The tissues of a living organism are very sensitive to fluctuations in pH - outside the permissible range, denaturation of proteins occurs: cells are destroyed, enzymes lose the ability to perform their functions, and the death of the organism is possible

What is pH (hydrogen index) and acid-base balance

The ratio of acid and alkali in any solution is called acid-base balance(ASR), although physiologists believe that it is more correct to call this ratio the acid-base state.

KShchR is characterized by a special indicator pH(power Hydrogen - “hydrogen power”), which shows the number of hydrogen atoms in a given solution. At a pH of 7.0 they speak of a neutral environment.

The lower the pH level, the more acidic the environment (from 6.9 to O).

An alkaline environment has a high pH level (from 7.1 to 14.0).

The human body is 70% water, so water is one of its most important components. T atehuman has a certain acid-base ratio, characterized by pH (hydrogen) indicator.

The pH value depends on the ratio between positively charged ions (forming an acidic environment) and negatively charged ions (forming an alkaline environment).

The body constantly strives to balance this ratio, maintaining a strictly defined pH level. When the balance is disturbed, many serious diseases can occur.

Maintain the correct pH balance for good health

The body is able to properly absorb and store minerals and nutrients only with the proper level of acid-base balance. The tissues of a living organism are very sensitive to fluctuations in pH - outside the permissible range, denaturation of proteins occurs: cells are destroyed, enzymes lose the ability to perform their functions, and the death of the organism is possible. Therefore, the acid-base balance in the body is strictly regulated.

Our body uses hydrochloric acid to break down food. In the process of vital activity of the body, both acidic and alkaline breakdown products are required, and more of the former are formed than the latter. Therefore, the body’s defense systems, which ensure the invariability of its ASR, are “tuned” primarily to neutralize and remove, first of all, acidic decomposition products.

Blood has a slightly alkaline reaction: The pH of arterial blood is 7.4, and that of venous blood is 7.35 (due to excess CO2).

A pH shift of even 0.1 can lead to severe pathology.

When the blood pH shifts by 0.2, a coma develops, and by 0.3, the person dies.

The body has different PH levels

Saliva is a predominantly alkaline reaction (pH fluctuation 6.0 - 7.9)

Typically, the acidity of mixed human saliva is 6.8–7.4 pH, but with high salivation rates it reaches 7.8 pH. The acidity of the saliva of the parotid glands is 5.81 pH, of the submandibular glands - 6.39 pH. In children, on average, the acidity of mixed saliva is 7.32 pH, in adults - 6.40 pH (Rimarchuk G.V. et al.). The acid-base balance of saliva, in turn, is determined by a similar balance in the blood, which nourishes the salivary glands.

Esophagus - Normal acidity in the esophagus is 6.0–7.0 pH.

Liver - the reaction of gallbladder bile is close to neutral (pH 6.5 - 6.8), the reaction of hepatic bile is alkaline (pH 7.3 - 8.2)

Stomach - sharply acidic (at the height of digestion pH 1.8 - 3.0)

The maximum theoretically possible acidity in the stomach is 0.86 pH, which corresponds to an acid production of 160 mmol/l. The minimum theoretically possible acidity in the stomach is 8.3 pH, which corresponds to the acidity of a saturated solution of HCO 3 - ions. Normal acidity in the lumen of the body of the stomach on an empty stomach is 1.5–2.0 pH. The acidity on the surface of the epithelial layer facing the lumen of the stomach is 1.5–2.0 pH. The acidity in the depths of the epithelial layer of the stomach is about 7.0 pH. Normal acidity in the antrum of the stomach is 1.3–7.4 pH.

It is a common misconception that the main problem for humans is increased stomach acidity. It causes heartburn and ulcers.

In fact, a much bigger problem is low stomach acidity, which is many times more common.

The main cause of heartburn in 95% is not an excess, but a lack of hydrochloric acid in the stomach.

A lack of hydrochloric acid creates ideal conditions for the colonization of the intestinal tract by various bacteria, protozoa and worms.

The insidiousness of the situation is that low stomach acidity “behaves quietly” and goes unnoticed by humans.

Here is a list of signs that suggest a decrease in stomach acidity.

• Discomfort in the stomach after eating.
• Nausea after taking medications.
• Flatulence in the small intestine.
• Loose stools or constipation.
• Undigested food particles in the stool.
• Itching around the anus.
• Multiple food allergies.
• Dysbacteriosis or candidiasis.
• Dilated blood vessels on the cheeks and nose.
• Acne.
• Weak, peeling nails.
• Anemia due to poor iron absorption.

Of course, an accurate diagnosis of low acidity requires determining the pH of gastric juice(for this you need to contact a gastroenterologist).

When acidity is high, there are many drugs to reduce it.

In the case of low acidity, there are very few effective remedies.

As a rule, hydrochloric acid preparations or vegetable bitters are used to stimulate the secretion of gastric juice (wormwood, calamus, peppermint, fennel, etc.).

Pancreas - pancreatic juice is slightly alkaline (pH 7.5 - 8.0)

Small intestine - alkaline reaction (pH 8.0)

Normal acidity in the duodenal bulb is 5.6–7.9 pH. The acidity in the jejunum and ileum is neutral or slightly alkaline and ranges from 7 to 8 pH. The acidity of small intestine juice is 7.2–7.5 pH. With increased secretion it reaches 8.6 pH. The acidity of the secretion of the duodenal glands is from pH 7 to 8 pH.

Large intestine - slightly acidic reaction (5.8 - 6.5 pH)

This is a slightly acidic environment, which is maintained by normal microflora, in particular, bifidobacteria, lactobacilli and propionobacteria due to the fact that they neutralize alkaline metabolic products and produce their acidic metabolites - lactic acid and other organic acids. By producing organic acids and reducing the pH of the intestinal contents, normal microflora creates conditions under which pathogenic and opportunistic microorganisms cannot multiply. This is why streptococci, staphylococci, klebsiella, clostridia fungi and other “bad” bacteria make up only 1% of the entire intestinal microflora of a healthy person.

Urine is predominantly slightly acidic (pH 4.5-8)

When eating foods containing animal proteins containing sulfur and phosphorus, mostly acidic urine (pH less than 5) is excreted; in the final urine there is a significant amount of inorganic sulfates and phosphates. If the food is mainly dairy or vegetable, then the urine tends to become alkalized (pH more than 7). The renal tubules play a significant role in maintaining acid-base balance. Acidic urine will be produced in all conditions leading to metabolic or respiratory acidosis as the kidneys compensate for changes in acid-base status.

Skin - slightly acidic reaction (pH 4-6)

If your skin is prone to oiliness, the pH value may approach 5.5. And if the skin is very dry, the pH can be 4.4.

The bactericidal property of the skin, which gives it the ability to resist microbial invasion, is due to the acidic reaction of keratin, the peculiar chemical composition of sebum and sweat, and the presence on its surface of a protective water-lipid mantle with a high concentration of hydrogen ions. The low molecular weight fatty acids it contains, primarily glycophospholipids and free fatty acids, have a bacteriostatic effect that is selective for pathogenic microorganisms.

Genitals

The normal acidity of a woman's vagina ranges from 3.8 to 4.4 pH and averages 4.0 to 4.2 pH.

At birth, a girl's vagina is sterile. Then, within a few days, it is populated by a variety of bacteria, mainly staphylococci, streptococci, and anaerobes (that is, bacteria that do not require oxygen to live). Before the onset of menstruation, the acidity level (pH) of the vagina is close to neutral (7.0). But during puberty, the walls of the vagina thicken (under the influence of estrogen, one of the female sex hormones), the pH decreases to 4.4 (i.e., acidity increases), which causes changes in the vaginal flora.

The uterine cavity is normally sterile, and the entry of pathogenic microorganisms into it is prevented by lactobacilli that populate the vagina and maintain the high acidity of its environment. If for some reason the acidity of the vagina shifts towards alkaline, the number of lactobacilli drops sharply, and in their place other microbes develop that can enter the uterus and lead to inflammation, and then to problems with pregnancy.

Sperm

The normal acidity level of sperm is between 7.2 and 8.0 pH. An increase in the pH level of sperm occurs during an infectious process. A sharply alkaline reaction of sperm (acidity approximately 9.0–10.0 pH) indicates prostate pathology. When the excretory ducts of both seminal vesicles are blocked, an acidic reaction of the sperm is observed (acidity 6.0–6.8 pH). The fertilizing ability of such sperm is reduced. In an acidic environment, sperm lose motility and die. If the acidity of the seminal fluid becomes less than 6.0 pH, the sperm completely lose their motility and die.

Cells and intercellular fluid

In the cells of the body the pH is about 7, in the extracellular fluid it is 7.4. Nerve endings that are outside cells are very sensitive to changes in pH. When mechanical or thermal damage occurs to tissues, cell walls are destroyed and their contents reach the nerve endings. As a result, the person feels pain.

Scandinavian researcher Olaf Lindahl conducted the following experiment: using a special needle-free injector, a very thin stream of solution was injected through the skin of a person, which did not damage the cells, but acted on the nerve endings. It has been shown that it is hydrogen cations that cause pain, and as the pH of the solution decreases, the pain intensifies.

Similarly, a solution of formic acid, which is injected under the skin by stinging insects or nettles, directly “acts on the nerves.” The different pH values ​​of tissues also explain why with some inflammations a person feels pain, and with others - not.

Interestingly, injecting clean water under the skin produced particularly severe pain. This phenomenon, strange at first glance, is explained as follows: when cells come into contact with clean water as a result of osmotic pressure, they rupture and their contents affect the nerve endings.

Table 1. Hydrogen indicators for solutions

Solution	RN
HCl	1,0
H2SO4	1,2
H2C2O4	1,3
NaHSO4	1,4
N 3 PO 4	1,5
Gastric juice	1,6
Wine acid	2,0
Lemon acid	2,1
HNO2	2,2
Lemon juice	2,3
Lactic acid	2,4
Salicylic acid	2,4
Table vinegar	3,0
Grapefruit juice	3,2
CO 2	3,7
Apple juice	3,8
H2S	4,1
Urine	4,8-7,5
Black coffee	5,0
Saliva	7,4-8
Milk	6,7
Blood	7,35-7,45
Bile	7,8-8,6
Ocean water	7,9-8,4
Fe(OH)2	9,5
MgO	10,0
Mg(OH)2	10,5
Na 2 CO 3
Ca(OH)2	11,5
NaOH	13,0

Fish eggs and fry are especially sensitive to changes in pH. The table allows us to make a number of interesting observations. pH values, for example, immediately indicate the relative strength of acids and bases. A strong change in the neutral environment as a result of the hydrolysis of salts formed by weak acids and bases, as well as during the dissociation of acidic salts, is also clearly visible.

Urine pH is not a good indicator of overall body pH, and it is not a good indicator of overall health.

In other words, no matter what you eat and no matter what your urine pH, you can be absolutely sure that your arterial blood pH will always be around 7.4.

When a person consumes, for example, acidic foods or animal protein, under the influence of buffer systems, the pH shifts to the acidic side (becomes less than 7), and when consumed, for example, mineral water or plant foods, it shifts to alkaline (becomes more than 7). Buffer systems keep the pH within the acceptable range for the body.

By the way, doctors claim that we tolerate a shift to the acid side (that same acidosis) much easier than a shift to the alkaline side (alkalosis).

It is impossible to shift the pH of the blood by any external influence.

THE MAIN MECHANISMS FOR MAINTAINING BLOOD PH ARE:

1. Blood buffer systems (carbonate, phosphate, protein, hemoglobin)

This mechanism acts very quickly (fractions of a second) and therefore belongs to the fast mechanisms for regulating the stability of the internal environment.

Bicarbonate blood buffer quite powerful and most mobile.

One of the important buffers of blood and other body fluids is the bicarbonate buffer system (HCO3/CO2): CO2 + H2O ⇄ HCO3- + H+ The main function of the bicarbonate buffer system of the blood is the neutralization of H+ ions. This buffer system plays a particularly important role since the concentrations of both buffer components can be adjusted independently of each other; [CO2] - through respiration, - in the liver and kidneys. Thus, it is an open buffer system.

The hemoglobin buffer system is the most powerful.
It accounts for more than half of the buffer capacity of the blood. The buffering properties of hemoglobin are determined by the ratio of reduced hemoglobin (HHb) and its potassium salt (KHb).

Plasma proteins due to the ability of amino acids to ionize, they also perform a buffer function (about 7% of the buffer capacity of the blood). In an acidic environment they behave as acid-binding bases.

Phosphate buffer system(about 5% of the blood buffer capacity) is formed by inorganic blood phosphates. The properties of an acid are exhibited by monobasic phosphate (NaH 2 P0 4), and the properties of bases are exhibited by dibasic phosphate (Na 2 HP0 4). They function on the same principle as bicarbonates. However, due to the low content of phosphates in the blood, the capacity of this system is small.

2. Respiratory (pulmonary) regulation system.

Because of the ease with which the lungs regulate CO2 concentrations, this system has significant buffering capacity. Removal of excess amounts of CO 2 and regeneration of bicarbonate and hemoglobin buffer systems are carried out by the lungs.

