Which term refers to the volume of blood filling the heart just before contraction?

Which term refers to the volume of blood filling the heart just before contraction?

• A. End-diastolic volume
• B. Afterload
• C. Cardiac output
• D. Preload

Answer: (D)

Preload is the amount of stretch on the ventricular muscle fibers at the end of filling, which comes from how much blood returns to and fills the ventricle. When the heart fills, the ventricular walls are stretched to their initial length, and this stretch sets how forcefully the ventricle will contract. The phrase about filling volume before contraction aligns with preload because it describes the loading condition that governs the upcoming squeeze of the heart. The actual blood volume in the ventricle at that moment is called end-diastolic volume, but preload focuses on the mechanical state (the stretch) produced by that filling. Afterload is the pressure the ventricle must overcome to eject blood, cardiac output is the total flow produced, and end-diastolic volume is the specific volume present at the end of diastole.

Preload is the amount of stretch on the ventricular muscle fibers at the end of filling, which comes from how much blood returns to and fills the ventricle. When the heart fills, the ventricular walls are stretched to their initial length, and this stretch sets how forcefully the ventricle will contract. The phrase about filling volume before contraction aligns with preload because it describes the loading condition that governs the upcoming squeeze of the heart. The actual blood volume in the ventricle at that moment is called end-diastolic volume, but preload focuses on the mechanical state (the stretch) produced by that filling. Afterload is the pressure the ventricle must overcome to eject blood, cardiac output is the total flow produced, and end-diastolic volume is the specific volume present at the end of diastole.