ABSTRACT The gastrointestinal tract is an active dynamic system that implements a number of important life support processes [30,2,57,87,203]. Impact of emergency situations on structures performing barrier-protective functions remain largely unexplored. In recent years, ideas about the role of the epithelium of the digestive tract have expanded, significant, and it has been found to be significant in loss of renal function [7,8,2]. Therefore, the epithelium of the gastrointestinal tract should be considered not only as a selective barrier to penetration of toxic substances into the interstitium, but also a key link in decontamination endogenous intoxication. The barrier-protective function of the digestive system is associated with border tissues, which have a strict morphological organization. These phenomena are as diverse as nature physical, chemical or biological aggression on the internal environment of the body can be various. Process layering data is important for practical use of the phenomenon of "layered defense", when stress or damage increases secretion and secretion, increases proliferation and desquamation of the epithelium, as well as migration of neutrophilic leukocytesfrom the bloodstream to the epithelial layer. [22].Under normal conditions, the gastrointestinal tract is considered a balanced ecosystem where there is a certain habitat - physical space. The state of the mucous membrane of the small intestine, the main participant in the absorption processes and excretion of metabolic products deserves the most attention. It has been found that oral administration enterosorbents (Karbovit and Polypefan) in intact rats does not cause mucosal changes membrane of the jejunum and ileum and does not affect the state of enterocytes. However, in some in some cases, ES enhances the secretion of goblet cells, especially in the apical part of the intestinal villi [22]. At the same time, a relatively large number of Pannet cells were registered in crypts, and Lamina the propria around them contains many immune-competent plasmocytes and neutrophils. Electron microscopic examination of various parts of the small intestine showed that when mercury chloride injected into rats, the number of microvilli of enterocytes was shortened and decreased, and the number mitotically dividing cells increased. In this case, there is a pronounced vacuolization of enterocytes observable; vacuoles glow with electronics and contain flocculent material. Side cells emptied, Pannett cells contain a small amount of secretory granules. Characteristic feature of the effect of mercury poisoning on the mucous membrane of the small intestine is inhibition of the reaction of cells of the connective base. The protective barrier of the mucous membrane of the gastrointestinal tract consists of three levels: luminal, epithelial and connective tissue