The volume of blood pumped out by the heart ventricles in each contraction is called what?

• A. Heart Rate
• B. Venous Return
• C. Stroke Volume
• D. Elasticity of Cardiac Fibres

Answer: (C)

The key idea is the amount of blood the heart pumps out with each beat. This is stroke volume—the volume ejected by the ventricles per contraction, usually measured in milliliters per beat. It, together with heart rate, determines cardiac output (cardiac output = stroke volume × heart rate). Typical resting stroke volume is around 70 mL, but it can vary with factors like venous return, contractility, and afterload.

Heart rate tells you how many times the heart beats each minute, not how much blood is ejected per beat. Venous return refers to how much blood comes back to the heart and influences stroke volume, but it is not the volume ejected per beat itself. Elasticity of cardiac fibres relates to how the heart muscle stretches and contracts, which affects preload and contractility, but again does not define the volume ejected per beat.

So the term that describes the volume pumped out per contraction is stroke volume.