Normal intestinal microflora. Gram-positive strict anaerobes
The large intestine is the lower part of the digestive tract. It begins with a short segment with an appendix and is responsible for the absorption of water, individual vitamins are synthesized here and proteins are finally broken down. Due to the peristalsis of the large intestine, defecation occurs. AT infancy the process is reflex, later - controlled by the cerebral cortex. The exception to the rule is sick people, alcoholics. The final formation of feces is carried out by a number of bacteria, the imbalance between which becomes dysbacteriosis of the large intestine.
Feces are abundantly formed when eating plant foods. Fiber additionally enhances the process of contractions of smooth muscles. Human waste is 70-80% water, the dry residue is half represented by bacteria, mostly dead. Information surprises, with ignorance of trivial facts. It is estimated that the total mass of bacteria in the human gastrointestinal tract reaches 3 kg. Feces are formed (in normal condition) 0.5 kg. Diet changes these ratios to a large extent. A starving person rarely feels the need to defecate.
When not proper nutrition the colon suffers. Chemical industry does not stand still, the incorrect application of modern achievements of science does not in the best way affects areas of human life. Putrefactive, fermentation processes, due to the absorption of products into the blood, cause poisoning of the body. At health resorts, therapeutic enemas are carried out, which allow unloading the lower gastrointestinal tract.
The number of bacteria grows as it moves from the stomach to the anus, the section in question serves as a haven for hundreds of strains. Researchers count 500 species. Approximate composition:
- 90% are bifidus and lactobacilli, cultures that advertising promises to restore with the help of yogurts. Strains constitute the main group (obligate) involved in digestion.
- Auxiliary conglomerate form enterococci, Escherichia.
- 1% falls on yeast, clostridia, citrobacter, staphylococci.
The normal balance of the microflora of the colon is involved in the formation of immunity. Some researchers assign a similar role to the mysterious appendix. Members of the main group form in the process of life a number of organic acids that regulate the pH factor, prevent the reproduction of pathogenic flora, while maintaining health lower section GIT. Other functions of microflora:
- Synthesis, assimilation of minerals and vitamins.
- Formation of antibodies, cytokines, interferons.
- Fermentation of carbohydrates, dissolution of fiber.
- Protein hydrolysis.
- Stimulation of peristalsis.
- Production of biologically active substances.
From a short list, a direct link between dysbacteriosis and constipation is visible. The causes and symptoms of the interaction are poorly understood.
The influence of food on the composition of microflora
Ignorance of patients leads to the search for drugs instead of establishing a diet. Difficulty complements the inability to draw up a proper nutrition plan. Examples of the action of products in the area under consideration:
- The consumption of plant foods increases the proportion of enterococci and zubacteria in the microflora.
- Animal products grow clostridia and bacteroids, reducing the content of bifidobacteria. A partial decrease is observed in the department of enterococci.
The role of yoghurts is known - an increase in the number of bifidobacteria. Advertising is silent about other components, and knowledge about groups of bacteria in humans is insufficient.
Own regulation of microflora
The body tries to protect itself from dysbacteriosis, whose symptoms and causes are little studied. The mucous membrane produces a number of substances that regulate the population of the biocenosis:
Intestinal dysbacteriosis in adults is caused by a violation motor activity(peristalsis) of smooth muscle. Effective is impossible without deep knowledge about the immune system, forming a comprehensive treatment.
Causes of the disease
In addition to irrational nutrition and an unhealthy lifestyle, excessive intake leads to diseases. medicines predominantly antibiotics. For treatment (dysbacteriosis of the small intestine), doctors prescribe just the means that destroy the microflora. Due to lack of knowledge, the struggle often goes in the wrong direction, leading to sad consequence. This is a common reason why parents do not want to be vaccinated for dysbacteriosis in infants. Most babies suffer from the disease at the age of one.
You can often hear the question: is dysbacteriosis transmitted from person to person? The microflora passes even with an ordinary kiss, not to mention oral sex. There is a risk of infection through such contact.
An additional cause of imbalance in the intestines is food rich in preservatives. Passion for canned food, products with a long shelf life is harmful. There is no point in spending money on Bifiform and Bifidumbacterin, reducing treatment to zero in the wrong way nutrition.
