How is the process of swallowing. Swallowing disorders: causes, syndrome "coma in the throat. Concomitant factors of swallowing disorders

The swallowing reflex is very similar to the act of breathing in that a person performs them unconsciously. These unconditional reactions of the body do not need to be specially studied. They are available to every living being from birth, because without them it would be impossible to ensure survival. However, sometimes swallowing can be disturbed. Why this violation of the reflex act occurs and how to get rid of the problem, we will consider further.

What is the swallowing reflex?

Various muscles take part in the act of swallowing: mouth, tongue, pharynx and esophagus. Their actions are clearly coordinated, so the food or liquid that a person consumes can only enter the stomach.

In addition, the swallowing reflex is regulated by the central nervous system. Thanks to this, a person can take a sip when he sees fit, that is, he can do this action arbitrarily. Several so-called cranial nerves take part in the regulation. In addition, there is a special swallowing center in the brain.

Consider what happens during the act of swallowing in order to understand why the swallowing reflex can be impaired:

At the first stage, the food enters the oral cavity, where it softens. This process takes no more than 10 seconds;
Next, the glossopharyngeal nerve is activated, which innervates the root of the tongue. Food is pushed towards the back of the throat. It is at this stage that most often a violation occurs, which leads to a violation of the swallowing reflex;
At the moment when the larynx is pulled up, the cricoid cartilage moves back, which closes the entrance to the trachea. After that, the muscles of the pharynx contract, and the lump passes into the esophagus without entering the trachea.

How and why can swallowing be disturbed?

The causes of a violation of the swallowing reflex can come from different systems: nervous, digestive, etc. However, most often, swallowing disorders, or dysphagia, appear due to disorders in the central nervous system. These include:

brain injury;
Stroke;
Spasm of the muscles of the esophagus;
Myasthenia gravis and muscular dystrophy;
Multiple sclerosis;
Parkinson's disease;
Dermatomyositis;
Tumors of various localization.

At the slightest sign of difficulty swallowing, you should immediately seek help. Violation of the swallowing reflex leads to rapid depletion of the body due to the fact that the latter does not receive enough nutrients. In addition, patients choke on food, which leads to throwing it into the respiratory tract. This, in turn, can lead to the development of pneumonia.

What are the types and degrees of dysphagia

All the reasons that can cause a violation of the swallowing reflex are divided into two types:

Mechanical - blockage of the lumen of the esophagus with too large a piece of food or narrowing of the lumen of the esophagus or external pressure on it;
Functional - associated with a violation of peristalsis and relaxation of the muscles of the pharynx and esophagus.

According to the complexity, 4 degrees of manifestation of a violation of the swallowing reflex are distinguished:

Swallowing is slightly difficult, it is impossible to swallow only very large pieces of food or volumes of liquid;
It becomes impossible to swallow any solid food. At the same time, the patient can easily consume food in semi-liquid or liquid form;
A patient with a swallowing disorder can consume nutrients only in a liquid consistency;
Swallowing becomes completely impossible.

How does swallowing disorder manifest?

The first manifestations of dysphagia make themselves felt by the patient with pain that occurs at the time of swallowing. You should pay attention if coughing attacks often occur during meals. Especially if at the same time the patient experiences throwing food into the nasal passages.

In addition, a characteristic symptom of a violation of the swallowing reflex is increased salivation and a feeling of suffocation. Often, the patient may make an additional complaint of heartburn, discomfort in the solar plexus area, or a lump in the esophagus.

How to restore the pharyngeal reflex

Most often, a violation of the swallowing reflex does not act as an independent disease, but as a symptom indicating a more serious problem. In this regard, treatment should be carried out in combination with the underlying disease.

If the problem lies in disorders of the gastrointestinal tract, then drug treatment is usually prescribed. It consists in taking substances that reduce the acidity of gastric juice, as well as antacids. In addition, patients need to strictly adhere to the diet.

Sometimes swallowing disorders can be caused not only by diseases, but also by psychological disorders. Treatment in this case is carried out not only with strict adherence to diet and posture when eating, but also with the passage of psychotherapy.

