles is ​ (b)   .

• closed
• increasing
• open
• decreasing
• open and closed
• staying the same

Answer explanation

When the heart is in any isovolumetric (contraction or relaxation), the volume is the heart is constant (look at the volume graph). When the heart is contracting, pressure is increasing. Think about a person squeezing on a balloon, as the balloon is squeezed (contracting) the pressure inside the balloon is increasing.

Organize these options into the right categories

Groups:

(a) Systole

,

(b) Diastole

• Ventricles relaxing

• 
• Lowest pressure in the ventricles

• Highest pressure in ventricles

• Blood entering the ventricles (filling)

• Ventricles contracting

• Blood leaving ventricles (ejection)

• 

Closure of the Atrioventricular (AV) valves occurs at the onset (beginning) of which phase in the cardiac cycle?

• isovolumetric contraction

• isovolumetric

  relaxation

• rapid ejection

• rapid filling

Answer explanation

When the AV valves close, it is the beginning of Isovolumetric Contraction. This is when ventricular pressure becomes greater than atrial pressure causing the AV valves to close. At this point ALL four valves in the heart are closed (isovolumetric), and the ventricles are in systole (contracting) so pressure is increasing.

What LETTER on the volume graph indicates End Diastolic Volume (EDV)?

• B

• C

• F

• G

Answer explanation

EDV is the max volume in the ventricles.

What NUMBER indicates ventricular systole?

• 3

• 5

• 6

• 7

Answer explanation

Ventricular systole (contraction) contains isovolumetric contraction (#1) and ejection (#5), so number 6 contains both of those.

What NUMBER indicates when the atria are contracting?

• 2

• 3

• 4

• 7

Answer explanation

Look what happens right before #4 on the ECG. The P-wave! That is the depolarization of the atria (electrical current going through the atria). This causes the atria to contract. Look at atrial pressure (yellow in color) during #4, it is increasing which is a result of the atria contracting (squeezing).