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Cardiac Cycle
Steps 1-6
Steps | Action | Action Defined |
---|---|---|
Cardiac Cycle Step 1 | Isovolumetric Contraction (vol. of blood in ventricles is the EDV) | a. QRS has just occurred. b. Contraction of ventricles causes the Ventricular pressure to rise above atrial pressure. AV valves CLOSE. c. Ventricular Pressure is less than Aortic Pressure and the Semilunar valves CLOSE. |
Cardiac Cycle Step 2 | Ejection (Vol. of blood ejected: SV) | a.Contraction of ventricle -> ventricular preasure rises above Aortic pressure -> Semilunar valves OPEN. b.Ventricular pressure higher than atrial pressure -> AV valves CLOSED. |
Cardiac Cycle Step 3 | Ventricular Pressure drops below Aortic Pressure | the T wave occurs |
Cardiac Cycle Step 4 | Isovolumetric Relaxation (vol. of blood in the ventricle: ESV) | a. Back Pressure causes semilunar valves to CLOSE. b. AV Valves are still CLOSED. |
Cardiac Cycle Step 5 | Rapid Filling of Ventricles | a.ventricular pressure drops below atrial pressure. b. AV valves OPEN c. Rapid ventricular filling occurs. |
Cardiac Cycle Step 6 | Atrial Systole | Atrial Contraction. Push 10-30% more blood into the ventricle. |