Final answer:
Stroke volume (SV) refers to the volume of blood pumped by the left ventricle per beat. The left ventricle is focused upon because it is the primary chamber responsible for pumping blood throughout the systemic circuit. Stroke volume is important in determining cardiac output and ejection fraction, which assesses heart function.
Step-by-step explanation:
Stroke volume (SV) is the volume of blood pumped from the left ventricle of the heart per beat. It is specifically measured from the left ventricle because it is the major pumping chamber responsible for ejecting blood into the systemic circuit through the aorta via the aortic semilunar valve. The pressure generated by the left ventricle has to be greater than that of the right ventricle since it has to overcome the high pressure in the aorta to circulate blood throughout the body. Both the right and left ventricles pump the same amount of blood to maintain a consistent cardiac output, which is the volume of blood the heart pumps in one minute and is calculated as heart rate multiplied by stroke volume (CO = HR × SV).
During the ventricular ejection phase of the cardiac cycle, the left ventricle contracts, creating a pressure that forces blood out of the heart. Normal stroke volume ranges between 70–80 mL, and this is calculated by the difference between end-diastolic volume (EDV) and end-systolic volume (ESV), which is the amount of blood present in the ventricle at the end of the filling phase (approximately 130 mL) minus the amount remaining after contraction (50–60 mL). Stroke volume is also used to calculate the ejection fraction, which is the percentage of blood pumped out of the ventricle with each beat.