No less often, dysphagia appears in patients after a stroke. It takes at least 2-3 weeks to restore the lost swallowing function in patients. Until the reflex to recover, the patient is transferred to food using a nasogastric tube. However, the treatment does not end there, since the patient will still have to regularly perform special exercises to stimulate the restoration of the lost swallowing function.

In this regard, let us consider in more detail on the basis of what exercises the treatment of the swallowing reflex is based:

First of all, the patient begins with an imitation of a sip. Such attempts should be repeated at least 10 times a day;
Next, an exercise is performed in which the patient makes a yawn. It also needs to be repeated at least 10 times;
With the successful completion of the previous exercises, the tasks become a little more complicated and now the person is offered to try to gargle;
For training, imitation of snoring or coughing is also suitable;
In order to train the muscles of the soft palate, the patient is offered to touch it with the tip of the tongue. This procedure is performed first with the mouth open and then closed.

Such training is recommended for the patient only under the supervision of a qualified specialist. It is strictly forbidden to force the patient to do what he cannot do the first time. All exercises require regularity. In addition, you can not rush a person who has had a stroke, because the swallowing reflex takes time to recover. If the patient after a stroke does not neglect the exercises, then all impaired functions are easily restored.

Dysphagia is a difficulty in swallowing, is a manifestation of pathologies of the nervous system, as well as the upper gastrointestinal tract. In the presence of any dysphagia, even episodic, and especially constantly recurring, it is necessary to seek medical help, because it can indicate very serious diseases.

Brief anatomy

There are 26 muscles involved in normal swallowing, all of which are innervated by 5 cranial nerves. Swallowing is divided into three phases:

oral phase. This stage begins upon completion of chewing food, when the food coma is displaced to the level of the pharynx. Takes less than 1 second. It is the only component of swallowing that is consciously controlled by the cerebral cortex.
pharyngeal phase. At this stage, soft-palatal pharyngeal closure occurs, the larynx rises, protection of the airways and peristaltic movement of the breast down the pharynx, bypassing the level of the open cricopharyngeal muscle. The phase is reflexively controlled by the swallowing center located in the medulla oblongata. Its duration is less than 1 second.
Esophageal phase. It consists in the action of gravity, together with a coordinated and progressive contraction of the muscles of the esophagus, the breast moves down to the gastroesophageal sphincter. As a rule, it lasts 8-20 seconds.

Symptoms

Manifestations of dysphagia indicate a violation of the passage of food through the esophagus. Swallowing at the same time does not cause discomfort to a person. But after it, there is a “stopping and getting stuck” of a lump in the throat, there is a feeling of fullness in the posterior part of the sternum. In most cases, difficulty swallowing is not accompanied by pain, they are possible in the presence of diffuse spasm of the esophagus.

There are such main signs of dysphagia:

the promotion of food into the esophagus in the pharynx is disturbed, the lump is thrown into the nasal or oral cavity;
a feeling of suffocation is characteristic;
there is a cough;
saliva is abundantly separated;
aspiration pneumonia (inflammation of the lung tissue due to the penetration of a foreign body into it) is possible;
it is impossible to swallow food completely or it takes great effort to do so.

As a rule, the symptoms of dysphagia are caused by eating solid foods, especially in the initial stages. Swallowing improves when the food is washed down with water. Liquid food is usually much easier to take, although it happens that dysphagia is present even with a simple swallow of water.

Classification and degrees

Regarding the localization of the pathological process, there are:

Oropharyngeal (oropharyngeal) dysphagia - in this case, there are difficulties in the transition of food from the pharynx to the esophagus. It develops due to pathologies of the muscles of the pharynx, peripharyngeal muscles or nervous diseases.
Esophageal (esophageal) dysphagia - occurs due to the overlap of the lumen of the esophagus or impaired movement of its muscles. Conditionally divided into lower, upper and middle.
Crycopharyngeal incoordination is an uncoordinated contraction of the circular fibers of the upper esophageal sphincter.
Dysphagia arising from the squeezing of the esophagus by large vessels passing nearby (the aorta and its branches). It develops in the case of pathologies of these vessels.

There are also 4 degrees of the disease:

Difficulty swallowing only solid food.
Unable to eat solid food; with soft and semi-liquid, there are no difficulties.
A person is able to eat exclusively liquid food.
Complete inability to perform the act of swallowing.

