7.4 - The cardiac cycle

Question 1

Cardiac output

Answer 1

1. Measure the heart rate- This is the number of heart beats per minute.
2. Measure the stroke volume- This is the volume of blood that is pumped out of the left ventricle during ventricular systole.
3. Calculate the cardiac output - cardiac output = heart rate x stroke volume

Question 2

Stages of the cardiac cycle:

Answer 2

stage 1 - atrial systole

stage 2 - ventricular systole

stage 3 - diastole

Question 3

Stage 1 - Atrial systole

Answer 3

• The ventricles relax, and the atria contract.
• This increases the atrial pressure.
• The atrioventricular valves open.
• Blood flows into the ventricles

Question 4

Stage 2 - Ventricular systole

Answer 4

• The ventricles contract, and the atria relax.
• The ventricular pressure increases.
• The semi-lunar valves open, and the atrioventricular valves close.
• Blood flows into the arteries.

Question 5

Stage 3 - Diastole

Answer 5

• The ventricles and atria relax.
• The semi-lunar valves close.
• Blood flows passively into the atria.