The Resistance Vasculature

Abstract

In the same way that the relationships among voltage, current, and resistance in parallel-and series-coupled electric circuits used to be outlined in schematic diagrams according to Ohm’s law, similar principles are useful in visualizing the principal hemo dynamic events in the cardiovascular system, though here the related Poiseuille’s law prevails. When the events in the various ardiovascular compartments are so approached, the capillaries stand out as the obvious key feature, simply because the diffusion and iltration-absorption exchange across their walls fulfill the essential purpose of the circulatory system, i.e., the maintenance of an optimal milieu intmeur for the tissue cells. All other parts of the system, as well as the superimposed neurohormonal ontrol echanisms, finally serve to keep capillary flow, pressure, and perfused surface area well adjusted to the prevailing exchange needs in the various tissues. It is mainly when some of these must ransiently be given priority that centrally governed redistributions are induced between the parallel-coupled systemic circuits.