The reasons

Dysphagia can occur due to a number of diseases:

Cancer of the pharynx or benign tumors. At the same time, in addition to difficulties with swallowing, uncomfortable sensations appear in the throat, swallowing is accompanied by pain that radiates to the ear area.
Pharyngeal "pocket" - usually this pathology is congenital in nature, while the mucous membrane protrudes and forms a pocket. Accompanied by difficulty with swallowing, bad breath, a protruding sac can be seen on the neck.
Stroke - in this case, dysphagia is accompanied by other signs: asymmetry of the muscles of the face, paralysis of the limbs, difficulty understanding or reproducing speech, confusion.
Encephalitis - dysphagia develops as a result of impaired consciousness (inadequacy, agitation or stopper), fever and other signs of brain damage: low blood pressure, impaired breathing.
Botulism - at the same time, the patient's eyes double, the person is not able to read the text, wide pupils are characteristic, which do not react to light. As a rule, it is accompanied by labored breathing. In the case of botulism, pressure and temperature indicators do not change.
Myasthenia - there is weakness of the muscles of the face, it is difficult for a person to chew, weakness of the muscles of the arms and legs.
Parkinson's disease - here in the foreground are motor and mental disorders, the presence of tremor is characteristic.
Multiple sclerosis - in addition to dysphagia, there may be: blurred vision, paresthesia, speech disorders, weakness of the upper and lower extremities, cognitive impairment.
Guillain-Barré syndrome - at the beginning of the disease, the temperature rises, after - pain in the arms and legs appears. Then the range of motion in the limbs is reduced, paralysis may develop, which rises from the legs up and captures the muscles of the chest and abdomen.

Lump in throat syndrome

Complaints about the presence of a "coma" in the throat (or scientifically"globus pharyngeus") are the most common when visiting an otolaryngologist. According to statistics, about 45% of all people experienced similar sensations. This syndrome was first studied as a manifestation of hysteria, but later it was found that psychiatric causes occur only in a fraction of all patients with a "lump in the throat."

This pathology develops due to several reasons:

There is indeed a foreign body in the throat that interferes with swallowing. Sensations of a lump in the throat can provoke the appearance of edema of the uvula of the soft palate, formations or cysts, an increase in the palatine or lingular tonsil. This case occurs infrequently and is very easily determined by a medical examination.
There is a sensation of a foreign object, but there is really nothing in the throat. The most common case. Usually such sensations are caused by reflux disease. Reflux is the backflow of stomach contents into the esophagus and throat. "Lump" is actually a spasm of the muscles of the pharynx, provoked by the contents of the stomach (the latter, due to increased acidity, burns the mucous membranes of the throat and esophagus). In addition to "coma in the throat" chronic pharyngitis may be present.
psychological reasons. Often, swallowing difficulties are observed after severe stressful situations, in a state of strong fear or excitement.

At this point in time, the "lump in the throat" syndrome is not well understood, but, as a rule, it does not pose a threat to the patient's life. Also, the causes that caused the development of pathology are usually easily eliminated. Of course, in order to identify the exact causes and prescribe appropriate therapy, you should consult a doctor.

Nervous dysphagia

Its other name is functional. It arises as a result of neuroses of various etiologies - that is, inorganic diseases of the nervous system. It can develop in childhood and adolescence, as well as in adults under 40 years old; in older men, the disease practically does not occur.

In children, neurosis occurs even at a very early age. At first, they are manifested by decreased appetite, frequent regurgitation, vomiting, and disturbed sleep. At school age, such children have increased soreness, thinness, transport intolerance, and poor appetite.

In adults, nervous dysphagia occurs for the first time due to a strong psychotraumatic situation, it is characterized by choking followed by difficulty in breathing. This causes the person to have a panic attack.

Difficulty swallowing in children

The main causes of dysphagia in children are various pathologies of the nervous system, for example, such as cerebral palsy (the risks of this condition are especially high in case of paralysis of both arms and legs at the same time).

Very high risks in children suffering from athetosis (constant involuntary movements), which are often congenital. It is possible to develop difficulties with swallowing and with muscle diseases, in the case of spina bifida, Arnold-Chiari anomalies. Congenital anomalies in the development of the esophagus and pharynx, Rossolimo-Bekhterev syndrome can lead to dysphagia.

