The influence of pulse pressure oscillations on the processes of transcapillary exchange in the hemodynamics has been investigated by experimental and numerical methods. The active role of microvessel walls in the mass transfer has been confirmed. On the basis of the generalized nonstationary Starling scheme patterns of transcapillary exchange with alternation of the filtration and reabsorption processes have been determined. Flows in the interstitial space have been modeled numerically. It has been established that the presence of pulsations promotes enhancement of the transcapillary exchange.

The results of many years study of physical processes in link of microhemocirculation using high sensitive physical methods are presented. Some of revealed phenomena allowed to suggest and to prove new concept of transcapillary exchange based on active interaction of blood with blood vessel.

Investigations are aimed at studying the blood circulation biomechanics, the physical mechanisms of the cardiovascular system transport function, and regularities of branching and dichotomic division and merging of blood flows at the level of bifurcations of large arterial blood vessels and microvessels. An analysis of created protacrylic casts of the heart and blood vessel cavities has revealed new anatomical peculiarities: funnel-shapedness of the configuration of heart and vessel chambers, tangentiality of atrial orifices and ventricular apertures, and tangentiality of branching of arterial blood vessels at the level of bifurcations. An original method of X-ray contrast cineangiocardiography has been developed. It has allowed, for the first time at the system level, to visualize the helical character of blood motion in the heart atriums and ventricles, arteries, and veins. In hydrodynamic investigations of the blood circulation system, the physical laws of conservation with a local dynamic approach for funnel-shaped canals were used. The performed fundamental investigations of the structural-functional organization of the cardiovascular system have allowed the authors to make a number of scientific discoveries. Briefly, their essence is in the following: The phenomenon of formation of a helical blood flow in the cardiovascular system shows new anatomical-functional principles in the greater and lesser circulations; The universal phenomenon of formation of a twisted flow of biological media in the canals of transport systems reveals the general physical mechanism in the organization and sustaining of a helical blood flow in the transport function of the cardiovascular system. This helical flow is created by a twisting wave excited in the channel walls by contraction of spirally oriented muscle and elastic elements; The property of a twisted liquid flow is to create a tractive force in funnel-shaped canals of variable circular section, and discloses the nature of arterial diastolic pressure due to the energy of rotational motion of a helical blood flow. Diastolic pressure is used to overcome the vascular resistance; The law of hemodynamics in arteries reveals a mathematical relation between the dynamic and kinematic characteristics of the helical blood flow; The law of branching of large arterial blood vessels establishes an unambiguous mathematical relation between the morphometric parameters of blood vessels, and the kinematic and dynamic parameters of the helical flow at the level of bifurcations of arteries and veins; The law of branching of blood microvessels reveals an unambiguous mathematical relation between the morphometric parameters of blood microvessels, the kinematic and dynamic parameters of the Poiseuille flow of blood in arterioles, capillaries, and venules. On the basis of the scientific discoveries, a new direction has been created. It makes it possible to develop new technologies of diagnostics, treatment, and prophylaxis in medical practice.

In this paper, some results of clinical and experimental investigations of the biomechanics of pulmonary ventilation are presented. Direct visualization of the motion of non-homogenous gas media in the human respiratory system during inspiration has been obtained for the first time. The existence of the phenomenon of formation of a helical counterflow of gas media at pulmonary ventilation has been proved experimentally. The results obtained can serve as a basis for the development of new methods of controlled respiration and special apparatuses for use in clinical medicine: anesthesiology, resuscitation, and intensive care.

Introduction The purpose of this paper is to confirm clinically and experimentally the concept of helical countercurrent flow of gas media at pulmonary ventilation proposed by the authors earlier [1, 2]. The reason for the creation of the new concept was the detected contradictions in traditional concepts of the motion of gas media in the respiratory system. In the traditional concepts of pulmonary ventilation biomechanics, the replacement of gas media in the non-flow-through pulmonary ventilation system is realized due to irregular convective transport. In this model of pulmonary ventilation, the replacement of inspired fresh air by used expired air cannot be efficient, and must not take place at small inspiration volumes. In normal physiological conditions, however, the per cent of the carbon dioxide and oxygen in the expired volume indicated that gas exchange is much more effective than it followed from the well-known model. The idea of helical countercurrent ventilation has made it possible to resolve these contradictions. Theoretically, this idea did not contradict the physical laws of aerodynamics. Experiments with spiral deposition of tobacco smoke in cylindrical glass tubes under the action of gravity demonstrated this. In addition, peculiarities of the organization of structural elements of the pulmonary tracheobronchial tree, such as the right-twisted corrugated relief on the inner walls of air canals and the ratios between their cross-section areas at dichotomous branching, provided conditions necessary for the existence of a countercurrent helical motion. It combines two gas jets spirally embracing each other but having opposite flow velocities. To prove irrefutably the correctness of new concepts of the external respiration mechanism, it was necessary to perform a decisive experiment resulting in direct observations of regular helical motion of gas media in the respiratory system. No experimental observations on the detection of real motion of gas flows at pulmonary ventilation have been performed up to now. This paper provides a description of a method and results of clinical experiments in which direct visualization of the motion of gas media at natural pulmonary ventilation has been realized. The results of previous investigations were considered to be sufficient for the development of controlled respiration methods. Controlled respiration is widely used in anesthesiology,

In this paper, the physical mechanisms of transcapillary exchange of the living organism are investigated. Laboratory animals are the object of this investigation, and original laser and electrophysiological methods are used as experimental tools.

The processes of diffusion and filtration are slow, and therefore a full cycle of gas exchange and metabolism at the level of capillaries of the blood circulation system cannot be realized in such a short time. A special laser setup was created for noncontact, noninvasive investigation of microcirculation and transcapillary exchange in a living object. With the help of investigations by using this setup, a phenomenon unknown before, that of the formation of an acoustic field in the lumens of microvessels (arterioles, capillaries, and venules) was discovered. With the help of the laser method, we detected that the transverse motion of the walls of microvessels in the high-frequency range really takes place. The authors advanced the problem of active interaction of moving erythrocytes in microvessels with smooth muscle cells of their walls for the first time. In blood vessels, smooth muscle elements are packed spirally. We suggest that there exists a special mechanism of regulation of metabolic processes.

The study of the phenomenon of acoustic field generation in the lumens of microvessels has been continued. The results of comparative experiments on animals and control test objects are presented. The research was made under normal physiological conditions and with artificial suppression of cardiovascular activity. A direct dependence of the frequency of oscillations of microvessel walls on the velocity of the blood flow was established.

In this paper, experimental results of investigations of the physical mechanism of transcapillary exchange by the method of phase sensitive laser spectroscopy of light scattering are presented. Acoustic oscillations of the walls of microvessels (arterioles, capillaries, and venules) which provide transcapillary exchange have been detected for the first time.

The general physical mechanism of formation of the helical blood flow of biological media in canals of the cardiovascular, alimentary, and urinary-excretory systems has been decoded. The possibility of elucidating the physical mechanisms of microcirculation and trans-capillary exchange with the use of the laser method is discussed.