At rest, a person emits 230 ml of carbon dioxide per minute, or about 15 thousand mmol per day. When carbon dioxide is removed from the blood, approximately an equivalent amount of hydrogen ions disappears. Therefore, breathing plays an important role in maintaining acid-base balance. So, if the acidity of the blood increases, then the increase in the content of hydrogen ions leads to an increase in pulmonary ventilation (hyperventilation), while carbon dioxide molecules are excreted in large quantities and the pH returns to normal levels.

An increase in the content of bases is accompanied by hypoventilation, as a result of which the concentration of carbon dioxide in the blood increases and, accordingly, the concentration of hydrogen ions, and the shift in the blood reaction to the alkaline side is partially or completely compensated.

Consequently, the external respiration system can quite quickly (within a few minutes) eliminate or reduce pH shifts and prevent the development of acidosis or alkalosis: increasing pulmonary ventilation by 2 times increases the blood pH by about 0.2; reducing ventilation by 25% can reduce pH by 0.3-0.4.

3. Renal (excretory system)

Acts very slowly (10-12 hours). But this mechanism is the most powerful and is able to completely restore the body's pH by removing urine with alkaline or acidic pH values. The participation of the kidneys in maintaining acid-base balance is the removal of hydrogen ions from the body, the reabsorption of bicarbonate from the tubular fluid, the synthesis of bicarbonate when there is a deficiency and removal when there is an excess.

The main mechanisms for reducing or eliminating shifts in blood acid-rich hormone, implemented by kidney nephrons, include acidogenesis, ammoniaogenesis, phosphate secretion and the K+, Ka+ exchange mechanism.

The mechanism for regulating blood pH in the whole organism is the combined action of external respiration, blood circulation, excretion and buffer systems. Thus, if excess anions appear as a result of increased formation of H 2 CO 3 or other acids, they are first neutralized by buffer systems. At the same time, breathing and blood circulation intensify, which leads to an increase in the release of carbon dioxide by the lungs. Non-volatile acids, in turn, are excreted in urine or sweat.

Normally, the pH of the blood can change only for a short time. Naturally, if the lungs or kidneys are damaged, the body’s functional capabilities to maintain pH at the proper level are reduced. If a large number of acidic or basic ions appear in the blood, only buffer mechanisms (without the help of excretion systems) will not keep the pH at a constant level. This leads to acidosis or alkalosis. published

©Olga Butakova “Acid-base balance is the basis of life”

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What is the environment in the small intestine?

Small intestine

The small intestine is usually divided into the duodenum, jejunum and small intestine.

Academician A. M. Ugolev called the duodenum “the hypothalamic-pituitary system of the abdominal cavity.” It produces the following factors that regulate the body’s energy metabolism and appetite.

1. Transition from gastric to intestinal digestion. Outside the digestive period, the contents of the duodenum have a slightly alkaline reaction.

2. Several important digestive ducts from the liver and pancreas and their own Brunner’s and Lieberkühn’s glands, located deep in the mucous membrane, open into the cavity of the duodenum.

3. Three main types of digestion: cavity, membrane and intracellular under the influence of pancreatic secretions, bile and own juices.

4. Absorption of nutrients and excretion of some unnecessary ones from the blood.

5. Production of intestinal hormones and biologically active substances that have both digestive and non-digestive effects. For example, hormones are formed in the mucous membrane of the duodenum: secretin stimulates the secretion of the pancreas and bile; cholecystokinin stimulates gallbladder motility, opens the bile duct; villikinin stimulates the motility of the villi of the small intestine, etc.

The jejunum and small intestine are about 6 m long. The glands secrete up to 2 liters of juice per day. The total surface of the inner lining of the intestine, including villi, is about 5 m2, which is approximately three times larger than the outer surface of the body. That is why processes occur here that require a large amount of free energy, that is, associated with the assimilation (assimilation) of food - cavity and membrane digestion, as well as absorption.

The small intestine is the most important organ of internal secretion. It contains 7 types of different endocrine cells, each of which produces a specific hormone.

The walls of the small intestine have a complex structure. The cells of the mucosa have up to 4000 outgrowths - microvilli, which form a rather dense “brush”. There are about 50-200 million of them on 1 mm2 of the surface of the intestinal epithelium! Such a structure - it is called a brush border - not only sharply increases the absorption surface of intestinal cells (20-60 times), but also determines many functional features of the processes occurring on it.

In turn, the surface of the microvilli is covered with glycocalyx. It consists of numerous thin winding filaments that form an additional pre-membrane layer that fills the pores between the microvilli. These threads are a product of the activity of intestinal cells (enterocytes) and “grow” from the membranes of microvilli. The diameter of the filaments is 0.025-0.05 microns, and the thickness of the layer along the outer surface of intestinal cells is approximately 0.1-0.5 microns.

The glycocalyx with microvilli plays the role of a porous catalyst; its significance is that it increases the active surface. In addition, microvilli are involved in the transfer of substances during the operation of the catalyst in cases where the pores have approximately the same dimensions as the molecules. In addition, microvilli are able to contract and relax in a rhythm of 6 times per minute, which increases the speed of both digestion and absorption. The glycocalyx is characterized by significant water penetration (hydrophilicity), gives the transfer processes a directed (vector) and selection (selective) nature, and also reduces the flow of antigens and toxins into the internal environment of the body.

Digestion in the small intestine. The process of digestion in the small intestine is complex and easily disrupted. With the help of cavity digestion, mainly the initial stages of hydrolysis of proteins, fats, carbohydrates and other nutrients (nutrients) are carried out. Hydrolysis of molecules (monomers) occurs in the brush border. The final stages of hydrolysis occur on the microvilli membrane, followed by absorption.

What are the features of this digestion?

1. High free energy appears at the interface between water - air, oil - water, etc. Due to the large surface of the small intestine, powerful processes occur here, so a large amount of free energy is required.

The state in which the substance (food mass) is located at the phase boundary (near the brush border in the pores of the glycocalyx) differs from the state of this substance in the bulk (in the intestinal cavity) in many ways, in particular in terms of energy level. As a rule, surface food molecules have more energy than those in the deep phase.

2. Organic matter (food) reduces surface tension and therefore collects at the interface. Favorable conditions are created for the transition of nutrients from the middle of the chyme (food mass) to the surface of the intestine (intestinal cell), that is, from cavity to membrane digestion.

3. Selective separation of positively and negatively charged food substances at the phase boundary leads to the emergence of a significant phase potential, while the molecules at the surface boundary are mostly in an oriented state, and in the depths - in a chaotic state.

4. Enzymatic systems that provide parietal digestion are included in the composition of cell membranes in the form of spatially ordered systems. From here, properly oriented food monomer molecules, due to the presence of phase potential, are directed to the active center of the enzymes.

5. At the final stage of digestion, when monomers are formed that are accessible to bacteria inhabiting the intestinal cavity, it occurs in the ultrastructures of the brush border. Bacteria do not penetrate there: their size is several microns, and the size of the brush border is much smaller - 100–200 angstroms. The brush border acts as a kind of bacterial filter. Thus, the final stages of hydrolysis and the initial stages of absorption occur under sterile conditions.

6. The intensity of membrane digestion varies widely and depends on the speed of movement of liquid (chyme) relative to the surface of the small intestinal mucosa. Therefore, normal intestinal motility plays an extremely important role in maintaining a high rate of parietal digestion. Even if the enzymatic layer is preserved, the weakness of the mixing movements of the small intestine or the too rapid passage of food through it reduces parietal digestion.

The above mechanisms contribute to the fact that with the help of cavity digestion, mainly the initial stages of the breakdown of proteins, fats, carbohydrates and other nutrients are carried out. The breakdown of molecules (monomers) occurs in the brush border, that is, an intermediate stage. On the microvilli membrane, the final stages of cleavage occur, followed by absorption.

In order for food to be processed efficiently in the small intestine, the amount of food mass must be well balanced with the time of its movement along the entire intestine. In this regard, digestive processes and absorption of nutrients are distributed unevenly throughout the small intestine, and enzymes that process certain food components are located accordingly. Thus, fat in food significantly affects the absorption and assimilation of nutrients in the small intestine.

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Signs of small intestinal disease

The most common diseases of the small intestine - the causes of their occurrence, main manifestations, principles of diagnosis and correct treatment. Is it possible to cure these diseases on your own?

A few words on the anatomy and physiology of the small intestine as a part of the human digestive system

In order for a person to understand the essence of diseases and the basic principles of their treatment, it is necessary to understand at least the very basics of the morphology of organs and the principles of their functioning. The small intestine is located predominantly in the epigastric and mesogastric sections of the abdomen (that is, in the upper and middle), consists of three conventional sections (duodenum, jejunum and ileum), the ducts of the liver and pancreas open into the descending section of the duodenum (they secrete into the lumen the intestines have their own secretions in order for the normal digestion process to take place). The small intestine connects the stomach and large intestine. A very important feature that affects the functioning of the gastrointestinal tract is that the stomach and large intestine have an acidic environment, and the small intestine is alkaline. This feature is provided by the pyloric sphincter (at the border of the stomach and duodenum), as well as by the ileocecal valve - the border between the small and large intestines.

It is in this anatomical section of the gastrointestinal tract that the processes of breakdown of proteins, fats and carbohydrates into monomer molecules (amino acids, glucose, fatty acids) take place, which are absorbed by special cells of the parietal digestive system and are carried throughout the body through the bloodstream.

The main manifestations and symptoms that characterize any pathology of the small intestine

Like any other disease of the gastrointestinal tract, all pathologies of the small intestine are manifested by dyspeptic syndrome (that is, this concept includes bloating, nausea, vomiting, abdominal pain, rumbling, flatulence, bowel dysfunction, weight loss, and so on). It is quite problematic for the unenlightened layman to understand that it is the small intestine that is affected, for several reasons:

1. The symptoms of diseases of the small and large intestines have much in common;
2. In addition to the fact that problems may arise directly with the small intestine itself, pathology is often associated with dysfunction of other organs with which the small intestine is anatomically and functionally connected (in most cases, the liver, pancreas or stomach).
3. Pathological phenomena can have a mutually aggravating effect, this can significantly affect the clinic. So, as a rule, a person who is far from medicine will say that he simply has a “stomach ache” and does not have unknown problems with the small intestine.

What diseases of the small intestine exist and what can they be associated with?

In most cases, pathological manifestations arising from problems with the small intestine are caused by two points:

1. Maldigestion – indigestion;
2. Malabsorption - impaired absorption.

It should be noted that these pathologies can have a fairly severe course. If digestion or absorption is severely impaired, there will be signs of a significant lack of nutrients, vitamins, macro and microelements. The person will begin to lose weight sharply, pale skin, hair loss, apathy, and instability to infectious diseases will be noted.

It is necessary to understand that both of these syndrome complexes are manifestations of some etiological process, that is, secondary phenomena. There is, of course, congenital enzymatic deficiency (for example, lactose indigestibility), but this process is a severe hereditary pathology that necessarily manifests itself in the first days of life. In most cases, all digestive and absorption disorders have their own underlying causes:

1. Enzyme deficiency, due to any pathology of the liver, pancreas (or Vutter's papilla, which opens into the lumen of the duodenum - through it bile and pancreatic juice enter the small intestine; what is most interesting is the lion's share of all malignant tumors that arise in the small intestine , is associated precisely with the defeat of this structure).
2. Resection (removal through surgery) of a large section of the small intestine. In this case, all the problems are related to the fact that the absorption area is simply not large enough to supply the human body with the necessary amount of nutrients.
3. Endocrine pathology, affecting metabolic processes, can also cause digestive disorders (in most cases, diabetes mellitus or thyroid dysfunction).
4. Chronic inflammatory processes.
5. Poor nutrition (eating large amounts of fatty and fried foods, irregular meals).
6. Psychosomatic nature. Everyone remembers very well the saying that all our illnesses come from “nerves.” That's exactly how it is. Short-term severe stress, and constant neuropsychic stress at work and at home, with a high degree of probability can cause dyspeptic syndrome associated with impaired absorption or digestion. It should be noted that in this case, maldigestion and malabsorption can be considered independent nosological units (that is, diseases, in simpler terms). In other words, a kind of diagnosis is made - an exception. That is, when carrying out additional examination methods, it is impossible to identify any underlying factor that allows us to talk about a specific etiology (origin) of pathological changes in the functioning of the small intestine.

Another, more dangerous and fairly common disease of the small intestine is an ulcer of the duodenum (its bulbar section). The same Helicobacter pylori as in the stomach, everything is unchanged, similar symptoms and manifestations. Headaches, belching and blood in the stool. Very dangerous complications are possible, such as perforation (perforation of the duodenum with its contents entering the sterile abdominal cavity and subsequent development of peritonitis) or penetration (due to the progression of the pathological process, the so-called “soldering” of it with a nearby organ occurs). Naturally, an ulcer of the duodenal bulb is preceded by duodenitis, which usually develops due to poor nutrition - its manifestations will include periodic abdominal pain, belching and heartburn. It should be noted that due to the characteristics of the modern lifestyle, this pathology is becoming increasingly widespread, especially in developed countries.

