| Newtonian fluid |
A Newtonian fluid is a fluid whose viscosity remains constant whatever the level of the applied force or the time during which the force is applied |
| Non-newtonian fluid |
A non-newtonian fluid is a fluid whose viscosity changes with the level and/or the time of the force application |
| Shear rate |
This is the velocity gradient measured across the diameter of a fluid-flow channel. In vascular physiology, shear rate depends on blood flow and the vessel radius |
| Shear stress |
This is the external force acting on an object or surface parallel to the slope or plane in which it lies; the stress tending to produce shear. In hemorheology, shear stress is the product of blood viscosity by shear rate |
| Shear thinning |
This is the rheological behavior of a fluid where viscosity decreases when the force applied increases |
| Thixotropy |
A thixotropic fluid is a fluid whose viscosity is a function not only of the shearing stress, but also of the previous history of motion within the fluid |
| Blood viscosity |
It is a measure of the resistance of blood (i.e., plasma + blood cells) to flow |
| Plasma viscosity |
It is a measure of the resistance of plasma to flow |
| Red blood cell deformability |
This is the ability of red blood cell to change its shape under a given level of applied force, without rupture. It depends on the elasticity and integrity of the membrane, the cytosolic viscosity and the ratio surface/volume of the cell |
| Red blood cell elasticity |
Red blood cell (membrane) elasticity is the ability of red blood cell to recover its initial shape after a deformation obtained for a given force. It depends on the membrane integrity |
| Red blood cell aggregation |
Red blood cells are able to form reversible aggregates. These aggregates depend on the ability of the cells to aggregate (i.e., aggregability) and on plasma factors that may favor the formation of these aggregates (such as fibrinogen) |
| Red blood cell disaggregation threshold |
This is the force needed to disperse RBC aggregates |