Signs, treatment and prevention of dysbacteriosis
In addition to indigestion and other signs of gastrointestinal upset, researchers note the possibility of black plaque on the teeth. With a similar sign, it is recommended to drink a course of vitamin A. Vitamin A is also present in food. An available source is the yolk of chicken eggs.
Garlic and onions are good in prevention. There are known methods of treatment when garlic is washed down with milk without chewing, which blocks bad smell. Products are taken fresh, without cooking.
Many doctors note the ability of yeast (beer drinks are sold in the pharmacy) to normalize the work of the gastrointestinal tract. The benefits are the abundance of B vitamins, the regulation of the pH factor. Doctors say about the benefits of eating warm food, they advise avoiding dry food. The release of heat in the colon is important, affecting the ratio of bacterial strains. Try to eat warm food instead of cold yogurt.
Sports
In the last 20 years, a healthy lifestyle has become fashionable. People try to eat less, move more. Movie stars, famous personalities become an example for fans. Moreover, in calls to follow a diet and work physically. The screen life of the stars bears little resemblance to the stage image.
For example, Julia Roberts set herself the goal of doing 10,000 ab reps daily (before gaining worldwide fame). And successfully completed the program. Physical exercise serves as a reliable protection against most diseases for many people. For example, dysbacteriosis increases with stagnation of blood during seated life.
The problem of the connection between lack of physical activity and a number of diseases has been studied by a group led by Dr. Cooper in the United States. The result was fitness. Cooper believes that to keep fit you need to walk 10 km daily. Consider your own schedule. Sometimes it is worth taking a short walk instead of waiting for a fixed-route taxi, or walking to a store close to home.
Enemas
A simple way to eliminate the symptoms and causes of dysbacteriosis is a rectal enema. Patients are concerned about the question: is it possible to make an enema to yourself? The procedure is as follows:
- To intestines with the help of Esmarch's mug, strengthen the vessel 1.5 meters above the body.
- Lie on your left side, pressing your knees to your chest.
- Insert the tip into the rectum at least 5 cm.
- Apply liquid.
- Remain in the accepted position or kneel in a prayer pose.
Consequences of dysbacteriosis
Some scientists tend to link malnutrition with the development of cancer. Acute intestinal dysbacteriosis as a cause dangerous disease, is it really possible? It would be useful to recall the words of Kashpirovsky about programming for a cure. Positive thinking, combined with a favorable ethical background, protects against some diseases. It has been shown that 99.99% of cancer cases are caused by poisoning ... with one's own feces.
The pathogenic flora formed in the final stages of digestion is dangerous. In ancient times, a connection was suggested between malignant tumors and mold. For example, feeding birds with rotten food dramatically increases the number of sick individuals in the population. Scientists go further, claiming that heart disease has a similar root. The complete chain looks like this:
- Sclerosis.
- Arthritis.
Be careful when dealing with sick people, observe personal hygiene.
The role of microflora in the large intestine
Let's take a closer look at the activities of microorganisms that live in the large intestine.
More than 400–500 different types of bacteria live here. According to scientists, in 1 g of their bowel movements, on average, there are 30-40 billion! A natural question arises: why are there so many of them?
It turns out that the normal microflora of the large intestine is not only involved in the final link of the digestive processes and has protective function in the gut, but from dietary fiber (cellulose, pectin, and other non-digestible plant material) produces a range of important vitamins, amino acids, enzymes, hormones, and other nutrients. Under conditions of a normally functioning intestine, it is able to suppress and destroy a wide variety of pathogenic and putrefactive microbes.
The waste products of microbes have a regulatory effect on the autonomic nervous system, and also stimulate the immune system.
For the normal functioning of microorganisms, a certain environment is necessary - a slightly acidic environment and dietary fiber. In most of the intestines of normally eating people, conditions in the large intestine are far from desirable.
Rotting feces create an alkaline environment. And this environment already contributes to the growth of pathogenic microflora.
E. coli synthesize B vitamins, which act as technical supervision, preventing uncontrolled tissue growth, supporting immunity, that is, providing anti-cancer protection.
