Total resistance against which blood is pumped

• A. Preload
• B. Afterload
• C. Cardiac output
• D. Contractility

Answer: (B)

The main idea here is afterload—the pressure the ventricle must generate to push blood into the arterial system during systole. It represents the total resistance the heart has to overcome, mainly the systemic vascular resistance and arterial pressure. When afterload is high, the ventricle must work harder to eject blood, which can reduce stroke volume and raise myocardial oxygen demand. This differs from preload (the filling pressure/volume before contraction), cardiac output (the amount pumped per minute), and contractility (the intrinsic strength of contraction). So the total resistance against which the heart must pump is afterload.