Organic components of saliva. How food is broken down in the human oral cavity: saliva enzymes and stages of digestion. What are the functions of human saliva?

To sustain life, first of all, people need food. Products contain a lot essential substances: mineral salts, organic elements and water. Nutrient components are the building material for cells and a resource for constant human activity. During the decomposition and oxidation of compounds, a certain amount of energy is released, which characterizes their value.

The process of digestion begins oral cavity. The product is processed by the digestive juice, which acts on it with the help of the contained enzymes, due to which, even when chewing, complex carbohydrates, proteins and fats are transformed into molecules that are absorbed. Digestion is a complex process that requires exposure to products of many components synthesized by the body. Proper chewing and digestion is the key to health.

Functions of saliva in the process of digestion

The digestive tract includes several main organs: the oral cavity, pharynx with esophagus, pancreas and stomach, liver and intestines. Saliva performs many functions:

What happens to food? The main task of the substrate in the mouth is to participate in digestion. Without it, certain types of foods would not be broken down by the body or would be dangerous. The liquid wets the food, the mucin glues it into a lump, preparing it for swallowing and movement through the digestive tract. It is produced depending on the quantity and quality of food: less for liquid food, more for dry food, and does not form when drinking water. Chewing and salivation can be attributed to the most important process of the body, at all stages of which there is a change in the consumed product and the delivery of nutrients.

Composition of human saliva

Saliva is colorless, tasteless and odorless (see also: what to do if you have ammonia breath?). It can be saturated, viscous or very rare, watery - it depends on the proteins that make up the composition. The glycoprotein mucin gives it the appearance of mucus and makes it easier to swallow. It loses its enzymatic qualities soon after it enters the stomach and mixes with its juice.

The oral fluid contains a small amount of gases: carbon dioxide, nitrogen and oxygen, as well as sodium and potassium (0.01%). It contains substances that digest some carbohydrates. There are other components of organic and inorganic origin, as well as hormones, cholesterol, vitamins. It is 98.5% water. The activity of saliva can be explained by the huge number of elements contained in it. What functions does each of them perform?

organic matter

The most important component of the intraoral fluid are proteins - their content is 2-5 grams per liter. In particular, these are glycoproteins, mucin, A and B globulins, albumins. It contains carbohydrates, lipids, vitamins and hormones. Most of protein is mucin (2-3 g / l), and due to the fact that it contains 60% carbohydrates, it makes saliva viscous.

About a hundred enzymes are present in the mixed liquid, including ptyalin, which is involved in the breakdown of glycogen and its conversion into glucose. In addition to the presented components, it contains: urease, hyaluronidase, glycolysis enzymes, neuraminidase and other substances. Under the action of the intraoral substance, food changes and transforms into the form necessary for assimilation. With pathology of the oral mucosa, diseases internal organs used frequently laboratory research enzymes to identify the type of disease and the causes of its formation.

What substances can be classified as inorganic?

The composition of the mixed oral fluid includes inorganic components. These include:

Mineral components create an optimal reaction of the environment to incoming food, maintain the level of acidity. A significant part of these elements is absorbed by the mucous membrane of the intestines, stomach and sent to the blood. The salivary glands are actively involved in maintaining the stability of the internal environment and the functioning of organs.

The process of salivation

The production of saliva occurs both in the microscopic glands of the oral cavity, and in the large: parolingual, submandibular and parotid pairs. The canals of the parotid glands are located near the second molar from above, the submandibular and sublingual canals are brought out under the tongue at one mouth. Dry foods produce more saliva than wet foods. The glands under the jaw and tongue synthesize 2 times more fluid than the parotid glands - they are responsible for the chemical processing of products.

An adult produces about 2 liters of saliva per day. The release of fluid throughout the day is uneven: during the use of products, active production begins up to 2.3 ml per minute, in a dream it decreases to 0.05 ml. In the oral cavity, the secret obtained from each gland is mixed. It washes and moisturizes the mucous membrane.

Salivation is controlled by the autonomic nervous system. Increased fluid synthesis occurs under the influence taste sensations, olfactory stimuli and when irritated by food during chewing. Excretion is significantly slowed down by stress, fright and dehydration.

