Gastrointestinal tract - structure, anatomy and physiology of organs

Isn't it paradoxical - people, even humanitarians, who have nothing to do with technology, are well versed in the design of their car, own computer, but when it comes to the structure of the human body, it is difficult to say on which side the liver is located and where pancreas. The striking "ignorance" of the majority in this matter is most likely based on the fact that many do not want to burden themselves with unnecessary knowledge. But knowledge of anatomy cannot be called superfluous. Sometimes the ability to recognize certain symptoms in time helps a person not to become disabled or saves his life. And such cases are not uncommon. This is why knowing your body composition is important. Especially the structure of one of the largest, complexly designed and important of its systems - the gastrointestinal tract.

How does the digestion process take place?

Between the entry of food into the oral cavity and the elimination of its residual elements from the body, a time elapses from 24 hours to two days. During this time, food overcomes a five-meter distance and undergoes various kinds of metamorphosis.

By the way. The digestive tract in the human body stretches almost five meters (average 4.8 m). This is the average length of the system from the larynx to the anus.

1. The digestion process begins in the oral cavity, where the food goes through the first stage of grinding (crushed by the teeth) and primary processing (salivary enzymes). It is here, in the first digestive stage, that starch is broken down.
   

   Oral cavity

2. Further, the resulting mushy substance in various degrees of grinding (depending on how much the product was in the mouth and how carefully it was chewed) is sent down into the esophagus.
   

   Digestion in the mouth

3. The esophagus has one function - to deliver food to the stomach. For this, its walls are equipped with muscle valves that direct food to the stomach, even if the person does not occupy a strictly vertical position when swallowing food.
   

   Esophagus

4. In the stomach - the main "depot", where the first part of the digestion process takes place, food is delayed for the period necessary for its processing (usually two to four hours). The empty stomach (without food) has a volume of half a liter. This is on average, but the rates do not normally differ much in adults. It is located in the upper abdominal area, slightly shifted to the left. An acidic environment forms in the stomach, which breaks down protein, animal collagens and assimilates vitamins.
   

   Stomach

5. The food then travels to the small intestine, which is the first in its path. Doctors say that the area of ​​a straightened intestine is 40 m², but no one will straighten it in order to measure it - these are only calculated experimental theoretical data. Here food is delayed for another four hours.
   

   Small intestine

6. The small intestine is divided into three sections. The first duodenum is the most important. In it, the digestion processes are completed by 80%.
7. Further, substances that have already lost their nutritional value travel through the sections of the large intestine, where they are finally emptied (water, sugar and everything that has not yet been released are released from them).
   

   Colon lymphatic vessels and nodes

8. In the large intestine, residual food fragments are enveloped in mucus, and a so-called residual lump is formed, which is excreted from the body through the rectum through the anus.
   

   Rectum anatomy

Table. Elements of the gastrointestinal tract.

Structural element	Description
Oral cavity	The starting point of the digestive tract. It takes food and prepares it.
Pharynx	Sends food from the mouth to the esophagus.
Esophagus	Redirects food to the stomach.
Stomach	Partially digests food.
Intestines	Completes the digestion process and removes leftovers.

But the GI tract is not limited to the esophagus, stomach, and intestines. Many other organs and systems are involved in digestion directly or indirectly.

Internal organs involved in the digestive tract

Starting from the level of the duodenum, in the immediate vicinity or some distance from it, the vital internal organs are located one way or another, participating in the digestive process and activity of the gastrointestinal tract.

Liver and gallbladder

On the right, the hypochondrium is occupied by the liver. Without it, the body's metabolic processes are impossible. The organ produces bile, which is sent to the gallbladder and from there is supplied to the gastrointestinal zone, where it is directly involved, along with gastric juice, in the digestion of food. Also, thanks to the liver, the glucose level in the blood is maintained, toxins (poisons, alcohol) that enter the body are detoxified. This is where the synthesis of bilirubin, the activation of vitamin D and the breakdown of hormones take place.

Pancreas

Its location can be judged by its name. It is located under the stomach, near the posterior abdominal wall, with an offset to the left. It is engaged in the production of hormones, thanks to which glucose metabolism is possible. It also produces juice enriched with digestive enzymes (pancreatic), which is redirected through the duct of the same name into the duodenum.

How the gastrointestinal tract works

Sometimes it happens that a person cannot even decide which doctor to turn to when a problem in the gastrointestinal tract is discovered. The specialty of the doctor is called a gastroenterologist, but in the process of diagnosis and treatment they can participate, depending on the disease and its localization: therapist, oncologist, proctologist, surgeon, otolaryngologist.

By the way. Knowledge and understanding of the gastrointestinal tract device will help everyone to decide which doctor to go to with certain complaints, because, at least in most cases, the patient's self-diagnosis is erroneous, but being aware of the problem and having basic anatomical information gives a positive result.

The device and functions of the oral cavity

This is where it all starts when food enters the mouth. The oral cavity is a confined space. Lips are located in front, on the contrary, there is a hard and soft palate, the tongue is located below, and the cheeks are on the sides.

