There are two phases of the cardiac cycle when all the four heart valves are open: the isovolumetric contraction phase and the isovolumetric relaxation phase.
What do you mean by Cardiac cycle?
The Cardiac cycle may be defined as the stages involves in the transformation of deoxygenated blood to oxygenated blood in the lungs and pumping it by the heart to the body through the aorta.
The phase of isovolumetric contraction is associated with the systole, while the phase of volumetric relaxation is associated with the diastole.
The atria and ventricles of the heart both proceed through systole and diastole phases which occur simultaneously.
Therefore, there are two phases of the cardiac cycle when all four heart valves are open: the isovolumetric contraction phase and the isovolumetric relaxation phase.
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