Phases of the Cardiac Cycle

Ventricular Filling (mid to late Ventricular Diastole)

AV valves are fully open and rapid filling of atria which leads to a rapid filling of the ventricles

SA Node fires during this phase

SL Valves are fully closed

Ventricular Systole (Atrial Diastole)—Isovolumetric Contraction

When ventricles begin to contract, which means AV valves begin to close, SL valves begin to open

Implies both ventricles are filling up with the same amount of blood

Ventricular Systole (Atrial Diastole)—Ventricular Ejection Phase

Blood discharge from ventricular chambers

SL valves must be fully opened, AV valves must be fully closed

Blood leaves the heart via the SL valves

Isovolumetric Relaxation (Early Ventricular Diastole)

Slow Initial filling of the atria

Discharge of blood out of the pulmonary trunk and aorta

AV valves slowly start to open up, SL valves slowly start to close