Barrier function

Barrier functions - a set of biochemical and physical-chemical processes in the cell membrane, governing the admission of various substances from the surrounding extracellular fluid in the cell.
Barrier functions provide the constancy of the internal environment of the body, which consists of the higher animals and human blood and lymph. Barrier functions are carried out so-called histo-hematic barriers. They perform two main functions: 1) regulation of the physical and chemical consistency and quality of the biological characteristics of the intercellular fluid; 2) protection of cells of various organs and tissues from harmful substances that may enter the body. Among histo-hematic barriers the most important and well-studied is the blood-brain barrier. It regulates the supply of vital substances from the blood in the nervous tissue and cerebrospinal fluid and protecting it from the penetration of foreign substances.

The barrier function of the state and activities of the special physiological mechanisms - barriers; the main function of which is to maintain the relative constancy of the composition and properties of the internal environment of an organism (blood and tissue fluid). Conventionally, there are barriers external (skin, mucous membranes, respiratory, digestive and excretory AIDS) and internal (in the terminology of different authors: histo-hematic, the blood-parenchymatous, gistiotitarnaya, tissue), located between the blood and tissue (intercellular) liquid organs and tissues. Through internal barriers in the tissue fluid selectively act necessary for the supply of cells substances and displays products of cellular metabolism.
Each organ has its own special barrier, functional characteristic of which is determined by morphological and physiological features of this body. Barriers regulate the exchange of substances between the blood and tissue elements (regulated function) and prevent the authorities from the receipt artificially introduced into the body of alien substances and toxic metabolism products formed at some pathological States of organism (protective function). From the barrier function depends largely sensitivity of organs and tissues to the bacteria, poisons and toxins. The manifestation of the protective functions of the barriers due to the uneven distribution of injected into the blood various chemical and biologically active substances, the absence of the effect in the treatment of some medicinal products.
The state of any authority, its trophic and the influence exerted on him other organs and physiological systems, are in close contact with barrier mechanisms. Increased permeability of the relevant barriers does any body more receptive, and its reduction is less sensitive, less susceptible to substances circulating in the blood or entered into it with some experimental or therapeutic purposes.
Reducing the resistance of the individual barriers in relation to various pathogenic agents present in the blood, can cause diseases of the organ. Under the influence of different factors (physiological, physical, chemical, infectious, and so on) permeability barriers changes - increased in some cases and decreases in others. This property barriers can be used for targeted impact on the individual organs or the entire body. Large plasticity barrier mechanisms, their adaptation to the conditions of external and internal environment are essential for the normal existence of the body, maintaining a certain level of physiological functions, protection from infection, intoxication, functional and organic disorders.
Anatomical substrate internal barriers are mainly the capillary endothelium and precapillaries, the structure of which is different in different organs. Physiological activity of barriers depends on the permeability of the walls of blood vessels, and from diverse neuro-endocrine-humoral influences governing the relationship between an organism and its environment, on the one hand, and between the blood and tissue fluids.
The problem barrier function is widely developed in the USSR (the works of L. S. Shtern al., A. A. Bogomolets, N. D. Strazhesko, B. N. The mogilnitsky, A. I. Smirnova-Castle, G.N. Kassil, N.N. Zaiko, AL Rapoport and others). A number of methods of barrier functions (introduction of various dyes, intravital microscopy, microsiga, radioisotope indication, electron microscopy, and so on). In most cases, a judgment on the barrier function of the applied method of quantitative determination in organs and tissues entered in the blood of the indicator that is not always a specific index of the functional state of the barriers, and in many cases depends on the intensity interstitial exchange.
Among internal barriers most studied in detail of the blood-brain barrier is a physiological mechanism that regulates the exchange of substances between the blood and Central nervous system, and protects the brain and spinal cord from foreign substances introduced into the blood, or from products impaired tissue metabolism, formed in the body. New section of science is the study of intracellular barriers, which began in the Soviet and foreign laboratories.
Gematologicheskij barrier. Liquid eye anterior chamber is significantly different in composition from the blood plasma: protein, enzymes and antibodies in the chamber moisture is empty or contains a small number. In respect of electrolytes difference is their concentration in the chamber moisture and blood can not be explained by simple filtering or dialysis. Analysis of the data on the penetration of various substances in the liquid eyes, and research with the use of radioactive isotopes suggest that between blood and fluids eyes there is an active regulatory and protective biological membrane (gematologicheskij barrier), performing barrier function.
Histological studies suggest that anatomical substrate gematologicheskogo barrier is a vascular endothelium, which have a very active properties. A noticeable influence on the function gematologicheskogo barrier has trigeminal nerve, and the autonomic nervous system. The possibility of the conditioned reflex change of permeability of vessels anterior segment of the eyeball indicates the existence of a control function gematologicheskogo barrier on the part of the cerebral cortex.