Active enzymes involved in the digestion of food

The digestive system transforms nutrients obtained with products, turning them into molecules. They become fuel for tissues, cells and organs that continuously perform metabolic functions. The absorption of vitamins and microelements occurs at all levels.

Food is digested from the moment it enters the mouth. Here, mixing with the oral fluid, which includes enzymes, is carried out, the food is lubricated and sent to the stomach. Substances contained in saliva break down the product into simple elements and protect the human body from bacteria.

Why do saliva enzymes work in the mouth but stop functioning in the stomach? They only operate in alkaline environment, and then, in the gastrointestinal tract, it changes to acidic. Proteolytic elements work here, continuing the stage of assimilation of substances.

Amylase enzyme or ptyalin - breaks down starch and glycogen

Amylase is a digestive enzyme that breaks down starch into carbohydrate molecules, which are absorbed in the intestines. Under the action of the component, starch and glycogen are converted into maltose, and with the help of additional substances they are converted into glucose. To detect this effect, eat a cracker - when chewed, the product exhibits a sweet aftertaste. The substance works only in the esophagus and in the mouth, converting glycogen, but loses its properties in the acidic environment of the stomach.

Ptyalin is produced by the pancreas and salivary glands. The type of enzyme produced by the pancreas is called pancreatic amylase. The component completes the stage of digestion and absorption of carbohydrates.

Lingual lipase - for the breakdown of fats

The enzyme promotes the conversion of fats into simple compounds: glycerol and fatty acids. In the oral cavity, the process of digestion begins, and in the stomach, the substance stops working. A little lipase is produced by the stomach cells, the component specifically breaks down milk fat and is especially important for babies, because it makes the process of assimilation of products and the absorption of elements easier for their underdeveloped digestive system.

Varieties of protease - for protein cleavage

Protease is a general term for enzymes that break down proteins into amino acids. There are three main types produced in the body:

Stomach cells produce pepsicogen, an inactive component that turns into pepsin upon contact with acid environment. It breaks peptides - the chemical bonds of proteins. The pancreas is responsible for the production of trypsin and chymotrypsin. small intestine. When already processed gastric juice and fragmentally digested food is sent from the stomach to the intestines, these substances contribute to the formation of simple amino acids that are absorbed into the blood.

Why is there a lack of enzymes in saliva?

Proper digestion is mainly dependent on enzymes. Their deficiency leads to incomplete digestion of food, diseases of the stomach and liver may occur. Symptoms of their lack are heartburn, flatulence, and frequent belching. After a while, headaches may appear, work will be disrupted endocrine system. A small amount of enzymes leads to obesity.

Usually the production mechanisms active substances laid genetically, therefore, the violation of the activity of the glands is innate. Experiments have shown that a person receives enzyme potential at birth, and if it is spent without replenishing, it will quickly run out.

The processes occurring in the body can be controlled. To simplify its work, it is necessary to consume fermented food: steamed, raw, high-calorie (bananas, avocados).

The reasons for the lack of enzymes include:

their small supply from birth;
eating foods grown in soil poor in enzymes;
eating overcooked, fried food without raw vegetables and fruits;
stress, pregnancy, diseases and pathologies of organs.

The work of enzymes does not stop in the body for a minute, supporting every process. They protect a person from diseases, increase endurance, destroy and remove fats. With their small amount, incomplete splitting of products occurs, and the immune system begins to fight with them, as with an alien body. This weakens the body and leads to exhaustion.

Digestion begins already in the oral cavity in the form of mechanical processing of food and wetting it with saliva. Saliva is an important component that prepares the food bolus for further digestion. It can not only moisturize food, but also disinfect. Saliva also contains many enzymes that begin to break down simple components even before food is processed by gastric juice.