By the way. Communication with the digestive system, the starting point of which the oral cavity is, is carried out with the help of the pharynx. It is in the throat isthmus that food from the oral cavity passes into the pharyngeal cavity.

The soft palate contains muscles that help to carry out the act of swallowing. The tongue is also a muscular organ, thanks to which swallowing and partially chewing manipulations are performed.

By the way. The papillae covering the tongue are necessary for the sensation of taste (at the tip - sweet, at the root - bitter, in the middle and on the side - sour).

Of course, here, in the oral cavity, there is a dentoalveolar apparatus, which chews food, crushing it for further passage into the esophagus. The salivary glands produce a salivary enzyme for its primary breakdown.

Pharynx function

The main function of the pharynx is to attach the esophagus to the oral cavity. It is a posterior muscle tube. It has three parts: the nasopharynx, the oropharynx and the larynx itself. That is why the problems of the digestive system at this local level can be solved with the participation of an otolaryngologist.

By the way. Here is a very important organ - the epiglottis septum, which, during swallowing movements, when food rushes into the esophagus, blocks the entrance to the respiratory tract so that it does not get there.

The structure of the esophagus

In the esophagus, as already noted, nothing special happens with food. It passes through several zones - cervical, thoracic and abdominal, and moves food from the mouth to the stomach, practically without processing it.

An important property of the esophagus (which the stomach also has) is to stretch. When the food ball begins to move from the pharynx, the esophagus stretches. As soon as its path approaches the goal - the stomach, it contracts and pushes food there.

By the way. Liquid, well-chewed and moistened with saliva food moves along the esophagus in one and a half seconds. It takes seven seconds to transport hard, poorly chewed food.

The esophagus ends with a muscular valve called the sphincter. He persistently directs food into the stomach, no matter what position the person takes at the same time, not allowing it to return to the esophagus (antireflux).

Here it all comes down to transporting food further to the gastric zone faster and without damaging the mucous membrane. To do this, the walls secrete mucus, which makes it easier for food to slip easily.

Important! The muscles in the esophagus are designed in such a way that the peristaltic wave is extinguished by each subsequent sip, if the previous one has not yet reached the stomach. This is why you shouldn't drink something in one gulp or eat too quickly. This inhibits peristalsis and leads to relaxation of the sphincter muscles, which can subsequently cause reflux esophagitis.

Characteristics of the stomach

In this organ, food processing takes place, which is preliminary. The main digestion and excretion of substances necessary for the body from food is carried out in the duodenal zone of the small intestine.

In the stomach, acid begins to act on food. Enzymes also come into play here. It looks like a bag, which is rather loose in the body. From above it is attached by the esophagus, from below by the intestines. And mobility allows the walls to stretch in such a way that the organ's capacity can reach three liters, while its length is only about 25 centimeters.

Below, at the bottom of the stomach, there is also a sphincter, which sends food into the intestines, not allowing it, along with bile, to be thrown back.

The walls of the stomach touch all the organs that are located in the abdominal cavity. It contacts the spleen and pancreas, adrenal gland and kidney, diaphragm and abdominal wall. Therefore, the pain and discomfort experienced by this organ may not be associated with its condition, but formed by the condition of neighboring organs.

By the way. Interesting fact. Many people believe that food is digested in the stomach in the order in which it gets there. This is completely wrong, since it is in the stomach that it mixes, forming a homogeneous mass, which is sent to the intestines for final processing.

Small and large intestine

First comes the small part of the intestine, which gradually thickens. The organ begins with the duodenum, ends with a straight line.

By the way. The intestine is called so because its length is equal to the width of 12 fingers (official observation made by an unknown doctor).

The small intestine is divided into three sections. The first is the duodenum (this is where bile is poured in for digestion). The second is the jejunum. The third is a "copy" of the skinny, iliac, which, in fact, is its continuation.

Immediately after the stomach, surrounding the pancreas, is the duodenum, in which the main digestion of food takes place. Here, the acid of the contents coming from the stomach is neutralized with the help of bile and pancreatic juice.

Having passed the small intestine, food loses almost all useful components and partially moisture. In the thick, everything else is taken away.

It consists of four zones:

• cecum;
• appendix;
• colon;
• straight.

Here the digestive process continues and ends. The large intestine takes water, sugar, and anything else you can digest from food.

By the way. The colon's main function is not to digest. It is home to many bacteria that support the microflora not only in the intestines, but throughout the body.

Also, here food debris is enveloped in mucus in order to freely move to the rectum.

The fascinating and rewarding journey of food through the digestive tract ends in the anal canal, from where residual elements undigested by the system are removed through the opening of the anus.

Having an idea of ​​the structure of the gastrointestinal tract, each person can understand when his work is disrupted, in which sector a failure occurs, and what serious problem this can cause. Having formulated this information at an appointment with a doctor of the corresponding specialization, the patient will provide invaluable diagnostic support to help you take the right and timely action to keep it health.

Video - The structure of the gastrointestinal tract