A few words about all other diseases of the small intestine

The above are pathologies that make up the lion's share of all diseases that can be associated with this part of the gastrointestinal tract. However, it is necessary to remember about other pathologies - helminthic infestations, neoplasms of various parts of the small intestine, foreign bodies that can enter this part of the gastrointestinal tract. Today, helminthiasis is relatively rare (mainly in children and residents of rural areas). The frequency of damage by malignant neoplasms of the small intestine is negligible (most likely, this is due to the high specialization of the cells lining the inner wall of this part of the intestine); foreign bodies reach the duodenum very rarely - in most cases, their “advancement” ends in the stomach or esophagus.

What should a person do if he has been experiencing manifestations of dyspeptic syndrome for a long period of time?

The most important thing is to respond in time to alarming symptoms (pain, belching, heartburn, blood in the stool) and seek help from a doctor. Understand the most important thing: gastroenterological pathology is not an area where it can “go away on its own” or where the disease can be eliminated by self-medication. This is not a runny nose or chicken pox, where the disease itself will destroy a person’s immunity.

First, you need to pass several tests and undergo additional examination methods. The required complex includes:

• General blood test, biochemical blood test with determination of the renal-hepatic complex;
• General urine analysis;
• Fecal analysis for worm eggs and coprocytogram;
• Ultrasound of the abdominal organs;
• Consultation with a gastroenterologist.

This list of examinations will confirm or exclude most of the most common diseases of the small intestine, establish the cause of pain, belching, flatulence, weight loss and other most typical symptoms. However, it is also necessary to remember the need to carry out differential diagnosis with other diseases that have a similar clinical picture and to determine the root cause of any disease.

For this (as well as in the case of the slightest suspicion of a tumor process), it is necessary to carry out an endoscopic biopsy followed by histological examination, in case of suspected pathology of the papilla of Futter - RCP, in order to exclude concomitant pathology of the large intestine - sigmoidoscopy.

Only after you are 100% sure that the correct diagnosis has been made can you begin to treat the patient, prescribe medications for pain and other symptoms.

Basic principles of therapy (treatment)

Considering that the treatment of gastroenterological pathology should be carried out by a therapist together with a gastroenterologist, it is not entirely correct to give any specific recommendations in terms of dosages of drug therapy (treatment with tablets and injections, to put it more simply). The most important thing that the patient must remember is that the basis of treatment for most causes of dyspeptic syndrome is nutritional correction and psychological balance, and the elimination of stress factors. Only your attending physician will prescribe medications to you. Taking other drugs is strictly prohibited; self-medication can lead to irreparable consequences.

So we exclude fried, fatty, smoked foods and all fast food from the diet, and switch to four meals a day. More rest and less stress, a positive attitude and strict adherence to all medical prescriptions - such treatment will bring the expected result.

ATTENTION! All information about medicines and folk remedies is posted for informational purposes only. Be carefull! You should not take medications without consulting a doctor. Do not self-medicate - uncontrolled use of drugs leads to complications and side effects. At the first signs of intestinal disease, be sure to consult a doctor!

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12. THIN QUIET

14.7. DIGESTION IN THE SMALL INTESTINE

The general laws of digestion, valid for many species of animals and humans, are the initial digestion of nutrients in an acidic environment in the stomach cavity and their subsequent hydrolysis in a neutral or slightly alkaline environment of the small intestine.

Alkalization of acidic gastric chyme in the duodenum with bile, pancreatic and intestinal juices, on the one hand, stops the action of gastric pepsin, and on the other, creates an optimal pH for pancreatic and intestinal enzymes.

The initial hydrolysis of nutrients in the small intestine is carried out by enzymes of pancreatic and intestinal juices using cavity digestion, and its intermediate and final stages are carried out using parietal digestion.

Nutrients (mainly monomers) formed as a result of digestion in the small intestine are absorbed into the blood and lymph and are used to satisfy the energy and plastic needs of the body.

14.7.1. SECRETORY ACTIVITY OF THE SMALL INTESTINE

The secretory function is carried out by all parts of the small intestines (duodenum, jejunum and ileum).

A. Characteristics of the secretory process. In the proximal part of the duodenum, in its submucosal layer, there are Brunner's glands, which in structure and function are in many ways similar to the pyloric glands of the stomach. The juice of Brunner's glands is a thick, colorless liquid of a slightly alkaline reaction (pH 7.0-8.0), which has slight proteolytic, amylolytic and lipolytic activity. Its main component is mucin, which performs a protective function, covering the mucous membrane of the duodenum with a thick layer. The secretion of Brunner's glands sharply increases under the influence of food intake.

Intestinal crypts, or Lieberkühn's glands, are located in the mucous membrane of the duodenum and the rest of the small intestine. They surround each villi. Not only crypts, but also cells of the entire mucous membrane of the small intestine have secretory activity. These cells have proliferative activity and replenish the rejected epithelial cells at the tips of the villi. Within 24-36 hours they move from the crypts of the mucous membrane to the apex of the villi, where they undergo desquamation (morphonecrotic type of secretion). Entering the cavity of the small intestine, epithelial cells disintegrate and release the enzymes they contain into the surrounding fluid, due to which they participate in cavity digestion. Complete renewal of surface epithelial cells in humans occurs on average within 3 days. Intestinal epithelial cells covering the villus have a striated border on the apical surface formed by microvilli with a glycocalyx, which increases their absorption capacity. On the membranes of microvilli and the glycocalyx there are intestinal enzymes transported from enterocytes, as well as adsorbed from the cavity of the small intestine, which take part in parietal digestion. Goblet cells produce a mucous secretion that has proteolytic activity.

Intestinal secretion includes two independent processes - separation of the liquid and dense parts. The dense part of the intestinal juice is insoluble in water; it is

consists mainly of desquamated epithelial cells. It is the dense part that contains the bulk of the enzymes. Contractions of the intestine promote the desquamation of cells close to the stage of rejection and the formation of lumps from them. Along with this, the small intestine is capable of intensively separating liquid juice.

B. Composition, volume and properties of intestinal juice. Intestinal juice is a product of the activity of the entire mucous membrane of the small intestine and is a cloudy, viscous liquid, including a dense part. A person secretes 2.5 liters of intestinal juice per day.

The liquid part of the intestinal juice, separated from the dense part by centrifugation, consists of water (98%) and dense substances (2%). The dense residue is represented by inorganic and organic substances. The main anions of the liquid part of the intestinal juice are SG and HCO3. A change in the concentration of one of them is accompanied by an opposite shift in the content of the other anion. The concentration of inorganic phosphate in the juice is significantly lower. Among the cations, Na+, K+ and Ca2+ predominate.

The liquid part of the intestinal juice is isoosmotic to the blood plasma. The pH value in the upper part of the small intestine is 7.2-7.5, and with an increase in the rate of secretion it can reach 8.6. The organic substances of the liquid part of the intestinal juice are represented by mucus, proteins, amino acids, urea and lactic acid. The enzyme content in it is low.

The dense part of the intestinal juice is a yellowish-gray mass that looks like mucous lumps, which include decaying epithelial cells, their fragments, leukocytes and mucus produced by goblet cells. Mucus forms a protective layer that protects the intestinal mucosa from excessive mechanical and chemical irritation of the intestinal chyme. The intestinal mucus contains adsorbed enzymes. The dense part of the intestinal juice has significantly greater enzymatic activity than the liquid part. More than 90% of all secreted enterokinase and most of the other intestinal enzymes are contained in the dense part of the juice. The main part of the enzymes is synthesized in the mucous membrane of the small intestine, but some of them enter its cavity from the blood through recretion.

B. Enzymes of the small intestine and their role in digestion. In intestinal secretions and mucous membranes

The lining of the small intestine contains more than 20 enzymes involved in digestion. Most enzymes of intestinal juice carry out the final stages of digestion of nutrients, which began under the action of enzymes of other digestive juices (saliva, gastric and pancreatic juices). In turn, the participation of intestinal enzymes in cavity digestion prepares the initial substrates for parietal digestion.

The intestinal juice contains the same enzymes that are formed in the mucous membrane of the small intestine. However, the activity of enzymes involved in cavity and parietal digestion can vary significantly and depends on their solubility, ability to adsorb and strength of connection with the membranes of enterocyte microvilli. Many enzymes (leucine aminopeptidase, alkaline phosphatase, nuclease, nucleotidase, phospholipase, lipase] synthesized by epithelial cells of the small intestine exhibit their hydrolytic effect first in the area of ​​the brush border of enterocytes (membrane digestion), and then after their rejection and breakdown, the enzymes pass into contents of the small intestine and are involved in cavity digestion. Enterokinase, highly soluble in water, easily passes from desquamated epithelial cells into the liquid part of the intestinal juice, where it exhibits maximum proteolytic activity, ensuring the activation of trypsinogen and, ultimately, all proteases of the pancreatic juice. leucine aminopeptidase is present in the secretions of the small intestine in quantities, which breaks down peptides of various sizes to form amino acids. Intestinal juice contains cathepsins, which hydrolyze proteins in a slightly acidic environment. Alkaline phosphatase hydrolyzes monoesters of orthophosphoric acid. Acid phosphatase has a similar effect in an acidic environment. The secretion of the small intestine contains a nuclease that depolymerizes nucleic acids and a nucleotidase that dephosphorylates mononucleotides. Phospholipase breaks down the phospholipids of the intestinal juice itself. Cholesterol esterase breaks down cholesterol esters in the intestinal cavity and thereby prepares it for absorption. The secretion of the small intestine has weak lipolytic and amylolytic activity.

The main part of intestinal enzymes takes part in parietal digestion. Formed as a result of cavity

Digestion under the influence of os-amylase of pancreatic juice, the products of carbohydrate hydrolysis undergo further breakdown by intestinal oligosaccharidases and disaccharidases on the membranes of the brush border of enterocytes. Enzymes that carry out the final stage of carbohydrate hydrolysis are synthesized directly in intestinal cells, localized and firmly fixed on the membranes of enterocyte microvilli. The activity of membrane-bound enzymes is extremely high, so the limiting link in the absorption of carbohydrates is not their breakdown, but the absorption of monosaccharides.

In the small intestine, the hydrolysis of peptides under the action of aminopeptidase and dipeptidase continues and ends on the membranes of the brush border of enterocytes, resulting in the formation of amino acids that enter the blood of the portal vein.

Parietal hydrolysis of lipids is carried out by intestinal monoglyceride lipase.

The enzyme spectrum of the mucous membrane of the small intestine and intestinal juice changes under the influence of diet to a lesser extent than that of the stomach and pancreas. In particular, the formation of lipase in the intestinal mucosa does not change with either increased or decreased fat content in food.

14.7.2. REGULATION OF INTESTINAL SECRETION

Eating inhibits the secretion of intestinal juice. At the same time, the separation of both the liquid and dense parts of the juice is reduced without changing the concentration of enzymes in it. This reaction of the secretory apparatus of the small intestine to food intake is biologically expedient, since it eliminates the loss of intestinal juice, including enzymes, until the chyme enters this part of the intestine. In this regard, in the process of evolution, regulatory mechanisms have been developed that ensure the separation of intestinal juice in response to local irritation of the mucous membrane of the small intestine during its direct contact with the intestinal chyme.

Inhibition of the secretory function of the small intestine during food intake is due to the inhibitory effects of the central nervous system, which reduce the response of the glandular apparatus to the action of humoral and local stimulating factors. An exception is the secretion of the Brunner's glands of the duodenum, which increases during the act of eating.

Stimulation of the vagus nerves enhances the secretion of enzymes in intestinal juice, but does not affect the amount of juice secreted. Cholinomimetic substances have a stimulating effect on intestinal secretion, and sympathomimetic substances have an inhibitory effect.

In the regulation of intestinal secretion, local mechanisms play a leading role. Local mechanical irritation of the mucous membrane of the small intestine causes an increase in the separation of the liquid part of the juice, not accompanied by a change in the content of enzymes in it. Natural chemical stimulators of secretion of the small intestine are products of the digestion of proteins, fats, and pancreatic juice. Local exposure to the products of digestion of nutrients causes the separation of intestinal juice rich in enzymes.

The hormones enterocrinin and duocrinin, produced in the mucous membrane of the small intestine, stimulate the secretion of the Lieberkühn and Brunner glands, respectively. They enhance intestinal secretion of GIP, VIP, and motilin, while somatostatin has an inhibitory effect on it.

Hormones of the adrenal cortex (cortisone and deoxycorticosterone) stimulate the secretion of adaptable intestinal enzymes, promoting a more complete implementation of nervous influences that regulate the intensity of production and the ratio of various enzymes in the composition of intestinal juice.

14.7.3. CAVITY AND WALL DIGESTION IN THE SMALL INTESTINE

Cavity digestion occurs in all parts of the digestive tract. As a result of cavity digestion in the stomach, up to 50% of carbohydrates and up to 10% of proteins undergo partial hydrolysis. The resulting maltose and polypeptides in the gastric chyme enter the duodenum. Together with them, carbohydrates, proteins and fats that are not hydrolyzed in the stomach are evacuated.

