We discuss a suite of factors that should theoretically impact rheological properties of marine mammal blood, including: shear rate and the tendency for RBC aggregation; shapel/deformability of RBC; Hctvariability; and the cellular rheological behavior of RBC
Two of the fundamental concepts in rheology require some pre liminary discussion: Newtonian fluids and shear rate. Newtonian fluids are often described as"simple" fluids(e.g., water, salt solutions). For these fluids, viscosity changes are driven only by temperature alterations: viscosity decreases with increasing temperature but is not affected by flow conditions. In contrast, non-Newtonian fluids(e.g., whole blood) are complex fluids where the inherent properties of the fluid alter the viscosity depending not only on temperature but also on shear rate. Shear itself can best be described as visualizing the stream lines or layers that form as a fluid is flowing through a tube. Since the velocity of flow is ze at the wall and increases toward the center, layers move at different speeds. The difference of speed between adjacent streamlines or layers divided by the distance separating these layers defines the rate at which the layers are being sheared" against one another and hence shear rate The units of shear rate are unusual and arise due to a velocity term such as cm/sec being divided by a distance such as cm leaving time the denominator. Note that for a given in size tube, shear rate increases with volumetric flow rate