Human digestive system splitting. How does the human digestive system work? Oral cavity and its contents

After all, during our lives we eat about 40 tons of different foods, which directly affect almost all aspects of our life. It is no coincidence that in ancient times they said: “Man is what he eats.”

Human digestive system carries out the digestion of food (through its physical and chemical processing), absorption of products, breakdown through the mucous membrane into the lymph, as well as the removal of undigested residues.

The process of grinding food begins in the mouth. There it is softened by saliva, chewed and sent down the throat. Next, the formed food bolus enters the esophagus into the stomach.

Thanks to the acidic gastric juice, a very complex enzymatic process of food digestion begins in this muscular organ.

Enzymes are protein substances that accelerate chemical processes in cells.

The structure of the digestive system

The human digestive system consists of the gastrointestinal tract and auxiliary organs (salivary glands, liver, pancreas, gall bladder, etc.).

Conventionally, there are three sections of the digestive system.

• The anterior section includes the organs of the oral cavity, pharynx and esophagus. Here, mainly mechanical processing of food is carried out.
• The middle section consists of the stomach, small and large intestines, liver and pancreas; in this section, the chemical processing of food, the absorption of nutrients and the formation of feces are carried out mainly.
• The posterior section is represented by the caudal part of the rectum and ensures the removal of feces from the body.

Organs of the digestive system

We will not consider all the organs of the digestive system, but will present only the main ones.

Stomach

The stomach is a muscular sac, the volume of which in adults is 1.5-2 liters. Gastric juice contains caustic hydrochloric acid, so every two weeks the inner lining of the stomach is replaced with a new one.

Food moves through the digestive tract by contraction of the smooth muscles of the esophagus, stomach and intestines. This is called peristalsis.

Small intestine

The small intestine is a section of the human digestive tract located between the stomach and large intestine. From the stomach, food enters the 6-meter small intestine (duodenum, jejunum and ileum). It continues to digest food, but with pancreatic and liver enzymes.

Pancreas

The pancreas is the most important organ of the digestive system; largest gland. Its main function of external secretion is to secrete pancreatic juice, which contains digestive enzymes necessary for the complete digestion of food.

Liver

The liver is the largest internal human organ. It cleanses the blood of toxins, monitors blood glucose levels and produces bile, which breaks down fats in the small intestine.

Gallbladder

The gallbladder is an organ that stores bile coming from the liver for release into the small intestine. Anatomically it is part of the liver.

Colon

The large intestine is the lower, final part of the digestive tract, namely the lower part of the intestine, in which water is mainly absorbed and formed feces are formed from food gruel (chyme). The muscles of the colon work independently of the will of the person.

Soluble sugars and proteins are absorbed through the walls of the small intestine and enter the blood, while undigested residues move on to the large intestine (cecum, colon and rectum).

There, water is absorbed from the food masses, and they gradually become semi-solid and are ultimately eliminated from the body through the rectum and anus.

Interesting facts about the digestive system

When chewing food, the jaw muscles develop a force of up to 72 kg on the molars, and up to 20 kg on the incisors.

By the age of three, a child has grown 20 baby teeth. From the age of six to seven, baby teeth fall out and permanent teeth grow in their place. A person has 32 of these teeth.

What are vitamins

Vitamins (from Latin vita- life) are substances without which the full functioning of all human organs is impossible. They are found in various foods, but mainly in vegetables, fruits and herbs. Vitamins are designated by letters of the Latin alphabet: A, B, C, etc.

Together with food, we receive a supply of “fuel” that provides cells with energy (fats and carbohydrates), “building materials” necessary for the growth and repair of our body (proteins), as well as vitamins, water and minerals.

A deficiency of one or another substance can adversely affect human health.

The human digestive system is an extremely important and complex mechanism. If you have any discomfort after eating, and this discomfort persists for a long time, be sure to consult a gastroenterologist.

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The human digestive system occupies one of the honorable places in the arsenal of knowledge of a personal trainer, solely for the reason that in sports in general and in fitness in particular, almost any result depends on diet. Gaining muscle mass, losing weight, or keeping it off largely depends on what kind of “fuel” you put into your digestive system. The better the fuel, the better the result will be, but the goal now is to understand exactly how this system works and works and what its functions are.

