If plasma volume increases, what is the effect on venous return?

• A. It remains unchanged.
• B. It decreases via dehydration.
• C. It increases venous return due to greater preload from expanded plasma volume.
• D. It causes unstable venous return.

Answer: (C)

When plasma volume increases, venous return rises because more blood in the circulation means a larger amount of blood is available to flow back to the heart. This expands the stressed volume, raises the mean systemic filling pressure, and increases preload (the filling of the ventricles). With greater preload, the heart can eject more blood, so venous return increases to match the higher circulating volume. This isn’t consistent with remaining unchanged or decreasing due to dehydration, and it isn’t inherently unstable—volume expansion simply boosts the return of blood to the heart.