The Cardiac Cycle

Question 1

What are the 3 stages in the cardiac cycle?

Answer 1

1.) atrial systole/ventricular diastole
2.) ventricular systole/atrial diastole
3.) diastole

Question 2

What happens during atrial systole stage?

Answer 2

• atrai contract, increasing pressure in the chambers which causes the atrioventricular valves to open as blood is forced into ventricles from atria
• semi lunar valves closed
• ventricles relax

Question 3

What happens during the ventricular systole stage?

Answer 3

• ventricles contract, increasing the pressure which makes it higher in the ventricles than the atria, forcing the atrioventricular valves shut
• pressure in higher in ventricle than aorta/ pulmonary artery do blood is forced into the arteries making the semi-lunar valves open
• blood is flowing into the atria which is relaxing

Question 4

What happens during the diastole stage?

Answer 4

• ventricles and atria both relax
• higher pressure in aorta/ pulmonary artery which closes the semi-lunar valves to prevent backflow into ventricles and blood entering through arteries
• blood flowing into atria increase the pressure which makes the atrioventricular valves open

Question 5

What is cardiac output?

Answer 5

the volume of blood which leaves the ventricle in one minute

Question 6

How do you calculate cardiac output?

Answer 6

cardiac output = heart rate x stroke volume
heart rate = beats per minute
stroke volume = volume of blood that leaves the heart each beat