The digestive system is designed to provide the body with nutrients and components and remove residual digestive products from it. Food entering the body is first crushed by the teeth in the oral cavity, then through the esophagus it enters the stomach, where it is digested, then in the small intestine, under the influence of enzymes, the digestive products break down into individual components, and in the large intestine, feces (residual digestive products) are formed. , which is ultimately subject to evacuation from the body.

The structure of the digestive system

The human digestive system includes the organs of the gastrointestinal tract, as well as auxiliary organs, such as the salivary glands, pancreas, gall bladder, liver and more. The digestive system is conventionally divided into three sections. The anterior section, which includes the organs of the oral cavity, pharynx and esophagus. This department carries out food grinding, in other words, mechanical processing. The middle section includes the stomach, small and large intestines, pancreas and liver. Here the chemical processing of food, the absorption of nutritional components and the formation of residual digestive products occur. The posterior section includes the caudal part of the rectum and removes feces from the body.

Structure of the human digestive system: 1- Oral cavity; 2- Palate; 3- Tongue; 4- Language; 5- Teeth; 6- Salivary glands; 7- Sublingual gland; 8- Submandibular gland; 9- Parotid gland; 10- Pharynx; 11- Esophagus; 12- Liver; 13- Gallbladder; 14- Common bile duct; 15- Stomach; 16- Pancreas; 17- Pancreatic duct; 18- Small intestine; 19- Duodenum; 20- Jejunum; 21- Ileum; 22- Appendix; 23- Large intestine; 24- Transverse colon; 25- Ascending colon; 26- Caecum; 27- Descending colon; 28- Sigmoid colon; 29- Rectum; 30- Anal opening.

Gastrointestinal tract

The average length of the digestive canal in an adult is approximately 9-10 meters. It contains the following sections: oral cavity (teeth, tongue, salivary glands), pharynx, esophagus, stomach, small and large intestine.

• Oral cavity- an opening through which food enters the body. On the outside it is surrounded by lips, and inside it there are teeth, tongue and salivary glands. It is inside the oral cavity that food is crushed by the teeth, moistened with saliva from the glands and pushed into the throat by the tongue.
• Pharynx– a digestive tube connecting the oral cavity and the esophagus. Its length is approximately 10-12 cm. Inside the pharynx, the respiratory and digestive tracts intersect, therefore, to prevent food from entering the lungs during swallowing, the epiglottis blocks the entrance to the larynx.
• Esophagus- an element of the digestive tract, a muscular tube through which food from the pharynx enters the stomach. Its length is approximately 25-30 cm. Its function is to actively push crushed food to the stomach, without any additional mixing or pushing.
• Stomach- a muscular organ located in the left hypochondrium. It acts as a reservoir for swallowed food, produces biologically active components, digests and absorbs food. The volume of the stomach ranges from 500 ml to 1 liter, and in some cases up to 4 liters.
• Small intestine– part of the digestive tract located between the stomach and large intestine. Enzymes are produced here, which, in conjunction with enzymes of the pancreas and gall bladder, break down digestive products into individual components.
• Colon- the closing element of the digestive tract, in which water is absorbed and feces are formed. The walls of the intestine are lined with mucous membrane to facilitate the passage of residual digestive products out of the body.

Structure of the stomach: 1- Esophagus; 2- Cardiac sphincter; 3- Fundus of the stomach; 4- Body of the stomach; 5- Greater curvature; 6- Folds of the mucous membrane; 7- Pyloric sphincter; 8- Duodenum.

Auxiliary organs

The process of digesting food occurs with the participation of a number of enzymes that are contained in the juice of some large glands. In the oral cavity there are ducts of the salivary glands, which secrete saliva and moisten both the oral cavity and food with it to facilitate its passage through the esophagus. Also in the oral cavity, with the participation of salivary enzymes, the digestion of carbohydrates begins. Pancreatic juice and bile are secreted into the duodenum. Pancreatic juice contains bicarbonates and a number of enzymes such as trypsin, chymotrypsin, lipase, pancreatic amylase and more. Bile accumulates in the gallbladder before entering the intestines, and bile enzymes allow fats to be separated into small fractions, which accelerates their breakdown by the enzyme lipase.

