What occurs during diastole in the cardiac cycle?

During diastole in the cardiac cycle, the heart muscles relax, allowing the chambers of the heart to fill with blood, which is accurately described in the provided answer. This phase is crucial for the heart's functionality because it enables the ventricles to receive blood from the atria, replenishing the oxygenated blood necessary for circulation during the subsequent contraction phase, known as systole.

In this period of rest, the pressure in the heart chambers decreases, leading to the passive filling of the ventricles as blood flows in from the atria, which is driven by the difference in pressure. This filling phase is vital for ensuring that the heart has sufficient volume of blood to pump out to the body during the next contraction.

While the opening of the mitral valve typically occurs during diastole to facilitate this filling, it is important to note that the specific action of blood flowing into the ventricles is a more direct representation of what occurs during this phase. As such, the process described captures the essence of diastole effectively. Proper functioning during this phase is critical for maintaining an adequate cardiac output and overall cardiovascular health.