Doctor was right Gerzon, stating that cancer is Nature's revenge for improperly eaten food. In his book The Cancer Cure, he says that out of 10,000 cancers, 9,999 are the result of poisoning from one's own feces, and only one is the result of irreversible changes degenerative organism.
formed during decay food products mold contributes to the development of serious pathology in the body. By cleansing the colon and liver, you will be convinced of the correctness of the above, you will see the mold that has come out of you in the form of black shreds!
An external sign of mold formation in the body and the degeneration of the mucous membranes of the large intestine, as well as vitamin A deficiency, is the formation of black plaque on the teeth. When putting things in order in the large intestine and sufficient supply of the body with vitamin A (carotene), this plaque will disappear.
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According to the Ministry of Health, the total biomass of microbial cells in the gastrointestinal tract of an adult is on average 3-4 kg. About 450 species of microorganisms live in the gastrointestinal tract, and their total number reaches 100,000,000,000,000 cells.
The intestinal microflora performs many functions of processing, digestion, hydrolysis of both food and substances excreted from the body. As a result of their vital activity, various microorganisms are in symbiosis (mutually beneficial relationships) with each other during the digestion of a particular food or excreted substances.
The main task of intestinal microorganisms is precisely the digestion of food. It is on what substances contained in food that they will get, and it will depend on which microorganisms will actively multiply, and which will be oppressed due to lack of nutrition for their development.
The intestinal microflora consists of the microflora of the small intestine, appendix, and large intestine.
The microflora of the small intestine provides a small part of the total balance of microorganisms living in the human intestine. It is mainly present in the distal ileum in an amount of about 1,000,000 cells, which is one hundred millionth of the total number of microorganisms living in the intestine. At the same time, half of these microorganisms are accounted for by bacteroids and bifidobacteria. At the same time, in the proximal (upper) section of the small intestine, microorganisms are either absent or present in a meager amount and disappear after the passage of a lump of food.
AT small intestine The process of digestion of food occurs mainly due to enzymatic processes. In this case, all enzymes (enzymes) are synthesized by the cells of the small intestine itself. As a result of these processes macromolecular compounds break down into simple ones and are immediately absorbed by the walls of the small intestine. For example, the disaccharide lactose cow's milk It is decomposed by the enzyme lactase into two sugars - glucose and galactose, and they are immediately absorbed into the blood. In the small intestine, primarily enzymatic processes of decomposition and absorption of food components occur.
The microflora of the appendix has not been studied enough. Since it was previously believed that the appendix was a rudiment that our body did not need, it was removed at the first opportunity. However latest research It has been proven that the appendix plays a very important role in maintaining the normal microflora of the large intestine. It is in the appendix that the human body deposits bifidoactive carbohydrates, on which microorganisms subsequently colonize. If there are many bifidoactive polysaccharides in the appendix, then bifidobacteria will develop on them, which in the future will enter the caecal part of the large intestine. If there are no bifidoactive carbohydrates in the human diet, then instead of forming a normal microflora fermenting sugars, an abnormal microflora that feeds on proteins will develop in the appendix, which causes putrefactive processes to develop. If they tighten, then this leads to inflammation of the appendix itself (appendicitis) and possibly peritonitis (inflammation of the peritoneum).
Thus, the appendix is, as it were, a “fermenter”, where one or another microflora is maintained, which then enters the large intestine.
Simple nutrients do not enter there, as they are absorbed in the small intestine. Only indigestible food components (fiber, hemicellulose, mucopolysaccharides secreted by the intestinal walls, spent parts of cells) get here. Some of these components are deposited in the appendix, where bifidobacteria and bacteroids will colonize on them (many people know that plant seeds, sunflower husks and other indigestible food components accumulate in the appendix).
In this section of the intestine, primarily processes associated with the vital activity of microorganisms occur. Depending on what a person eats, how much food ingredients are absorbed in the small intestine and what residues enter the large intestine, on that basis certain microorganisms form colonies. Despite the presence of various types of microorganisms in the large intestine, with proper nutrition, only certain types of them are colonized, while others are suppressed.