• Salivary glands divided into small and large. Small ones are located in the oral mucosa and are classified by location (buccal, labial, lingual, molar and palatine) or by the nature of the discharge products (serous, mucous, mixed). The sizes of the glands vary from 1 to 5 mm. The most numerous among them are the labial and palatal glands. The major salivary glands are divided into three pairs: parotid, submandibular and sublingual.
• Pancreas- an organ of the digestive system that secretes pancreatic juice, which contains digestive enzymes necessary for the digestion of proteins, fats and carbohydrates. The main pancreatic substance of duct cells contains bicarbonate anions that can neutralize the acidity of residual digestive products. The islet apparatus of the pancreas also produces the hormones insulin, glucagon, and somatostatin.
• Gallbladder acts as a reservoir for bile produced by the liver. It is located on the lower surface of the liver and is anatomically part of it. The accumulated bile is released into the small intestine to ensure normal digestion. Since in the process of digestion itself, bile is not needed all the time, but only periodically, the gallbladder doses its supply with the help of bile ducts and valves.
• Liver- one of the few unpaired organs in the human body that performs many vital functions. It also participates in the digestive processes. Provides the body's needs for glucose, transforms various energy sources (free fatty acids, amino acids, glycerin, lactic acid) into glucose. The liver also plays an important role in neutralizing toxins that enter the body with food.

Structure of the liver: 1- Right lobe of the liver; 2- Hepatic vein; 3- Aperture; 4- Left lobe of the liver; 5- Hepatic artery; 6- Portal vein; 7- Common bile duct; 8- Gallbladder. I- Path of blood to the heart; II- Path of blood from the heart; III- Path of blood from the intestines; IV- The path of bile to the intestines.

Functions of the digestive system

All functions of the human digestive system are divided into 4 categories:

• Mechanical. Involves chopping and pushing food;
• Secretory. Production of enzymes, digestive juices, saliva and bile;
• Suction. Absorption of proteins, fats, carbohydrates, vitamins, minerals and water;
• Highlighting. Removing the remains of digestive products from the body.

In the oral cavity, with the help of teeth, tongue and the secretion product of the salivary glands, during chewing, primary processing of food occurs, which consists of grinding it, mixing it and moistening it with saliva. Further, during the process of swallowing, food in the form of a lump descends through the esophagus into the stomach, where it is further chemically and mechanically processed. In the stomach, food accumulates and mixes with gastric juice, which contains acid, enzymes and breakdown proteins. Next, food in the form of chyme (liquid contents of the stomach) enters in small portions into the small intestine, where its chemical processing continues with the help of bile and secretion products of the pancreas and intestinal glands. Here, in the small intestine, nutrients are absorbed into the blood. Those food components that are not absorbed move further into the large intestine, where they undergo breakdown under the influence of bacteria. In the colon, water is also absorbed, and then feces are formed from residual digestive products that have not been digested or absorbed. The latter are removed from the body through the anus during defecation.

Structure of the pancreas: 1- Accessory duct of the pancreas; 2- Main pancreatic duct; 3- Tail of the pancreas; 4- Body of the pancreas; 5- Neck of the pancreas; 6- Uncinate process; 7- Papilla of Vater; 8- Lesser papilla; 9- Common bile duct.

Conclusion

The human digestive system is of exceptional importance in fitness and bodybuilding, but of course it is not limited to them. Any intake of nutrients into the body, such as proteins, fats, carbohydrates, vitamins, minerals and more, occurs precisely through the digestive system. Achieving any muscle gain or weight loss results also depends on your digestive system. Its structure allows us to understand which way food goes, what functions the digestive organs perform, what is absorbed and what is excreted from the body, and so on. Not only your athletic performance, but, by and large, your overall health depends on the health of your digestive system.

The human digestive system is a complex system of organs responsible for the breakdown and absorption of nutrients supplied with food. The complex of digestive organs includes: oral cavity, esophagus, stomach, small intestine, large intestine, rectum. In addition, the digestive system also includes the liver, gallbladder and bile ducts, and pancreas. Topographically, the digestive organs include the head, cervical, thoracic, abdominal and pelvic parts of the digestive organs.

