During which phase does the left ventricle receive the majority of its blood volume?

The left ventricle receives the majority of its blood volume during the rapid filling phase of the cardiac cycle. This phase occurs directly after the mitral valve opens, following ventricular relaxation. During rapid filling, the pressure in the left atrium is greater than that in the left ventricle, which allows blood to quickly flow into the ventricle. This is a crucial time when the ventricle fills with blood, preparing it for the next contraction.

Following this phase, the left ventricle enters the isovolumetric contraction phase, where all valves are closed and the ventricle contracts without any blood volume change, making it a phase that does not involve filling. The systolic phase focuses on the ejection of blood into the aorta and does not emphasize ventricle filling. Similarly, the isovolumetric relaxation phase occurs after ejection when the heart is not filling with blood, as the mitral valve has not yet opened.

Overall, the rapid filling phase is essential for maximizing ventricular volume and ensuring effective cardiac output, hence making it the phase during which the left ventricle receives the majority of its blood volume.