Microorganisms that form the basis of the microflora of the large intestine healthy person, are represented by beneficial bifidobacteria (100,000,000-10,000,000,000 cells) and lactobacilli (1,000,000-100,000,000), as well as opportunistic microbes - Escherichia coli with normal enzymatic properties (10,000,000-100,000,000). These microorganisms ensure the stability of the colony and prevent colonization of the large intestine by foreign microbes.
Thus, in a healthy person, the normal microflora is represented, if we reduce part of the zeros, in the following ratio: for 100 cells of bifidobacteria in the large intestine there should be 1 cell of lactobacillus, 1-10 cells of Escherichia coli, 1 cell of other microorganisms. This optimal quantitative and qualitative proportion of microorganisms in the human large intestine should be maintained in every possible way.
Once again, we note that the dominant position in this proportion is occupied by bifidobacteria, which determine the normality of the biological balance of the microflora of the large intestine at all stages of the development of the human body, starting from breastfeeding. It is this proportion that is the norm for a person. Such a symbiosis of microorganisms is quite stable and does not allow the development of other microorganisms in the large intestine.
MAIN FUNCTIONS OF THE NORMAL MICROFLORA OF THE INTESTINAL TRACT
Normal microflora (normoflora) gastro- intestinal tract is a necessary condition for the life of an organism. The microflora of the gastrointestinal tract in the modern sense is considered as the human microbiome...
normoflora(microflora in a normal state) or
The normal state of the microflora (eubiosis) - is qualitative and quantitativethe ratio of various microbial populations of individual organs and systems that maintains the biochemical, metabolic and immunological balance necessary to maintain human health.The most important function of the microflora is its participation in the formation of the body's resistance to various diseases and the prevention of colonization of the human body by foreign microorganisms.In any microbiocenosis, including intestinal, there are always permanently inhabiting species of microorganisms
- 90% related to the so-called. obligate microflora ( synonyms: main, autochthonous, indigenous, resident, obligatory microflora), which has a leading role in maintaining symbiotic relationships between the macroorganism and its microbiota, as well as in the regulation of intermicrobial relations, and there are also additional (associated or facultative microflora) - about 10% and transient ( random species, allochthonous, residual microflora) - 0.01%Those. the entire intestinal microflora is subdivided into:
- obligate - home orobligatory microflora , about 90% of total number microorganisms. The composition of the obligate microflora mainly includes anaerobic saccharolytic bacteria: bifidobacteria (Bifidobacterium), propionic acid bacteria (Propionibacterium), bacteroids (Bacteroides), lactobacilli (Lactobacillus);
The stomach contains little microflora, much more of it in thin department intestines and especially in the large intestine. It is worth noting that suction fat soluble substances the most important vitamins and trace elements occurs predominantly in the jejunum. Therefore, the systematic inclusion in the diet of probiotic products and dietary supplements, which
Intestinal absorption- this is the process of the entry of various compounds through a layer of cells into the blood and lymph, as a result of which the body receives all the substances it needs.
The strongest absorption occurs in small intestine. Due to the fact that small arteries branching into capillaries penetrate into each intestinal villus, absorbed nutrients easily penetrate into liquid media organism. Glucose and proteins broken down to amino acids are absorbed into the blood only moderately. Blood carrying glucose and amino acids is sent to the liver where carbohydrates are deposited. Fatty acids and glycerin - a product of the processing of fats under the influence of bile - are absorbed into the lymph and from there enter the circulatory system.
The picture on the left(scheme of the structure of the villi of the small intestine): 1 - cylindrical epithelium, 2 - central lymphatic vessel, 3 - capillary network, 4 - mucous membrane, 5 - submucosal membrane, 6 - muscular plate of the mucous membrane, 7 - intestinal gland, 8 - lymphatic channel.
One of the meanings of microflora large intestine is that it is involved in the final decomposition of the remnants of undigested food.
