Question

Venous return to the heart during quiet standing is facilitated by all of the following factors, except:

• A. Calf muscle contraction during standing
• B. Valves in perforators
• C. Sleeves of deep fascia
• D. Gravitational increase in arterial pressure

Hint:

Gravity makes blood pool in the legs while standing, so it hinders venous return.

Answer 1

The Correct Option is D

Step 1: This is a negative question. Three options help return venous blood to the heart against gravity while standing, and one does not.
Step 2: The calf muscle pump (A) is the main mechanism. Contraction of the calf muscles squeezes the deep veins and pushes blood upward toward the heart, helped by the one way valves.
Step 3: Valves in the perforating veins (B) allow flow only from superficial to deep veins and prevent backflow, so they aid upward return and stop pooling.
Step 4: The tight sleeve of deep fascia around the leg muscles (C) makes the muscle pump more effective by ensuring contractions compress the deep veins rather than letting them bulge.
Step 5: Gravity during standing does raise the arterial pressure in the feet, but it equally raises the venous pressure and makes blood pool in the legs. Gravity opposes venous return to the heart, it does not assist it. So option D is the exception.
Conclusion: The factor that does not facilitate venous return is the gravitational increase in arterial pressure. Answer is option D.