| Flap 1 |
Flap 2 |
| STEP 1 - Atrial Systole | As atria contract, rising atrial pressures push blood into the ventricles thru the open right and left AV valves. |
| STEP 2 - Atrial Systole | Start of atrial systole, ventricles already filled 70%. As atria contract, rising atrial pressure provide the remaining 30 percent by pushing blood thru the open AV valves. Atrial systole 'tops off' ventricles. |
| STEP 3 - Atrial Systole | End of atrial systole, each ventricle contains maximum amount of blood that it will hold in cardiac cycle = End diastolic volume EDV |
| STEP 4 - Ventricular Systole. | ventricles are contracting. bloow flow has yet to occur. ventricles contract isometrically: generate tension and pressure. flow does not occur. isovolumetric contraction: all valves closed. volume constant and pressure rises. |
| STEP 5 - Ventricular Systole | Once ventricle pressure exceeds that in arterial trunks. semilunar valves open and blood flows into pulmonary and aortic trunks = ventricular ejection. isotonically contract: muscle cells shorten. tension constant. |
| STEP 6 - Ventricular Systole | near end of VS, ventricular pressure falls.blood in aorta + pulmonary trunk now starts to flow twrd ventricles-> closes semilunar valves. pressure rises again as arterial walls recoil, amt of blood remaining in ventricle = end systolic volume |
| STEP 7 - Ventricular Diastole | all heart valves closed.vent. myocardium relaxing vent pressures higher than atrial pressures blood cannot flow into ventricles. isovolumetric relaxation; rapid drop in pressure over this period
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| STEP 8 - Ventricular Diastole | when ventricular pressure fall below atria. atrial pressure forces valves open.blood flows into ventricles. both atria + vent = diatole. vent. pressure continues to fall > chambers expand. |
