BIOPHYSICS

From Big Medical Encyclopedia

BIOPHYSICS — the science studying physical properties and the phenomena both in the whole organism, and in separate bodies, fabrics, cells and also physical. - chemical bases of processes of life activity.

Throughout B.'s development as science in it two sections were selected, each of which differs in the methodological orientation.

The first section (the physical direction, or actually biological physics) studies physics and physical properties of an organism in general or separate components it components. This section B. deals with common problems of physical thermodynamics of protein and its transformations, a heatmass exchange, physics of muscular contraction and physical properties of sokratitelny proteins etc. Biological systems at the same time are studied preferential as physical, physical and mathematical modeling is used; here the mathematical biophysics adjoins.

The second section B. carrying preferential biological orientation studies physical. - chemical bases of processes of life activity. Historically it arose on the basis of physical chemistry and includes studying of private questions of thermodynamics, kinetics and catalysis of biological processes; physical. - chemical bases of the electric phenomena in living cell; physical chemistry of colloidal state of protoplasm etc. This section B. can conditionally be identified with biophysical chemistry (see); it is closely connected with organic chemistry and biochemistry, physiology, a pathophysiology and others medical - biol, sciences.

On the basis of B.'s achievements and in connection with requests of applied medicine there was a number of new disciplines, adjacent to B.: medical physics (see) and radiobiology (see) which cornerstone a number of basic researches in the field of interaction of atomic, electromagnetic and corpuscular radiations with live objects is.

In B. allocate a complex of data from its various departments which found application in medicine under the conditional name «medical biophysics». Here it is possible to refer studying of effects of radiation on the basis of the analysis physical. - chemical mechanisms of the priming reactions arising in a cell at action of radiation. Studying physical belongs to the field of medical biophysics. - chemical properties of separate substances and connections in a cell and their changes it is normal also of pathology, and also studying of influence on an organism of such factors as vibration (see), acceleration (see), zero gravity (see) etc.

Rapid development of B. in the middle of 20 century in many respects was promoted by development of nuclear power, astronautics and other areas of human activity which demanded development of ways of protection of a human body against action of ionizing radiation, vibration, accelerations and other physical. factors.

Both called above the directions B. are given by the relevant departments on physical. faculties of universities and in technical colleges, on the one hand, and on biol, faculties of universities, medical and veterinary schools — with another, the trained specialists having various programs and profiles and big differences in the scientific orientation.

Methods of biophysics are widely used in theoretical and applied medicine, they give the chance to obtain information on physical. - the chemical processes which are directly the cornerstone of emergence of pathological processes. The biophysics left a big mark on the doctrine about pathology, on theoretical ideas of an inflammation, hypostasis, nephrite, mechanisms of a water balance, membrane permeability of cells and their disturbances at pathology etc.

Biophysical. by methods study therapeutic effect of action various physical. the factors applied in physical therapy. The electrophysiology and neurology using biophysical are closely connected with B. it is normal of idea of the nature of excitement and carrying out in nerves or at interpretation of some pathological manifestations. In ophthalmology widely use B.'s achievements in the field of the photochemical processes happening in visual bodies. The large role is played by B. in understanding of primary mechanisms of radiation injury and development of measures of prevention of its treatment.

B. it is integrally connected with pharmacology and toxicology since helps to understand physical. - chemical mechanisms of effect of various medicinal substances (drugs, poisons), and also quantitative indices of their toxic action. B. it is closely connected with immunology, virology (methods B., in particular, play a large role in identification of the nature of viruses, phages).

In medical practice also other biophysical methods are used (electrodiagnosis, colloid chemical reactions, methods of assessment physical. - chemical properties of erythrocytes, spectral methods, methods of conductivity etc.).

«Physical» B. in a smaller measure is connected with medicine since long had purely theoretical character and had practical value only in dosimetry of radiations. In a crust, time of communication of this direction B. with medicine extend, through molecular biology it entered the area of molecular pathology when diseases contact disturbances in a structure of large biopolymer molecules, napr, hemoglobin, etc.

