What is the term for the amount of blood ejected from a ventricle in one contraction?

• A. Stroke Volume
• B. Cardiac Output
• C. Blood Pressure
• D. Baroreceptor Reflex

Answer: (A)

Stroke volume is the amount of blood ejected from a ventricle with each heartbeat. In the cardiac cycle, the ventricle fills during diastole to reach end-diastolic volume, then contracts to push blood out, leaving end-systolic volume. The difference between these volumes is the stroke volume (SV = EDV − ESV). This value is typically around 70 mL in a healthy adult and can vary with preload, contractility, and afterload. Cardiac output, by contrast, is the product of stroke volume and heart rate, representing blood pumped per minute. Blood pressure is the force of blood against arterial walls, not the per-beat volume, and the baroreceptor reflex helps regulate blood pressure rather than defining the amount ejected with each contraction.