Afterload is defined as what?

Afterload is defined as what?

• A. The pressure in the atria that must be overcome.
• B. The pressure the ventricles must overcome to eject blood.
• C. The volume of blood ejected per beat.
• D. The rate of SA node firing.

Answer: (B)

Afterload is the pressure the ventricle must overcome to eject blood during systole. This opposing pressure mainly comes from the arterial system the ventricle pumps into—the aorta for the left ventricle and the pulmonary artery for the right ventricle—together with the systemic or pulmonary vascular resistance. When afterload is higher, the ventricle must generate more pressure to achieve ejection, which can lower stroke volume if contractility doesn’t compensate. For comparison, atrial pressure relates to filling (preload), stroke volume is the amount ejected per beat, and heart rate reflects SA node firing.

Afterload is the pressure the ventricle must overcome to eject blood during systole. This opposing pressure mainly comes from the arterial system the ventricle pumps into—the aorta for the left ventricle and the pulmonary artery for the right ventricle—together with the systemic or pulmonary vascular resistance. When afterload is higher, the ventricle must generate more pressure to achieve ejection, which can lower stroke volume if contractility doesn’t compensate. For comparison, atrial pressure relates to filling (preload), stroke volume is the amount ejected per beat, and heart rate reflects SA node firing.