In the large intestine, digestion ends with the hydrolysis of undigested food residues. During hydrolysis in the large intestine, enzymes that come from the small intestine and enzymes from intestinal bacteria are involved. There is an absorption of water, mineral salts (electrolytes), splitting vegetable fiber, the formation of feces.Microflora plays a significant (!) role in
peristalsis, secretion, absorption and cellular composition intestines. The microflora is involved in the decomposition of enzymes and other biologically active substances. Normal microflora provides colonization resistance - protection of the intestinal mucosa from pathogenic bacteria, suppressing pathogenic microorganisms and preventing infection of the organism.Bacterial enzymes break down undigested in the small intestine. The intestinal flora synthesizes vitamin K and B vitamins, a number of irreplaceable amino acids and enzymes needed by the body.With the participation of microflora in the body, there is an exchange of proteins, fats, carbons, bile and fatty acids, cholesterol, procarcinogens (substances that can cause cancer) are inactivated, excess food is disposed of and feces are formed. The role of normoflora is extremely important for the host organism, which is why its violation ( dysbacteriosis) and the development of dysbiosis in general leads to serious metabolic and immunological diseases.The composition of microorganisms in certain parts of the intestine depends on many factors: lifestyle, nutrition, viral and bacterial infections, as well as drug treatment especially taking antibiotics. Many diseases of the gastrointestinal tract, including inflammatory diseases, can also disrupt the intestinal ecosystem. This imbalance results in frequent digestive problems: bloating, dyspepsia, constipation or diarrhea, etc.
To learn more about the role of the gut microbiome in maintaining gastrointestinal health, see the article:
See additionally:
The gut microflora (gut microbiome) is an extraordinarily complex ecosystem. One individual has at least 17 bacterial families, 50 genera, 400-500 species, and an indeterminate number of subspecies. The intestinal microflora is divided into obligate (microorganisms that are constantly part of the normal flora and play an important role in metabolism and anti-infective protection) and facultative (microorganisms that are often found in healthy people, but are conditionally pathogenic, i.e. capable of causing disease when reduced microorganism resistance). The dominant representatives of the obligate microflora are bifidobacteria.
Table 1 shows the most famous
functions of the intestinal microflora (microbiota), while its functionality is much wider and is still being studied|
Table 1 Main functions of the gut microbiota |
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Main functions |
Description |
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Digestion |
|
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Protective functions |
Synthesis of immunoglobulin A and interferons by colonocytes, phagocytic activity of monocytes, proliferation of plasma cells, formation of intestinal colonization resistance, stimulation of the development of the intestinal lymphoid apparatus in newborns, etc. |
|
Synthetic function |
Group K (participates in the synthesis of blood coagulation factors); B 1 (catalyses the reaction of decarboxylation of keto acids, is a carrier of aldehyde groups); В 2 (electron carrier with NADH); B 3 (electron transfer to O 2); B 5 (precursor of coenzyme A, involved in lipid metabolism); В 6 (carrier of amino groups in reactions involving amino acids); В 12 (participation in the synthesis of deoxyribose and nucleotides); |
|
Detoxification function |
including neutralization of certain types of drugs and xenobiotics: acetaminophen, nitrogen-containing substances, bilirubin, cholesterol, etc. |
|
Regulatory function |
regulation of the immune, endocrine and nervous systems(the latter - through the so-called " gut-brain-axis» - It is difficult to overestimate the importance of microflora for the body. Thanks to the achievements modern science it is known that the normal intestinal microflora takes part in the breakdown of proteins, fats and carbohydrates, creates conditions for the optimal flow of digestion and absorption in the intestine, takes part in the maturation of immune system cells, which ensures strengthening protective properties organism, etc.The two main functions of the normal microflora are: barrier pathogenic agents and stimulation of the immune response: BARRIER ACTION. The intestinal microflora has suppressive effect on the reproduction of pathogenic bacteria and thus prevents pathogenic infections.
