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Biomedical subjects

M E Mazurov

Publications and source records attributed to M E Mazurov.

9 recordsLinked to original sources
PubMed1991

[The synchronizing interaction and mechanism of the formation of the common rhythm of the cardiac pacemaker. I. The modeling of the interaction of 2 pacemaker elements].

The main physiologic hypotheses in establishing a common rhythm of the heart sino-atrial node (SAN) have been considered. A mathematical model of SAN which takes into account the interaction between pace-makers in pairs has been proposed. A quantitative description of common rhythm establishing taking into account interaction in pairs has been obtained, the expressions for the period of common rhythm, a delay and the rate of stimulation distribution have been found. A comparison of calculated and experimental data is given.

Action Potentials↗
PubMed1976

[Kinematics of crawling locomotion. I. Ideal elastic model].

One-dimensional model of polysegmental ideal-elastic body is considered, movements of which in the free state are described by wave equation. Regimes of creeping without the loss of initial energy are examined, when the moments of attachment of the segment boundaries to the substrate are synchroneous with instantaneous stopping of free oscillations. Possibility of the existence of two coordination patterns--unconcerted and concerted metachrony is shown. In the last case velocity of the metachronal wave is equal to velocity of an elastic wave, which propagates along segments in the result of attachments or deattachments of boundaries.

Locomotion↗
PubMedDate not supplied

[Identification of nonlinear models of biological membranes by the method of fixed voltage].

A mathematical substantiation of the method suggested by Hodkin and Huxley in 1952 for the identification of nonlinear systems is presented. A procedure for the application of this method was developed, which involves creating the structure of a mathematical model, carrying out a series of tests with specially chosen signals, and finding the unknown parameters. The basic requirements to admissible sets of entrance and target signals and the operator of the system were determined. It was shown that it should be quite continuous, the minimal number of unknown parameters and the minimal complexity of structure of the operator should provide the required quality of approximation. The merits and demerits of the mathematical models of Hodkin-Huxley and Noble, and the procedures used for their creation are discussed. The structure of the operator for the identification of mathematical models of excitable membranes when a large number of membrane currents is considered is offered. It was found that nonlinear electric properties of biological membranes can be identified using tests with other kinds of "fixed" parameters, for example, the method of "fixed" current, the fixed linearly increasing voltage, and others.

Cell Membrane↗
PubMedDate not supplied

[Rhythmogenesis in the sinoatrial unit of the heart].

The most significant experimental data about the formation of a uniform rhythm of the sinoatrial unit of the heart for both the intact sinoatrial unit of the heart and cardiomyocytes in cellular structures are presented. The basic mathematical models for studying the processes of synchronization in the sinoatrial unit of the heart are described, including equations of Noble, Bonhoffer, and van der Pol and modified axiomatic models. The basic results obtained using the mathematical models are presented. The major reasons influencing the formation of a uniform rhythm were revealed: the form of a potential pacemaker in the phase of slow diastolic depolarization, its porosity, the force of connection between pacemaker and electric capacity of pacemakers. A study of rhythmogenisis on the basis of the modified axiomatic model was carrud out. The method allows one to calculate the uniform rhythm of the sinoatrial unit of the heart in view of the mutual influence of pacemaker cells, including the force of connection, electric capacity of cells, their possible clusterization. It was shown that generally the uniform rhythm of the sinoatrial unit of the heart is formed on an intermediate level of all pacemaker cells.

Heart Rate↗
PubMedDate not supplied

[A study of synchronization of the sinus unit upon stimulation from auricles].

The excitation of the sinoatrial unit from heart auricles of the frog has been studied. Potentials were recorded by means of microelectrodes inserted to pacemaker of the sinoatrial unit. It has been established that auricles can impart the rhythm to the sinoatrial unit due to electric and electromechanical influence, and electromechanical influence is of greater significance. Specific transitions accompanying the establishment of the stationary rhythm have been studied. A mathematical model of transitions of the establishment of the rhythm of the sinoatrial unit, which is based on diophant methods is offered. The catculations performed by means of the mathematical model coincide well with results of experimental studies. The stabilizing role of auricles in the formation of the rhythm of the sinoatrial unit has been established.

Animals↗
PubMedDate not supplied

[A mechanism for setting a single rhythm for a multipacemaker sinoatrial node].

Interaction of the system of n pacemaker cells modelling the work of the heart sinoatrial node was studied. Suggesting the interaction additivity an expression was obtained for the system single rhythm. Dependence of the system single rhythm and propagation velocity of excitation delay on the number of pacemakers of the leading centre and connection force between the pacemakers was investigated. The results obtained qualitatively, agree with the experimental evidence available.

Humans↗
PubMedDate not supplied

[The mechanism of setting the common rhythm of the pacemaker pair in the sinoatrial node].

Principal physiological hypotheses concerning the setting of united rhythm in the heart sinoatrial node (SAN) are considered. A mathematical model of SAN is proposed which takes into account properties of individual elementary pacemakers and their interaction. Assuming paired interaction of the pacemakers there are revealed the main P.D. parameters, affecting the setting of the united rhythm. Quantitative expressions are obtained for the united rhythm period, delay and propagation velocity of the excitation. The calculated data are compared with the experimental ones. The hypothesis concerning the setting of the united rhythm as a result of the interaction of SAN pacemakers is confirmed.

Animals↗
PubMedDate not supplied

[Effect of an anomalous broadening of the synchronization band after electric stimulation of heart tissues].

Synchronization effects of the second order induced by a change of the action potential (AP) shape in relation to the frequency of periodic stimulation were studied. Mechanism of anomalous increase of the synchronization band at periodic stimulation of the heart fibers was explained. By means of a modified method of synchronization diagrams the synchronization bands were calculated for possible stimulation regimes taking into account a change in RP shape and dynamic threshold (DT) depending on the frequency of the initiated regimes. Regions of stimulating signals parameters (multiplicity regions or prolonging regions) were discovered, within the range of which the same stimulating signal may induce different synchronization regimes. Physiological meaning of the existence of anomalous synchronization regimes which significantly broaden the adaptation possibilities of the heart is discussed.

Action Potentials↗