Stages of The Cardiac Cycle
AV valves* | Semilunar valves† | Status of ventricles and atria | |
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1. early diastole |
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• whole heart is relaxed
• ventricles are expanding and filling |
2. atrial systole |
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• atria contract and pump blood
• additional 10–40% filling of ventricles |
3. isovolumic ventricular contraction |
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• ventricular myocytes begin to contract
• ventricle volume unchanged |
4. ventricular ejection |
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• ventricles fully contract
• pump blood to rest of body |
5. Isovolumic ventricular relaxation |
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• ventricles relax
• ventricle volume unchanged |
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