The entry into the small intestine of bile, pancreatic and intestinal juices, containing a full range of enzymes (carbohydrases, proteases and lipases) necessary for the hydrolysis of carbohydrates, proteins and fats, ensures high efficiency and reliability of cavity digestion at optimal pH values ​​of the intestinal contents throughout the small intestine (about 4 m). By-

Lost digestion in the small intestine occurs both in the liquid phase of the intestinal chyme and at the phase boundary: on the surface of food particles, rejected epithelial cells and flocculi (flakes) formed by the interaction of acidic gastric chyme and alkaline duodenal contents. Cavitary digestion ensures the hydrolysis of various substrates, including large molecules and supramolecular aggregates, resulting in the formation of mainly oligomers.

Parietal digestion successively occurs in the layer of mucous membranes, the glycocalyx and on the apical membranes of enterocytes.

Pancreatic and intestinal enzymes, adsorbed from the cavity of the small intestine by the layer of intestinal mucus and glycocalyx, implement mainly the intermediate stages of hydrolysis of nutrients. The oligomers formed as a result of cavity digestion pass through the layer of mucous membranes and the glycocalyx zone, where they undergo partial hydrolytic cleavage. The products of hydrolysis arrive at the apical membranes of enterocytes, into which intestinal enzymes are built in, carrying out membrane digestion itself - the hydrolysis of dimers to the stage of monomers.

Membrane digestion occurs on the surface of the brush border of the epithelium of the small intestine. It is carried out by enzymes fixed on the membranes of the microvilli of enterocytes - at the border separating the extracellular environment from the intracellular one. Enzymes synthesized by intestinal cells are transferred to the surface of microvilli membranes (oligo- and disaccharidases, peptidases, monoglyceride lipase, phosphatases). The active centers of enzymes are oriented in a certain way towards the surface of the membranes and the intestinal cavity, which is a characteristic feature of membrane digestion. Membrane digestion is ineffective for large molecules, but is a very effective mechanism for breaking down small molecules. With the help of membrane digestion, up to 80-90% of peptide and glycosidic bonds are hydrolyzed.

Hydrolysis on the membrane - at the border of intestinal cells and chyme - occurs on a huge surface with submicroscopic porosity. Microvilli on the surface of the intestine turn it into a porous catalyst.

Intestinal enzymes themselves are located on the membranes of enterocytes in close proximity to the transport systems responsible for absorption processes, which ensures the coupling of the final stage of digestion of nutrients and the initial stage of absorption of monomers.

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GIT MICROFLORA

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Normal microflora (normoflora) of the gastrointestinal tract is a necessary condition for the life of the body. The microflora of the gastrointestinal tract in the modern understanding is considered as the human microbiome...

Normal flora (microflora in a normal state) or Normal state of microflora (eubiosis) is a qualitative and quantitative ratio of diverse populations of microbes in individual organs and systems, maintaining the biochemical, metabolic and immunological balance necessary to maintain human health. The most important function of microflora is its participation in the formation of the body's resistance to various diseases and ensuring the prevention of colonization of the human body by foreign microorganisms.

In any microbiocenosis, including intestinal, there are always permanently living species of microorganisms related to the so-called. obligate microflora (synonyms: main, autochthonous, indigenous, resident, obligate microflora) - 90%, as well as additional (accompanying or facultative microflora) - about 10% and transient (random species, allochthonous, residual microflora) - 0.01%

Those. the entire intestinal microflora is divided into:

• obligate - the main or obligatory microflora. The permanent microflora includes anaerobes: bifidobacteria, propionibacteria, bacteroides, peptostreptococci and aerobes: lactobacilli, enterococci, Escherichia coli, which make up about 90% of the total number of microorganisms;
• facultative - accompanying or additional microflora: saprophytic and opportunistic microflora. Represented by saprophytes (peptococci, staphylococci, streptococci, bacilli, yeast fungi) and aero- and anaerobic bacilli. Opportunistic enterobacteria include representatives of the family of intestinal bacteria: Klebsiella, Proteus, Citrobacter, Enterobacter, etc. They make up about 10% of the total number of microorganisms;
• residual (including transient) - random microorganisms, less than 1% of the total number of microorganisms.

The stomach contains little microflora, much more in the small intestine and especially much in the large intestine. It is worth noting that the absorption of fat-soluble substances, the most important vitamins and microelements occurs mainly in the jejunum. Therefore, the systematic inclusion in the diet of probiotic products and dietary supplements, which contain microorganisms that regulate intestinal absorption processes, becomes a very effective tool in the prevention and treatment of nutritional diseases.

Intestinal absorption 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 most intensive absorption occurs in the small intestine. Due to the fact that small arteries branching into capillaries penetrate into each intestinal villi, absorbed nutrients easily penetrate into the body fluids. Glucose and proteins broken down into amino acids are absorbed into the blood mediocre. Blood carrying glucose and amino acids is sent to the liver, where carbohydrates are deposited. Fatty acids and glycerol - a product of fat processing under the influence of bile - are absorbed into the lymph and from there enter the circulatory system.

In the figure on the left (diagram of the structure of the villi of the small intestine): 1 - cylindrical epithelium, 2 - central lymphatic vessel, 3 - capillary network, 4 - mucous membrane, 5 - submucous membrane, 6 - muscular plate of the mucous membrane, 7 - intestinal gland, 8 - lymphatic channel.

One of the significance of the microflora of the large intestine is that it is involved in the final decomposition of undigested food residues. 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. Absorption of water, mineral salts (electrolytes), breakdown of plant fiber, and formation of feces occurs.

Microflora plays a significant (!) role in peristalsis, secretion, absorption and cellular composition of the intestine. 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 body. Bacterial enzymes break down fiber fibers that are undigested in the small intestine. Intestinal flora synthesizes vitamin K and B vitamins, a number of essential amino acids and enzymes necessary for the body. With the participation of microflora in the body, the exchange of proteins, fats, carbons, bile and fatty acids, cholesterol occurs, procarcinogens (substances that can cause cancer) are inactivated, excess food is utilized and feces are formed. The role of normal flora is extremely important for the host organism, which is why its disruption (dysbacteriosis) and the development of dysbiosis in general leads to serious diseases of a metabolic and immunological nature.

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 antibiotics. Many gastrointestinal diseases, including inflammatory diseases, can also disrupt the intestinal ecosystem. The result of this imbalance is common digestive problems: bloating, indigestion, constipation or diarrhea, etc.

See additionally:

COMPOSITION OF NORMAL MICROFLORA

The intestinal microflora is an incredibly complex ecosystem. One individual has at least 17 families of bacteria, 50 genera, 400-500 species and an indefinite 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 opportunistic, i.e. capable of causing diseases when reduced resistance of the macroorganism). The dominant representatives of obligate microflora are bifidobacteria.

BARRIER ACTION AND IMMUNE PROTECTION

It is difficult to overestimate the importance of microflora for the body. Thanks to the achievements of modern science, it is known that normal intestinal microflora takes part in the breakdown of proteins, fats and carbohydrates, creates conditions for optimal digestion and absorption processes in the intestine, takes part in the maturation of cells of the immune system, which ensures enhanced protective properties of the body, etc. . The two most important functions of normal microflora are: barrier against pathogenic agents and stimulation of the immune response:

BARRIER ACTION. Intestinal microflora has a suppressive effect on the proliferation of pathogenic bacteria and thus prevents pathogenic infections.

The process of attachment of microorganisms to epithelial cells involves complex mechanisms. Bacteria of the intestinal microflora suppress or reduce the adhesion of pathogenic agents through competitive exclusion.

For example, bacteria of the parietal (mucosal) microflora occupy certain receptors on the surface of epithelial cells. Pathogenic bacteria that could bind to the same receptors are eliminated from the intestines. Thus, microflora bacteria prevent the penetration of pathogenic and conditionally pathogenic microbes into the mucous membrane. Also, permanent microflora bacteria help maintain intestinal motility and the integrity of the intestinal mucosa. It should be noted that propionic acid bacteria have fairly good adhesive properties and attach to intestinal cells very reliably, creating the aforementioned protective barrier...

IMMUNE INTESTINAL SYSTEM. More than 70% of immune cells are concentrated in the human intestine. The main function of the intestinal immune system is to protect against bacteria entering the blood. The second function is the elimination of pathogens (pathogenic bacteria). This is ensured by two mechanisms: congenital (inherited by the child from the mother; people have antibodies in their blood from birth) 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 defense is stimulated. Intestinal microflora influence specific accumulations of lymphoid tissue. Due to this, the cellular and humoral immune response is stimulated. Cells of the intestinal immune system actively produce immunolobulin A, a protein that is involved in providing 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 intestines, not only an excessive growth of pathogenic microbes is observed, but also a general decrease in the body’s immune defense. Normal intestinal microflora plays a particularly important role in the life 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 in the figure Left: Colony of acidophilus bacillus (x 1100), Right: Destruction of Shigella flexneri (a) (Shigella flexneri is a type of bacteria that causes dysentery) under the influence of bacteriocin-producing cells of acidophilus bacillus (x 60000)

See also: Functions of normal intestinal microflora

HISTORY OF STUDYING THE COMPOSITION OF GIT MICROFLORA

The history of studying the composition of the microflora of the gastrointestinal tract (GIT) began in 1681, when the Dutch researcher Antonie Van Leeuwenhoek first reported his observations of bacteria and other microorganisms found in human feces, and hypothesized the coexistence of various types of bacteria in the gastrointestinal tract. -intestinal tract.

In 1850, Louis Pasteur developed the concept of the functional role of bacteria in the fermentation process, and the German physician Robert Koch continued research in this direction and created a technique for isolating pure cultures that allows the identification of specific bacterial strains, which is necessary to distinguish between pathogenic and beneficial microorganisms.

In 1886, one of the founders of the doctrine of intestinal infections, F. Esherich, first described Escherichia coli (Bacterium coli communae). Ilya Ilyich Mechnikov in 1888, working at the Louis Pasteur Institute, argued that the human intestine contains 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 action of 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 20th century.

In 1955 Peretz L.G. showed that E. coli in healthy people is one of the main representatives of normal microflora and plays a positive role due to its strong antagonistic properties against pathogenic microbes. Research on the composition of the intestinal microbiocenosis, its normal and pathological physiology, and the development of ways to positively influence the intestinal microflora, begun more than 300 years ago, continues to this day.

HUMAN AS A HABITAT FOR BACTERIA

The main biotopes are: gastrointestinal tract (oral cavity, stomach, small intestine, large intestine), skin, respiratory tract, urogenital system. But the main interest for us here is the organs of the digestive system, because... the bulk of various microorganisms live there.

The microflora of the gastrointestinal tract is the most representative; the mass of the intestinal microflora in an adult is more than 2.5 kg, and its number is up to 1014 CFU/g. Previously, it was believed that the microbiocenosis of the gastrointestinal tract includes 17 families, 45 genera, more than 500 species of microorganisms (the latest data - about 1500 species) are constantly being adjusted.

Taking into account new data obtained from studying the microflora of various gastrointestinal biotopes using molecular genetic methods and gas-liquid chromatography-mass spectrometry, the total genome of gastrointestinal bacteria contains 400 thousand genes, which is 12 times the size of the human genome.

The parietal (mucosal) microflora of 400 different parts of the gastrointestinal tract, obtained during endoscopic examination of various parts of the intestines of volunteers, was analyzed for homology of sequenced 16S rRNA genes.

As a result of the study, it was shown that the parietal and luminal microflora includes 395 phylogenetically distinct groups of microorganisms, of which 244 are completely new. Moreover, 80% of new taxa identified during molecular genetic research belong to uncultivated microorganisms. Most of the putative new phylotypes of microorganisms are representatives of the genera Firmicutes and Bacteroides. The total number of species is approaching 1500 and requires further clarification.

The gastrointestinal tract communicates through the sphincter system with the external environment of the world around us and, at the same time, through the intestinal wall, with the internal environment of the body. Thanks to this feature, the gastrointestinal tract has 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 designated as “endotrophic microflora of the human intestinal biotope.” Human endotrophic microflora is divided into three main groups. The first group includes eubiotic indigenous or eubiotic transient microflora that is beneficial to humans; the second - neutral microorganisms that are constantly or periodically sown from the intestines, but do not affect human life; the third group includes pathogenic or potentially pathogenic bacteria (“aggressive populations”).

CAVITY AND WALL MICROBIOTOPE OF THE GASTROINTESTINAL TRACT

In microecological terms, the gastrointestinal biotope can be divided into tiers (oral cavity, stomach, intestinal sections) and microbiotopes (cavity, parietal and epithelial).

The ability to apply in the parietal microbiotope, i.e. Histadhesiveness (the property of being fixed and colonizing tissues) determines the essence of the transient or indigeneity of 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 participate in the creation of colonization resistance of the body, which is a unique mechanism of the anti-infective barrier system.

The cavity microbiotope throughout the gastrointestinal tract is heterogeneous; its properties are determined by the composition and quality of the contents of a particular tier. The tiers have their own anatomical and functional characteristics, so their contents differ in the composition of substances, consistency, pH, speed of movement and other properties. These properties determine the qualitative and quantitative composition of the cavity microbial populations adapted to them.