History of biophysics

Purely formally attempts of use of laws of physics can be referred to biology by the time of emergence of physics. However similar attempts were naive from the point of view of their use and the phenomena externally similar with physical had obviously mechanistic character as the main role in them was played by external analogies — biol., were treated as physical. manifestations. So, e.g., in the middle of 19 century as model of an explanation of the mechanism of muscular contraction the piezoelectric effect was offered (the phenomenon of change of volume of crystals under the influence of electric field), on the principle to-rogo the model — the rubber films shifted by metal plates, which are reduced under the influence of electric zero was designed. At the same time attempts of use of laws of physics and mechanics had a positive exit. So, J. Borelli explained with laws of mechanics all forms of motion of animals, including muscular contraction and digestion. U. Garvey on the basis of quantitative measurements and use of laws of hydraulics created the doctrine about blood circulation. L. Galvani's researches (discovery in 1791 of animal electricity) which brought in a result to creation became a stage in B.'s development electrophysiologies (see), and also attracted interest in studying of the mechanism of an origin of bioelectric potential and their value in fiziol, processes (see Bioelectric potential). The first attempt of an explanation of origins of bioelectric potential is connected with a name E. Du Bois-Reymond (middle of 19 century). It showed communication of excitement with development of electric activity. Idea of membranes became direct development of views of Du Bois-Reymond as about interfaces on which there is a formation of electric charge J. Bernstein became the author to-rogo. Opening of the first law of thermodynamics — communication between work and heat — was a powerful incitement for development bio-energetics (see). The big role in B.'s formation belongs to the German physiologist and the physics Mr. Helmholtz. It gave the description of an eye as optical system, described operation of the acoustic device from physical positions, for the first time measured rate of propagation of nervous excitement. Being one of creators of thermodynamics, Helmholtz made the first attempt to apply the second law of thermodynamics to live organisms.

An important event for the time was emergence of the cable theory of excitement and carrying out an electric impulse (the beginning of 20 century) proceeding from the fact of detection of high electric resistivity of a nervous cover and rather high conductivity of a core (see Excitement). As physical model of this phenomenon the electric cable with a metal core and an external cover — the insulator served. This theory promoted development of ideas of electric properties of nervous tissue. Great interest was attracted by model of nervous excitement, the offered Lilly (R. Lillie) which showed that if to place a metal wire in solution of strong acid and mechanically to damage its surface (oxide) layer, then in this system there are potentials according to the characteristics reminding the electric phenomena which arise at spread of activation on nerves. This model was exposed to the detailed analysis, was widely discussed in literature and stimulated further researches of electric properties of nervous tissue.

With emergence in physics of quantum-mechanical ideas of the nature of radiations (the 20th years) there was a theory [D. Li, W. I. Altman, H. V. Timofeev-Resovsky, etc.], trying to explain from quantum positions patterns of action of radiations on organisms — the so-called theory of targets and hits. This theory explained action of different types of radiations (ultra-violet, x-ray, and also nuclear) with probability of hit of active particles in so-called hypothetical sensitive volume. This theory though did not achieve the main objective in an explanation of the mechanism of radiation injury, however played a big role in detection of quantitative dependences between the dose and energy absorbed by an object as well as in development of some theoretical questions of genetics and, in particular, the theory of a gene.

Emergence biophysical. chemistry (chemical biophysics, or physical. - chemical biology) it is closely connected with the physical chemistry which arose from need of synthesis of bonds between physical. properties of molecules and their chemical activity. Success achieved by various sections of physical chemistry (electrochemistry, colloid chemistry, kinetics of chemical reactions, thermodynamics etc.), showed that many mechanisms biol, the phenomena can be understood with physical. - the chemical points of view.

I. M. Sechenov, using methods of physical chemistry and the mathematical analysis, studied dynamics of respiratory process and established at the same time quantitative laws of solubility of gases in biol, liquids. He suggested to call area of this sort of researches molecular physiology.

A great influence on development biophysical. researches the theory of electrolytic dissociation of S. Arrhenius rendered (1887). It showed that physical. - chemical activity of salts is connected with emergence of the loaded ions. At once there was an assumption that biol, the role of salts is connected with their dissociation on ions, and on the basis of this theory the Kiev physiologist 13. Yu. Chagovets constructed the original theory of excitement — the so-called condenser theory of excitement, edges quickly won world popularity. At the same time there was an idea of cellular membranes as substrate, on Krom ions form electrically the loaded layers, creating at the same time rest potential.