Clinically, dysphagia in children is manifested by the following symptoms:

the baby consumes a very small amount of food;
breastfeeds or consumes mixtures for a long time;
after drinking and eating, a cough occurs and the face turns red;
during feeding, the neck and head are in an unusual position;
shortness of breath may occur, although it may not be very pronounced with a small amount of food entering the trachea;
mixture or milk appears on the nose.

It is worth alerting in the case of frequent pneumonia and bronchitis, the onset of asthma, if close relatives do not suffer from it. All this may also indicate problems with the innervation of the esophagus.

Diagnostics

The diagnosis is established on the basis of a test with swallowing solid or liquid food. Further, it is necessary to conduct a series of studies, with the help of which the root cause of the development of dysphagia is revealed, namely:

x-ray examination of the esophagus using a contrast agent (barium);
ultrasound diagnostics of the thyroid gland;
fibrogastroduodenoscopy;
magnetic resonance imaging of the brain.

It is mandatory to undergo an examination by an otolaryngologist.

Treatment

First of all, in the process of treatment, it is important to establish the causes that provoked the appearance of pathology. Based on them, this or that type of therapy will already be prescribed. To alleviate the manifestations of the disease, various medicines are used.

They also carry out a number of activities:

The patient is cleaned of the respiratory tract from food debris.
A light diet is prescribed, fatty, heavy foods, carbonated drinks, tea and coffee are excluded from the diet. It is recommended to consume dairy products, cereals and soups. You should eat only at certain times. You can eat light varieties of meat and fish in the form of mashed potatoes.
Assign drugs that lower the acidity of the gastrointestinal tract and medicines belonging to the group of antacids.

In cases where dysphagia has arisen due to weakened muscles or their dysfunction, the patient is prescribed special exercises to restore muscle tone.

In severe forms of the disease, they resort to surgical intervention, radiation therapy is carried out, the patency of the esophagus expands, and endoscopic methods of biological and chemical effects are used on the affected areas of the digestive tract.

Complications

The consequences of dysphagia can be divided into social and psychological. Eating is a social act, and as a result of the physical changes that make eating difficult, the taste sensation of eating food can be greatly reduced. I also have psychological problems, including: a craving for solitude, a feeling of depression and anxiety. All this directly affects the quality of life of the patient.

Swallowing disorders can provoke various serious complications, which include malnutrition, weight loss, dehydration, as a person cannot take liquid and food in the quantities necessary to maintain a normal level of hydration and nutritional status.

swallowing- a reflex muscle act, in which, as a result of contraction of some and relaxation of other muscles, a food lump - a bolus is transferred through the pharynx and esophagus to the stomach.

Phases of swallowing

The act of swallowing is divided into three phases: oral, pharyngeal and esophageal.

During oral phase, performed arbitrarily, from food chewed in the mouth, moistened with saliva and become slippery, a bolus is formed - a food lump with a volume of about 5-15 ml. The movements of the tongue and cheeks move the bolus to the back of the tongue. With tongue contractions, the food bolus is pressed against the hard palate and transferred to the root of the tongue behind the anterior palatoglossal arches.

next phase, pharyngeal, fast, short, involuntary. Irritation of the receptors of the root of the tongue causes a contraction of the muscles that lift the soft palate, thus closing the communication of the pharynx with the nasal cavity in order to prevent food from entering it. The movements of the tongue push the food bolus into the pharynx. In this case, there is a contraction of the muscles that displace the hyoid bone and cause the larynx to rise. To prevent food from entering the respiratory tract, the epiglottis blocks the entrance to the larynx. The pressure in the mouth increases, and in the pharynx it decreases, thus facilitating the movement of the bolus of food into the pharynx. The reverse movement of food into the oral cavity is prevented by the raised root of the tongue and the palatoglossal arches tightly adjacent to it. When a bolus enters the pharynx, the longitudinal pharyngeal elevator muscles: stylopharyngeal and tubopharyngeal lift the pharynx upward, and the constrictors of the pharynx sequentially, from the upper to the lower constrictor, contract, as a result of which the bolus is pushed towards the esophagus.

