Elastic thrust of the lungs its origin and meaning. The essence of breathing - mechanics, biochemical processes

Date: 03.03.2020

The components of the elements necessary for conducting orthodontic correction are not only braces, arcs and ligatures, but also elastic thrust on braces. Patients additional devices deliver small discomfort, but fix the bite, alas, without them it is impossible. In the article, we will consider the main tasks of elastics, their types and rules of use.

In clinical practice, orthodontics use not only elastic rubberry, but also metal, teflon ligatures, as well as Kobayashi ligatures. We will analyze their main characteristics.

Ligatures on structural elements of braces - wings are attached. Their main purpose consists in fixing the arc. Once in 3-4 weeks it is necessary to change the gum, because elastic ligatures under the influence of saliva lose their former physical properties. And if the correction is not coming in a timely manner, the bracket system will simply stop working. Available transparent, white, multicolored elastics are presented, made by stamping.
Metal ligatures are made of stainless steel. They are also fixed on wings with a special toolkit. Apply, as a rule, at the final stage of treatment to consolidate the result. Rubber for braces in their structure are not irritated by the surface of the mucous, as they are made from latex. The tips of the metal ligatures can slightly rub the mucous membrane. If redness appeared, it is necessary to refer to the doctor to smooth out the contours or in order to insulate the protruding elements.
Kobayashi ligatures are essentially the same metallic ligatures, the difference is only in the presence of a special bending at the tip. The hook is formed using a point welding method. The main tasks consist in fixing the intermittent elastic thrust, elastic chains or springs.
Teflon coated ligatures are a good compromise solution that simultaneously ensure the aesthetics and reliability of ligation. Application on the surface of steel thin Teflon layer allows you to achieve an ideal combination of ligatures with ceramic or sapphire braces.

Elastic power components

Ligatures are designed to hold the arc, fix them immediately after installing braces. But besides ligatures there are elastic power gum, the material for the manufacture of which is the hypoallergenic surgical tires. The power modules are used after the equalization stage of the dental rows. These include:

chains;
thread;
traction.

The strength of the action differences the elastics: light (small forces), medium (medium), Heavy (high amplitude, heavy). The pressure on the teeth from the use of elastic rubber band should not exceed 20-25 g / mm 2. Using excessive forces can lead to complications. Therefore, Heavy marking thrust is used very rarely.

It is important to note: each package indicates the strength of the action of certain elastic modules. And what is interesting, this pressure is achieved when tensile the gum is three times the greater of its original diameter.

Chains

Chains can be transparent, gray or colored. Consist from rings related to each other in a single solid system. Fix the links on the wings of braces or on hooks of Kobayashi ligatures. For the closure of small, medium and large gaps, the orthodontists use chains with an appropriate step length.

Elastic chains are designed to perform the following tasks:

closing diasthemia;
elimination of three and gaps that occurred after the removal of the teeth;
corrections of the crookanomalia - turning the tooth around its axis;
cabinet movement of teeth.

It is important to note: since all additional correction elements are retention points that contribute to the accumulation of plaque, cleaning braces with rubber bands requires not only a toothbrush and paste. It is necessary to include brush and irrigators to the daily oral hygiene instruments.

Thread

The elastic thread is considered a worthy alternative chain. On the one hand covers the bracket, to the point of the support is attached using the node. The functions of the thread are as follows:

moving teeth;
closing of the gaps;
consolidation of dentition;
stretching formed, but not cut (or not completely cutting) teeth.

The elastic thread is often used when using lingual correction techniques.

Traction

Why do elastic traction need? Elastics are designed to correct the intercelion contacts. They differ in diameter and thickness. For convenience and facilitate memorization (both doctors and patients) of various elastics, ORMCO offers special labeling "ZOO", where each diameter of elastic thrust corresponds to the name of a certain animal.

The use of elastics is shown in the identification of the following pathologies in patients:

distal bite;
mesial bite;
cross bite;
open bite;
dizoklusion - no contact between the teeth of the upper and lower jaw on a certain area of \u200b\u200bthe dentition;
stretching not completely cutting teeth.

To correct the dental pathologies, the orthodontists use various options for fastening elastics.

