Biological Asymmetry and Cardiovascular Blood Transport

Abstract

Asymmetry is a very remarkable property of biological structures and functions. Most publications concerning asymmetry are related to brain function. However, as will be shown in this study, the asymmetry in the cardiovascular system plays an important role with respect to optimization of functions. Weibel (Cambridge, MA, 2000) has used the name “symmorphosis” to describe the ideal interrelation between structure and function. Therefore, asymmetry is a component of symmorphosis, both in terms of architecture as well as of time and time courses. The asymmetry of the heart chambers enables the “mechanism of the movement of the plane of the valves” to improve the pumping function. The time course of the contraction of the heart and of the ejection into the large arteries is asymmetric in time in order to minimize energy consumption. The so-called Liebau effect that permits valveless pumping of fluids depends on the asymmetric properties of conduits. One important example of the Liebau effect appears to be in the function of the coronary vascular system. It can be shown that there are several mechanisms to produce valveless pumping. The common denominator of several simple models described in the following sections is the dependence of the unidirectional pumping effect on asymmetry. It appears that many additional examples of transport effects concerning fluids or gases in biology as well as in engineering have some connection with the Liebau effect.