Biophysical features of arterioles of the big circle of blood circulation

Blood flows from arteries of elastic type in the resistive vessels possessing smoothly-muscular cells, which being reduced, actively change a gleam of vessels. Hemodynamic resistance is adjusted so. Volumetric speed of a blood-groove and a blood pressure in bodies depend from hemodynamic resistance. Hence, resistive vessels are the major regulators of hemodynamic. Typical representatives of arteries of muscular type are arterioles of the big circle of blood circulation. Arteries with diameter from ten up to hundred microns have such name. They have the general structural attribute - presence expressed smoothly-muscular environments.

The powerful muscular environment causes the basic functional property of arterioles - an active vascular tone. It is controllable tonic reduction of smoothly-muscular cells of a vascular wall. Changes of a vascular tone lead to narrowing or expansion of a gleam of arterioles and, hence, render the expressed influence on hemodynamic resistance. Due to an active vascular tone arterioles most effectively carry out the basic functions of arteries of muscular type: 1) maintenance of the certain level of a blood pressure in system of blood circulation; 2) redistribution of blood between bodies depending on need for it of each of them.

The basic means of sufficient delivery of blood to all bodies which at present require it, serves maintenance of superfluous pressure in system of blood circulation. It allows to change essentially volumetric speed of a blood-groove, managing rather a small amount of blood (the weight of blood at the person makes 1/13 part of weight of a body). Thus, arteries of muscular type are intended for maintenance in system of blood circulation of such superfluous pressure which provides reliable redistribution of blood between bodies in any conditions. Therefore аarterioles on their functional purpose can be assimilated to a water tower - they create maintenance of a blood pressure in an arterial channel. Infringement of this function of arterioles leads to a collapse (to a heavy faint with loss of consciousness at sharply developing vascular insufficiency which expression is first of all falling of a blood pressure). Thus, smoothly-muscular cells of arterioles of the big circle predetermine work, which heart should make (a myocardium of left ventricle) to overcome the general peripheral resistance of vessels.

The second function of arteries of muscular type - redistribution of blood between organs depending on need for it - is provided with work arterioles as «vascular cranes». From Puasal’s equation follows, that depending on a gleam of arterioles volumetric speed of a blood-groove in organ, to which they belong, and its changes are proportional to changes of radius of this gleam in the fourth degree.

Due to change of a tone of arterioles, being skeletal muscles, volumetric speed of a blood-groove in them increases at physical work in some tens times. Redistribution of blood between internal organs and a skin is connected with regulation of a vascular tone. Even within the limits of one body there is continuous «a game of vessels»: one arteriole is narrowed, others - extend. As a result the weight of blood in different sites of body is constantly redistributed. So the best blood supply at a minimum level of work of a cardiac muscle is reached. The greater role in development of some pathological processes belongs by arterioles.

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