The digestive tract (digestive tube) is understood as a part of the digestive apparatus that has a tubular structure: the esophagus, stomach, small and large intestines. Food enters the digestive system through the oral cavity, which is the initial organ of digestion. The digestive organs are 12 meters long and work in two phases. The mechanical phase occurs mainly in the oral cavity and consists of breaking up the food eaten into particles small enough to be swallowed. The chemical phase represents the transformation of food into substances absorbed by the body, which is achieved through the action of various juices secreted by the digestive glands. The final organ of the digestive system is the anus (anus).

The mouth is the entry point for food and the beginning of the digestive system. The oral cavity is lined with mucous membrane. The ducts of the salivary glands open into it. Salivary glands - these three pairs of glands secrete saliva, which moistens and begins the chemical processing of food. At the bottom of the mouth are the tongue and teeth that chew food. With the help of the tongue, a person tastes and mixes food. The ability to taste allows you to distinguish between sweet, sour, salty and bitter; the sense of smell allows you to distinguish many odors. Taste is perceived by taste endings located on the surface of the tongue; smell - olfactory receptors, which are located in the upper part of the nasal mucosa.

The mouth goes into the throat. Swallowing begins voluntarily and continues automatically. During swallowing, the epiglottis closes the entrance to the larynx, and food does not enter the respiratory tract. The epiglottis is a cartilage located between the larynx and pharynx. The pharynx and stomach are connected by the esophagus, a muscular tube lined with mucous membrane. Food moves down the esophagus through muscle contraction and relaxation - called peristalsis - and enters the stomach through a ring-shaped muscular sphincter that opens and closes. The sphincter prevents food from going back into the esophagus.

The stomach is an organ located in the abdominal cavity. He receives food already moistened with saliva and chewed, mixes it with gastric juice and pushes it through the pylorus into the duodenum. The cells lining the stomach produce three important substances: mucus, hydrochloric acid and pepsinogen, a precursor to the enzyme pepsin. Mucus envelops the cells of the stomach lining. Hydrochloric acid forms an acidic environment in the stomach, which is necessary for the transformation of pepsinogen into pepsin, an enzyme that breaks down proteins. The high acidity of the stomach is a good barrier to infection, as it destroys most bacteria.

From the stomach, food enters the initial part of the small intestine - the duodenum - through the pyloric sphincter in portions that the small intestine can digest. The duodenum receives pancreatic enzymes from the pancreas and bile from the liver. These secretions enter the duodenum through an opening that is located in the center of the eminence - the large duodenal nipple. The mucous membrane of the duodenum over a larger area has folds with small processes - villi. The villi have microvilli. This structure ensures better absorption of nutrients. The rest of the small intestine is located below the duodenum and consists of the jejunum and ileum. This is where the absorption of fats and other nutrients mainly occurs. In general, the small intestine is a part of the digestive tract, 4 to 7 meters long, where pancreatic and gastric juices, bile enter, and where nutrients are absorbed. The consistency of intestinal contents gradually changes as the food mass passes through the small intestine.

The liver is a vital organ for the body. It accumulates glycogen, which is an energy reserve, and secretes bile necessary for the digestion of fats. Bile is secreted from the liver through the right and left hepatic ducts, which join to form the common hepatic duct. Between meals, bile produced by the liver accumulates and is concentrated in the gallbladder.

The gallbladder is an organ located at the bottom of the liver. Food entering the duodenum entails hormonal and nervous signals that cause the gallbladder to contract. As a result, bile is secreted into the duodenum and mixed with its contents.

The large intestine is the last part of the digestive tract. It consists of the cecum, colon and rectum, where water from food is absorbed and feces from undigested foods are formed. The colon is home to many bacteria that break down certain substances to help the body digest food and produce essential elements such as vitamin K.

