The peripheral resistance against which the ventricle pushes blood into the aorta is referred to as which?

• A. Contractility
• B. Venous Return
• C. Afterload
• D. Preload

Answer: (C)

The main concept here is afterload—the pressure the ventricle must generate to eject blood into the arterial system. The peripheral resistance in the arterial tree provides this load. When the ventricle contracts during systole, it has to overcome the pressure in the aorta and the systemic arteries to open the aortic valve and push blood forward. That opposing pressure is afterload, with arterial pressure and systemic vascular resistance being key determinants.

So why is this the best fit? Afterload directly describes the workload the heart must overcome to eject blood. If the arteries are highly resistant or stiff (high systemic vascular resistance, hypertension, or aortic stenosis), afterload rises, making it harder to eject blood and potentially reducing stroke volume unless contractility or preload adjusts. Preload, by contrast, is about filling—the end-diastolic volume/pressure the ventricle receives. Contractility refers to the heart’s intrinsic ability to contract, independent of loading. Venous return relates to how much blood returns to the heart, affecting preload rather than the pressure the ventricle pushes against.

In short, afterload is the pressure in the circulation that the ventricle must overcome to eject blood into the aorta, and peripheral resistance is a primary component of that load.