The Cardiac Cycle

Question 1

What is one cardiac cycle?

Answer 1

one heartbeat

Question 2

What are the three phases of the cardiac cycle?

Answer 2

diastole
atrial systole
ventricular systole

Question 3

What happens in diastole?

Answer 3

• atria and ventricles relaxed
• pressure decreases
• blood from vena cava and pulmonary veins drawn into the atria
• semilunar valves close , prevent blood flowing back into the ventricles
• atrioventricular valves closed

Question 4

What happens in atrial systole?

Answer 4

• blood fills atria
• increases pressure
• blood pushes against atrioventricular valves and blood enters the ventricles.
• walls of atria contract, forcing the av valves open
• blood is forced into the ventricles.

Question 5

What happens in ventricular systole?

Answer 5

• walls of the ventricle contract.
• pressure inside ventricles increases
• forces open the semilunar valves
• blood is pumped into the aorta and pulmonary artery
• pressure closes the av valves.