Bioelectric theory

In 1848 du Bois-Reymond [21] suggested that the surfaces of biological formations have a property similar to the electrode of a galvanic cell and that this is the source of bioelectric phenomena observed in damaged tissues. The properties of biological membranes could not, however, be explained before at least the basic electrochemistry of simple models was formulated. The thermodynamic relationships for membrane equilibria were derived by Gibbs in 1875 [29], but because the theory of electrolyte solutions was formulated first by Arrhenius as late as 1887, Gibbs does not mention either ions or electric potentials. 

Autonomous phenomena in multicellular systems are considered in the section on bioelectric patterning in cell aggregates. A mathematical model is considered which describes the cell aggregate via macroscopic variables--concentrations and voltage. Cells are "smeared out" to formulate the theory in terms of continuum variables. A nonlinear integral operator is introduced to model the intercellular transport that corrects the cruder diffusion-like terms usually assumed. This transport term is explicitly related to the properties of cell membranes. 

Cowan and coworkers (4 ) in the theory of neuronal interactions in the brain. These equations have been shown to yield a great variety of self-organizing phenomena and hence such phenomena are certain to arise in the present theory. Finally we note that in the limit of small R the theory reduces to the small gradient theory. In the section°on bioelectric patterning we shall demonstrate some aspects of self-organization in this model. 

Let us investigate the onset of steady bioelectric patterns. For these steady states dc/3t = 0, dv/dt = 0, and hence we must solve (56,57) with (6U) by setting 9c/dt = 0 in (57). Bifurcation theory shows that when a critical value of a parameter (such as a bath concentration) attains a critical value, small amplitude patterns arise from the uniform state ( V 1 here) in a pattern dictated usually by the equations linearized about the uniform state. The bifurcation condition for this patterning onset thus occurs when we can find solutions of... 

As noted in the chapter on Volume Conductor Theory, most bioelectric field problems can be formulated in terms of either the Poisson or the Laplace equation for electrical conduction. Since Laplace s equation is the homogeneous counterpart of the Poisson equation, we will develop the treatment for a general three-dimensional Poisson problem and discuss simplifications and special cases when necessary. 

In 1945, Lundegardh put forward an explanation of ion transport in terms of redox reactions. The redox reactions occurring in respiration were considered as the source of bioelectric phenomena. Describing the oxidation of Fe " ion to Fe " in enzymes, Lundegardh proposed that since Fe " ion attracts one more anion than the Fe " " ion, the process of Fe /Fe redox reaction causes the movement of anions in the opposite direction to that of the electrons. Since the principal postulate of this theory was regarded as charge separation in connection with ionic trans-... 

D. S. Fensom, "The Bioelectric Potentials of Plants and Their Functional Significance. I An Electrokinetic Theory of Transport, Can. J. Botany 35, 573-582 (1957). 

Piezoelectric properties have been found in human hair and other keratinized materials. This is also the case for bone and tendon. Bone remodeling has been attributed to piezoelectricity. The theory is that the mechanical stress on a bone generates bioelectricity that in turn influences bone growth. Because most biomaterials exhibit piezoelectric properties, it is not strange that there are many theories postulating piezoelectric effects in tissue for example, that the transducer mechanism in the inner ear, in the hair follicles, and of touch and vibrational sensitivity is piezoelectric. Results in the literature are often with dry sample, and the question remains as to the importance of piezoelectricity in living, highly conductive tissue. 

Johnsen et al. (2011) showed that the measurements of electro-osmosis in human skin, shown in Figure 8.40, can be closely mimicked by using memristor theory. They also explain the memristive mechanisms involved in electro-osmosis. An introduction to using memristor theory in bioimpedance and bioelectricity is given in Johnsen (2012). The whole concept has also been expanded to include memcapacitors and meminductors (Di Ventra et al., 2009). 

Miller, H.A., Harrison, D.C., 1974. Biomedical Electrode Technology. Theory and Practice. Acad. Press. Morucci, J.-R, Valentinuzzi, M.E., Rigaud, B., Felice, C.J., Chauveau, N., Marsili, P.-M., 1996. Bioelectrical impedance techniques in medicine. Crit. Rev. Biomed. Eng. 24, 223—681. 

Some changes and additions have been made in this edition An electrode is the most important component of any bioimpedance and bioelectric measuring systems. To make the book easier to read, we have dedicated a specific chapter to electrodes. Furthermore, we have extended the chapter on models with a comprehensive tutorial on statistical analysis of bioimpedance data. We have also included the Kelvin probe, memristor theory, and the concept of universality (scaling properties) and we have expanded the survey on impedance analyzers. 

Neu WK, Neu JC (2009) Theory of electroporation. In Kroll MW, Tchou PJ, Efimov IR (eds) Cardiac bioelectric therapy. Springer, New York... 

Metting van Rijn, A. C., Peper, A., and Grimbergen, C. A. (1990). High-quality recording of bioelectric events—Part 1 Interference reduction, theory and practice. Medical Biological Engineering Computing, 28(5), 389-97. 

Tropisms have been used as an exquisite test of the ability of a plant to selectively control its growth, since one side of a stem grows more rapidly than the other side of that same stem. The traditional explanation is the theory of the Lateral Transport of Auxin proposed by Went and Cholodny [32]. This theory states that the tropism induces lateral transport of lAA, thus causing more lAA to accumulate on one side of the stem than on the other. The theory is adequate, except there has been no explanation of how lateral transport of lAA is attained. We have developed a working theory to explain tropisms and lateral transport based upon our experiments, as described above, and upon the earlier studies of changes in the bioelectric potential of plant tissues induced by environmental stimuli. 

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