Final answer:
The majority of ventricular filling during resting conditions is caused by passive blood flow during the diastole phase of the cardiac cycle, contributing to 70-80 percent of the ventricular capacity.
Step-by-step explanation:
During resting conditions, the majority of ventricular filling is caused by passive blood flow into the ventricles during diastole. The atria receive venous blood continuously, which allows the ventricles to be filled with approximately 70-80 percent of their capacity due to inflow during ventricular diastole. Although the atria demonstrate a contractile phase known as the "atrial kick", which actively pumps blood into the ventricles and contributes the remaining 20-30 percent of ventricular filling, it is the diastolic phase that accounts for most of the ventricular filling.
The majority of ventricular filling during resting conditions is caused by the atrial contraction, also known as the 'atrial kick'. While most ventricular filling occurs while both atria and ventricles are in diastole, the atrial kick contributes the remaining 20-30 percent of filling.