The parietal microbiotope is the most important structure that limits the internal environment of the body from the external one. It is represented by mucous deposits (mucus gel, mucin gel), a glycocalyx located above the apical membrane of enterocytes and the surface of the apical membrane itself.

The wall microbiotope is of the greatest (!) interest from the point of view of bacteriology, since it is in it that beneficial or harmful interactions with bacteria for humans occur - what we call symbiosis.

It should be noted that in the intestinal microflora there are 2 types:

• mucosal (M) flora - mucosal microflora interacts with the mucous membrane of the gastrointestinal tract, forming a microbial-tissue complex - microcolonies of bacteria and their metabolites, epithelial cells, goblet cell mucin, fibroblasts, immune cells of Peyre's patches, phagocytes, leukocytes, lymphocytes, neuroendocrine cells;
• luminal (L) flora - luminal microflora is located in the lumen of the gastrointestinal tract and does not interact with the mucous membrane. The substrate for its life activity is indigestible dietary fiber, on which it is fixed.

Today it is known that the microflora of the intestinal mucosa is significantly different from the microflora of the intestinal lumen and feces. Although every adult's intestine is inhabited by a certain combination of predominant bacterial species, the composition of the microflora can change depending on lifestyle, diet and age. A comparative study of the microflora in adults who are genetically related to one degree or another revealed that the composition of the intestinal microflora is influenced more by genetic factors than by nutrition.

Mucosal microflora is more resistant to external influences than luminal microflora. The relationship between mucosal and luminal microflora is dynamic and determined by many factors:

Endogenous factors - the influence of the mucous membrane of the digestive canal, its secretions, motility and the microorganisms themselves; exogenous factors - influence directly and indirectly through endogenous factors, for example, the intake of one or another food changes the secretory and motor activity of the digestive tract, which transforms its microflora.

MICROFLORA OF THE ORAL CAVITY, ESOPHAGUS AND STOMACH

Let's consider the compositions of normal microflora of different parts of the gastrointestinal tract.

The oral cavity and pharynx carry out preliminary mechanical and chemical processing of food and assess the bacteriological danger of bacteria penetrating into the human body.

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, and a large number of anaerobes. In total, the oral microflora includes more than 200 types of microorganisms.

On the surface of the mucosa, depending on the hygiene products used by the individual, about 103–105 MK/mm2 is detected. 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 histadhesis, inhibit the colonization of the mouth by fungi of the genus Candida and staphylococci.

The microflora transiently passing through the esophagus is unstable, does not show histadhesiveness to its walls and is characterized by an abundance of temporarily present species that enter from the oral cavity and pharynx. Relatively unfavorable conditions for bacteria are created in the stomach due to increased acidity, the influence of proteolytic enzymes, the rapid motor-evacuation function of the stomach and other factors that limit their growth and reproduction. Here microorganisms are contained in quantities not exceeding 102–104 per 1 ml of content. Eubiotics in the stomach primarily colonize the cavity biotope; the wall microbiotope is less accessible to them.

The main microorganisms active in the gastric environment are acid-fast representatives of the genus Lactobacillus, with or without a histagesive relationship to mucin, some types of soil bacteria and bifidobacteria. Lactobacilli, despite their short residence time in the stomach, are capable, in addition to their antibiotic effect in the gastric cavity, of temporarily colonizing the parietal microbiotope. As a result of the combined action of the protective components, the bulk of microorganisms that enter the stomach die. However, if the functioning of the mucous and immunobiological components is disrupted, some bacteria find their biotope in the stomach. Thus, due to pathogenicity factors, the Helicobacter pylori population is established in the gastric cavity.

A little about stomach acidity: The maximum theoretically possible acidity in the stomach is 0.86 pH. The minimum theoretically possible acidity in the stomach is 8.3 pH. Normal acidity in the lumen of the body of the stomach on an empty stomach is 1.5–2.0 pH. The acidity on the surface of the epithelial layer facing the lumen of the stomach is 1.5–2.0 pH. The acidity in the depths of the epithelial layer of the stomach is about 7.0 pH.

MAIN FUNCTIONS OF THE SMALL INTESTINE

The small intestine is a tube about 6 m long. It occupies almost the entire lower part of the abdominal cavity and is the longest part of the digestive system, connecting the stomach with the large intestine. Most of the food is already digested in the small intestine with the help of special substances - enzymes.

The main functions of the small intestine include cavity and parietal hydrolysis of food, absorption, secretion, and barrier protection. In the latter, in addition to chemical, enzymatic and mechanical factors, the indigenous microflora of the small intestine plays a significant role. It takes an active part in cavity and wall hydrolysis, as well as in the processes of absorption of nutrients. The small intestine is one of the most important links ensuring the long-term preservation of eubiotic parietal microflora.

There is a difference in the colonization of cavity and parietal microbiotopes by eubiotic microflora, as well as 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, while the wall microbiotope has a relatively stable homeostasis. In the thickness of the mucous deposits, populations with histaghesive properties to mucin are preserved.

The proximal small intestine normally contains relatively small amounts of gram-positive flora, consisting mainly of lactobacilli, streptococci and fungi. The concentration of microorganisms is 102–104 per 1 ml of intestinal contents. As we approach the distal parts of the small intestine, the total number of bacteria increases to 108 per 1 ml of contents, and at the same time additional species appear, including enterobacteria, bacteroides, and bifidobacteria.

BASIC FUNCTIONS OF THE LARGE INTESTINE

The main functions of the large intestine are the reserve and evacuation of chyme, residual digestion of food, excretion and absorption of water, absorption of some metabolites, residual nutrient substrate, electrolytes and gases, formation and detoxification of feces, regulation of their excretion, maintenance of barrier protective mechanisms.

All of the above functions are performed with the participation of intestinal eubiotic microorganisms. The number of colon microorganisms is 1010–1012 CFU per 1 ml of contents. Bacteria account for up to 60% of feces. Throughout the life of a healthy person, anaerobic species of bacteria predominate (90–95% of the total composition): bifidobacteria, bacteroides, lactobacilli, fusobacteria, eubacteria, veillonella, peptostreptococci, clostridia. From 5 to 10% of the colon microflora are aerobic microorganisms: Escherichia, Enterococcus, Staphylococcus, various types of opportunistic Enterobacteriaceae (Proteus, Enterobacter, Citrobacter, Serration, etc.), non-fermenting bacteria (Pseudomonas, Acinetobacter), yeast-like fungi of the genus Candida and etc.

Analyzing the species composition of the colon microbiota, it is necessary to emphasize that, in addition to the indicated anaerobic and aerobic microorganisms, its composition includes representatives of non-pathogenic protozoan genera and about 10 intestinal viruses. Thus, in healthy individuals, there are about 500 species of various microorganisms in the intestines, most of which are representatives of the so-called obligate microflora - bifidobacteria, lactobacilli, non-pathogenic Escherichia coli, etc. 92-95% of the intestinal microflora consists of obligate anaerobes.

1. Predominant bacteria. Due to anaerobic conditions in a healthy person, the normal microflora in the large intestine is dominated (about 97%) by anaerobic bacteria: bacteroides (especially Bacteroides fragilis), anaerobic lactic acid bacteria (for example, Bifidumbacterium), clostridia (Clostridium perfringens), anaerobic streptococci, fusobacteria , eubacteria, veillonella.

2. A small part of the microflora consists of aerobic and facultative anaerobic microorganisms: gram-negative coliform bacteria (primarily Escherichia coli - E.Coli), enterococci.

3. In very small quantities: staphylococci, Proteus, pseudomonads, fungi of the genus Candida, certain types of spirochetes, mycobacteria, mycoplasmas, protozoa and viruses

The qualitative and quantitative COMPOSITION of the main microflora of the large intestine in healthy people (CFU/g feces) varies depending on their age group.

The figure shows the characteristics of the growth and enzymatic activity of bacteria in the proximal and distal parts of the large intestine under different conditions of molarity, mM (molar concentration) of short-chain fatty acids (SCFA) and pH value, pH (acidity) of the medium.

“The number of floors of bacterial settlement”

For a better understanding of the topic, we will give brief definitions of the concepts of what aerobes and anaerobes are.

Anaerobes are organisms (including microorganisms) that obtain energy in the absence of oxygen by substrate phosphorylation; the final products of incomplete oxidation of the substrate can be oxidized to produce more energy in the form of ATP in the presence of the final proton acceptor by organisms performing oxidative phosphorylation .

Facultative (conditional) anaerobes are organisms whose energy cycles follow an anaerobic path, but are able to exist with the access of oxygen (i.e., they grow in both anaerobic and aerobic conditions), in contrast to obligate anaerobes, for which oxygen is destructive .

Obligate (strict) anaerobes are organisms that live and grow only in the absence of molecular oxygen in the environment; it is destructive for them.

Aerobes (from the Greek aer - air and bios - life) are organisms that have an aerobic type of respiration, that is, the ability to live and develop only in the presence of free oxygen, and growing, as a rule, on the surface of nutrient media.

Anaerobes include almost all animals and plants, as well as a large group of microorganisms that exist due to the energy released during oxidation reactions that occur with the absorption of free oxygen.

Based on the ratio of aerobes to oxygen, they are divided into obligate (strict), or aerophiles, which cannot develop in the absence of free oxygen, and facultative (conditional), capable of developing at low oxygen levels in the environment.

It should be noted that bifidobacteria, as the most strict anaerobes, colonize the zone closest to the epithelium, where a negative redox potential is always maintained (not only in the colon, but also in other, more aerobic biotopes of the body: in the oropharynx, vagina, on the skin covers). Propionic acid bacteria are less strict anaerobes, i.e. facultative anaerobes and can only tolerate low partial pressures of oxygen.

Two biotopes differing in anatomical, physiological and environmental characteristics - the small and large intestines - are separated by an effectively functioning barrier: the baugin valve, which opens and closes, allowing the contents of the intestine to pass through only in one direction, and keeps the contamination of the intestinal tube in the quantities necessary for a healthy body.

As the contents move inside the intestinal tube, the partial pressure of oxygen decreases and the pH value of the environment increases, due to which a “STAGE” of vertical settlement of various types of bacteria appears: aerobes are located highest, facultative anaerobes are located below, and strict anaerobes are even lower.

Thus, although the bacterial content in the mouth can be quite high - up to 106 CFU / ml, it decreases to 0-10 CFU / ml in the stomach, rising to 101-103 CFU / ml in the jejunum and 105-106 CFU / ml in distal parts of the ileum, followed by a sharp increase in the amount of microbiota in the colon, reaching a level of 1012 CFU/ml in its distal parts.

CONCLUSION

The evolution of humans and animals took place in constant contact with the world of microbes, as a result of which close relationships were formed between macro- and microorganisms. The influence of gastrointestinal microflora on maintaining human health, its biochemical, metabolic and immune balance is undoubted and has been proven by a large number of experimental works and clinical observations. Its role in the genesis of many diseases continues to be actively studied (atherosclerosis, obesity, irritable bowel syndrome, nonspecific inflammatory bowel diseases, celiac disease, colorectal cancer, etc.). Therefore, the problem of correcting microflora disorders is, in fact, a problem of preserving human health and creating a healthy lifestyle. Probiotics and probiotic products ensure the restoration of normal intestinal microflora and increase the body's nonspecific resistance.

