Cardiac cycle

Question 1

When do heart valves produce a sound?

Answer 1

When they shut, they normally dont produce a sound when they open

Question 2

What is the cardiac cycle?

Answer 2

all events that occur from the beginning of one heart beat to the beginning of the next

Question 3

What are the 5 events in the cardiac cycle?

Answer 3

1) passive filling
2) Atrial contraction
3) isovolumetric ventricular contraction
4) ventricular ejection
5) isovolumetric ventricular relaxation

Question 4

What occurs in passive filling?

Answer 4

Ventricle fills. Mitral valve is open so blood flows via pressure gradient from atria to ventricle.
aortic/pulmonary valve closed.

Question 5

What occurs in atrial contraction?

Answer 5

Filling of the ventricle is completed by a contraction of the atria.

Question 6

What occurs in isovolumetric ventricular contraction?

Answer 6

Both valves are closed so no volume is entering or leaving the ventricle.
When the ventricular pressure exceeds the atrial pressure, the mitral/tricuspid valve closes.
High ventricular pressure in this stage

Question 7

What occurs in Vetricular ejection?

Answer 7

• Valve opens (aortic or pulmonary) and ejects blood into the artery.
• When pressure in ventricle exceeds that of the aorta/pulmonary artery the aortic valve/pulmonary valve will open.
• When opposite occurs, valves will close

Question 8

What occurs in isovolumetric ventricular relaxation?

Answer 8

• Both valves close again so no blood entering or leaving ventricle and the ventricle is relaxing.
• when ventricular pressure falls below atrial pressure, mitral valve/tricuspid valve will open- new cycle

Question 9

What percentage of ventricular filling occurs in the passive filling stage and what percentage occurs in the atrial contraction stage?

Answer 9

80% passive

20% atrial contraction

Question 10

What produces the first heart sound?

Answer 10

Closing of the mitral/tricuspid valve in isovolumetric ventricular contraction.

Question 11

What prodcues the second heart sound?

Answer 11

When the aortic/pulmonary valve close after ventricular ejection

Question 12

How does arterial pressure not fall to zero during diastole?

Answer 12

-The large arteries are elasticated so stretch when fill with blood then recoil when blood leaves them allowing lesser surface area.