PHSI 208 Lecture Notes - Lecture 19: Heart Valve, Cardiac Cycle, Diastole
Document Summary
Sequence of electrical and mechanical events in a complete heart beat. 2 main events for a complete cardiac cycle. Ventricular systole (contraction: isovolumic ventricular contraction, ventricular ejection. Ventricular diastole (relaxation: isovolumic ventricular relaxation, ventricular filling. Coincides with the peak of the r-wave of the ecg. Between the closure of atrioventrical (av) valves: when ventricular pressure exceeds atrial pressure, and the opening of the semilunar valves, when ventricular pressure exceeds aortic pressure (arterial diastolic pressure) Blood volume in the ventricle during this period is known as end-diastolic (edv) Increase in the atrial pressure is observed: caused by the closure of av valve. 1st low-pitched heart sound can be heart in this period: often being described as lubb sound, caused by the closure of av valves. Begins with the opening of the semilunar valves (av valves are now closed) Further sub-divided into 2 phases: rapid ejection phase. Starts with the initial opening of the semilunar valves.
