The endothelial vessel wall shear stress ("shear stress")

The main role of the arterial wall is to resist haemodynamic pressures: transverse pressure, due to blood pressure and tangential pressures, produced by shear forces of blood on the endothelium. A shear pressure, observed, is defined as a stress applied - parallel or tangential - to a material, unlike a normal pressure, that is applied perpendicular. Vascular endothelium is exposed to hemodynamic stress generated by blood flow known as the vascular wall shear stress. Shear stress is defined as the force exerted per unit area of the vessel wall by blood flow and depends on the blood viscosity velocity and blood flow. The amount of vessel wall shear stress is expressed in dynes/cm(2), physiological values being between 1-6 dynes/cm(2) in the venous system, while in the arterial system these values are at least 10 to 15 dynes/cm(2).