<prompt> Venous return to hea during quiet standing is facilitated by all of the following factors exceptCalf muscle contraction during standingValves in perforationsSleeves of deep faciaGravitational increase in aerial pressure  <response>: 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 Hgcm 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 dthe effect of gravity. Ref: Grays 38ep38-1597 