As you know, a person cannot live without air for more than three minutes. At this, the reserves of oxygen dissolved in the blood are depleted, and starvation of the brain occurs, which is manifested by fainting, and in severe cases - coma and even death. Of course, people trained in a certain way were able to extend the airless period to five, seven, and even ten minutes, but this is hardly possible for an ordinary person. The metabolic processes occurring in the body require a constant supply of oxygen molecules, and the respiratory system copes well with this task.
Stages of breathing
Oxygen exchange between the body and the environment takes place in four stages:
- Air will enter from the external environment into the lungs and fill all available space.
- Diffusion of gases occurs, including oxygen, through the wall of the alveoli (structural unit of the lungs) into the blood.
- Hemoglobin, which is found in red blood cells, binds most of the oxygen and carries it around the body. A small part dissolves in the blood unchanged.
- Oxygen leaves hemoglobin compoundsand passes through the wall of the vessel into the cells of tissues and organs.
Note that the respiratory system is involved in this process only at the initial stage, the rest depends on the nature of the blood flow, its properties and the level of tissue metabolism. In addition, the lungs are involved in heat transfer, elimination of toxic substances, voice formation.
Anatomy
The entire respiratory system is divided into two sections, depending on the relative position of the organs.
The upper respiratory tract consists of the nasal and oral cavities, nasopharynx, oropharynx, pharynx and pharynx. And for the most part they are cavities formed by the walls of the bones of the skull or the muscular-connective tissue frame.
The lower respiratory tract includes the larynx, trachea and bronchi. Alveoli are not included in this classification, as they are an integral part of the parenchyma of the lungs and the terminal section of the bronchi at the same time.
Briefly about each constituent unit of the respiratory tract.
Nasal cavity
This is a bone and cartilage formation, which is located on the front of the skull. It consists of two non-communicating cavities (right and left) and a partition between them, which forms a winding course. Inside the nasal cavity is covered with a mucous membrane that has a large number of blood vessels. This feature helps to warm the passing air during inhalation. And the presence of small cilia allows you to filter out large dust particles, pollen and other dirt. In addition, it is the nasal cavity that helps a person to distinguish between odors.
Nasopharynx, oropharynx, pharynx and pharynx serve to pass warm air into the larynx. The structure of the organs of the upper respiratory tract is closely related to the anatomy of the skull and almost completely repeats its musculoskeletal framework.
Larynx
The human voice forms directly in the larynx. It is there that the vocal cords are located, which vibrate during the passage of air through them. It is similar to strings, but due to structural features (length, thickness), their capabilities are not limited to one tone. The sound of the voice is amplified due to the proximity of the intracranial sinuses or cavities, which create a certain resonance. But voice is not speech. Articulate sounds are formed only with the coordinated work of all the constituent elements of the upper respiratory tract and the nervous system.
The trachea, or windpipe, is a tube that consists of cartilage on one side and ligaments on the other. Its length is ten to fifteen centimeters. At the level of the fifth thoracic vertebra, it divides into two main bronchi: left and right. The structure of the organs of the lower respiratory tract is mainly represented by cartilage, which, when connected, form tubes that conduct air into the depths of the lung parenchyma.
Isolation of the respiratory system
Pleura is the outer thin shell of the lung, represented by serous connective tissue. Outwardly, it can be mistaken for a shiny protective coating, and this is not so far from the truth. It covers the internal organs from all sides, and is also located on the innersurface of the chest. Anatomically, two parts of the pleura are distinguished: one actually covers the lungs, and the second lines the chest cavity from the inside.
Visceral leaf
That part of the membrane, which is located on top of the internal organs, is called the visceral, or pulmonary pleura. It is tightly soldered to the parenchyma (actual substance) of the lungs, and it can only be separated by surgery. It is thanks to such close contact and repetition of all the contours of the organ that it is possible to distinguish the furrows that divide the lung into lobes. These areas are called none other than the interlobar pleura. Passing over the entire surface of the lungs, the connective tissue surrounds the root of the lung to protect its vessels, nerves and the main bronchus, and then passes to the chest wall.
Pariate leaf
Starting from the point of transition, a sheet of connective tissue is called "parietal, or parietal pleura". This is due to the fact that its attachment will no longer be to the lung parenchyma, but to the ribs, intercostal muscles, their fascia and diaphragm. An important feature is that the serous membrane remains intact throughout, despite differences in topographic names. Anatomists, for their own convenience, distinguish between the costal, diaphragmatic and mediastinal sections, and the part of the pleura above the apex of the lung is called the dome.
Cavity
There is a small gap between the two layers of the pleura (no more than seven tenths of a millimeter), this is the pleural cavity of the lungs. She's filled with secretswhich is produced directly by the serous membrane. Normally, a he althy person produces only a few milliliters of this substance daily. The pleural fluid is necessary to soften the friction force that occurs between the sheets of connective tissue during breathing.
Pathological conditions
Mostly diseases of the pleura are inflammatory. As a rule, this is rather a complication than an independent disease, as a rule, it is considered by doctors in conjunction with other clinical symptoms. Tuberculosis is the most common reason why the pleura becomes inflamed. This infectious disease is widespread among the population. In the classic version, the primary infection occurs through the lungs. The structure of the respiratory organs causes the transition of inflammation and the pathogen from the parenchyma to the serous membrane.
In addition to tuberculosis, the culprits of inflammation of the pleura can be tumor, autoimmune processes, allergic reactions, pneumonia caused by streptococci, staphylococci and pyogenic flora, injuries.
Pleuritis by nature are dry (fibrinous) and exudative (exudative).
Dry inflammation
In this case, the vascular network inside the connective tissue sheets swells, and a small amount of liquid flows out of it. It folds in the pleural cavity and forms dense masses that are deposited on the surface of the lungs. In severe cases, these raids are so numerous that a hard shell forms around the lung, which prevents a person from breathing. Suchthe complication cannot be corrected without surgery.
Effusion inflammation
If the pleural fluid is produced in a significant amount, then they talk about exudative pleurisy. It, in turn, is divided into serous, hemorrhagic and purulent. It all depends on the nature of the fluid that is between the connective tissue sheets.
If the liquid is clear or slightly hazy, yellow in color, then this is a serous effusion. It contains a lot of protein and a small amount of other cells. Maybe in such a volume that it fills the entire chest cavity, squeezing the organs of the respiratory system and preventing them from working.
If the doctor saw during the diagnostic puncture that there is red liquid in the chest, then this indicates that there is damage to the vessel. The reasons can be different: from a penetrating wound and a closed fracture of the ribs with displacement of fragments to the melting of lung tissue by a tuberculous cavity.
The presence of a large number of leukocytes in the exudate makes it cloudy, with a yellow-green tint. This is pus, which means that the patient has a bacterial infection with serious complications. Purulent pleurisy is otherwise called empyema. Sometimes accumulations of inflammatory fluid give a complication to the heart muscle, causing pericarditis.
As we can see, the respiratory system consists of more than just the lungs. It includes the nose and mouth, pharynx and larynx with ligaments, trachea, bronchi, lungs and, of course, the pleura. This is a whole complex of organs, which harmoniouslyworks by delivering oxygen and other atmospheric air gases to the body. In order to maintain this mechanism in order, it is necessary to undergo regular fluorography, avoid acute respiratory infections and constantly increase your immunity. Then the negative impact of the environment will be less reflected in the function of the respiratory system.