Developing this idea from quantitative positions, V. Nernst (1899) will create the quantitative theory of excitement and outputs the law allowing to calculate thresholds of excitement depending on time of influence at electric irritation. This law allows to explain change of an excitation threshold depending on the frequency of alternating current and to calculate in advance a possibility of use of high-frequency sources of electric current for deep warming up of body tissues (diathermy).

The theory of ionic excitement was developed by P. P. Lazarev who entered idea of existence of a threshold critical point of the coagulation of cellular proteins responsible for emergence of excitement. In the twenties 20 century this theory was finally formulated by it. In a crust, time it appears in literature as the theory of excitement of Nernst — Lazareva.

In 1910 Geber showed that conductivity of erythrocytes depends on the frequency of alternating current. Having used currents of high frequency, R. Geber established that at frequencies about a megahertz conductivity of erythrocytes in several tens of times is higher, than conductivity at acoustical frequencys, and corresponds to conductivity of 0,1 M of solution of potassium chloride. It was established that change of conductivity depending on the frequency of the enclosed electric current is characteristic of living cells and on value of the relation of low-frequency resistance to high-frequency it is possible to estimate viability of cells. Possible by this criterion it was accurate to determine the moment of death of cells at action of low temperatures, toxicants etc. The method of conductivity began to be used at assessment of viability of erythrocytes and other cells of fabrics, during the studying of properties of membranes of cells — from a position of assessment of their permeability for electrolytes. In 1911 D. Donnan formulated the theory of electrolytic balance (see. Membrane equilibrium), with the help a cut it was given physical. - a chemical explanation for existence ionic (on potassium and chlorine) gradients in living cells, cellular electric potentials and differences of osmotic pressure. This theory continues to a crust, time to play the leading role in understanding of a role of membranes and electrolytic gradients.

Numerous researches showed that, in addition to protein, the large role in cellular membranes is played by lipidic substances. There was Natanson's theory very popular in the thirties about a mosaic structure of cellular membranes and an arrangement in them of lipids and proteins.

By 30th years 20 century the main consistent patterns of permeability of cells in connection with chemical and electric properties of substances were determined. It was shown that not loaded molecules get into the cells according to the molecular radius loaded — depending on the electric properties, and liporastvorimy — depending on degree of solubility in lipids of membranes. The found patterns formed the basis of all subsequent theoretical constructions and, in particular, at creation of models of a structure of membranes; there was a great interest in understanding physical. - chemical structures of that substrate, from to-rogo living material and membranes is constructed. There was a point of view that proteins and lipids are connected in living cells in the uniform lipoprotein complex having high lability that live protein and taken from cells — are not identical. So, V. V. Lepeshkin developed the concept about the main lipoprotein complex which in pure form does not manage to be allocated and which he called vitaidy.

V. V. Lepeshkin suggested that instability of this complex defines death of protoplasm at various influences, and also that at destruction of a lipoprotein main complex (at bond breaking a lipid — protein) there has to be a radiation — chemiluminescence (see. Biokhemilyuminestsention ). Despite imperfection of the equipment of that time, it managed to record on a photographic plate the radiation of animal and vegetable fabrics at the time of their death under the influence of strong acids.

The big role in B.'s development belongs to school of the American researcher Zh. Loeb who raised a question of sense and the principles physical. - chemical researches of living matter. He noted a role of physical chemistry and perspective of its use at a research of chemical processes in live systems. Its methodological installations were reflected in two monographs («Dynamics of living material» and «An organism as whole from the physical and chemical point of view») which were translated into many European languages, including and into Russian (1906). Loeb carried out a thought of need of intravital studying physical. - chemical processes. To them it was given physical. - chemical interpretation of ion antagonism (see. Ions ), an artificial parthenogenesis, and also to properties of proteins in live systems.

