TURGOR (Latin of turgere to be bulked up) — the general concept characterizing ability of cells, soft tissues and bodies of animals to show resistance to various mechanical influences.
The terms «turgor» and «tourist's mountain pressure» appeared originally in phytophysiology. In relation to a plant cell of T. means intracellular hydrostatic pressure. This pressure causes tension of a cellular cover, a cut it is important for keeping fit of plants, their stability. Later the term «turgor» gained distribution and for the description of hmekhanichesky properties of cells, soft tissues and bodies of animals.
Ability to resist to mechanical tension at the zooblasts which do not have a cellular cover (see the Cell), is defined by a cytoskeleton, a cellular surface, their interaction creating a dynamic mechanical framework of a cell and also operation of ionic pumps and channels, intensity of exchange processes, etc. The influences destroying components of a cytoskeleton, a cellular surface or inhibiting active transport of ions lower rigidity of cells.
Mechanical characteristics of cells are closely connected with their ability to phagocytosis, locomotion, participation in a morphogenesis and change in fiziol. and patol. processes (e.g., at division, a differentiation, tumoral transformation). Ability of blood cells to deformation in many respects defines its rheological characteristics (see Viscosity, the Rheology). In particular, increase in rigidity of erythrocytes leads to increase in resistance to a flow of blood in capillaries, i.e. to disturbance of microcirculation (see).
Mechanical characteristics of soft tissues and bodies are defined by mechanical parameters of the cells making them, intercellular contacts, all other components, their relative positioning, size ABP, intensity of a water salt metabolism and other factors. Maintenance of mechanical characteristics of fabrics and bodies (e.g., connecting fabric, band bodies, lungs, an integument) at the necessary level is essential to performance of the main functions by them. Definition of turgor of skin, hypodermic cellulose and other soft tissues has a certain diagnostic value in a wedge, practice. Mechanical characteristics of fabrics and bodies change at disturbances of the water salt metabolism (see) accompanying many diseases of kidneys and went. - kish. a path, at disturbances of blood circulation, tumoral growth, aging of an organism (see the Old age, aging) etc.
Studying of mechanical characteristics, and also other biophysical parameters of cells, fabrics and bodies can be used for the forecast of diseases, differential diagnosis, identification of mechanisms patol. processes and objective control of their current, development of prostheses. E.g., at patients with psoriasis relative viscosity of epidermis (see Skin) sharply falls in the period of an aggravation, increases in the course of treatment, but does not reach the values inherent to epidermis of healthy people. These observations can be used for preliminary identification of the contingent of the persons predisposed to this form of pathology and also for forecasting of a recurrence of a disease. Attempts to use the blood given about viscosity and rigidity of erythrocytes as nonspecific indicators of a condition of an organism become.
For assessment of mechanical characteristics of zooblasts usually measure pressure necessary for breakdown of a cellular surface by a microneedle or its absorptions in a microcapillary, with simultaneous registration of size of deformation. By means of other technique estimate a share of the cells which remained not destroyed in suspension after standard mechanical influence or watch deformation of the cell attached to substrate under the influence of the set shifting loading.
Mechanical characteristics of fabrics and bodies measure both in static, and in dynamic the modes, applying pressure to their surface or watching distribution of pulse wave, applying ultrasonic and other methods. E.g., for mechanical test of epidermis to its surface paste an end face of the cylindrical probe with a diameter of 3 mm by means of medical glue. Later 30 — 60 sec. the probe connected to the sensor of force is set in progress with the set speed in the direction, perpendicular by surfaces of an integument in the field of measurement. Register force necessary for a separation of the pasted site of epidermis. The trajectory of a gap passes in epidermis, along a contour of the site impregnated with glue i.e. between near-surface layers of cells. Advance of the surface surrounding the pasted site is limited to the case of the sensor of force. Repeated measurements on the neighboring sites with various speeds of shift allow to construct dependence of force of a separation on speed and to estimate viscosity of epidermis.
Bibliography: Braginskaya F. I.
, etc. Studying of ultrasonic hemolysis of erythrocytes is normal also at pathology, Biophysics, t. 27, century 4, page 679, 1982; Volkov E. I. also It is black fi-sk y D. S. Biological investigations of the physical organization of plasma membranes of normal and tumor cells, Izv. Academy of Sciences of the USSR, it is gray. biol., No. 1, page 29, 1981; Ivens And. and With to e R. Mekhanik's fi-varnish and thermodynamics of biological membranes, the lane with English, M., 1982; Markin V. S. The organization of membranes in the plane of a layer and a form of a cell, the Biological investigations of the theory, Biophysics, t. 26, century 1, page 158, 1981; Regi-r e r S. A. Lectures on biological mechanics, p.1, M., 1980; Special issue on measurement of physical properties of skin, J. invest. Derm., v. 69, No. 3, 1977.
A. G. Melikyants.