This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
Venous return to hea during quiet standing is facilitated by all of the following factors except 
Select and explain. 
A. Calf muscle contraction during standing, B. Valves in perforations, C. Sleeves of deep facia, D. Gravitational increase in aerial pressure
C: Sleeves of deep facia
Answer: C: Sleeves of deep facia 
Explanation: Gravitational increase in the aerial pressure during (quite) standing does not facilitate (enhance/ improve ) venous return to hea because as a result of same increment in venous pressure the pressure gradient driving the circulation is not altered. In the other words effect of gravity, increase the same amount of absolute pressure both within the aeries & veins of lower limb on standings. So the net pressure gradient ( aery - venous) driving circulation remains unaltered. The amount of Gravitational effect is 0.77 mm Hg/cm of veical distance below (+) or above (-) the hea level at the density of normal blood, both for aerial &venous pressure. Site the pressure in any vessel (aery or vein) below hea level is increased or above hea level is decreased by 0.77 mm Hg per centimetre d/the effect of gravity. Ref: Gray's 38e/p38-1597