One of the first processes which became an object of attention of B. with physical. - chemical positions, there were mechanisms causing turgor of cells, and the first object, for Krom began to work in this direction — erythrocytes. So, as a result of works of the Hamburger (the end of 19 century) on osmotic properties of erythrocytes there was a technique of a hematocrit, edges was long enough used in clinic. Drew to itself attention and the phenomenon of hemolysis which research led to idea of hemolitic firmness of erythrocytes as an important indicator of morbid condition. Researches on swelling of colloids under the influence of various substances, especially acids and alkalis, drew attention of pathologists who applied colloid and chemical patterns to studying of the phenomena of hypostasis. The first physical. - the chemical theory of hypostasis was created at the end of the last century by Fischer (O. Fischer). In the book «Hypostasis and Nephrite» he considered cytoplasm as a haemo gene colloid and from colloid and chemical positions tried to interpret the pathological manifestations accompanying hypostasis.

The research Schad (H. Schade) which created the school in medical biophysics led to creation of the theory of inflammatory process. The inflammation was considered by it as active process of swelling of colloids of connecting fabric under the influence of a hyperoxemia of the environment (primary, in his opinion, changes of properties of colloids) with subsequent change of their ionic structure and electric charge. It generalized results of the researches in this direction in the book «Physical Chemistry in Internal Medicine», edges left in Russian translation in 1911. This theory was considerably added with researches of D. Abramson who explained migration of leukocytes from a circulatory bed in the inflammatory center from positions of an active electrotaxis — under the influence of the electric potentials arising on border of the inflammatory center with normal fabric. The principles of this theory can be used for development of ideas of essence of an inflammation. The essential role was played by discovery of osmotic pressure of blood proteins at maintenance of osmotic balance in a blood channel. It caused significant progress in creation of artificial blood substitutes. In addition to the original position about need of maintenance of ion-antagonistic balance, there was a requirement of creation of small additional (oncotic) pressure by means of colloid substances. This opening found practical application during creation of blood substitutes even in World War I.

At the beginning of 20 century one of founders of chemical kinetics S. Arrhenius became interested in a possibility of interpretation physical. - the chemical nature of immunological reactions by studying of their kinetics. In cooperation with immunologists to them it was established that immunological reactions submit to laws of chemical kinetics — temperature, concentration and that methods physical. - the chemical analysis can be used for studying of the reactions proceeding in live organisms. These achievements allowed to make significant progress in detection of features of course of chemical processes at some physiological and morbid conditions.

Consideration with physical was a stage in B.'s development. - the chemical points of view of the reactions arising in living cells at action various pharmakol, and toxicants, in particular narcotic. As a result of numerous researches physical. - chemical properties of a cell (permeability, electric properties, etc.) normal and their changes at effect of various narcotic substances patterns physical were revealed. - chemical character. So, it was established that the anesthesia reduces permeability of cellular membranes. Trying to establish correlation between physical. - chemical properties of drugs and narcotic action, Overton (E. Overton, 1899) on model oil — water established that than narcotic force is higher, especially distribution towards oil is shifted. Thus, narcotic effect of substance of subjects is more, than above its solubility in lipids. This model led to creation of the first biophysical theory of an anesthesia by Overton according to which the effect of an anesthesia is caused by accumulation of narcotic substances on a surface of cells in a lipidic phase of membranes that leads to change of permeability and from here to decrease in a metabolism. Other theory (Traube's theory) put forward kapillyarnoaktivny properties of drugs as the operating factor. According to this theory there has to be a correlative dependence between surface intention and narcotic activity. It was established that with lengthening of a carbon chain and increase of capillary activity narcotic action (the so-called rule of Traube) respectively increases. Works on studying physical. - the chemical mechanism of narcotic action caused emergence of a large number of models which in combination with fiziol, an experiment allowed to expand information on a structure of a membrane, interrelation of proteins and lipids in it. The considerable attention was paid to studying of the mechanism of action of the toxic agent on living material. These researches were caused by need of knowledge of mechanisms of effect of the toxic agents applied in World War I and findings of ways of protection against them.