Water. Makes up more than 98.5% of the total secret. Everything is dissolved in it. active ingredients: enzymes, salts and more. The main function is to moisten food and dissolve the substances in it to facilitate the further movement of the food bolus through the gastrointestinal tract and digestion.
Salts of various acids (trace elements, alkali metal cations). They are a buffer system that is able to maintain the necessary acidity of the food bolus before it enters the stomach environment. Salts can increase the acidity of food in case of its insufficiency or alkalinize it in case of excessively high acidity. With pathology and an increase in salt content, they can be deposited in the form of stones with the formation of gingivitis.
Mucin. A substance that has adhesive properties, which allows you to collect food into a single lump, which will then move in one conglomerate through the entire gastrointestinal tract.
Lysozyme. Natural protector with bactericidal properties. Able to disinfect food, provides protection of the oral cavity from pathogens. If the component is insufficient, pathologies such as caries, candidiasis can develop.
Opiorfin. An anesthetic substance that can anesthetize overly sensitive oral mucosa, rich in nerve endings, from mechanical irritation with solid food.
Enzymes. The enzymatic system is able to start the digestion of food and prepare it for further processing in the stomach and intestines. The breakdown of food begins with carbohydrate components, since further processing may require energy costs, which provide sugar.

The table shows the content of each component of saliva

saliva enzymes

Amylase

An enzyme capable of breaking down complex carbohydrate compounds, turning them into oligosaccharides, and then into sugar. The main compound that the enzyme acts on is starch. It is thanks to the action of this enzyme that we can feel the sweet taste of the product during its mechanical processing. Further breakdown of starch continues under the action of pancreatic amylase in the duodenum.

Lysozyme

The main bactericidal component, which, in essence, performs its properties due to the digestion of bacterial cell membranes. In fact, the enzyme is also able to break down the polysaccharide chains located in the shell of the bacterial cell, due to which a hole appears in it, through which liquid quickly flows and the microorganism bursts like a balloon.

Maltase

An enzyme capable of breaking down maltose is a complex carbohydrate compound. This produces two molecules of glucose. Works in combination with amylase up to small intestine, where in the duodenum it is replaced by intestinal maltase.

Lipase

Saliva contains lingual lipase, which first begins the processing of complex fatty compounds. The substance it acts on is triglyceride, after being treated with an enzyme, it is broken down into glycerol and fatty acids. Its action ends in the stomach, where gastric lipase comes to replace it. For children, it is lingual lipase that has greater value, since the first begins the digestion of milk fats of breast milk.

Proteases

The conditions necessary for adequate digestion of proteins are absent in saliva. They are able to break down only already denatured protein components into simpler ones. The main process of protein digestion begins after the denaturation of protein chains under the action of of hydrochloric acid in the intestine. However, the proteases contained in saliva are also very important for the normal digestion of food.

Other elements

Other elements include no less important compounds that ensure the correct formation of the food bolus. This process is important as the beginning of adequate and complete digestion.

Mucin

A sticky substance that is able to gather together a food bolus. Its action continues until the release of processed food from intestinal tract. It contributes to the uniform digestion of chyme, and thanks to the mucus-like consistency, it greatly facilitates and softens its movement along the tract. The substance also performs a protective function by enveloping the gums, teeth, and mucous membranes, which significantly reduces the traumatic effect of solid unprocessed food on delicate structures. In addition, the sticky consistency promotes the adhesion of disease-causing agents, which are subsequently destroyed by lysozyme.

Opiorfin

A natural antidepressant, a neurogenic mediator that can act on nerve pain endings, blocking the transmission of pain impulses. This allows you to make the chewing process painless, although hard particles often injure the mucous membrane, gums, and the surface of the tongue. Naturally, microdoses are released in saliva. There is a theory that the pathogenetic mechanism is an increase in the release of opiate, due to the dependence that is formed in humans, the need for irritation of the oral cavity increases, an increase in the secretion of saliva - and therefore opiorphin.

Buffer systems

Various salts that provide the necessary acidity for the normal functioning of the enzyme system. They also create the necessary charge on the surface of the chyme, which contributes to the stimulation of peristaltic waves, mucus of the internal mucous membrane lining the gastrointestinal tract. Also, these systems contribute to the mineralization of tooth enamel and its strengthening.

epidermal growth factor

A protein hormonal compound that promotes the launch of regenerative processes. Cell division of the oral mucosa occurs at lightning speed. This is understandable, since they are damaged much more often than any other, as a result of mechanical stress and bacterial attacks.