third phase, esophageal, involuntary and, in comparison with the previous ones, longer. When swallowing a liquid, it lasts 1-2 seconds, when swallowing a bolus of solid food - 8-9 seconds.

swallowing is a natural process of the body during meals. During the act of swallowing, the muscles of the throat make more than a hundred movements throughout the day. It is one of those processes that you hardly notice until disturbances occur. During swallowing, the circular muscle of the upper esophagus, called the sphincter, relaxes. This process moves the contents of the mouth through the throat into the digestive system. This process proceeds smoothly in the absence of tension, fear. With these emotional states, spasms occur in the pharynx. swallowing problems or dysphagia accompanied by pain and discomfort in the throat. This serious violation of the body's natural reflexes must be treated.

Causes of swallowing disorders

Causes of violations of the act of swallowing can be mainly divided into mechanical and functional. The first arise as a result of a discrepancy between the size of a piece of food and the lumen of the esophagus. Functional arise with violations of peristalsis. It should be borne in mind that a violation of swallowing as a result leads to exhaustion of the body, weight loss, coughing. Pneumonia may also develop.

Narrowing of the lumen of the esophagus can also be a swallowing problem. It can happen as a result of:

edema (tonsillitis, stomatitis);
stenosis (food and pharyngeal);
scars (burns, postoperative);
malignant tumors (cancer of the esophagus);
benign formations (polyps, tonsillitis).

There may also be external pressure on the esophagus, as a result of:

enlargement of the thyroid gland;
cervical spondylitis;
diverticulum;
osteophyte.

Functional disorders swallowing is associated with impaired muscle function when:

paralysis of the tongue;
damage to the glossopharyngeal nerve;
diseases of the muscles of the pharynx and esophagus (stroke);
damage to the smooth muscles of the esophagus (neuropathy, myopathy, alcoholism).

Approximately 50% of people with swallowing disorders have experienced a stroke. There may also be quite rare causes of violations of the act of swallowing, namely:

Parkinson's disease;
multiple sclerosis;
cerebral paralysis;
chronic inflammation of the lungs;
systemic scleroderma (connective tissue disease);
esophagitis (inflammation of the esophageal mucosa).

Concomitant factors of swallowing disorders

It must be understood that swallowing disorders are also associated with the following factors:

pain and shortness of breath;
cough during and after swallowing;
feeling of lack of air in the process of swallowing.

Syndrome "coma in the throat"

The sensation of a lump in the throat is a common complaint of patients visiting an otolaryngologist. There are several reasons for this feeling:

There is an object in the throat that interferes with the act of swallowing;
reflux disease;
chronic pharyngitis;
psychological factors.

Reflux is the backflow of stomach contents into the esophagus and further into the throat. Muscle spasm in the pharynx, which causes the sensation of "coma", is provoked by gastric contents (the acidic contents of the stomach burn the mucous membrane of the esophagus and throat). Quite often, the appearance of the "coma in the throat" syndrome is facilitated by stressful situations, a state of strong excitement or fear.

Consequences of swallowing disorders

It should be taken seriously to eliminate the causes of the disease, as complications can be serious. In severe cases, there may be:

Esophagitis (inflammation of the esophagus);
development of esophageal cancer;
aspiration pneumonia;
lung abscesses;
pneumosclerosis.

Prevention of swallowing disorders

To avoid problems with swallowing, you need to eat a rational and balanced diet, stop smoking. It is also important to follow up with a doctor and treat throat diseases in time. In some cases, swallowing disorders can be caused in children by swallowing small toys and parts. You need to keep an eye on them and do not buy toys with too small details.

Treatment of swallowing disorders

Treatment primarily depends on the cause of the swallowing problem. Today, swallowing disorders do not pose a serious threat to the life of the patient, if you turn to a specialist in time. The doctor will help determine the cause and eliminate it. If the patient has tumors that cause swallowing disorders, an additional consultation with an oncologist is necessary. With neurological causes of swallowing disorders, a psychotherapist is consulted. The attending physician prescribes to the patient a special diet, almost all products are consumed in the form of puree, so as not to irritate the esophagus. If the patient is not capable of self-feeding, feeding occurs through a tube or intravenously. With muscle dysfunction, special exercises are prescribed, sometimes the esophagus is expanded. Massage for dysphagia is also effective. In the case of gastroesophageal reflux or esophagitis, the prescribed drugs will reduce stomach acidity.

