The Cardiac Cycle

Question 1

Name and describe the stages of the cardiac cycle between S2 and S1.

Answer 1

• late diastole - both sets of chambers are relaxed and ventricles fill passively.
• artial systole - atrial contraction forces a small amount of additional blood into the ventricles.

Question 2

Describe what is happening inside the heart when S1 can be heard?

Answer 2

Isovolumic ventricular contraction - first phase of ventricular contraction pushes atrioventricular valves closed but does not create enough pressure to open semilunar valves

Question 3

Name and describe the stage of the cardiac cycle between S1 and S2.

Answer 3

• ventricular ejection - as ventricular pressure rises and exceeds pressure in the arteries, semilunar valves open and blood is ejected

Question 4

What is happening in the heart when S2 can be heard?

Answer 4

Isovolumic ventricular relaxation - as the ventricles relax, pressure in ventricles falls, blood flows back into the cusps of the semilunar valves and snaps them closed

Question 5

Define end systolic volume.

Answer 5

The amount left in the ventricle at the end of contraction.

Question 6

Define end diastolic volume.

Answer 6

The maximum amount of blood inside the ventricle.

Question 7

What could a sound heard between S1 and S2 indicate?

Answer 7

• aortic stenosis
• pulmonary valve stenosis
• mitral regurgitation
• tricuspid regurgitation

Question 8

What could a sound heard between S2 and S1 indicate?

Answer 8

• mitral stenosis
• tricuspid stenosis
• aortic regurgitation
• pulmonary regurgitation