1B The Circulatory System - Cardiac Cycle

What is the cardiac cycle?

Answer explanation

The sequence of events involved in one cycle of contraction and relaxation of the heart.

It involves 3 stages: atrial systole, ventricular systole and diastole.

What are the three stages in cardiac cycle?

Answer explanation

Atrial systole, Ventricular systole and Diastole

Which of the following occurs during atrial systole?

• Ventricles contract.

• Blood is forced into the ventricles.

• Ventricles and atria relaxed.

• SL valves open.

Which of the following does not occur during ventricular systole?

• AV valves close.

• SL valves open.

• Atrial diastole coincides with ventricular systole.

• Ventricular volume increased.

Outline what happens to the valves at 1.

Answer explanation

AV valves close.

Outline what happens to the valves at 3.

Answer explanation

Aortic valves close.

Which point showing atrial systole?

• 3

• 1 and 2

• 3 and 4

• 1

Answer explanation

Aortic valves close.

Which point showing ventricular systole?

• 3

• 1 and 2

• 3 and 4

• 2

Answer explanation

Aortic valves close.

During atrial systole, .................................... decreases, ............................... increases.

During ventricular systole, the pressure in the ventricles rises above that in the atria. This forces the ......................... valves to close.