Alternative view on blood and blood plasma in the vasculature

Results of an experimental study of blood properties are reported. To approach the boundary conditions of blood biophysics in a real flow, the viscoelastic measurements are carried out on surfaces coated with a 10-nm thick fibrous layer composed of extracellular matrix protein. For native whole blood, a plateau of the shear elastic modulus as a function of frequency is observed. It is concluded that a slow flow of blood plasma close to the vessel wall can generate a stationary plasma layer that contributes to the functional width of surface layers in blood vessels. The shear stress term calculated from the wall shear rate and blood viscosity becomes imprecise if it does not include the existence of this intermediate layer.