The cardiac cycle

Question 1

Atrial systole

Answer 1

Atria contract forcing the av valves to open and blood flows into ventricles

Question 2

Ventricular systole

Answer 2

Contraction of ventricles causes the atrioventricular valves to close and semi-lunar valves to open allowing blood to leave through the pulmonary artery and aorta

Question 3

Cardiac diastole

Answer 3

Atria and ventricles relax , blood pressure inside chambers decreases and the semi lunar valves close