WE SYSTEMATIZE GENERAL INFORMATION ABOUT THE IMPORTANCE OF NORMAL GIT MICROFLORA FOR HUMANS

GIT MICROFLORA:

• protects the body from toxins, mutagens, carcinogens, free radicals;
• is a biosorbent that accumulates many toxic products: phenols, metals, poisons, xenobiotics, etc.;
• suppresses putrefactive, pathogenic and conditionally pathogenic bacteria, pathogens of intestinal infections;
• inhibits (suppresses) the activity of enzymes involved in the formation of tumors;
• strengthens the body's immune system;
• synthesizes antibiotic-like substances;
• synthesizes vitamins and essential amino acids;
• plays a huge role in the digestion process, as well as in metabolic processes, promotes the absorption of vitamin D, iron and calcium;
• is the main food processor;
• restores the motor and digestive functions of the gastrointestinal tract, prevents flatulence, normalizes peristalsis;

Before moving on, I will repeat questions that, it seems to me, are now not at all difficult to answer thanks to the information about digestion at hand. 1. What determines the need to normalize the pH of the medium (weakly alkaline) of the large intestine? 2. What variants of the acid-base state are possible for the environment of the large intestine? 3. What causes the deviation of the acid-base state of the internal environment of the large intestine from the norm? So, alas and ah, we have to admit that from all that has been said about the digestion of a healthy person, it does not at all follow the need to normalize the pH environment of his large intestine. Such a problem does not exist during normal functioning of the gastrointestinal tract, this is quite obvious. The large intestine in a full state has a moderately acidic environment with a pH of 5.0-7.0, which allows representatives of the normal microflora of the large intestine to actively break down fiber and participate in the synthesis of vitamins E, K, group B (BV) and others biologically active substances. At the same time, the friendly intestinal microflora performs a protective function, carrying out the destruction of facultative and pathogenic microbes that cause rotting. Thus, the normal microflora of the large intestine determines the development of natural immunity in its owner. Let's consider another situation when the large intestine is not filled with intestinal contents. Yes, in this case the reaction of its internal environment will be determined as slightly alkaline, due to the fact that a small volume of slightly alkaline intestinal juice is released into the lumen of the large intestine (approximately 50-60 ml per day with a pH of 8.5-9.0 But even this time there is not the slightest reason to fear putrefactive and fermentative processes, because if there is nothing in the large intestine, then, in fact, there is nothing to rot. Moreover, there is no need to fight such alkalization, because this is the physiological norm of a healthy body. I believe that unjustified actions to acidify the large intestine can bring nothing but harm to a healthy person. Where then does the problem of alkalization of the large intestine come from, which needs to be fought, what is it based on? It seems to me that the whole point is that, unfortunately, this problem is presented as an independent one, whereas, despite its significance, it is only a consequence of the unhealthy functioning of the entire gastrointestinal tract. Therefore, it is necessary to look for the reasons for deviations from the norm not at the level of the large intestine, but much higher - in the stomach, where a full-scale process of preparing food components for absorption takes place. It is the quality of food processing in the stomach that directly determines whether it will subsequently be absorbed by the body or sent undigested to the large intestine for disposal. As you know, hydrochloric acid plays a vital role in the digestion process in the stomach. It stimulates the secretory activity of the gastric glands, promotes the conversion of the proenzyme pepsinogen, which is unable to influence proteins, into the enzyme pepsin; creates an optimal acid-base balance for the action of gastric juice enzymes; causes denaturation, preliminary destruction and swelling of food proteins, ensures their breakdown by enzymes; supports the antibacterial effect of gastric juice, i.e., the destruction of pathogenic and putrefactive microbes. Hydrochloric acid also promotes the passage of food from the stomach to the duodenum and further participates in the regulation of the secretion of the duodenal glands, stimulating their motor activity. Gastric juice quite actively breaks down proteins or, as they say in science, has a proteolytic effect, activating enzymes in a wide pH range from 1.5-2.0 to 3.2-4.0. At optimal acidity of the environment, pepsin has a splitting effect on proteins, breaking peptide bonds in the protein molecule formed by groups of various amino acids. "As a result of this effect, a complex protein molecule breaks down into simpler substances: peptones, peptides and proteases. Pepsin ensures the hydrolysis of the main protein substances included in meat products, and especially collagen, the main component of connective tissue fibers. Under the influence of pepsin, the breakdown of proteins begins. However, in the stomach, splitting reaches only peptides and albumoses - large fragments of the protein molecule. Further splitting of these derivatives of the protein molecule occurs in the small intestine under the action of enzymes of intestinal juice and pancreatic juice. In the small intestine, amino acids formed during the final digestion of proteins dissolve in the intestinal contents and are absorbed into the blood. And it is quite natural that if the body is characterized by any parameter, there will always be people in whom it is either increased or decreased. Deviation towards increase has the prefix “hyper”, and towards decrease - “hypo” "Patients with impaired secretory function of the stomach are no exception in this regard. In this case, a change in the secretory function of the stomach, characterized by an increased level of hydrochloric acid with its excessive secretion - hypersecretion, is called hyperacid gastritis or gastritis with increased acidity of gastric juice. When the opposite is true and less than normal hydrochloric acid is released, we are dealing with hypocidal gastritis or gastritis with low acidity of gastric juice. In the case of a complete absence of hydrochloric acid in the gastric juice, they speak of anacid gastritis or gastritis with zero acidity of the gastric juice. The disease “gastritis” itself is defined as inflammation of the gastric mucosa, in a chronic form accompanied by a restructuring of its structure and progressive atrophy, disruption of the secretory, motor and endocrine (absorptive) functions of the stomach. It must be said that gastritis is much more common than we think. According to statistics, gastritis in one form or another is detected during a gastroenterological examination, i.e. examination of the gastrointestinal tract, in almost every second patient. In the case of hypocidal gastritis, caused by a decrease in the acid-forming function of the stomach and, consequently, the activity of gastric juice and a decrease in the level of its acidity, the food gruel coming from the stomach into the small intestine will no longer be as acidic as with normal acid formation. And then throughout the entire intestine, as shown in the chapter “Basics of the digestive process,” only consistent alkalization is possible. If, with normal acid formation, the acidity level of the contents of the large intestine decreases to a slightly acidic and even neutral reaction, pH 5-7, then in the case of reduced acidity of gastric juice, in the large intestine the reaction of the contents will already be either neutral or slightly alkaline, with a pH of 7-8 . If food gruel, slightly acidified in the stomach and not containing animal proteins, takes on an alkaline reaction in the large intestine, then if it contains animal protein, which is a pronounced alkaline product, the contents of the large intestine become seriously and permanently alkalized. Why for a long time? Because due to the alkaline reaction of the internal environment of the large intestine, its peristalsis is sharply weakened. Let's remember what the environment is like in an empty large intestine? - Alkaline. The opposite statement is also true: if the environment of the large intestine is alkaline, then the large intestine is empty. And if it is empty, a healthy body will not waste energy on peristaltic work, and the large intestine rests. Rest, which is completely natural for a healthy intestine, ends with a change in the chemical reaction of its internal environment to acidic, which in the chemical language of our body means - the large intestine is full, it’s time to work, it’s time to compact, dehydrate and move the formed feces closer to the exit. But when the large intestine is filled with alkaline contents, the large intestine does not receive a chemical signal to stop resting and start working. Moreover, the body still believes that the large intestine is empty, and meanwhile the large intestine continues to fill up and fill up. And this is already serious, since the consequences can be the most severe. The notorious constipation will probably turn out to be the most harmless of them. In the case of a complete absence of free hydrochloric acid in the gastric juice, as occurs with anacid gastritis, the enzyme pepsin is not produced in the stomach at all. The process of digesting animal proteins under such conditions is even theoretically impossible. And then almost all of the eaten animal protein ends up in an undigested form in the large intestine, where the reaction of the feces will be highly alkaline. It becomes quite obvious that the processes of decay simply cannot be avoided. This gloomy forecast is compounded by another sad condition. If at the very beginning of the gastrointestinal tract, due to the lack of hydrochloric acid, there was no antibacterial effect of gastric juice, then pathogenic and putrefactive microbes introduced with food and not destroyed by gastric juice, entering the large intestine on a well-alkalinized “soil”, receive the most favorable conditions for life and begin to multiply rapidly. At the same time, having a pronounced antagonistic activity towards representatives of the normal microflora of the large intestine, pathogenic microbes suppress their vital activity, which leads to disruption of the normal digestion process in the large intestine with all the ensuing consequences. Suffice it to say that the end products of putrefactive bacterial decomposition of proteins are toxic and biologically active substances such as amines, hydrogen sulfide, methane, which have a poisonous effect on the entire human body. The consequence of this abnormal situation is constipation, colitis, enterocolitis, etc. Constipation, in turn, gives rise to hemorrhoids, and hemorrhoids provoke constipation. Considering the putrefactive properties of excrement, it is very possible for various types of tumors to appear in the future, even malignant ones. In order to suppress putrefactive processes under the current circumstances, restore normal microflora and motor function of the large intestine, of course, you need to fight to normalize the pH of its internal environment. And in this case, I perceive cleansing and acidification of the large intestine according to N. Walker’s method with enemas with the addition of lemon juice as a reasonable solution. But at the same time, all this seems to be more cosmetic than a radical means of combating alkalinity of the large intestine, since in itself it in no way can eliminate the root causes of such a disastrous situation in our body.

14.11.2013

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In the small intestine, almost complete breakdown and absorption of food proteins, fats, and carbohydrates into the bloodstream and lymph flow occurs.

From the stomach at 12 p.c. Only chyme can be supplied - food processed to a liquid or semi-liquid consistency.

Digestion at 12 p.c. is carried out in a neutral or alkaline environment (fasting pH 12 b.c. is 7.2-8.0). was carried out in an acidic environment. Therefore, the contents of the stomach are acidic. Neutralization of the acidic environment of gastric contents and the establishment of an alkaline environment is carried out in 12 p.c. due to the secretions (juices) of the pancreas, small intestine and bile entering the intestine, which have an alkaline reaction due to the bicarbonates present in them.

Chyme from the stomach in 12 p.c. comes in small portions. Irritation of the pyloric sphincter receptors from the stomach by hydrochloric acid leads to its opening. Irritation of the pyloric sphincter receptors by hydrochloric acid from the side of the 12th p.c. leads to its closure. As soon as the pH in the pyloric part is 12 p.c. changes in the acidic direction, the pyloric sphincter contracts and the flow of chyme from the stomach into the 12th p.c. stops. After restoring the alkaline pH (on average in 16 seconds), the pyloric sphincter allows the next portion of chyme to pass from the stomach, and so on. At 12 p.m. pH ranges from 4 to 8.

At 12 p.m. after neutralizing the acidic environment of the gastric chyme, the action of pepsin, the enzyme of gastric juice, stops. in the small intestine continues in an alkaline environment under the influence of enzymes that enter the intestinal lumen as part of the secretion (juice) of the pancreas, as well as in the composition of the intestinal secretion (juice) from enterocytes - the cells of the small intestine. Under the influence of pancreatic enzymes, cavity digestion occurs - the breakdown of food proteins, fats and carbohydrates (polymers) into intermediate substances (oligomers) in the intestinal cavity. Under the action of enterocyte enzymes, the parietal (near the inner wall of the intestine) oligomers to monomers is carried out, that is, the final breakdown of food proteins, fats and carbohydrates into constituent components that enter (absorb) into the circulatory and lymphatic systems (into the bloodstream and lymph flow).

For digestion in the small intestine, it is also necessary, which is produced by liver cells (hepatocytes) and enters the small intestine through the bile ducts (bile tract). The main component of bile, bile acids and their salts, are necessary for the emulsification of fats, without which the process of fat breakdown is disrupted and slowed down. The bile ducts are divided into intra- and extrahepatic. The intrahepatic bile ducts (ducts) are a tree-like system of tubes (ducts) through which bile flows from hepatocytes. Small bile ducts are connected to a larger duct, and the collection of larger ducts forms an even larger duct. This union is completed in the right lobe of the liver - the bile duct of the right lobe of the liver, in the left - the bile duct of the left lobe of the liver. The bile duct of the right lobe of the liver is called the right bile duct. The bile duct of the left lobe of the liver is called the left bile duct. These two ducts form the common hepatic duct. At the porta hepatis, the common hepatic duct joins the cystic bile duct, forming the common bile duct, which goes to the 12th p.c. The cystic bile duct drains bile from the gallbladder. The gallbladder is a reservoir for storing bile produced by liver cells. The gallbladder is located on the lower surface of the liver, in the right longitudinal groove.

The secretion (juice) is formed (synthesized) by acinar pancreatic cells (pancreatic cells), which are structurally united into acini. The cells of the acinus form (synthesize) pancreatic juice, which enters the excretory duct of the acinus. Neighboring acini are separated by thin layers of connective tissue in which blood capillaries and nerve fibers of the autonomic nervous system are located. The ducts of neighboring acini merge into interacinous ducts, which, in turn, flow into larger intralobular and interlobular ducts lying in the connective tissue septa. The latter, merging, form a common excretory duct, which runs from the tail of the gland to the head (structurally, the pancreas is divided into the head, body and tail). The excretory duct (Wirsungian duct) of the pancreas, together with the common bile duct, obliquely penetrates the wall of the descending part of the 12th p.c. and opens inside 12 p.c. on the mucous membrane. This place is called the major (Vaterian) papilla. In this place there is the smooth muscle sphincter of Oddi, which also functions on the principle of a nipple - it allows bile and pancreatic juice to pass from the duct into the 12th p.c. and blocks the flow of contents 12 p.c. into the duct. The sphincter of Oddi is a complex sphincter. It consists of the sphincter of the common bile duct, the sphincter of the pancreatic duct (pancreatic duct) and the sphincter of Westphal (sphincter of the major duodenal papilla), which ensures the separation of both ducts from the 12 p.c.. Sometimes 2 cm above the major papilla there is a small papilla - formed accessory, non-permanent small (Santorini) pancreatic duct. The Helly sphincter is located in this location.

Pancreatic juice is a colorless transparent liquid that has an alkaline reaction (pH 7.5-8.8) due to the content of bicarbonates. Pancreatic juice contains enzymes (amylase, lipase, nuclease and others) and proenzymes (trypsinogen, chymotrypsinogen, procarboxypeptidases A and B, proelastase and prophospholipase and others). Proenzymes are the inactive form of an enzyme. Activation of pancreatic proenzymes (conversion into their active form - enzyme) occurs in 12 p.c.

Epithelial cells 12 p.c. – enterocytes synthesize and release the enzyme kinasegen (proenzyme) into the intestinal lumen. Under the influence of bile acids, kinaseogen is converted into enteropeptidase (enzyme). Enterokinase cleaves hecosopeptide from trypsinogen, resulting in the formation of the enzyme trypsin. To implement this process (to convert the inactive form of the enzyme (trypsinogen) into the active one (trypsin)), an alkaline environment (pH 6.8-8.0) and the presence of calcium ions (Ca2+) are required. The subsequent conversion of trypsinogen into trypsin occurs in 12 p.c. under the influence of the resulting trypsin. In addition, trypsin activates other pancreatic enzymes. The interaction of trypsin with proenzymes leads to the formation of enzymes (chymotrypsin, carboxypeptidases A and B, elastases and phospholipases, and others). Trypsin exhibits its optimal effect in a slightly alkaline environment (at pH 7.8-8).