Protective. It consists in disinfecting food and protecting the oral mucosa and tooth enamel from mechanical damage.
Digestive. Enzymes contained in saliva begin digestion already at the stage of grinding food.
Mineralizing. Allows you to strengthen tooth enamel, due to solutions of salts contained in saliva.
Cleansing. The abundant secretion of saliva contributes to the self-cleaning of the oral cavity, due to its washing.
Antibacterial. The components of saliva have a bactericidal property, due to which many pathogens do not penetrate beyond the oral cavity.
excretory. Saliva contains metabolic products (such as ammonia, various toxins, including medicinal ones), when spitting out, the body gets rid of toxins.
Anesthetic. Due to the content of opiorphin, saliva is able to temporarily anesthetize small cuts, and also provides painless food processing.
Speech. Thanks to water component provides moisture to the oral cavity, which helps articulate speech.
Healing. Thanks to the content of epidermal growth factor, it contributes to the fastest healing all wound surfaces, therefore, reflexively, with any cut, we try to lick the wound.

Saliva is a complex biological fluid produced by specialized glands and secreted into the oral cavity. The chemical composition of saliva determines the condition and functioning of the teeth and oral mucosa.

There are concepts of "saliva - the secret of the salivary glands (parotid, submandibular, sublingual, small glands of the oral cavity)" and "mixed saliva or oral fluid", which, in addition to the secrets of various salivary glands, contains microorganisms, desquamated epithelial cells and other components. The volume of mixed saliva is supplemented by fluid that diffuses through the oral mucosa and gingival fissure fluid.

In an adult, 0.5-2 liters of saliva is normally secreted per day.

Saliva is a cloudy, viscous liquid with a density of 1.002-1.017. The viscosity of saliva (according to the Ostwald method) ranges from 1.2-2.4 units. It is due to the presence of glycoproteins, proteins, cells. With multiple caries, the viscosity of saliva, as a rule, increases and can reach 3 units. An increase in the viscosity of saliva reduces its cleansing properties and mineralizing ability.

The pH of saliva at rest varies according to different authors, within the range of 6.5-7.5, i.e. close to neutral.

In some pathological conditions, the pH of saliva can shift both to the acidic (up to 5.4 units) and alkaline (up to 8 units) sides. Acidification of the environment leads to a sharp undersaturation of saliva with hydroxyapatite and, therefore, increases the rate of enamel dissolution. Alkalinization of saliva has the opposite effect and should lead to stone formation.

Acidity depends on the rate of salivation, the buffer capacity of saliva, the hygienic state of the oral cavity, the nature of the food, the time of day, and age. With a low rate of saliva secretion and poor oral hygiene, saliva pH usually shifts to the acid side. At night, the pH of saliva decreases, in the morning its value is the lowest, in the evening it rises. With age, there is a tendency to reduce the acidity of saliva and increase caries resistance.

The buffer capacity of saliva is the ability to neutralize acids and bases (alkalis) due to the interaction of bicarbonate, phosphate and protein systems. It has been established that the intake of carbohydrate food for a long time reduces, and the intake of high-protein food increases the buffer capacity of saliva. The high buffering capacity of saliva is one of the factors that increase the resistance of teeth to caries.

2. Functions of saliva.

Saliva performs a variety of functions: digestive, protective, bactericidal, trophic, mineralizing, immune, hormonal, etc.

Saliva is involved in initial stage digestion, wetting and softening food. In the oral cavity, under the action of the enzyme α-amylase, carbohydrates are broken down.

The protective function of saliva is that, washing the surface of the tooth, the oral fluid constantly changes its structure and composition. At the same time, glycoproteins, calcium, proteins, peptides and other substances are deposited from saliva on the surface of the tooth enamel, which form a protective film - a "pellicule" that prevents organic acids from affecting the enamel. In addition, saliva protects the tissues and organs of the oral cavity from mechanical and chemical influences (mucins).

Saliva also performs an immune function due to secretory immunoglobulin A synthesized by the salivary glands of the oral cavity, as well as immunoglobulins C, D and E of serum origin.

Salivary proteins have nonspecific protective properties: lysozyme (hydrolyzes the β-1,4-glycosidic bond of polysaccharides and mucopolysaccharides containing muramic acid in the cell walls of microorganisms), lactoferrin (participates in various body defense reactions and immunity regulation).

