ABSTRACT
The tone of a vascular smooth muscle cell has been shown to be dependent upon the intracellular concentration of free calcium. Turning the attention to vascular resistance, this can be defined as a measure of friction between the wall of the blood vessel, the blood and between the components of blood themselves which oppose flow. Vascular resistance depends upon the viscosity of blood the geometry of the vessel. The traditional definition of the factors that can influence the radius of blood vessels did make any distinction between arterioles and veins. Moreover, it stated that these factors can originate from within the blood vessel itself, local controls which serve the metabolic needs of the tissue in which they occur, from the rest of the cardiovascular system, reflex controls which integrate coordinate the needs of the whole body. Returning to loss of end organ responsiveness in hyperbilirubinemia, the mechanism of this phenomenon has been investigated by Bomzon and his colleagues.