In Russia K. A. Timiryazev studied photosynthetic activity of certain sites of a solar range in connection with distribution of energy in it and features of an absorption spectrum of a chlorophyll (see Photosynthesis). A. F. Samoylov described acoustic properties of a middle ear. M. N. Shaternikov, having used thermodynamic representations, carried out studying of the energy balance of an organism (1910 — 1920). In the USSR (1919) according to personal instructions of V. I. Lenin Ying t of biophysics Narkomzdrava was created by the USSR which was headed by P. P. Lazarev. Here wide-ranging studies on studying of carrying out and excitement of a nerve were put, the ionic theory of excitement, the theory of color sight (A. N. Tsvetkov), mechanisms of action of a radiant energy on organisms and other scientific problems were developed. Here S. I. Vavilov (questions of extreme sensitivity of a human eye), P. A. Rehbinder and V. V. Yefimov worked (studying physical. - chemical mechanisms of permeability and its communication with surface intention), etc.

The great influence on B.'s development was exerted by N. K. Koltsov, on an initiative to-rogo at Moscow un-those the department physical was created. - chemical biology.

His pupils widely developed questions of influence physical. - chemical environmental factors on cell activity and its separate structures. In 1931 the laboratory physical was open. - chemical biology in Ying-those biochemistry to them. And. N. Bach in Moscow, the cut ran D. JI. Rubenstein. At All-Union in-those experimental medicine (VIEM) the department of biophysics was created, in Krom P. P. Lazarev, G. M. Frank, etc. successfully worked. Ying t of biological physics Academy of Sciences of the USSR and department of biophysics biologo-soil f-that MSU was in the early fifties organized; after department of biophysics were organized at the Leningrad university and other high fur boots.

Current state of biophysics

Achievements of physics, chemical physics, emergence of new experimental methods of a research, and also ideas and methods cybernetics (see) and the disciplines which are grouped around it opened ample opportunities for understanding of laws of functioning of live systems and determined growth and the direction of development of modern biophysics.

Methods B. (its physical direction) allowed to reveal a spatial relationship of atoms in molecules of cellulose, hemoglobin, etc. Progress in identification of space disturbances of bio-molecules at some so-called molecular pathologies is connected with B. (e.g., drepanocytic anemia). Physical. by methods study a structure of nucleic acids in connection with their role in transfer and storage of genetic information, and also proteins and processes of conformation which in them happen. One of the major problem problems of B. is the question of mechanisms of turning into cells of organisms physical. energy in chemical (see. Photobiology , Photochemistry ). Here the problem of energy conversion at action on organisms of ionizing radiation which induce the chemical transformations causing radiation injury adjoins. Primary processes of interaction of radiation with living matter are studied by radiation biophysics. This section is closely connected with prevention of radiation injury — antiradiation chemical protection. Other party of this question is the problem photosensitization (see), the cut is a classical example a sensitization of integuments to visible light owing to accumulation of products of active disintegration of haematoporphyrins as a result of disbolism at a disease of a pellagra there. Studying of mechanisms of a sensitization gains big activity in connection with emergence in the atmosphere and water of the substances possessing the photosensitizing action presently — garbage of the chemical industry. B. reveals mechanisms of their action and develops thin methods of their detection.

In the last decades there were shifts in ideas of physical. - the chemical, and electric processes proceeding in live systems. Organisms and cells began to consider as the open circuits exchanging with external environment substance and energy what the concept about stationarity of development biochemical evolved, from reactions as a necessary condition of normal existence (I. Prigozhin). Idea of pathology as disturbance of stationarity and coordination biochemical, reactions in cells is created, a cut caused development of the new methods allowing to obtain information on course of chemical reactions in cells is intravital (the kinetic methods which are based on a hemolyuminestsention, optical spectroscopy, radiospectroscopy, etc.).

From a position of thermodynamics of open circuits the problem of adaptation of cells and organisms to environmental conditions (temperature, composition of salt in solution, chemical factors etc.) is considered in B. Limits of adaptation are defined by a possibility of preservation of stationarity in development biochemical, reactions (see. Adaptation , biophysical mechanisms). The methods allowing to establish accurate thresholds of disturbance of stationarity and thresholds of adaptation in cells are developed; their use created a possibility of bystry assessment of adaptation limits of vegetable and animal organisms (e.g., assessment of optimal conditions of storage of the human fabrics intended for transplantation).

