Cardiac Cycle Flashcards
Diastole
Relaxing and Filling
0.5 seconds
Systole
Contracting and Pumping
0.3 seconds
Atrial Diastole (Phase 1)
> The atria fill with blood retuning from the body
Bicuspid and tricuspid valves are closed
Ventricular Diastole (Phase 2)
> The blood in the atria forces the atrioventricular valves open
The ventricles start to fill with blood
Atrial Systole (Phase 3)
> SA node impulse causes atria to contract
Remaining blood is sent into the ventricles via the atrioventricular valves
Semi-lunar valves stay close
Ventricular Systole (Phase 4)
> The impulse reaches the AV node, so the ventricles contract
Pressure rises, forcing the semi-lunar valves open
Blood is ejected out of the heart
Systemic circulatory system
> Consists of all of the vessels which carry oxygenated blood away from the heart via arteries and the aorta
Once oxygen is used by working tissues, blood is returned to the heart via veins and the vena cava
Pulmonary circulatory system
> Consists of the pulmonary artery that transports deoxygenated blood from the right atrium to the lungs
Re-oxygenated blood is returned to the heart via the pulmonary vein