Small phosphoproteins, histatins and staterins play an important role in the antimicrobial action. Cystatins are inhibitors of cysteine proteinases and may play a protective role in inflammatory processes in the oral cavity.

Mucins trigger a specific interaction between the bacterial cell wall and complementary galactoside receptors on the epithelial cell membrane.

The hormonal function of saliva is that the salivary glands produce the hormone parotin (salivaparotin), which contributes to the mineralization of the hard tissues of the tooth.

The mineralizing function of saliva is important in maintaining homeostasis in the oral cavity. The oral fluid is a solution supersaturated with calcium and phosphorus compounds, which underlies its mineralizing function. When saliva is saturated with calcium and phosphorus ions, they diffuse from the oral cavity into the tooth enamel, which ensures its “maturation” (compaction of the structure) and growth. The same mechanisms prevent the release of minerals from the tooth enamel, i.e. its demineralization. Due to the constant saturation of the enamel with substances from saliva, the density of the tooth enamel increases with age, its solubility decreases, which ensures a higher caries resistance of the permanent teeth of the elderly compared to the young.

We regularly swallow saliva. And we are used to the fact that the oral cavity is always wet and the cessation of sufficient production of this biological fluid is perceived with suspicion. As a rule, increased dryness in the mouth is a sign of a disease.

Saliva is a habitual and necessary biologically active liquid. Helps maintain the level of immune protection in the oral cavity, digestion of food. What is the composition of human saliva, fluid production rates, and physical and chemical properties?

Saliva is a biological substance secreted by the salivary glands. Fluid is produced by 6 large glands - submandibular, parotid, sublingual - and many small ones located in the oral cavity. Up to 2.5 liters of fluid is released per day.

The composition of the secretions of the salivary glands differs from the composition of the fluid in. This is due to the presence of food debris, the presence of microorganisms.

Functions of the biological fluid:

wetting the food bolus;
disinfecting;
protective;
promotes articulation and swallowing of the food bolus;
breakdown of carbohydrates in the oral cavity;
transport - the liquid wets the epithelium of the oral cavity and is involved in the metabolism between saliva and the mucous membrane of the oral cavity.

The mechanism of saliva production

Physical properties and composition of saliva

The biological fluid healthy person has a number of physical and chemical properties. They are presented in the table.

Table 1. Normal characteristics of saliva.

The main component of the oral fluid is water - up to 98%. The remaining components can be conditionally divided into acids, minerals, trace elements, enzymes, metal compounds, organics.

Organic composition

The vast majority of components of organic origin that make up saliva are of a protein nature. Their number varies from 1.4 to 6.4 g/l.

Types of protein compounds:

glycoproteins;
mucins - high molecular weight glycoproteins that ensure the ingestion of a food bolus - 0.9–6.0 g / l;
immunoglobulins of class A, G and M;
whey protein fractions- enzymes, albumins;
salivoprotein - a protein involved in the formation of deposits on the teeth;
phosphoprotein - binds calcium ions with the formation of tartar;
- participates in the processes of splitting di- and polysaccharides into smaller fractions;
maltase is an enzyme that breaks down maltose and sucrose;
lipase;
proteolytic component - for the breakdown of protein fractions;
lipolytic components - act on fatty foods;
lysozyme - has a disinfecting effect.

In the discharge of the salivary glands, insignificant amounts of cholesterol, compounds based on it, and fatty acids are found.

The composition of saliva

In addition, hormones are present in the oral fluid:

cortisol;
estrogens;
progesterone;
testosterone.

Saliva is involved in the wetting of food and the formation of a food bolus. Already in the oral cavity, enzymes break down complex carbohydrates into monomers.

Mineral (inorganic) components

Inorganic fractions in saliva are represented by acidic salt residues and metal cations.

The mineral composition of the secretion of the salivary glands:

chlorides - up to 31 mmol / l;
bromides;
iodides;
oxygen;
nitrogen;
carbon dioxide;
uric acid salts - up to 750 mmol / l;
anions of phosphorus-containing acids;
carbonates and bicarbonates - up to 13 mmol / l;
sodium - up to 23 mmol / l;
– up to 0.5 mmol/l;
calcium - up to 2.7 mmol / l;
strontium;
copper.

In addition, saliva contains small amounts of vitamins of various groups.

