Which statement best describes afterload?

Which statement best describes afterload?

• A. The amount of venous return to the heart
• B. The pressure the ventricle must overcome to eject blood
• C. The intrinsic rate of the SA node
• D. The end-systolic volume

Answer: (B)

Afterload is the pressure the ventricle must overcome during systole to eject blood. It mainly reflects the arterial pressure against which the heart pumps—things like systemic vascular resistance and the aortic pressure the left ventricle has to exceed to open the aortic valve. When afterload is high (as with hypertension or aortic stenosis), the ventricle must generate more pressure to eject blood, which can reduce stroke volume unless contractility increases. The other ideas aren’t afterload: venous return describes preload, the intrinsic rate of the SA node controls heart rate, and end-systolic volume is the amount of blood left in the ventricle after contraction (it’s affected by afterload but is not what afterload itself is).

Afterload is the pressure the ventricle must overcome during systole to eject blood. It mainly reflects the arterial pressure against which the heart pumps—things like systemic vascular resistance and the aortic pressure the left ventricle has to exceed to open the aortic valve. When afterload is high (as with hypertension or aortic stenosis), the ventricle must generate more pressure to eject blood, which can reduce stroke volume unless contractility increases.

The other ideas aren’t afterload: venous return describes preload, the intrinsic rate of the SA node controls heart rate, and end-systolic volume is the amount of blood left in the ventricle after contraction (it’s affected by afterload but is not what afterload itself is).