Diagonal symmetric thrust are designed to correct the distal and mesial bite.
Diagonal asymmetric are necessary to create a median line.
Box-elastics for braces are used in the front area in order to eliminate open bite.
Zigzago-like thrust are designed to create the right occlusive contacts between the teeth of the upper and lower jaw.
Triangular elastics contribute to the normalization of bite vertical.
Spaghetti thrust are aimed at eliminating pronounced forms of mesial or distal bite.

It is important to know: the effect of elastic traction increases with the movements of the lower jaw. There are clinical cases when when conducting an orthodontic correction, it is necessary to use horizontal and vertical elastics at the same time.

Rules of use of elastikov

Fixing the traction and patient training rules are carried out in the dental office by orthodontist. Patients should be extremely attentive, since they will have to independently perform this procedure at home and not once.

Why do you need to regularly change the thrust? It has been proven that after 2 hours after the fastening of elastics, the loss of their effectiveness is 30%, after 3 hours - 40%. To maintain a power impact at the required level, you need to replace 2-3 times a day.

After setting elastics, there may be a small discomfort. This is quite normal, physiologically reasonable phenomenon. But if you cannot fully open your mouth, problems with chewing, swallowing, you need to remove traction and contact a specialist.

It is important to note: an indicator that excessive force acts on the teeth is the appearance of pallor in the gums section after fixing the elastics.

Ligatures, chains, traction - all these elements are inalienable components of orthodontic correction. In addition to its immediate task, the thrust serve as a marker of how seriously the patient treats treatment. If the elastics wear from time to time, and not constantly, there will be no full-fledged positive dynamics. Therefore, to achieve the most productive result, you need to unconditionally fulfill all the prescriptions of orthodontist, to come to the correction and not forget about the compliance with the basic rules of hygiene.

Elastic lung thrust- The force with which the lungs seek to squeeze. It occurs due to the following reasons: 2 / 3Elastic lung thrust is due to surfactant - surface tension of the liquid, lining alveoli, about 30% – elastic lung and bronchi fibers, 3% – the tone of smooth muscle bronchi fibers. The strength of elastic thrust is always directed with the outside inside. Those. The magnitude of the extensibility and elastic thrust of the lungs is strongly influenced by the presence of an intrastallyolar surface surfactant - Substances, which is a mixture of phospholipids and proteins.

The role of surfactant:

1) reduces the surface tension in the alveols and thus increases the extensibility of the lungs;

2) stabilizes the alveoli, prevents the sticking of their walls;

3) reduces the resistance of the diffusion of gases through the Alveol wall;

4) prevents the alvetol edema by reducing the size of the surface tension in the alveoli;

5) facilitates the lighting of the lungs at the first breath of the newborn;

6) contributes to the activation of phagocytosis by alveolar macrophages and their motor activity.

The synthesis and replacement of the surfactant occurs pretty quickly, so violation of blood flow in the lungs, inflammation and swelling, smoking, excess and insufficiency of oxygen, some pharmacological preparations can reduce its reserves and increase the surface tension of the fluid in the alveoli. All this leads to their atelectasis or decay.

Pnemothorox.

Pnemothorox is called air intake in the intergeneral space arising from penetrating injuries of the chest, disorders of the tightness of the pleural cavity. At the same time, the lungs fall apart, since intrapleural pressure becomes the same with atmospheric. Effective gas exchange in these conditions is impossible. In humans, the right and left pleural cavities are not communicated, and due to this one-sided pneumothorox, for example, on the left, does not lead to the cessation of the pulmonary breathing of the right lung. Over time, the air from the pleural cavity is absorbed, and the sleeping light is repeated again and fills the whole chest cavity. Bilateral Pneumothoroxes are incompatible with life.

Maintaining the constancy of the composition of alveolar air is ensured by continuously carried out respiratory cycles - inhalation and exhalation. During the inhalation, the atmospheric air across the air junction enters the lungs, when exhaling, about the same amount of air is supplanted from the lungs. Due to the update of the part of the alveolar air, its constant is supported.

The act of breath is committed due to an increase in the volume of the thoracic cavity due to the reduction of the external oblique intercostal muscles and other inhalation muscles, providing the recurring of the ribs on the parties, and also due to the reduction of the diaphragm, which is accompanied by a change in the shape of its dome. The diaphragm becomes a cone, the position of the tendon center does not change, and the muscular areas are shifted towards the abdominal cavity, pushing organs back. With an increase in the amount of the chest, the pressure in the pleural gap decreases, the difference occurs between the pressure of the atmospheric air on the inner wall of the lungs and the pressure of the air in the pleural cavity to the outer wall of the lungs. The pressure of the atmospheric air on the inner wall of the lungs begins to prevail and causes an increase in the volume of the lungs, and consequently, the receipt of atmospheric air into the lungs.