The rectum is the last link of the large intestine and digestive tract, which connects the colon with the external environment. It begins just behind the sigmoid colon and includes the anus. Normally, the rectum is empty because stool accumulates higher up in the descending colon. Gradually the descending colon fills and stool passes into the rectum, causing the urge to defecate. The anus is the opening at the end of the digestive tract through which feces are removed from the body.

In a healthy person, all digestive organs function very harmoniously, thanks to fine regulation by the nervous system and a number of hormonal substances that are formed in the digestive system itself.

If we briefly characterize the process of digestion, it will be the movement of eaten food through the digestive organs, during which food is broken down into simpler elements. Small substances are able to be absorbed and assimilated by the body, and then pass into the blood and nourish all organs and tissues, allowing them to function normally.

Digestion is a process of mechanical crushing and chemical, mainly enzymatic, breakdown of food into substances that lack species specificity and are suitable for absorption and participation in the metabolism of the human body. Food entering the body is processed by enzymes produced by special cells. Complex food structures, such as proteins, fats and carbohydrates, are broken down with the addition of a water molecule. Proteins break down during digestion into amino acids, fats into glycerol and fatty acids, and carbohydrates into simple sugars. These substances are well absorbed, and then again synthesized into complex compounds in tissues and organs.

The length of the human digestive tract is 9 meters. The process of complete processing of food lasts from 24 to 72 hours and varies from person to person. The digestive system includes the following organs: oral cavity, pharynx, esophagus, stomach, small intestine, large intestine and rectum.

The process of digestion itself is divided into stages of digestion in humans, and they consist of the head, gastric and intestinal phases.

Head phase of digestion

This is the stage where the recycling process begins. A person sees food and smells it, his cerebral cortex is activated, signals of taste and smell begin to enter the hypothalamus and medulla oblongata, which are involved in the digestion process.

A lot of juice is released in the stomach, ready to accept food, enzymes are produced and saliva is actively secreted. Then the food enters the oral cavity, where it is mechanically crushed by chewing with the teeth. At the same time, food is mixed with saliva, and interaction with enzymes and microorganisms begins.

During the digestion process, a certain amount of food is broken down by saliva, which gives the taste of the food. Digestion in the oral cavity breaks down starch into simple sugars by the amylase enzyme found in saliva. Proteins and fats do not break down in the mouth. The whole process in the mouth lasts no more than 15-20 seconds.

The phase of processing food in the stomach of the body

The next phase of the digestion process continues in the stomach. This is the widest part of the digestive organs, capable of stretching and holding quite a lot of food. The stomach tends to contract rhythmically, and the incoming food is mixed with gastric juice. It contains hydrochloric acid, so it has an acidic environment necessary for breaking down food.

Food in the stomach is processed during the digestion process for 3-5 hours, undergoing digestion in every possible way, mechanically and chemically. In addition to hydrochloric acid, the effect is also produced by pepsin. Therefore, the breakdown of proteins into smaller fragments begins: low molecular weight peptides and amino acids. But the breakdown of carbohydrates in the stomach during digestion stops, because amylase stops its action under the pressure of an acidic environment. How does digestion occur in the stomach? Gastric juice contains lipase, which breaks down fats. Hydrochloric acid is of great importance; under its influence, enzymes are activated, denaturation and swelling of proteins occurs, and the bactericidal property of stomach juice is activated.

Please note: Carbohydrate foods remain in this organ for 2 hours during digestion, then they move to the small intestine. But protein and fatty foods are processed in it for 8-10 hours.

Then the food, partially processed by the digestive process and having a liquid or semi-liquid structure, mixed with gastric juice, falls in portions into the small intestine. The stomach contracts at regular intervals during digestion and food is squeezed into the intestines.

Digestive phase in the small intestine of the human body

The logical pattern of food processing in the small intestine is considered the most important in the entire process, because this is where nutrients are most absorbed. This organ contains intestinal juice, which has an alkaline environment and consists of bile that enters the department, pancreatic juice and fluid from the intestinal walls. Digestion at this stage does not last a short time for everyone. This occurs due to a lack of the lactase enzyme, which processes milk sugar, so milk is poorly digestible. Especially in people over 40 years of age. More than 20 different enzymes are involved in the intestinal tract to process food.

