1.1.6 Cardiac cycle

Question 1

Describe atrial systole

Answer 1

Blood flows into the atria, and is then put under pressure so to push through the AV valves into the ventricles

Question 2

Describe ventricular systole

Answer 2

The ventricles contract from the base up, increasing pressure so to push the AV valves closed and the SL valves open, so the blood can flow into the arteries

Question 3

Describe diastole

Answer 3

The atria and ventricles both relax. The SL valves are closed by backflow of blood. Low pressure in the atria helps draw in blood from the veins

Question 4

What is the cause of the heart’s beating sound?

Answer 4

The sound is caused by the closing of the AV and SL valves