Hope this helps, have a nice day!
A)Constant pumping from the heart which provides adequate pressure necessary to move the blood through the arteries and veins
B)Gravitational force
I think that different liquids have different freezing points because every liquid consists of different atoms and different things that make up the atom causing them to have different freezing points.
It is essential for accurate results that the correct volume of blood is sampled to achieve a correct concentration (and dilution, if liquid heparin is used), and that blood and anticoagulant are well mixed immediately after sampling.