Composition features

The composition of saliva can change with age, as well as in the presence of diseases.

The chemical composition of the oral fluid varies depending on the age of the patient, his current condition, the presence of bad habits, the speed of its production.

Saliva is a dynamic fluid, that is, the ratio various substances varies depending on what kind of food is in the oral cavity at the current time. For example, the use of carbohydrates, sweets contributes to an increase in glucose and lactate. Smokers have elevated levels of radon salts, unlike non-smokers.

A person's age has a significant effect. So, in older people, the level of calcium in the salivary fluid rises, which provokes the formation of tartar on the teeth.

Changes in quantitative indicators depend on general condition a person, the presence of chronic pathologies or an inflammatory process in acute stage. Also, drugs taken on an ongoing basis have a significant impact.

For example, with hypovolemia, diabetes going on a sharp decline production of salivary gland secretion, but the amount of glucose increases. With kidney diseases - uremia of various origins - nitrogen levels increase.

During inflammatory processes in the oral cavity, there is a decrease in lysozyme with an increase in enzyme production. This aggravates the course of the disease and contributes to the destruction of periodontal tissues. The lack of oral fluid is a cariogenic factor.

Subtleties of saliva secretion

0.5 ml of saliva per minute should be produced in a healthy person during the daytime

Controls the functioning of the salivary glands nervous system centered in the medulla oblongata. The production of salivary fluid varies depending on the time of day. At night and during sleep, its amount decreases sharply, during the daytime it increases. In a state of anesthesia, the work of the glands completely stops.

During wakefulness, 0.5 ml of saliva is secreted per minute. If the glands are stimulated - for example, during meals - they produce up to 2.3 ml of liquid secretion.

The composition of the discharge of each gland is different. When it enters the oral cavity, mixing occurs, and it is already called "oral fluid". Unlike the sterile secretion of the salivary glands, it contains useful and conditionally pathogenic microflora, metabolic products, desquamated epithelium of the oral cavity, which is separated from maxillary sinuses, sputum, red and white blood cells.

The pH indicators are influenced by compliance with hygiene requirements, the nature of the food. So, when stimulating the work of the glands, the indicators shift to the alkaline side, with a lack of fluid - to the acidic side.

With various pathological processes there is a decrease or increase in the secretion of oral fluid. So, with stomatitis, neuralgia of the branches trigeminal nerve, various bacterial diseases hyperproduction is observed. At inflammatory processes in respiratory system, the production of salivary gland secretion is reduced.

Some Conclusions

Saliva is a dynamic fluid that is sensitive to all processes occurring in the body at the current time.
Its composition is constantly changing.
Saliva performs many functions, in addition to wetting the oral cavity and food bolus.
Changes in the composition of the oral fluid may indicate pathological processes occurring in the body.

Instructions for use, saliva:

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Saliva(lat. saliva) is a colorless liquid secreted into the oral cavity by the salivary glands.

The characteristics of saliva secreted by different salivary glands are somewhat different. For physiology, an integral characteristic is important, therefore, the so-called mixed saliva.

Characteristics of human saliva

Mixed saliva of a healthy person in normal conditions is a viscous, slightly opalescent liquid. 99.4-99.5% of human saliva is water. The remaining 0.5–0.6% are organic and inorganic components. Among organic matter: proteins (1.4–6.4 g/l), mucin (mucus) (0.8–6.0 g/l), cholesterol (0.02–0.5 g/l), glucose (0. 1–0.3 g/l), ammonium (0.01–0.12 g/l), uric acid(0.005–0.03 g/l). From inorganic substances saliva contains anions of chlorides, bicarbonates, sulfates, phosphates; sodium, potassium, calcium, magnesium cations, as well as trace elements: iron, copper, nickel, etc.

The most important salivary enzymes are amylase and maltase, which act only in a slightly alkaline environment. Amylase breaks down starch and glycogen to maltose. Maltase breaks down maltose into glucose. Saliva also contains proteinases, lipases, phosphatases, lysozyme, etc.

The acidity of saliva depends on the rate of salivation. Typically, the acidity of mixed human saliva is 6.8–7.4 pH, but at a high rate of salivation it reaches 7.8 pH. The acidity of the saliva of the parotid glands is 5.81 pH, the submandibular glands - 6.39 pH. The density of saliva is 1.001–1.017.

