What is the expected effect on venous return when a person moves from supine to standing?

• A. Venous return decreases due to gravitational pooling; preload falls.
• B. Venous return increases.
• C. Venous return remains the same.
• D. Venous return increases due to venoconstriction.

Answer: (A)

When you stand up, gravity pulls more blood into the veins of the legs and abdomen. That causes blood to pool away from the central circulation, so less blood returns to the heart. The heart ends up with less filling (lower preload), which means the amount of blood returning to and entering the heart is reduced. Although the body can compensate with venoconstriction and muscle pumps to mobilize some of that pooling, the immediate and overall effect is a decrease in venous return.