The enzymes trypsin and chymotrypsin break down food proteins into oligopeptides. Oligopeptides are an intermediate product of protein breakdown. Trypsin, chymotrypsin, and elastase destroy intrapeptide bonds of proteins (peptides), as a result of which high-molecular-weight (containing many amino acids) proteins break down into low-molecular-weight (oligopeptides).

Nucleases (DNAases, RNases) break down nucleic acids (DNA, RNA) into nucleotides. Nucleotides under the action of alkaline phosphatases and nucleotidases are converted into nucleosides, which are absorbed from the digestive system into the blood and lymph.

Pancreatic lipase breaks down fats, mainly triglycerides, into monoglycerides and fatty acids. Phospholipase A2 and esterase also act on lipids.

Since dietary fats are insoluble in water, lipase acts only on the surface of the fat. The larger the contact surface between fat and lipase, the more active the breakdown of fat by lipases occurs. The fat emulsification process increases the contact surface between fat and lipase. As a result of emulsification, the fat is broken into many small droplets ranging in size from 0.2 to 5 microns. Emulsification of fats begins in the oral cavity as a result of grinding (chewing) food and wetting it with saliva, then continues in the stomach under the influence of gastric peristalsis (mixing food in the stomach) and the final (main) emulsification of fats occurs in the small intestine under the influence of bile acids and their salts. In addition, fatty acids formed as a result of the breakdown of triglycerides react with alkalis in the small intestine, which leads to the formation of soap, which further emulsifies fats. With a lack of bile acids and their salts, insufficient emulsification of fats occurs, and, accordingly, their breakdown and absorption. Fats are removed with feces. In this case, the feces become greasy, mushy, white or gray. This condition is called steatorrhea. Bile suppresses the growth of putrefactive microflora. Therefore, with insufficient formation and entry of bile into the intestines, putrefactive dyspepsia develops. With putrefactive dyspepsia, diarrhea = diarrhea occurs (feces are dark brown in color, liquid or mushy with a sharp putrefactive odor, foamy (with gas bubbles). Decay products (dimethyl mercaptan, hydrogen sulfide, indole, skatole and others) worsen general health (weakness, loss of appetite , malaise, chilling, headache).

The activity of lipase is directly proportional to the presence of calcium ions (Ca2+), bile salts, and the colipase enzyme. Under the action of lipases, triglycerides are usually incompletely hydrolyzed; this produces a mixture of monoglycerides (about 50%), fatty acids and glycerol (40%), di- and triglycerides (3-10%).

Glycerol and short fatty acids (containing up to 10 carbon atoms) are independently absorbed from the intestines into the blood. Fatty acids containing more than 10 carbon atoms, free cholesterol, and monoacylglycerols are water-insoluble (hydrophobic) and cannot pass from the intestine into the blood on their own. This becomes possible after they combine with bile acids to form complex compounds called micelles. The size of the micelle is very small - about 100 nm in diameter. The core of the micelles is hydrophobic (repels water), and the shell is hydrophilic. Bile acids serve as a conductor for fatty acids from the cavity of the small intestine to enterocytes (cells of the small intestine). At the surface of enterocytes, micelles disintegrate. Fatty acids, free cholesterol, and monoacylglycerols enter the enterocyte. The absorption of fat-soluble vitamins is interconnected with this process. Parasympathetic autonomic nervous system, hormones of the adrenal cortex, thyroid gland, pituitary gland, hormones 12 p.k. secretin and cholecystokinin (CCK) increase absorption, the sympathetic autonomic nervous system reduces absorption. The released bile acids, reaching the large intestine, are absorbed into the blood, mainly in the ileum, and are then absorbed (removed) from the blood by liver cells (hepatocytes). In enterocytes, with the participation of intracellular enzymes, phospholipids, triacylglycerols (TAG, triglycerides (fats) - a compound of glycerol (glycerol) with three fatty acids), cholesterol esters (a compound of free cholesterol with a fatty acid) are formed from fatty acids. Further, complex compounds with protein are formed from these substances in enterocytes - lipoproteins, mainly chylomicrons (CM) and in smaller quantities - high-density lipoproteins (HDL). HDL from enterocytes enters the bloodstream. ChMs are large in size and therefore cannot enter directly from the enterocyte into the circulatory system. From enterocytes, chemical substances enter the lymph, the lymphatic system. From the thoracic lymphatic duct, chemical substances enter the circulatory system.

Pancreatic amylase (α-Amylase) breaks down polysaccharides (carbohydrates) into oligosaccharides. Oligosaccharides are an intermediate product of the breakdown of polysaccharides consisting of several monosaccharides connected by intermolecular bonds. Among the oligosaccharides formed from food polysaccharides under the action of pancreatic amylase, disaccharides consisting of two monosaccharides and trisaccharides consisting of three monosaccharides predominate. α-Amylase exhibits its optimal action in a neutral environment (at pH 6.7-7.0).

Depending on the food consumed, the pancreas produces different amounts of enzymes. For example, if you eat only fatty foods, the pancreas will produce primarily an enzyme for digesting fats - lipase. In this case, the production of other enzymes will be significantly reduced. If there is only bread, then the pancreas will produce enzymes that break down carbohydrates. You should not overuse a monotonous diet, as a constant imbalance in the production of enzymes can lead to diseases.

Epithelial cells of the small intestine (enterocytes) secrete a secretion into the intestinal lumen, which is called intestinal juice. Intestinal juice has an alkaline reaction due to the content of bicarbonates in it. The pH of intestinal juice ranges from 7.2 to 8.6 and contains enzymes, mucus, other substances, as well as aged rejected enterocytes. In the mucous membrane of the small intestine, a continuous change in the layer of surface epithelial cells occurs. Complete renewal of these cells in humans occurs in 1-6 days. This intensity of formation and rejection of cells causes a large number of them in the intestinal juice (in a person, about 250 g of enterocytes are rejected per day).

Mucus synthesized by enterocytes forms a protective layer that prevents excessive mechanical and chemical effects of chyme on the intestinal mucosa.

Intestinal juice contains more than 20 different enzymes that take part in digestion. The main part of these enzymes takes part in parietal digestion, that is, directly at the surface of the villi, microvilli of the small intestine - in the glycocalyx. The glycocalyx is a molecular sieve that allows molecules to pass through to the intestinal epithelial cells, depending on their size, charge and other parameters. The glycocalyx contains enzymes from the intestinal cavity and synthesized by the enterocytes themselves. In the glycalyx, the final breakdown of intermediate products of the breakdown of proteins, fats and carbohydrates into their constituent components (oligomers to monomers) occurs. The glycocalyx, microvilli and apical membrane are collectively called the striated border.

Carbohydrases in intestinal juice consist mainly of disaccharidases, which break down disaccharides (carbohydrates consisting of two molecules of monosaccharides) into two molecules of monosaccharides. Sucrase breaks down the sucrose molecule into glucose and fructose molecules. Maltase breaks down the maltose molecule, and trehalase breaks down trehalose into two glucose molecules. Lactase (α-galactasidase) breaks down the lactose molecule into a molecule of glucose and galactose. A deficiency in the synthesis of one or another disaccharidase by the cells of the mucous membrane of the small intestine causes intolerance to the corresponding disaccharide. Genetically fixed and acquired lactase, trehalase, sucrase and combined disaccharidase deficiencies are known.

Intestinal juice peptidases cleave the peptide bond between two specific amino acids. Peptidases in intestinal juice complete the hydrolysis of oligopeptides, resulting in the formation of amino acids - the end products of the breakdown (hydrolysis) of proteins that enter (absorb) from the small intestine into the blood and lymph.

Nucleases (DNAases, RNases) of intestinal juice break down DNA and RNA into nucleotides. Nucleotides under the action of alkaline phosphatases and nucleotidases of intestinal juice are converted into nucleosides, which are absorbed from the small intestine into the blood and lymph.

The main lipase in intestinal juice is intestinal monoglyceride lipase. It hydrolyzes monoglycerides of any hydrocarbon chain length, as well as short-chain di- and triglycerides, and to a lesser extent medium-chain triglycerides and cholesteryl esters.

The secretion of pancreatic juice, intestinal juice, bile, and motor activity (peristalsis) of the small intestine is controlled by neurohumoral (hormonal) mechanisms. Control is carried out by the autonomic nervous system (ANS) and hormones that are synthesized by the cells of the gastroenteropancreatic endocrine system - part of the diffuse endocrine system.

In accordance with the functional characteristics of the ANS, the parasympathetic ANS and the sympathetic ANS are distinguished. Both of these departments of the ANS exercise control.

Which exercise control, come into a state of excitement under the influence of impulses that come to them from the receptors of the mouth, nose, stomach, small intestine, as well as from the cerebral cortex (thoughts, conversations about food, type of food, etc.). In response to impulses arriving at them, excited neurons send impulses along efferent nerve fibers to controlled cells. Near the cells, the axons of efferent neurons form numerous branches ending in tissue synapses. When a neuron is excited, a mediator is released from the tissue synapse - a substance with which the excited neuron influences the function of the cells it controls. The mediator of the parasympathetic autonomic nervous system is acetylcholine. The mediator of the sympathetic autonomic nervous system is norepinephrine.

Under the influence of acetylcholine (parasympathetic VNS), there is an increase in the secretion of intestinal juice, pancreatic juice, bile, and increased peristalsis (motor function) of the small intestine and gall bladder. Efferent parasympathetic nerve fibers approach the small intestine, pancreas, liver cells, and bile ducts as part of the vagus nerve. Acetylcholine exerts its effect on cells through M-cholinergic receptors located on the surface (membranes, membranes) of these cells.

Under the influence of norepinephrine (sympathetic ANS), peristalsis of the small intestine decreases, the formation of intestinal juice, pancreatic juice, and bile decreases. Norepinephrine exerts its effect on cells through β-adrenergic receptors located on the surface (membranes, membranes) of these cells.

The Auerbach plexus, an intraorgan division of the autonomic nervous system (intramural nervous system), takes part in the control of the motor function of the small intestine. Control is based on local peripheral reflexes. Auerbach's plexus is a dense continuous network of nerve nodes interconnected by nerve cords. Nerve ganglia are a collection of neurons (nerve cells), and nerve cords are the processes of these neurons. In accordance with the functional characteristics, Auerbach's plexus consists of neurons of the parasympathetic ANS and the sympathetic ANS. The nerve nodes and nerve cords of the Auerbach plexus are located between the longitudinal and circular layers of smooth muscle bundles of the intestinal wall, run in the longitudinal and circular direction and form a continuous nerve network around the intestine. Nerve cells of the Auerbach plexus innervate longitudinal and circular bundles of intestinal smooth muscle cells, regulating their contractions.

Two nerve plexuses of the intramural nervous system (intraorgan autonomic nervous system) also take part in controlling the secretory function of the small intestine: the subserous nerve plexus (sparrow plexus) and the submucosal nerve plexus (Meissner's plexus). Control is carried out on the basis of local peripheral reflexes. These two plexuses, like the Auerbach plexus, are a dense continuous network of nerve nodes connected to each other by nerve cords, consisting of neurons of the parasympathetic ANS and sympathetic ANS.

Neurons of all three plexuses have synaptic connections among themselves.

The motor activity of the small intestine is controlled by two autonomous rhythm sources. The first is located at the junction of the common bile duct into the duodenum, and the other is in the ileum.

The motor activity of the small intestine is controlled by reflexes that excite and inhibit intestinal motility. Reflexes that stimulate the motility of the small intestine include: esophageal-intestinal, gastrointestinal and enteric reflexes. Reflexes that inhibit the motility of the small intestine include: intestinal, rectoenteric, receptor relaxation (inhibition) reflex of the small intestine during eating.

The motor activity of the small intestine depends on the physical and chemical properties of chyme. The high content of fiber, salts, and intermediate hydrolysis products (especially fats) in chyme enhances the peristalsis of the small intestine.

S-cells of the mucous membrane 12 p.c. synthesize and secrete prosecretin (prohormone) into the intestinal lumen. Prosecretin is mainly converted into secretin (hormone) by the action of hydrochloric acid in the gastric chyme. The most intensive conversion of prosecretin to secretin occurs at pH = 4 or less. As pH increases, the conversion rate decreases in direct proportion. Secretin is absorbed into the blood and reaches pancreatic cells through the bloodstream. Under the influence of secretin, pancreatic cells increase the secretion of water and bicarbonates. Secretin does not increase the secretion of enzymes and proenzymes by the pancreas. Under the influence of secretin, the secretion of the alkaline component of pancreatic juice increases, which enters the 12 p.c. The greater the acidity of the gastric juice (the lower the pH of the gastric juice), the more secretin is formed, the more secreted in the 12 p.c. pancreatic juice with plenty of water and bicarbonates. Bicarbonates neutralize hydrochloric acid, the pH increases, the formation of secretin decreases, and the secretion of pancreatic juice with a high content of bicarbonates decreases. In addition, under the influence of secretin, bile formation and secretion of the glands of the small intestine increase.