Salivation

Salivation or salivation (lat. salivatio) is carried out by many salivary glands, among which there are three pairs of so-called big salivary glands . The largest of these are the parotid salivary glands. They are located below and in front auricle directly under the skin. Their weight is 20–30 g. Medium in size are the submandibular salivary glands with a mass of about 15 g. The smallest of the large salivary glands are the sublingual glands. Their mass is about 5 g and they are located under the mucous membrane of the bottom of the oral cavity. The rest of the glands are small.

Outside of food intake, the salivary glands secrete saliva in total at a rate of 0.3–0.4 ml/min. The rate of basal salivation is from 0.08 to 1.83 ml/min, stimulated by food - from 0.2 to 5.7 ml/min. The total amount of saliva secreted per day in a healthy person is 2–2.5 liters. Parotid glands secrete 25-35% of the total volume, submandibular - 60-70%, sublingual - 4-5%, small 8-10%. The saliva of the small glands is characterized by a high content of mucus. By excreting no more than 10% of the total volume of saliva, they secrete 70% of all mucus.

Quantity, chemical composition and characteristics of saliva change depending on the type of food taken and other factors (smoking, medicines), as well as in various diseases.

Salivation in children

Salivation in children under three months is insignificant and amounts to 0.6-6 ml of saliva per hour (with active sucking - up to 24 ml per hour). Starting from the age of 3-6 months, salivation in a child increases significantly, reaching a volume close to that of adults by the age of 7. In children school age the volume of unstimulated saliva secretion ranges from 12 to 18 ml per hour. In children, the acidity of mixed saliva is on average 7.32 pH (in adults - 6.40 pH).

Functions of saliva

Saliva performs a number of important functions for the body: digestive, protective, remineralizing, trophic, buffering, and others.

Saliva wets, liquefies, dissolves food. With the participation of saliva, a food bolus is formed. Saliva dissolves substrates for their further hydrolysis. The most active salivary enzymes are amylase, which breaks down polysaccharides and maltase, and breaks down maltose and sucrose into monosaccharides.

Moisturizing and coating the mucous membrane of the oral cavity with mucus contained in saliva protects the mucous membrane from drying out, cracking and exposure to mechanical stimuli. Washing the teeth and oral mucosa, saliva removes microorganisms and their metabolic products, food residues. The bactericidal properties of saliva are manifested due to the presence of lysozyme, lactoferrin, lactoperoxidase, mucin, cystatins in it.

This process of remineralization of tooth tissues is based on mechanisms that prevent the release of its components from the enamel and facilitate their entry from saliva into the enamel. Saliva at normal acidity (pH from 6.8 to 7.0) is supersaturated with ions, especially Ca 2+ and PO 4 3+ ions, as well as hydroxyapatite (the main component of tooth enamel). With an increase in acidity (decrease in pH), the solubility of enamel hydroxyapatite in the oral fluid increases significantly. Saliva also contains mumps, which increases tooth calcification.

Saliva is highly buffering to neutralize acids and alkalis and thus protect tooth enamel from destructive influence.

Scientific research considering, among other things, the issues of salivation and the characteristics of saliva in diseases of the gastrointestinal tract

Maev I.V., Barer G.M., Busarova G.A., Pustovoit E.V., Polikanova E.N., Burkov S.G., Yurenev G.L. Dental manifestations of gastroesophageal reflux disease // Clinical medicine. - 2005. - No. 11. S. 33–38.

Novikova V.P., Shabanov A.M. The state of the oral cavity in patients with gastroesophageal reflux disease (GERD) // Gastroenterology of St. Petersburg. - 2009. - No. 1. - With. 25–28.

Pustovoit E.V., Polikanova E.N. Changes in the indicators of mixed saliva in patients with gastroesophageal reflux disease on the background of antireflux therapy. Rossiyskaya stamotologiya. - Number 3. – 2009.

Egorova E.Yu., Belyakov A.P., Krasnova E.E., Chemodanov V.V. Metabolic profile of blood and saliva in gastroduodenal diseases in children // Vestnik IvGMA. - Issue. 3. - 2005. S. 13-19.