The small intestine consists of three parts that pass into each other and depend on the work of the neighbor:

• duodenum;
• skinny;
• ileum.

It is into the duodenum that bile flows from the liver and pancreatic juice during digestion, and it is their effect that leads to the digestion of food. Pancreatic juice contains enzymes that dissolve fats. Here carbohydrates are broken down into simple sugars and proteins. In this organ, the greatest absorption of food occurs; vitamins and nutrients are absorbed by the intestinal walls.

All carbohydrates, fats and parts of proteins are completely digested in the jejunum and ileum under the action of enzymes produced locally. The intestinal mucosa is strewn with villi - enterocytes. They absorb the products of protein and carbohydrate processing, which enter the blood, and fatty elements into the lymph. Due to the large area of ​​the intestinal walls and numerous villi, the absorption surface is approximately 500 square meters.

Next, the food enters the large intestine, where feces are formed, and the mucous membrane of the organ absorbs water and other useful microelements. The large intestine ends in a straight section connected to the anus.

The role of the liver in processing food in the body

The liver produces bile during digestion from 500 to 1500 ml per day. Bile is released into the small intestine and does a lot of work there: it helps emulsify fats, absorb triglycerides, stimulates lipase activity, improves peristalsis, inactivates pepsin in the duodenum, disinfects, improves hydrolysis and absorption of proteins and carbohydrates.

This is interesting: Bile does not contain enzymes, but is required for the breakdown of fats and fat-soluble vitamins. If it is produced in a small volume, then the processing and absorption of fats is disrupted, and they leave the body naturally.

How does digestion work without the gallbladder and bile?

Recently, surgical removal of the gallbladder, an organ in the form of a sac for storing and storing bile, has often been performed. The liver produces bile continuously, and it is required only at the time of food processing. When food is processed, the duodenum becomes empty and the need for bile disappears.

What happens when bile is absent and what is digestion without one of the main organs? If it is removed before changes begin in organs that are interdependent with it, its absence is tolerated normally. Bile, continuously produced by the liver, accumulates in its ducts during the digestion process, and then goes directly to the duodenum.

Important! Bile is released there, regardless of the presence of food in it, therefore, immediately after the operation you need to eat often, but little by little. This is required so that there will not be enough bile to process a large volume of food. Sometimes the body needs time to learn to live without the gallbladder and the bile it produces so that it finds a place to accumulate this fluid.

Digestion of food in the body's large intestine

The remains of unprocessed food then go to the large intestine, where they are digested for at least 10-15 hours. The large intestine measures 1.5 meters and contains three sections: cecum, transverse colon and rectum. The following processes occur in this organ: absorption of water and microbial metabolization of nutrients. Ballast is of great importance in the processing of food in the large intestine. It includes non-recyclable biochemical substances: fiber, resins, wax, hemicellulose, lignin, gums. That part of dietary fiber that is not broken down in the stomach and small intestine is processed in the colon by microorganisms. The structural and chemical composition of food affects the duration of absorption of substances in the small intestine and its movement through the gastrointestinal tract.

In the colon, during the digestion process, feces are formed, which include unprocessed food debris, mucus, dead cells of the intestinal mucosa, and microbes that constantly multiply in the intestine and cause fermentation and bloating.

Breakdown and absorption of nutrients in the body

The cycle of food processing and absorption of necessary elements in a healthy person lasts from 24 to 36 hours. Throughout its entire length, mechanical and chemical effects occur on food in order to break it down into simple substances that can be absorbed into the blood. It occurs throughout the gastrointestinal tract during the digestion process, the mucous membrane of which is strewn with small villi.

This is interesting: Normal absorption of fat-soluble foods requires bile and fats in the intestines. Blood capillaries are used to absorb water-soluble substances such as amino acids and monosaccharides.

We studied anatomy at school for a long time, and much was forgotten. Let's try to remember the structure of the digestive system and talk about what the various digestive organs are responsible for and what happens to the food we eat?

Human digestive system arranged amazingly rationally. It consists of two main parts - the digestive tract (canal), consisting of the pharynx, esophagus, stomach and intestines, and the digestive glands - salivary, pancreas, liver with gall bladder and glandular cells located in the mucous membrane of the digestive tract.