The transformation of prosecretin into secretin also occurs under the influence of ethyl alcohol, fatty acids, bile acids, and spice components.

The largest number of S cells is located in 12 p.c. and in the upper (proximal) part of the jejunum. The smallest number of S cells is located in the most distant (lower, distal) part of the jejunum.

Secretin is a peptide consisting of 27 amino acid residues. Vasoactive intestinal peptide (VIP), glucagon-like peptide-1, glucagon, glucose-dependent insulinotropic polypeptide (GIP), calcitonin, calcitonin gene-related peptide, parathyroid hormone, growth hormone-releasing factor have a chemical structure similar to secretin, and therefore, possibly a similar effect. , corticotropin releasing factor and others.

When chyme enters the small intestine from the stomach, I-cells located in the mucous membrane 12 p.c. and the upper (proximal) part of the jejunum begin to synthesize and release the hormone cholecystokinin (CCK, CCK, pancreozymin) into the blood. Under the influence of CCK, the sphincter of Oddi relaxes, the gallbladder contracts, and as a result, the flow of bile into the 12.p.c. increases. CCK causes contraction of the pyloric sphincter and limits the flow of gastric chyme into the 12th p.c., enhances the motility of the small intestine. The most powerful stimulators of the synthesis and release of CCK are dietary fats, proteins, and alkaloids of choleretic herbs. Dietary carbohydrates do not have a stimulating effect on the synthesis and release of CCK. Gastrin-releasing peptide also belongs to the stimulators of CCK synthesis and release.

The synthesis and release of CCK is reduced by the action of somatostatin, a peptide hormone. Somatostatin is synthesized and released into the blood by D-cells, which are located in the stomach, intestines, and among the endocrine cells of the pancreas (in the islets of Langerhans). Somatostatin is also synthesized by the cells of the hypothalamus. Under the influence of somatostatin, not only the synthesis of CCK decreases. Under the influence of somatostatin, the synthesis and release of other hormones decreases: gastrin, insulin, glucagon, vasoactive intestinal polypeptide, insulin-like growth factor-1, somatotropin-releasing hormone, thyroid-stimulating hormones and others.

Reduces gastric, biliary and pancreatic secretion, peristalsis of the gastrointestinal tract of Peptide YY. Peptide YY is synthesized by L-cells, which are located in the mucous membrane of the colon and in the final part of the small intestine - the ileum. When the chyme reaches the ileum, the fats, carbohydrates and bile acids of the chyme act on L-cell receptors. L cells begin to synthesize and release peptide YY into the blood. As a result, peristalsis of the gastrointestinal tract slows down, gastric, biliary and pancreatic secretions decrease. The phenomenon of slowing down the peristalsis of the gastrointestinal tract after the chyme reaches the ileum is called the ileal brake. Gastrin-releasing peptide is also a stimulator of peptide YY secretion.

D1(H) cells, which are located mainly in the islets of Langerhans of the pancreas and, to a lesser extent, in the stomach, colon and small intestine, synthesize and release vasoactive intestinal peptide (VIP) into the blood. VIP has a pronounced relaxing effect on the smooth muscle cells of the stomach, small intestine, colon, gall bladder, as well as the vessels of the gastrointestinal tract. Under the influence of VIP, blood supply to the gastrointestinal tract increases. Under the influence of VIP, the secretion of pepsinogen, intestinal enzymes, pancreatic enzymes, the content of bicarbonates in pancreatic juice increases, and the secretion of hydrochloric acid decreases.

Pancreatic secretion increases under the influence of gastrin, serotonin, and insulin. Bile salts also stimulate the secretion of pancreatic juice. Pancreatic secretion is reduced by glucagon, somatostatin, vasopressin, adrenocorticotropic hormone (ACTH), and calcitonin.

The endocrine regulators of the motor function of the gastrointestinal tract include the hormone Motilin. Motilin is synthesized and released into the blood by enterochromaffin cells of the mucous membrane 12 p.k. and jejunum. Bile acids stimulate the synthesis and release of motilin into the blood. Motilin stimulates peristalsis of the stomach, small and large intestines 5 times more strongly than the parasympathetic ANS mediator acetylcholine. Motilin, together with cholicystokinin, controls the contractile function of the gallbladder.

The endocrine regulators of motor (motor) and secretory functions of the intestine include the hormone Serotonin, which is synthesized by intestinal cells. Under the influence of this serotonin, peristalsis and secretory activity of the intestine are enhanced. In addition, intestinal serotonin is a growth factor for some types of symbiotic intestinal microflora. In this case, the symbiont microflora takes part in the synthesis of intestinal serotonin by decarboxylating tryptophan, which is the source and raw material for the synthesis of serotonin. With dysbiosis and some other intestinal diseases, the synthesis of intestinal serotonin decreases.

From the small intestine, chyme enters the large intestine in portions (about 15 ml). The ileocecal sphincter (Bauhinian valve) regulates this flow. The opening of the sphincter occurs reflexively: peristalsis of the ileum (the final part of the small intestine) increases pressure on the sphincter from the small intestine, the sphincter relaxes (opens), and chyme enters the cecum (the initial part of the large intestine). When the cecum is filled and stretched, the sphincter closes and the chyme does not return to the small intestine.

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Dysbacteriosis is any change in the quantitative or qualitative normal composition of the intestinal microflora...

... as a result of changes in the pH of the intestinal environment (decrease in acidity), which occur against the background of a decrease in the number of bifido-, lacto- and propionobacteria for various reasons... If the number of bifido-, lacto-, and propionobacteria decreases, then, accordingly, the amount of acidic metabolites produced decreases these bacteria to create an acidic environment in the intestines... Pathogenic microorganisms take advantage of this and begin to actively multiply (pathogenic microbes cannot tolerate an acidic environment)...

...moreover, the pathogenic microflora itself produces alkaline metabolites that increase the pH of the environment (decreasing acidity, increasing alkalinity), alkalization of the intestinal contents occurs, and this is a favorable environment for the habitat and reproduction of pathogenic bacteria.

Metabolites (toxins) of pathogenic flora change the pH in the intestine, indirectly causing dysbiosis, since as a result it becomes possible for the introduction of microorganisms foreign to the intestine, and the normal filling of the intestine with bacteria is disrupted. Thus, a kind of vicious circle , only aggravating the course of the pathological process.

In our diagram, the concept of “dysbacteriosis” can be described as follows:

For various reasons, the number of bifidobacteria and (or) lactobacilli decreases, which is manifested in the reproduction and growth of pathogenic microbes (staphylococci, streptococci, clostridia, fungi, etc.) of residual microflora with their pathogenic properties.

Also, a decrease in bifidobacteria and lactobacilli can be manifested by an increase in concomitant pathogenic microflora (Escherichia coli, enterococci), as a result of which they begin to exhibit pathogenic properties.

And of course, in some cases, the situation cannot be ruled out when beneficial microflora is completely absent.

These are, in fact, variants of various “plexuses” of intestinal dysbiosis.

What are pH and acidity? Important!

Any solutions and liquids are characterized pH value(pH - potential hydrogen - potential hydrogen), quantitatively expressing them acidity.

If the pH level is within

- from 1.0 to 6.9, then the environment is called sour;

— equal to 7.0 — neutral Wednesday;

— at a pH level from 7.1 to 14.0, the medium is alkaline.

The lower the pH, the higher the acidity; the higher the pH, the higher the alkalinity of the environment and the lower the acidity.

Since the human body is 60-70% water, the pH level has a strong impact on the chemical processes occurring in the body, and, accordingly, on human health. An unbalanced pH is a pH level at which the body's environment becomes too acidic or too alkaline for an extended period of time. Indeed, controlling pH levels is so important that the human body itself has developed functions to control the acid-base balance in every cell. All regulatory mechanisms of the body (including respiration, metabolism, hormone production) are aimed at balancing the pH level. If the pH level becomes too low (acidic) or too high (alkaline), the body's cells poison themselves with toxic emissions and die.

In the body, the pH level regulates blood acidity, urine acidity, vaginal acidity, semen acidity, skin acidity, etc. But you and I are now interested in the pH level and acidity of the colon, nasopharynx and mouth, stomach.

Acidity in the colon

Acidity in the colon: 5.8 - 6.5 pH, this is an acidic environment, which is maintained by normal microflora, in particular, as I already mentioned, bifidobacteria, lactobacilli and propionobacteria due to the fact that they neutralize alkaline metabolic products and produce their acidic metabolites - lactic acid and other organic acids...

...By producing organic acids and reducing the pH of the intestinal contents, normal microflora creates conditions under which pathogenic and opportunistic microorganisms cannot multiply. This is why streptococci, staphylococci, klebsiella, clostridia fungi and other “bad” bacteria make up only 1% of the entire intestinal microflora of a healthy person.

• The fact is that pathogenic and opportunistic microbes cannot exist in an acidic environment and specifically produce those same alkaline metabolic products (metabolites) aimed at alkalizing the intestinal contents by increasing the pH level, in order to create favorable living conditions for themselves (increased pH - hence - low acidity - hence - alkalization). I repeat once again that bifido, lacto and propionobacteria neutralize these alkaline metabolites, plus they themselves produce acidic metabolites that reduce the pH level and increase the acidity of the environment, thereby creating favorable conditions for their existence. This is where the eternal confrontation between “good” and “bad” microbes arises, which is regulated by Darwin’s law: “survival of the fittest”!

Eg,

• Bifidobacteria are able to reduce the pH of the intestinal environment to 4.6-4.4;
• Lactobacilli up to 5.5-5.6 pH;
• Propionic bacteria are capable of lowering the pH level to 4.2-3.8, this is actually their main function. Propionic acid bacteria produce organic acids (propionic acid) as the end product of their anaerobic metabolism.

As you can see, all these bacteria are acid-forming, it is for this reason that they are often called “acid-forming” or often simply “lactic acid bacteria”, although the same propionic bacteria are not lactic acid bacteria, but propionic acid bacteria...

Acidity in the nasopharynx and mouth

As I already noted in the chapter in which we examined the functions of the microflora of the upper respiratory tract: one of the functions of the microflora of the nose, pharynx and throat is a regulatory function, i.e. normal microflora of the upper respiratory tract is involved in the regulation of maintaining the pH level of the environment...

...But if “pH regulation in the intestines” is performed only by normal intestinal microflora (bifido-, lacto- and propionobacteria), and this is one of its main functions, then in the nasopharynx and mouth the function of “pH regulation” is performed not only by the normal microflora of these organs, as well as mucous secretions: saliva and snot...

• You have already noticed that the composition of the microflora of the upper respiratory tract differs significantly from the intestinal microflora; if in the intestines of a healthy person beneficial microflora (bifidobacteria and lactobacilli) predominate, then in the nasopharynx and throat opportunistic microorganisms (Neisseria, corynebacteria, etc.) predominantly live. ), lacto- and bifidobacteria are present there in small quantities (by the way, bifidobacteria may be completely absent). This difference in the composition of the microflora of the intestine and respiratory tract is due to the fact that they perform different functions and tasks (for the functions of the microflora of the upper respiratory tract, see Chapter 17).

So, acidity in the nasopharynx It is determined by normal microflora, as well as mucous secretions (snot) - secretions produced by the glands of the epithelial tissue of the mucous membranes of the respiratory tract. The normal pH (acidity) of mucus is 5.5-6.5, which is an acidic environment. Accordingly, the pH in the nasopharynx of a healthy person has the same values.

Acidity of the mouth and throat They are determined by their normal microflora and mucous secretions, in particular saliva. The normal pH of saliva is 6.8-7.4 pH Accordingly, the pH in the mouth and throat takes on the same values.

1. The pH level in the nasopharynx and mouth depends on its normal microflora, which depends on the condition of the intestines.

2. The pH level in the nasopharynx and mouth depends on the pH of mucous secretions (snot and saliva), this pH in turn also depends on the balance of our intestines.

Stomach acidity

Stomach acidity averages 4.2-5.2 pH, this is a very acidic environment (sometimes, depending on the food we eat, the pH can fluctuate between 0.86 - 8.3). The microbial composition of the stomach is very poor and is represented by a small number of microorganisms (lactobacteria, streptococci, Helicobacter, fungi), i.e. bacteria that can withstand such strong acidity.

Unlike the intestines, where acidity is created by normal microflora (bifido-, lacto- and propionobacteria), and also in contrast to the nasopharynx and mouth, where acidity is created by normal microflora and mucous secretions (snot, saliva), the main contribution to the overall acidity of the stomach is made by gastric juice is hydrochloric acid produced by the cells of the stomach glands, located mainly in the area of ​​the fundus and body of the stomach.

So, this was an important digression about “pH”, let’s continue now.

In the scientific literature, as a rule, four microbiological phases are distinguished in the development of dysbacteriosis...

You will learn from the next chapter exactly what phases exist in the development of dysbiosis; you will also learn about the forms and causes of this phenomenon, and about this type of dysbiosis when there are no symptoms from the gastrointestinal tract.