Table 1. Muscles providing light ventilation

Note. Muscle belonging to the main and subsidiary groups may vary depending on the type of breathing.

When inhale is over and the breathing muscles relax, the ribs and the dome of the diaphragm return to the inspire position, while the amount of the chest is reduced, the pressure in the pleural slit is reduced, the pressure on the outer surface of the lungs is increasing, the portion of the alveolar air is exhausted and exhaled.

The return of the ribs to the interior position is provided by the elastic resistance of the rib cartilage, a reduction in the inner oblique intercostal muscles, ventral gear muscles, abdominal muscles. The diaphragm returns to an inspire due to the resistance of the stomach walls, the abdominal organs, mixed when inhaling back and reduce the abdominal muscles.

The mechanism of inhalation and exhalation. Respiratory cycle

The breathing cycle includes breathing, exhale and pause between them. Its duration depends on the respiratory frequency and is 2.5-7 s. The duration of the inhalation in most people shorter the duration of the exhalation. The duration of the pause is very volatile, it may be absent between the breath and exhalation.

For initiation inha It is necessary that the inspiratory (activating breath) of the department, the volley of the nerve pulses arose and their parcel on the descending paths in the composition of the ventral and front part of the spinal cord of the spinal cord in its cervical and chest departments. These impulses should achieve the front horns of the front horns of the SZ-C5 segments, forming the diaphragmal nerves, as well as the grinding of Th2-Th6 breast segments that form intercostal nerves. The respiratory center of the spinal cord motoneurons activated the flows of signals along the diaphragmal and intercostal nerves to neuromuscular synapses and cause a reduction in the diaphragmal, external intercostal and interchors. This leads to an increase in the volume of the thoracic cavity due to the lowering of the diaphragm dome (Fig. 1) and movement (lifting with rotation) of the ribs. As a result, the pressure in the pleural gap decreases (up to 6-20 cm of water. Art. Depending on the depth of breath), the transpulmonal pressure increases, becomes more elastic thrust forces and they stretch, increasing volume.

Fig. 1. Changes in the size of the chest, lung volume and pressure in the pleural gap when inhaling and exhale

The increase in lung volume leads to a decrease in air pressure in the alveoli (with a calm breath, it becomes below atmospheric for 2-3 cm of water. Art.) And the atmospheric air along the pressure gradient enters the lungs. There is a breath. In this case, the volumetric speed of the air flow in the respiratory tract (o) will be directly proportional to the pressure gradient (ΔP) between the atmosphere and alveoli and inversely proportional to the resistance (R) of the respiratory tract for the air flow.

With a strengthened reduction in the muscles inhale, the chest is even more expanding and the volume of the lungs increases. The depth of the breath increases. This is achieved due to the reduction of the auxiliary inspiratory muscles, which include all the muscles attaching to the bones of the shoulder belt, spine or skull, capable of raising the ribs, the shovel and fix the shoulder blast belt with a reserved shoulders. The most important among these muscles are: large and small pectoral, staircase, breast-key-sorezswide and front gear.

The mechanism of exhalation It is distinguished by the fact that the calm exhalation occurs passively at the expense of the forces accumulated when inhaling. To stop the inhalation and switching inhale to exhale, it is necessary to stop sending the nerve pulses from the respiratory center to the spinal cord motnelones and the muscles inhale. This leads to the conjugate muscle relaxation, as a result of which the amount of the chest begins to decrease under the influence of the following factors: elastic thrust of the lungs (after deep inhalation and elastic thrust of the chest), the gravity of the chest, raised and derived from the stable position when inhaling, and pressure Abdominal organs on a diaphragm. To carry out reinforced exhalation, it is necessary to send the flux of nerve pulses from the center of the exhalation to the spinal cord motor mechanons, innervating exhalation muscles - the internal intercostal and abdominal muscles. Their reduction leads to an even greater decrease in the volume of the chest and removing the larger volume of air from the lungs due to the lifting of the diaphragm dome and the lowering of the ribs.