On the central place the problem of a structure and function of membranes moved forward. This problem interested B. for a long time, but earlier it concerned only a cellular membrane whereas in a crust, time range extended and membranes of organoids of cells became an object of attention: lysosomes, ribosomes, mitochondrions, microsomes etc. In modern biophysical aspect the membrane is considered as the chemical reactor of a cell or its separate organoid which generally regulates stationary development of biochemical reactions. From the point of view of B. the most important detail of membrane activity is transport of electrons. In this regard great attention of B. was drawn by the lipids and phospholipids which are substrate of electron transfer. Questions of physical are studied. - chemical structure of this substrate and mutual participation of proteins and lipids in creation of structure of membranes. The main objective of B. — obtaining intravital information on properties of these educations and their changes at various influences and pathological processes. The paramount role is got at the same time by development of methods which allow to analyze physical. - chemical properties of cells, without exerting impacts on them. Methods on measurement of dielectric properties, conductivity, electric potentials, spectral characteristics, chemo luminescences etc. are intensively developed in this direction.

Considerably possibilities of obtaining information on a condition of membranes by means of microelectrode technics extended. Possibilities of measurement of intracellular biopotentials and identification of mechanisms of intracellular electrochemical processes opened (see. Bioelectric potential ). Considerably the understanding of mechanisms of active transport and role of electric gradients in transfer of various substances through membranes of cells extended. The dominating role is played by researches in the direction of identification of the nature of transport of ions of sodium, potassium, calcium and those power sources which carry out it.

Due to the identification of a big role of lipids in functions of membranes B.'s attention is drawn to the lipoprotein unstable complexes which are the base construction material of membranes. In recent years the point of view gained distribution that these lipoprotein complexes are the most vulnerable (unreliable) details of cells. «Unreliability» of membranes is explained with the fact that in their lipidic part can arise spontaneously non-enzymatic, radical, oxidation reactions (see. Antioxidants ), developing with self-acceleration on the chain mechanism. Such uncontrollable reactions lead to destruction of lipoprotein structures and break mechanisms of transport of electrons. This so-called phenomenon of «reoxidation of membranes» attracted great interest since emergence of many pathological processes is connected with it (at radiation injury, at effect of toxicants etc.).

Because there are great difficulties in use of the EPR method (see. Electronic paramagnetic resonance ) during the studying of living cells, and the fact that he finds only long-living low-active radicals develops other methods. So, along with the hemolyuminestsention finding short-lived radicals of the oxidizing nature and allowing to obtain direct data on their presence at living cells methods of intravital detection of radicals by method develop copolymerization (see). The last occurs at introduction to cells of monomers, marked radioisotopes which are capable to be polymerized on the «radical» mechanism. The obtained data stimulated development of the concept that active radicals and «radical» reactions are characteristic satellites of pathological processes (carcinogenesis, inflammatory reactions etc.).

All these researches put a new problem — a problem of studying of mechanisms of stabilization of intracellular membranes and identification of the separate factors regulating oxidizing processes. The attention was drawn to antioxidants, or antioxidants, lipids of membranes (tocopherol, an ubikhinon etc.) and their antagonists.

Studying of antioxidants as regulators of oxidizing balance in lipidic structures of cells is the most important problem of modern B.

Aktivno researches in the field of studying of muscular contraction where mechano-chemical representations (widely are attracted see are conducted. Mechano-chemical processes ). Studying of a condition of water in a cell where new opportunities in connection with development of a method of a nuclear resonance of nuclear magnetic resonance (opened see is of considerable interest. Nuclear magnetic resonance ). Significant progress is observed in the field of studying of mechanisms of action on an organism external physical. factors [e.g., actions magnetic field (see) on processes of a hemopoiesis; many researches are devoted to action of electric field and factors, related].

The course B. with a practical training as a general education subject is entered into the USSR at all universities (biological and biologo-soil faculties) and medical higher education institutions.

In 1963 in the 2nd MMI the medicobiological faculty with department of biophysics which task — training of biophysicists of a medical profile is created. There is a row biophysical. scientific centers in which researches according to

B. V are carried out by the USSR it is Ying t of biophysics of Academy of Sciences of the USSR (Pushchino - on - Oka), Ying t of biophysics of the Ministry of Health of the USSR, department of biophysics biological f-that MSU, department of biophysics physical f-that MSU, department of biophysics Ying-that physics of the Siberian department of Academy of Sciences of the USSR, etc.

