88
2 Holographic Microscopy of Phase and Diffuse Objects …
cell interior is negatively charged concerning the environment, and the potential
difference on the membrane is about 60 mV. The appearance of “rest potential” in
the Bernstein theory is explained in the following way. It was assumed that membrane
was permeable only for K ions. It turned out that rest membrane is permeable for
Na and Cl ion also. Really, Na ions, which are in plenty in the environment, come
to the cell under the influence of diffusive and electric forces. Thus, it was assumed
that membrane has special mechanism—sodium pump, which provides so-called
active transport, i.e., takes Na ions out, against electrochemical potential gradient
consuming metabolism energy.
It is postulated in the Hodzhkin–Haksli model that ion channel, for example,
potassium, can be in one of the fifths conformational states, and only one of them is
conductive. This scheme is not the only possible if we proceed from the conditions
of coincidence with experimental data on the fixation of the material.
Not considering the question of membrane theory in detail it is possible to suppose
that future experiments in the creation of supersensitive measuring system, which
enables to divide K and Na ions contribution in the refraction, will be successful.
These ions cross the membrane of living nerve fibers using the wavelength-tuned
source in the researched range as it was done by the author together with the coauthors on resonance atomic moving of K and Na in the plasm (see Chap. 1, Sect. 1.3).
At the same time, the researchers were interested in the problems of nerve impulse
velocity calculations in homogeneous fiber and also complete excitation propagation
mode in active media, for example, in cardiac muscle. It is known that in myocardium
there may appear flutter phenomenon, or fibrillation, connected with spontaneous
electric activity of a medium. Famous mathematician N. Viner and A. Rozenblut
studied fibrillation. They introduced the notion of formal medium excitation where
the nature of excitation is insignificant and basic results were got.
Another group of works is connected with impulse velocity calculation based
on simple representation about physics of the process. Usually, it was amounted
to the fact that when some critical conditions were achieved, membrane capacity
discharge began or membrane generator with tailor-made-properties switched on.
Such physical modeling allows receiving analytical results and finding out physical
regularities.
The most intriguing question in the physics of nerve impulse is the action mechanism of ion channels of excited membranes operated by electric field. The change
of channel conductivity is either connected with the noticeable tuning of system
molecular geometry or induced by the change of electrostatic component of ion
energy.
It seems natural that in the first case the channel will work discretely on the
principle of “all or nothing”. In the second case, its conductivity will be changing
continuously. The measurement of current fluctuation spectrum makes it possible to
choose between these two possibilities. Thus, fluctuation analysis of ion current of
biological membranes becomes of special significance. But till the present moment,
there is still no clarity about the essence of electrical quantity characterizing the
channel state. So far, there is no any other method that would make it possible to
detect whether transfer or rotation of some excited groups at long distances take place
2 Holographic Microscopy of Phase and Diffuse Objects …
cell interior is negatively charged concerning the environment, and the potential
difference on the membrane is about 60 mV. The appearance of “rest potential” in
the Bernstein theory is explained in the following way. It was assumed that membrane
was permeable only for K ions. It turned out that rest membrane is permeable for
Na and Cl ion also. Really, Na ions, which are in plenty in the environment, come
to the cell under the influence of diffusive and electric forces. Thus, it was assumed
that membrane has special mechanism—sodium pump, which provides so-called
active transport, i.e., takes Na ions out, against electrochemical potential gradient
consuming metabolism energy.
It is postulated in the Hodzhkin–Haksli model that ion channel, for example,
potassium, can be in one of the fifths conformational states, and only one of them is
conductive. This scheme is not the only possible if we proceed from the conditions
of coincidence with experimental data on the fixation of the material.
Not considering the question of membrane theory in detail it is possible to suppose
that future experiments in the creation of supersensitive measuring system, which
enables to divide K and Na ions contribution in the refraction, will be successful.
These ions cross the membrane of living nerve fibers using the wavelength-tuned
source in the researched range as it was done by the author together with the coauthors on resonance atomic moving of K and Na in the plasm (see Chap. 1, Sect. 1.3).
At the same time, the researchers were interested in the problems of nerve impulse
velocity calculations in homogeneous fiber and also complete excitation propagation
mode in active media, for example, in cardiac muscle. It is known that in myocardium
there may appear flutter phenomenon, or fibrillation, connected with spontaneous
electric activity of a medium. Famous mathematician N. Viner and A. Rozenblut
studied fibrillation. They introduced the notion of formal medium excitation where
the nature of excitation is insignificant and basic results were got.
Another group of works is connected with impulse velocity calculation based
on simple representation about physics of the process. Usually, it was amounted
to the fact that when some critical conditions were achieved, membrane capacity
discharge began or membrane generator with tailor-made-properties switched on.
Such physical modeling allows receiving analytical results and finding out physical
regularities.
The most intriguing question in the physics of nerve impulse is the action mechanism of ion channels of excited membranes operated by electric field. The change
of channel conductivity is either connected with the noticeable tuning of system
molecular geometry or induced by the change of electrostatic component of ion
energy.
It seems natural that in the first case the channel will work discretely on the
principle of “all or nothing”. In the second case, its conductivity will be changing
continuously. The measurement of current fluctuation spectrum makes it possible to
choose between these two possibilities. Thus, fluctuation analysis of ion current of
biological membranes becomes of special significance. But till the present moment,
there is still no clarity about the essence of electrical quantity characterizing the
channel state. So far, there is no any other method that would make it possible to
detect whether transfer or rotation of some excited groups at long distances take place