Blood Motion: Turbulent or Laminar?

Introduction: The issue on the mode of blood motion in the bloodstream, where the arterial and venous flow is significantly different, has been of greater concern recently. However, the conclusions are largely based on the analysis of the geometric orientation in the wall of arteries of smooth muscle elements. The aim of our study was to examine the characteristics of the prominent configuration of cardial cavities and arterial vessels. Methods and Material:The material for study were specimens of human heart, rabbit aorta and arterial microvessels of rat salivary glands, examined by injection and corrosive methods, scanning and transmission electron microscopy. Results. Specific attachments are to be involved to transform the laminar flow of blood into the turbulent one. We hypothesize that appendages in the atria and muscular trabeculae of heart in the ventricles with particular orientation to the bloodstream from the atria into the aorta and pulmonary trunk should be assigned to such attachments. The longitudinal axes of the auricles are at the right angle to the axial blood flow from the atria to the ventricles. Compound relief of the right auricle is caused by the pectineal muscles and compound relief of the left auricle by the coral-like processes. Vortex flow is formed due to configuration of such relief in auricular systole, which is superimposed on the main bloodstream from the atria to the ventricles, making it turbulent. Ventricles of the heart, due to contractive activity of muscular trabeculae are the place of origination of vortex motion of blood in the initial parts of pulmonary and systemic circulations. Muscular trabeculae in the left ventricle have right-handed helical path with large slope of turns from the apex of the heart to its base, whereas in the right ventricle they are of left-handed flabelliform orientation from the cardiac apex to cardiac base. Such position suggests that the turbulence of blood flow, originating in the cardial cavities, is dictated by the need for even mixing of blood corpuscles while moving on the arteries. We believe that consumed energy could be enough for overcoming a resistance in the main arteries, in the wall of which there is a lack of active contraction elements. Intimal relief of the rabbit aorta is representad by the distinctly pronounced folds, longitudinally oriented on the steep spiral. They acquire especially steep (whirlpool or vortex) nature in the area of the opening into the intercostal arteries, which, as it is well known, in contrast to the aorta, are assigned into the arteries of the mixed type. Minor arterial microvessels (metarterioles-like type) have similar internal relief of the wall, which must extrude into the inner lumen of nuclear zones of endothelial cells. But the motion of blood in the arterial microvessels will greatly depend on the wave myogenic activity of smooth myocytes in their wall. Specific orientation of smooth muscle elements in the arterial microvessels is directed onto the formation of turbulent blood flow, contributing to its better mixing and ten-time increase in the intensity of metabolic processes. Сonclusion: The findings show that the conditions of hemodynamics in the great blood vessels suppose turbulent motion of blood that emerges in the cardial cavities, which is necessary for even mixing of blood corpuscles and their orderly distribution in homogeneous erythrocytic mass that would have been impossible in conditions of laminar motion of blood