As you know, a person cannot do without air for more than three minutes. On this, the reserves of oxygen dissolved in the blood are depleted, and brain starvation sets in, which manifests itself in 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, or 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.
Breathing stages
Oxygen exchange between the body and the environment takes place in four stages:
- Air will flow from the external environment to the lungs and fill all available space.
- There is a diffusion of gases, including oxygen, through the wall of the alveoli (a structural unit of the lungs) into the blood.
- Hemoglobin, which is found in red blood cells, binds most of the oxygen and carries it throughout the body. A small part dissolves in the blood unchanged.
- Oxygen leaves hemoglobin compounds and passes through the vessel wall into the cells of tissues and organs.
Note that in this process the respiratory system is involved 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, and voice formation.
Anatomy
The entire respiratory system is divided into two departments, 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 musculo-connective tissue skeleton.
The lower airways include the larynx, trachea, and bronchi. Alveoli are not included in this classification, since they are an integral part of the lung parenchyma and the terminal part of the bronchi simultaneously.
Briefly about each component of the respiratory tract.
Nasal cavity
This is a bone-cartilage formation that 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 passage. Inside the nasal cavity is covered with a mucous membrane, which has a large number of blood vessels. This feature helps warm the passing air during inspiration. 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 odors.
The nasopharynx, oropharynx, pharynx and pharynx serve to pass the warmed 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 flow through them. This is similar to strings, but due to the structural features (length, thickness), their capabilities are not limited to one tone. The sound of the voice is amplified due to the close proximity of the intracranial sinuses or cavities that create a certain resonance. But the voice is not speech yet. Articulate sounds are formed only with the coordinated work of all the constituent elements of the upper respiratory tract and nervous system.
A trachea, or respiratory throat, 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 is divided into two main bronchi: left and right. The structure of the organs of the lower respiratory tract is mainly represented by cartilage, which, when combined, form tubes that conduct air into the depths of the lung parenchyma.
Respiratory system isolation
Pleura is the outer thin membrane of the lung, represented by serous connective tissue. Outwardly, it can be mistaken for a brilliant protective coating, and this is not so far from the truth. It covers the internal organs on all sides, and is also located on the inner surface of the chest. Anatomically distinguish two parts of the pleura: one actually covers the lungs, and the second lining the chest cavity from the inside.
Visceral leaf
That part of the membrane that is located on top of the internal organs is called the visceral, or pulmonary pleura. It is tightly soldered to the parenchyma (actually the substance) of the lungs, and it can only be removed surgically. It is thanks to such close contact and repetition of all the contours of the organ that we can distinguish the grooves that divide the lung into lobes. These sites are called nothing more than interlobar pleura. Having passed over the entire surface of the lungs, the connective tissue surrounds the root of the lung to protect the vessels, nerves and main bronchus entering it, and then passes to the chest wall.
Parietal leaflet
Starting from the place of transition, a piece of connective tissue is called "parietal, or parietal pleura." This is due to the fact that its attachment will now not be to the lung parenchyma, but to the ribs, intercostal muscles, their fascia and diaphragm. An important feature is the fact that throughout the entire length of the serous membrane remains integral, despite the differences in topographic names. Anatomists for their own convenience distinguish between the costal, diaphragmatic and mediastinal departments, and part of the pleura above the apex of the lung is called the dome.
Cavity
Between two pleura sheets there is a small gap (not more than seven tenths of a millimeter), this is the pleural cavity of the lungs. It is filled with a secret that the serous membrane produces directly. Normally, a healthy person daily produces only a few milliliters of this substance. Pleural fluid is necessary to soften the frictional force that arises between sheets of connective tissue during breathing.
Pathological conditions
Basically, pleural diseases are inflammatory in nature. 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 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 system causes the transition of inflammation and the pathogen from the parenchyma to the serous membrane.
In addition to tuberculosis, the culprits of pleural inflammation can be tumor, autoimmune processes, allergic reactions, pneumonia caused by streptococci, staphylococci and pyogenic flora, injuries.
Pleurisy by nature are dry (fibrinous) and effusion (exudative).
Dry inflammation
In this case, the vascular network inside the connective tissue sheets swells, a small amount of fluid is sweated from it. It coagulates in the pleural cavity and forms dense masses that are deposited on the surface of the lungs. In severe cases, there are so many of these raids that a hard shell forms around the lung, which prevents a person from breathing. It is impossible to correct such a complication without surgical intervention.
Effusion inflammation
If pleural fluid is produced in significant quantities, then they speak of 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 cloudy, yellow in color, then this is a serous effusion. It contains a lot of protein and a small number of other cells. It can be in such a volume that it fills the entire chest cavity, compressing the organs of the respiratory system and interfering with their work.
If the doctor saw during the diagnostic puncture that there is a red fluid 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 of a tubercular cavern.
The presence in the exudate of a large number of white blood cells 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 also cause complications to the heart muscle, causing pericarditis.
As we can see, the respiratory system consists not only of the lungs. It includes the nose and mouth, pharynx and larynx with ligaments, trachea, bronchi, lungs and, of course, pleura. This is a whole complex of organs that works smoothly, delivering oxygen and other gases of atmospheric air to the body. In order to maintain this mechanism in order, it is necessary to undergo fluorography regularly, avoid acute respiratory infections and constantly improve your immunity. Then the negative environmental impact will be less reflected in the function of the respiratory system.