Physiology Heart, Circulation, and Blood b5dc0d7e Volume determining preload is A End diastolic volume of ventricles B End systolic volume C Volume of blood in aorta D Ventricular ejection volume High-Yield Explanation Ans. (a) End diastolic volume of ventriclesRef: Ganong, 25th ed/p.544Preload is End diastolic volume of ventriclesAfterload is the aortic pressure