Chewing- a physiological act, which consists in grinding food substances with the help of teeth and the formation of a food lump. Chewing ensures the quality of mechanical processing of food and determines the time of its stay in the oral cavity, has a reflex stimulating effect on the secretory and motor activity of the stomach and intestines. Chewing involves the upper and lower jaws, chewing and mimic muscles of the face, tongue, soft palate. Mechanical processing of food between the upper and lower rows of teeth is carried out due to the movement of the lower jaw relative to the upper. An adult in a row on the right and left has teeth of different functional purposes - 2 incisors and one canine (biting off food), 2 small and 3 large molars that crush and grind food - a total of 32 teeth. The chewing process has 4 phases- the introduction of food into the mouth, indicative, basic and the formation of food coca.

chewing is regulated reflexively. Excitation from receptors of the oral mucosa (mechano-, chemo- and thermoreceptors) is transmitted through afferent fibers of the II, III branches of the trigeminal, glossopharyngeal, superior laryngeal nerve and tympanic string in chewing center which is located in the medulla oblongata. Excitation from the center to the chewing muscles is transmitted through the efferent fibers of the trigeminal, facial and hypoglossal nerves. Excitation from the sensory nuclei of the brainstem along the afferent pathway through the specific nuclei of the thalamus switches to the cortical section of the gustatory sensory system, where the analysis and synthesis of information from the receptors of the oral mucosa is carried out.

At the level of the cerebral cortex, sensory impulses are switched to efferent neurons, which send regulatory influences along descending pathways to the chewing center of the medulla oblongata.

swallowing- a reflex act by which food is transferred from the RP to the stomach. The act of swallowing consists of 3 phases:

oral (arbitrary);

pharyngeal (involuntary, fast);

esophageal (involuntary, slow).

AT 1st phase the tongue pushes the food bolus down the throat.

In 2nd phase stimulation of pharyngeal entry receptors triggers a complex coordinated act, including:

raising the soft palate with blocking the entrance to the nasopharynx;

contraction of the muscles of the pharynx with pushing the food bolus into the esophagus;

opening of the upper esophageal sphincter.

AT esophageal phase stimulation of the esophagus triggers a peristaltic wave generated by both somatic nerves and intramural neurons. When the food bolus reaches the distal end of the esophagus, the lower esophageal sphincter opens briefly

Swallowing regulation mechanism:

The food lump irritates the receptors of the tongue, pharynx. In these receptors, APs are generated, which are sent in the form of nerve impulses along the afferent nerves (n. trigeminus, n. glossopharyngeus and superior laryngeal nerve) to the swallowing center, which is located in the medulla oblongata, just above the center of respiration. The swallowing center is excited and sends nerves along the efferent nerves (n. trigeminus, n. glossopharyngeus, n. hypoglossus, n. vagus) to the muscles, which promotes the food bolus in the oral cavity and pharynx.

The function of the swallowing center is closely related to the function of the SCC and the respiratory center. The act of swallowing is performed arbitrarily until the food bolus falls behind the palatine arches. Then the process of swallowing becomes involuntary. The possibility of voluntary swallowing indicates participation in the mechanism of swallowing of the CGM.

Solid food passes through the esophagus in 8-10 seconds, liquid - in 1-2 seconds. The food bolus moves along the esophagus with the help of peristaltic contractions of the muscles of the walls. The walls of the upper third of the esophagus contain striated muscles, the lower 2/3 - smooth muscles. The esophagus is innervated by parasympathetic and sympathetic nerves. Parasympathetic nerves (n. vagus) stimulate the motor function of the muscles of the esophagus, sympathetic nerves - weaken. From the esophagus, the food bolus enters the stomach, where it undergoes further mechanical and chemical processing.

69. Digestion in the stomach. Composition and properties of gastric juice. Regulation of gastric secretion. Phases of the separation of gastric juice. Features of gastric secretion during the digestion of proteins, fats, carbohydrates.

