a) Explain how the presence of formed particles (i.e. red cells) in blood makes its apparent viscosity around four times that of plasma. Explain also why this apparent viscosity should depend on flow rate.
b) In order to prepare a plasma sample, whole bood is centrifuged at 1200 rpm (20 revolutions per second). Given that the centrifugal acceleration is given by rω2 (ω= 2πf) and that the equivalent radius r is 10 cm, estimate how long blood samples should be centrifuged to ensure that the red blood cells will have packed down to the bottom of tubes in which the height of fluid is 5 cm. (Assume that the red blood cells obey Stoke's law).
c) Explain some of the problems in measuring whole blood viscosity and why some methods are more reliable than others.