Abroad: Great Britain — Laboratory of biophysics London un-that, departments of biophysics in the Cambridge and Edinburgh high fur boots; GDR — Ying t of biophysics (Berlin); The People's Republic of China — Ying t of biophysics (Beijing); Poland — Ying t of biochemistry and biophysics of AN of the Party of Russian Taxpayers (Warsaw); The USA — Yale un-t, Rock Feller un-t, Harvard un-t, Un-t of Washington (Saint Louis), Massachusetts technological in-t; France — Ying t of physical and chemical biology (Paris); Germany — Ying t of biophysics of society of Max Planck (Frankfurt am Main), Ying t of biological and medical physics, Goettingen un-t; Czechoslovakia — Ying t of biophysics (Brno); Japan — universities in Tokyo and Osaka.

Regularly gather (since 1961) the international congresses on biophysics convoked by the International union of theoretical and applied biophysics to-rogo are included into Central office representatives of the USSR. Societies of biophysicists exist in the USA, Great Britain. In Moscow there is a section of biophysics at the Moscow society of testers of the nature.

Modeling in biophysics

the Method of modeling in B. is applied to knowledge physical. - the chemical mechanisms which are the cornerstone of physiological and pathological processes. The main objective of such modeling — allocation of the studied phenomenon in a «pure» look, attempt to filter this or that process from the revolting factors and the accompanying phenomena in a complex system, to show essence of the studied process.

First of all for understanding physical. - the chemical processes proceeding in cells of the higher organisms simpler organisms or cells where the studied mechanisms are arranged more simply are used as models. So, e.g., during the studying of a role of ionic processes in carrying out excitement in nerves of the highest animals as model the alga of a nitell, and also nerve fibrils of a squid was used. For understanding of process of muscular contraction sokratitelny myonemes of protozoa and muscular fibrilla of the lowest organisms were widely used. During the studying biol, actions of a radiant energy are widely used cultures of cells on which it was succeeded to eliminate influence of the remote factors proceeding from systems of difficult organisms.

Along with the listed biological models are applied also purely physical. - chemical models which are under construction of the substances close to of what biological substrates are under construction. Such simple models can really reproduce these or those phenomena and are used during the check of any hypotheses.

In the absence of direct information on a structure of biological membranes artificial models played a big role in development of ideas of structure of membranes and about a role of this structure as cell membranes and organoids. Many models of the membranes constructed of lipids, phospholipids, proteins in various structural combinations are known. In such membranes it was possible to imitate, e.g., the phenomena of selective permeability. On models studying of effect of drugs was conducted and it was succeeded to output laws of narcotic effect and to estimate force of impact of drugs on the higher organisms.

In literature also many models of cellular division on which it was succeeded to reveal a role in this process of the substances having superficial activity are known; there are models of muscular contraction which proved a role some physical. - chemical factors in change of a configuration of polymers of protein; as model of pathological permeability of capillaries for leukocytes served artificially prepared gels etc.

In B. use also purely physical models. Combinations of electric resistance and tanks which at a transmission of electric current reproduce the patterns characteristic of live systems belong to such models, e.g. However in some cases similar models are not models in strict sense since nothing is told directly about the mechanism of the studied biological phenomenon and reproduce only behavior of biological system. Therefore they can be called analogs, turn into models only at introduction of a number of additional assumptions.

With transition to consideration of an organism and its functions as complex complete system use of mathematical modeling began. At the same time models are under construction as the sum of the interacting processes described by the differential equations. Such models allow to establish interrelation physical. - chemical processes. Shortchangings are conducted on the COMPUTER; for the decision also other mathematical receptions are attracted, in particular the theory of counts, edges allows to solve similar problems, without resorting to the differential equations. At the same time use the cybernetic methods applied to the analysis of complex biological systems, napr, bonds physical. - chemical structures of biological structures with physiological functions (in particular, lipoproteids in development of pathological processes).


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B. N. Tarusov.

Яндекс.Метрика