In the stomach, food mixed with saliva and mucus is retained from 3 to 10 hours for its mechanical and chemical processing. The stomach performs the following functions:

depositing food;

secretion of gastric juice;

mixing food with digestive juices;

its evacuation - movement in portions to the KDP;

absorption into the blood of a small amount of substances received with food;

excretion (excretion) together with gastric juice into the stomach cavity of metabolites (urea, uric acid, creatine, creatinine), substances that enter the body from outside (heavy metal salts, iodine, pharmacological preparations);

the formation of active substances (incretion) involved in the regulation of the activity of the gastric and other digestive glands (gastrin, histamine, somatostatin, motilin, etc.);

bactericidal and bacteriostatic action of gastric juice);

removal of poor-quality food, preventing it from entering the intestines.

Gastric juice is secreted by glands, which consist of main (glandulocytes, secrete enzymes), parietal (perital, secrete HCl) and accessory (mucocytes, secrete mucus) cells. In the fundus and body of the stomach, the glands consist of the main, parietal, and accessory cells. The pyloric glands are composed of principal and accessory cells and do not contain parietal cells. The juice of the pyloric region is rich in enzymes and mucoid substances and has an alkaline reaction. The juice of the fundus of the stomach is acidic.

The amount and composition of gastric juice:

During the day, a person secretes from 1 to 2 liters of gastric juice. The amount and composition of it depends on the nature of the food, its reactionary properties. The gastric juice of humans and dogs is a colorless transparent liquid with an acidic reaction (pH = 0.8 - 5.5). The acidic reaction is provided by HCl. Gastric juice contains 99.4% water and 0.6% solids. The dry residue contains organic (products of hydrolysis of proteins, fats, lactic acid, urea, uric acid, etc.) and inorganic (salts of Na, K, Mg, Ca, rhodanide compounds) substances. Gastric juice contains enzymes:

proteolytic (break down proteins) - pepsin and gastrixin;

Pepsin is released in an inactive form (pepsinogen) and activated by HCl. Pepsin hydrolyzes proteins to polypeptides, peptones, albumose and partially to amino acids. Pepsin is active only in an acidic environment. The maximum activity is manifested at pH = 1.5 - 3, then its activity weakens and gastrixin acts (pH = 3 - 5.5). There are no enzymes that break down carbohydrates (starch) in the stomach. Digestion of carbohydrates in the stomach amylase saliva until the chyme is completely oxidized. In an acidic environment, amylase is not active.

MeaningHCl:

converts pepsinogen into pepsin, creates an optimal environment for the action of pepsin;

softens proteins, promotes their swelling and thereby makes them more accessible for the action of enzymes;

promotes curdling of milk;

under its influence, a number of enzymes are formed in the duodenum and small intestine: secretin, pancreozymin, cholecystokinin;

stimulates the motor function of the gastrointestinal tract;

has bactericidal and bacteriostatic action.

The value of mucus (mucoid) in the stomach:

protects the gastric mucosa from the damaging effects of mechanical and chemical food irritants;

adsorbs enzymes, therefore contains them in large quantities and thereby enhances the enzymatic effect on food;

adsorbs vitamins A, B, C, protects them from destruction by gastric juice;

contains substances that stimulate the activity of the gastric glands;

contains the Castle factor, which promotes the absorption of vitamin B12.

On an empty stomach in a person, gastric juice is not secreted or is secreted in a small amount. On an empty stomach, mucus predominates, which has an alkaline reaction. The secretion of gastric juice occurs during preparation for a meal (fire juice according to Pavlov) and while food is in the stomach. At the same time, they distinguish:

latent period is the time from the start of food entry into the stomach to the start of secretion. The latent period depends on the excitability of the gastric glands, on the properties of food, on the activity of the nerve center that regulates gastric secretion.

juicing period- continues as long as food is in the stomach.

Aftereffect period.

Regulation of gastric secretion (RGS):

Currently distinguished:

complex-reflex phase of RHD;

humoral phase of RHD, which is divided into gastric and intestinal.

