The Cardiac Cycle

Question 0

Ventricular systole

Answer 0

Once the blood is in the ventricles, the atrioventricular valves close to stop back flow, and the ventricles contract from the base upwards. This forces the blood up through the arteries.

Question 1

Atrial systole

Answer 1

As the atria fill, the pressure increases. The atrioventricular valves open to allow blood to go to the ventricles, and the atria walls contract, force it through

Question 2

Diastole

Answer 2

Blood flows into the atria. The atria expand causing low blood pressure and drawing blood into them. The atrioventricular valves are closed. To prevent backflip from the arteries, the semilunar valves are also closed.