For example, bacteria of the parietal (mucosal) microflora occupy certain receptors on the surface of epithelial cells. Pathogenic bacteria, which could bind to the same receptors, are eliminated from the intestine. Thus, intestinal bacteria prevent the penetration of pathogenic and opportunistic microbes into the mucous membrane.(especially propionic acid bacteria) P. freudenreichii have fairly good adhesive properties and attach very securely to the intestinal cells, creating the said protective barrier.Also, bacteria of a constant microflora help maintain intestinal motility and the integrity of the intestinal mucosa. Yes, bactors - commensals of the large intestine during the catabolism of indigestible carbohydrates in the small intestine (the so-called dietary fiber) form short chain fatty acids (SCFA, short-chain fatty acids), such as acetate, propionate, and butyrate, which support barrier functions of the mucin layer mucus (increase the production of mucins and the protective function of the epithelium). IMMUNE SYSTEM OF THE INTESTINE. More than 70% of immune cells are concentrated in the human intestine. main function The immune system of the intestine is to protect against the penetration of bacteria into the blood. The second function is the elimination of pathogens (pathogenic bacteria). This is provided by two mechanisms: innate (inherited by the child from the mother, people from birth have antibodies in the blood) and acquired immunity (appears after foreign proteins enter the blood, for example, after suffering an infectious disease). Upon contact with pathogens, the body's immune defenses are stimulated. When interacting with Toll-like receptors, synthesis is triggered various types cytokines. The intestinal microflora affects specific accumulations of lymphoid tissue. This stimulates the cellular and humoral immune response. Cells of the intestinal immune system actively produce secretory immunolobulin A (LgA) - a protein that is involved in local immunity and is the most important marker of the immune response. ANTIBIOTIC-LIKE SUBSTANCES. Also, the intestinal microflora produces many antimicrobial substances that inhibit the reproduction and growth of pathogenic bacteria. With dysbiotic disorders in the intestine, there is not only an excessive growth of pathogenic microbes, but also a general decrease in the body's immune defenses.Normal intestinal microflora plays a particularly important role in the life of the body of newborns and children. Thanks to the production of lysozyme, hydrogen peroxide, lactic, acetic, propionic, butyric and a number of other organic acids and metabolites that reduce the acidity (pH) of the environment, bacteria of normal microflora effectively fight pathogens. In this competitive struggle of microorganisms for survival, antibiotic-like substances such as bacteriocins and microcins occupy a leading place. Below picture Left: Colony of acidophilus bacillus (x 1100), On right: Destruction of Shigella flexneri (a) (Shigella Flexner - a type of bacteria that causes dysentery) under the action of bacteriocin-producing cells of acidophilus bacillus (x 60,000)
It should be noted that almost all microorganisms in the intestinehave special form coexistence, which is called a biofilm. Biofilm iscommunity (colony)microorganisms located on any surface, the cells of which are attached to each other. Usually, cells are immersed in the extracellular polymeric substance secreted by them - mucus. It is the biofilm that performs the main barrier function from the penetration of pathogens into the blood, by eliminating the possibility of their penetration to epithelial cells. For more information about biofilm, see: HISTORY OF STUDYING THE COMPOSITION OF THE GIT MICROFLORA The history of the study of the composition of the microflora of the gastrointestinal tract (GIT) began in 1681, when the Dutch researcher Anthony van Leeuwenhoek first reported his observations on bacteria and other microorganisms found in human feces and put forward the hypothesis of the coexistence of different types of bacteria in the gastrointestinal tract. -intestinal tract. In 1850, Louis Pasteur developed the concept of functional the role of bacteria in the fermentation process, and the German physician Robert Koch continued research in this direction and created a method for isolating pure cultures, which makes it possible to identify specific bacterial strains, which is necessary to distinguish between pathogenic and beneficial microorganisms. In 1955 Peretz L.G. showed that intestinal coli of healthy people is one of the main representatives of the normal microflora and plays a positive role due to its strong antagonistic properties against pathogenic microbes. Started over 300 years ago, studies of the composition of the intestinal microbiocenosis, its normal and pathological physiology and the development of ways to positively influence the intestinal microflora continue to this day. HUMAN AS A BACTERIA HABITATThe main biotopes are: gastrointestinaltract(oral cavity, stomach, small intestine, large intestine), skin, Airways, urogenital system. But the main interest for us here are the organs digestive system, because the bulk of various microorganisms lives there. The microflora of the gastrointestinal tract is the most representative, the mass of intestinal microflora in an adult is more than 2.5 kg, with a population of up to 10 14 CFU / g. It was previously believed that the microbiocenosis of the gastrointestinal tract includes 17 families, 45 genera, more than 500 species of microorganisms (the latest data is about 1500 species) constantly being adjusted. Taking into account the new data obtained in the study of the microflora of various biotopes of the gastrointestinal tract using molecular genetic methods and the method of gas-liquid chromatography-mass spectrometry, the total genome of bacteria in the gastrointestinal tract has 400 thousand genes, which is 12 times larger than the size of the human genome. exposed analysis on the homology of sequenced genes 16S pRNA parietal (mucosal) microflora 400 various departments GI tract obtained from endoscopy various sections of the intestines of volunteers. As a result of the study, it was shown that the parietal and luminal microflora includes 395 phylogenetically isolated groups of microorganisms, of which 244 are absolutely new. At the same time, 80% of the new taxa identified in the molecular genetic study belong to non-cultivated microorganisms. Most of the proposed new phylotypes of microorganisms are representatives of the genera Firmicutes and Bacteroides. The total number of species is close to 1500 and requires further clarification. The gastrointestinal tract communicates with the gastrointestinal tract through a system of sphincters. external environment the world around us and at the same time through the intestinal wall - with the internal environment of the body. Due to this feature, the gastrointestinal tract has created its own environment, which can be divided into two separate niches: chyme and mucous membrane. The human digestive system interacts with various bacteria, which can be referred to as "endotrophic microflora of the human intestinal biotope". Human endotrophic microflora is divided into three main groups. The first group includes useful for humans eubiotic indigenous or eubiotic transient microflora; to the second - neutral microorganisms, constantly or periodically sown from the intestine, but not affecting human life; to the third - pathogenic or potentially pathogenic bacteria ("aggressive populations"). Cavity and wall microbiotopes of the gastrointestinal tractIn microecological terms, the gastrointestinal biotope can be divided into tiers (oral cavity, stomach, intestines) and microbiotopes (cavitary, parietal and epithelial). The ability to apply in the parietal microbiotope, i.e. histadhesiveness (the ability to fix and colonize tissues) determines the essence of transient or indigenous bacteria. These signs, as well as belonging to a eubiotic or aggressive group, are the main criteria characterizing a microorganism interacting with the gastrointestinal tract. Eubiotic bacteria are involved in the creation of colonization resistance of the organism, which is a unique mechanism of the system of anti-infective barriers. Cavitary microbiotope throughout the gastrointestinal tract is heterogeneous, its properties are determined by the composition and quality of the contents of a particular tier. Tiers have their own anatomical and functional features, so their content differs in the composition of substances, consistency, pH, speed of movement and other properties. These properties determine the qualitative and quantitative composition of cavity microbial populations adapted to them. Parietal microbiotope is the most important structure that limits the internal environment of the body from the external one. It is represented by mucous overlays (mucous gel, mucin gel), glycocalyx located above the apical membrane of enterocytes and the surface of the apical membrane itself. The parietal microbiotope is of the greatest (!) interest from the point of view of bacteriology, since it is in it that interaction with bacteria that is beneficial or harmful to humans occurs - what we call symbiosis.
To date, it is known that the microflora of the intestinal mucosa differs significantly from the microflora of the intestinal lumen and feces. Although each adult has a specific combination of predominant bacterial species in the gut, the composition of the microflora can change with lifestyle, diet, and age. A comparative study of the microflora in adults who are genetically related to one degree or another revealed that genetic factors influence the composition of the intestinal microflora more than nutrition.
Figure Note: FOG - fundus of the stomach, AOG - antrum of the stomach, duodenum - duodenum (:Chernin V.V., Bondarenko V.M., Parfenov A.I. Participation of the luminal and mucosal microbiota of the human intestine in symbiotic digestion. Bulletin of the Orenburg Scientific Center of the Ural Branch of the Russian Academy of Sciences (electronic journal), 2013, No. 4) The location of the mucosal microflora corresponds to the degree of its anaerobiosis: obligate anaerobes (bifidobacteria, bacteroids, propionic acid bacteria, etc.) occupy a niche in direct contact with the epithelium, followed by aerotolerant anaerobes (lactobacilli, etc.), even higher - facultative anaerobes, and then - aerobes .Translucent microflora is the most variable and sensitive to various exogenous influences. Changes in diets, environmental impacts, drug therapy, primarily affect the quality of the translucent microflora. See additionally: The number of microorganisms of mucosal and luminal microflora The mucosal microflora is more resistant to external influences than the luminal microflora. The relationship between mucosal and luminal microflora is dynamic and determined by the following factors:
MICROFLORA OF THE MOUTH, ESOPHAGUS AND STOMACHConsider the composition of the normal microflora of different parts of the gastrointestinal tract.