Complex reflex phase includes unconditioned reflex and conditioned reflex mechanisms of RHD. The complex reflex phase was carefully studied by Pavlov in experiments with imaginary feeding (showing food - a conditioned reflex mechanism). Parasympathetic and sympathetic nerves are of great importance in RHD. Pavlov's experiments with transection of nerves showed that the parasympathetic nerves increase secretion, while the sympathetic ones weaken it. The same patterns are observed in humans. The medulla oblongata regulates secretion and ensures digestion in the stomach. The hypothalamus makes an assessment of food and its need for the body. KGM provides the formation of eating behavior.

Phase of gastric secretion stimulate:

food that enters the stomach. It irritates the receptors in the gastric mucosa, they generate action potentials, which in the form of nerve impulses along the afferent nerves enter the digestive center in the medulla oblongata. It is excited and sends nerve impulses along the efferent nerves (n. vagus) and enhances secretion.

gastrin produced by the gastric mucosa stimulates the release of HCl.

histamine produced by the gastric mucosa.

products of protein hydrolysis (amino acids, peptides).

bombesin - stimulates the production of gastrin by G-cells.

Phase of gastric secretion slow down:

secretin - produced by the mucous membrane of the small intestine;

cholecystokinin-pancreozymin;

intestinal enzymes (GIP - gastric intestinal peptide and VIP-harmone, somatostatin, enterogastron, serotonin);

Chyme, coming from the stomach to the duodenum, inhibits the release of HCl in the stomach.

phase of intestinal secretion stimulate:

acidic chyme entering the intestine from the stomach irritates mechanoreceptors and chemoreceptors, they generate AP, which in the form of NI through afferent nerves enter the center of digestion in the medulla oblongata. It is excited and sends nerve impulses along the efferent nerves (n. vagus) to the glands of the stomach, stimulating their function.

enterogastrin - secreted by the intestinal mucosa, enters the bloodstream and acts on the glands of the stomach.

protein hydrolysis products. In the intestines, they are absorbed into the blood and with it they enter the glands of the stomach, stimulating their function.

phase of intestinal secretion slow down:

products of hydrolysis of fats and starch. In the intestines, they are absorbed into the blood and with it they enter the glands of the stomach, inhibiting their function.

secretin.

cholecystokinin-pancreozymin.

enterogastron.

Gastric secretion during the digestion of various nutrients.

Adaptation of the secretory apparatus of the stomach to the nature of food is due to its quality, quantity, and diet. A classic example of adaptive reactions of the gastric glands is studied by I.P. Pavlovian reaction of the digestive glands in response to a meal containing mainly carbohydrates (bread), proteins (meat), fats (milk).

The most effective stimulant of secretion is protein food. Proteins and products of their digestion have a pronounced sap action. After eating meat, a rather vigorous secretion of gastric juice develops with a maximum at the 2nd hour. It lasts about 7 hours. A prolonged meat diet leads to an increase in gastric secretion to all food irritants, an increase in acidity and the digestive power of gastric juice. This suggests that under the influence of strong causative agents of secretion, a steady restructuring occurs in the activity of the gastric glands and the mechanisms of their regulation.

carbohydrate food(bread) - a weaker causative agent of secretion of gastric juice. Bread is poor in chemical stimulants of secretion, therefore, after taking it, a secretory response develops with a maximum at the 1st hour (reflex separation of juice), and then sharply decreases and remains at a low level for a long time (due to weak mobilization of humoral mechanisms of excitation of glandulocytes). With long-term nutrition of a person with carbohydrates, the acidity and digestive power of the juice decrease, which is a consequence of the adaptation of the stomach glands to food containing a small amount, the products of incomplete hydrolysis of which stimulate the production of hydrochloric acid and pepsinogen.

Fats milk cause gastric secretion in 2 stages: inhibitory and excitatory. This explains the fact that after the intake of fatty foods, the maximum secretion of juice is observed only by the end of the 3rd hour. The first portions of milk that got from the stomach to the duodenum have an inhibitory effect on the secretion of gastric juice. As a result of long-term nutrition with fatty foods, there is an increase in gastric secretion to all food irritants due to the second half of the secretory period. The digestive power of juice when using fats in food is lower compared to the juice released for meat, but higher than when eating carbohydrate food.

The amount of nutrient juice, its acidity and proteolytic activity also depend on the amount and consistency of the food taken. As the volume of food increases, the secretion of gastric juice increases.