Final answer:
EDV, or end diastolic volume, also known as preload, is a key factor affecting stroke volume and represents the maximum ventricular blood volume at the end of atrial systole. Filling time, venous return, and the force needed to pump blood against vascular resistance (afterload) all play a role in influencing EDV, preload, and subsequently, stroke volume.
Step-by-step explanation:
One factor affecting stroke volume is EDV, or end diastolic volume, which represents maximum filling of the ventricle. EDV, also known as preload, is the amount of blood in the ventricles at the end of atrial systole just prior to ventricular contraction. Preload is directly proportional to EDV, meaning the greater the EDV is, the greater the preload is. Factors such as filling time, venous return, and atrial contraction can influence EDV and preload. For instance, sympathetic stimulation increases venous return, which in turn boosts EDV and preload.
The ventricles also need to overcome afterload, which is the resistance in blood vessels that the heart must exert force against to pump blood. During the ventricular ejection phase, blood is ejected from the heart into the circulation, and the volume pumped out is referred to as stroke volume, typically ranging from 70–80 mL. The remaining blood volume after this ejection is known as the end systolic volume (ESV). The interplay of these factors ensures the proper function of the cardiac cycle and the maintenance of efficient blood circulation throughout the body.