Saliva is the first digestive fluid that processes food substances and affects the penetrating microflora. The total content of bacteria in saliva is variable and averages 108 MK/ml. The normal microflora of the oral cavity includes streptococci, staphylococci, lactobacilli, corynebacteria, a large number of anaerobes. In total, the microflora of the mouth has more than 200 species of microorganisms. On the surface of the mucosa, depending on the hygiene products used by the individual, about 10 3 -10 5 MK / mm2 are found. The colonization resistance of the mouth is carried out mainly by streptococci (S. salivarus, S. mitis, S. mutans, S. sangius, S. viridans), as well as representatives of the skin and intestinal biotopes. At the same time, S. salivarus, S. sangius, S. viridans adhere well to the mucous membrane and dental plaque. These alpha-hemolytic streptococci, which have a high degree of histadgesia, inhibit the colonization of the mouth by fungi of the genus Candida and staphylococci.
The main microorganisms active in the gastric environment are acid resistant representatives of the genus Lactobacillus with or without a histadhesive relationship to mucin, some types of soil bacteria and bifidobacteria. Lactobacilli, despite a short residence time in the stomach, are capable, in addition to their antibiotic action in the stomach cavity, to temporarily colonize the parietal microbiotope. As a result of the joint action of protective components, the bulk of microorganisms that have entered the stomach die. However, in case of malfunction of the mucous and immunobiological components, some bacteria find their biotope in the stomach. So, due to pathogenicity factors, the population of Helicobacter pylori is fixed in the gastric cavity.
MAIN FUNCTIONS OF THE SMALL INTESTINE Small intestine
- This is a tube about 6m long. It occupies almost the entire lower part of the abdominal cavity and is the longest part of the digestive system, connecting the stomach to the large intestine. Most of the food is already digested in the small intestine with the help of special substances - enzymes (enzymes). To the main functions of the small intestine include cavity and parietal hydrolysis of food, absorption, secretion, as well as barrier-protective. In the latter, in addition to chemical, enzymatic and mechanical factors, significant role played by the indigenous microflora of the small intestine. It takes an active part in cavity and parietal hydrolysis, as well as in absorption processes. nutrients. The small intestine is one of the most important links that ensure the long-term preservation of the eubiotic parietal microflora. There is a difference in the colonization of cavitary and parietal microbiotopes with eubiotic microflora, as well as in the colonization of tiers along the length of the intestine. The cavity microbiotope is subject to fluctuations in the composition and concentration of microbial populations, the parietal microbiotope has a relatively stable homeostasis. In the thickness of the mucous overlays, populations with histadhesive properties to mucin are preserved. The proximal small intestine normally contains a relatively small amount of gram-positive flora, consisting mainly of lactobacilli, streptococci, and fungi. The concentration of microorganisms is 10 2 -10 4 per 1 ml of intestinal contents. As you approach the distal small intestine total bacteria increases to 10 8 per 1 ml of content, at the same time additional species appear, including enterobacteria, bacteroids, bifidobacteria. MAIN FUNCTIONS OF THE LARGE INTESTINE
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In 1886, one of the founders of the doctrine of intestinal infections F. Escherich first described intestinal coli (Bacterium coli communae). Ilya Ilyich Mechnikov in 1888, working at the Louis Pasteur Institute, argued that in intestines a human being inhabited by a complex of microorganisms that have an “autointoxication effect” on the body, believing that the introduction of “healthy” bacteria into the gastrointestinal tract can modify the effect intestinal microflora and counteract intoxication. The practical implementation of Mechnikov's ideas was the use of acidophilic lactobacilli for therapeutic purposes, which began in the USA in 1920-1922. Domestic researchers began to study this issue only in the 50s of the XX century.