The digestive canal, in a very simplified form, can be represented as a hollow tube 8-12 m long, which begins with the oral cavity (input) and ends with the anus (exit).

The walls of all organs of the digestive tract consist of smooth muscles, which ensure their motility. The internal part of these organs is lined with a mucous membrane, which protects their walls from microorganisms and mechanical influences. The walls contain glands and receptors that transmit information to the brain about the operation of the system and respond to problems - in this case we feel discomfort or pain.

At each stage of passage through the digestive canal, the food eaten undergoes various transformations.

Oral cavity- here food is mechanically crushed using teeth and tongue, partially disinfected, and also undergoes initial chemical treatment. Saliva contains the enzyme amylase (ptialin), which breaks down starch into sugars (if you chew even the most unleavened bread for a long time, you will feel a sweet taste). The more thoroughly food is chewed, the easier its further transformations occur in the digestive tract and the better it is absorbed. In addition, saliva contains a mucous substance - mucin, which envelops and “lubricates” food particles, facilitating their movement along the digestive canal.

Pharynx and esophagus ensure the passage of the food bolus further along the digestive tract. At the moment of swallowing, the cartilaginous epiglottis closes, so that food does not enter the respiratory system. Therefore, talking while eating is dangerous - a piece of food can get into the trachea and block breathing.

Stomach- an expanded part of the digestive tract (muscular sac) with a volume of 1.5 to 3 liters. The stomach has two muscular sphincters: one prevents food from returning back into the esophagus, the other (pylorus) opens the way from the stomach to the duodenum. The main part of the stomach is on the left side of the body, closer to the heart, so stomach pain often resembles heart pain. Produced by special glands in the mucous membrane, gastric juice consists of hydrochloric acid and the enzyme pepsin, which acts on protein molecules. Their amount depends on the nature of the food: in some cases, the environment may be very acidic and contain a lot of pepsin (for example, if you ate meat or fish), and in others, it may produce slightly acidic gastric juice poor in pepsin (when eating foods rich in carbohydrates). and fats). Pepsin partially breaks down proteins, and hydrochloric acid prepares complex sugars for further breakdown and kills microorganisms that come with food. In the stomach, food is not absorbed, with the exception of some water, simple sugars and salts. Alcohol and some medications are also quickly absorbed through the walls of the stomach.

Duodenum. When the acidity of the food bolus reaches a certain value, the pyloric sphincter opens and food enters the first section of the small intestine. The ducts of the pancreas exit into the duodenum, secreting pancreatic juice, which contains enzymes that break down proteins (trypsinogen and chymotrypsinogen), carbohydrates (amylase) and fats (lipase). The bile ducts through which bile enters also exit here. It activates pancreatic enzymes, emulsifies (converts into microscopic drops) fats, ensures the absorption of water-insoluble fatty acids, cholesterol, fat-soluble vitamins (D, E, K, A) and calcium salts, enhances the absorption of proteins and carbohydrates, and prevents the development of putrefactive processes .

Small intestine(jejunum and ileum) are the sections where all the main processes of digestion occur (it is here, and not in the stomach). Under the influence of intestinal enzymes and pancreatic juice, proteins, fats, carbohydrates and nucleic acids are broken down and absorbed. The small intestine is also where the bulk of vitamins and minerals are absorbed.

Colon consists of the cecum (including the appendix), colon, sigmoid and rectum. Here water is absorbed, feces are formed and excreted from the body. The large intestine contains a huge number of microorganisms that partially break down fiber, synthesize vitamins and nutrients, and also provide immunity.

Naturally, this is only a simplified picture; digestion processes are much more complex. As for the time required to digest food, it depends on many factors: the composition of the food, the state of the digestive system, the individual characteristics of the body, and even psychological factors, since food eaten with pleasure is processed and absorbed faster. In the stomach, food lingers for a period of time from 30 minutes (light fruits) to 3-5 hours (legumes, fatty meats, mushrooms). It can take up to 5 hours for the small intestine to completely process and absorb food, and in the large intestine it lingers for an average of 8-12 hours. This time may be longer if you have eaten a lot of complex foods.