The Cardiac Cycle

Question 1

what is the cardiac cycle?

Answer 1

an ongoing cycle of contraction and relaxations to ensure a constant flow of blood around the body

Question 2

what are the three processes of the cardiac cycle?

Answer 2

1. Atrial Systole
2. Ventricular Systole
3. Diastole

Question 3

describe the Atrial systole

Answer 3

• atria contract
• ventricles relax
• decreases chamber volume
• increases pressure inside atrium
• atrioventricular valves open
• blood flows into ventricles
• semi-lunar valves are shut

Question 4

describe the ventricular systole of the cardiac cycle

Answer 4

Ventricles contract, Atria Relax
- ventricles contract, decreasing their volume and increasing pressure
- pressure is higher in ventricles than atria, forcing the AV valves shut
- high ventricular pressure forces open the SL valves

Question 5

describe the Diastole of the cardiac cycle

Answer 5

Ventricles Relax, Atria Relax
- high pressure within the pulmonary artery and aorta close the SL
- this allows the passive flow of blood into the heart
- the atria contract, beginning the whole process again