Cardiac Cycle  Refers to pattern of ;  Systole (contraction)  Diastole (relaxation)  Shown by the heart in one complete cycle  On average this 1 cardiac cycle lasts 0.8 seconds (based on 75 bpm)

Diastole  Return of blood from venae cavae and pulmonary veins to atria  Causes atrial volume of blood to increase  Eventually atrial pressure > ventricular pressure  = AV valves are pushed open

Atrial systole  Atria (R&L) contract simultaneously pushing remainder of blood into ventricles  Ventricles are still in diastole and SL valves are closed

Ventricular systole  Contraction of ventricles and closure of AV valves. (‘lubb’)  Blood pressure in ventricles > pressure in arteries  = SL valves pushed open and blood pumped out of heart into aorta and pulmonary arteries.

Diastole  Higher pressure in arteries close SL valves again. (‘dupp’)  Cardiac cycle repeats

Heart Sounds  Normal  G-M G-M  Murmur  UA5k UA5k