Reducing the volume of the chest leads to a decrease in transpulmonal pressure. Elastic lung thrust becomes greater than this pressure and causes a decrease in lung volume. This increases the air pressure in the alveoli (3-4 cm water. Art. More atmospheric) and air pressure gradient comes out of the alveoli into the atmosphere. Exhaled.

Type of breathing It is determined by the magnitude of the contribution of various respiratory muscles into an increase in the amount of the chest cavity and filling the lungs by air when inhaling. If the inhale occurs mainly due to the reduction of the diaphragm and the displacement (down and forward) of the abdominal organs, then such breath is called abdominal or diaphragmal; If, due to the reduction of intercostal muscles - chest. Women prevailing breast breathing, in men - abdominal. In people performing severe physical work, as a rule, the abdominal type of breathing is set.

Work of breathing muscles

To carry out lung ventilation, it is necessary to spend the work that is performed by reducing the respiratory muscles.

With calm breathing in the conditions of the main exchange for the operation of the respiratory muscles, 2-3% of the entire energy consumed by the body is spent. With enhanced breathing, these costs can reach 30% of the energy cost level of the body. In people with diseases of the lungs and respiratory tract, these costs can be even big.

The operation of the respiratory muscles is spent on overcoming the elastic forces (lungs and chest), dynamic (viscous) resistance to the movement of air flow through the respiratory tract, inertial strength and severity of biased tissues.

The magnitude of the operation of the respiratory muscles (W) is calculated on the integral of the product of changes in the volume of light (V) and intrapharmal pressure (P):

60-80% of total costs are spent on overcoming elastic forces W. , viscous resistance - up to 30% W..

Viscosity resistance are presented:

the aerodynamic resistance of the respiratory tract, which is 80-90% of total viscous resistance and increases with an increase in the air flow rate in the respiratory tract. The volumetric speed of this thread is calculated by the formula

where R A. - the difference between the pressure in the alveoli and the atmosphere; R. - Resistance to respiratory tract.

When breathing through the nose it is about 5 cm of water. Art. L -1 * C -1, with breathing through the mouth - 2 cm of water. Art. l -1 * s -1. On the trachea, equity and segmental bronchi accounted for 4 times greater resistance than more distal areas of respiratory tract;

tissue resistance, which is 10-20% of total viscous resistance and is due to internal friction and inelastic deformation of the tissues of the chest and abdominal cavity;
inertia resistance (1-3% of total viscous resistance), due to the acceleration of air in respiratory tract (overcoming the inertia).

With a calm breath, work to overcome viscosity resistances is insignificant, but with reinforced breathing or with a violation of respiratory paths, the respiratory tract can sharply increase.

Elastic thrust of lungs and chest

Elastic lung thrust - the force with which the lungs seek to squeeze. Two thirds of the elastic lung thrust are caused by the surface tension of the surfactant and the fluid of the inner surface of the alveoli, about 30% is created by elastic fibers of the lungs and about 3% by the tone of smooth-muscle fibers of intra-light bronchi.

Elastic lung thrust - The force with which the lung fabric counteracts the pressure of the pleural cavity and provides an alvetol falling (due to the presence of a large number of elastic fibers and surface tension in the wall).

The magnitude of the elastic thrust of the lungs (e) is inversely proportional to the magnitude of their extensibility (C L):

The extensibility of the lungs in healthy people is 200 ml / cm of water. Art. and reflects an increase in lung volume (V) in response to increasing transpulmonal pressure (P) for 1 cm water. Article:

In the emphysema of the lungs, their extensibility increases, decreases when fibrosis.

The magnitude of the tensileness and elastic thrust of the lungs is strongly influenced by the presence of a structure from phospholipids and proteins formed by alveolar pneumocytes of the 2th type.

The surfactant plays an important role in maintaining the structure, properties of the lungs, relief of gas exchange and performs the following functions:

reduces surface tension in alveoli and increases lung extensibility;
prevents alveolting wall sticking;
increases the solubility of gases and facilitates their diffusion through the alveoli wall;
prevents the development of edema alveol;
makes it easy to disrupt the lungs at the first breath of the newborn;
contributes to the activation of phagocytosis by alveolar macrophages.

The elastic thrust of the chest will be created by the elasticity of intercostal cartilage, muscles, parietal pleura, connective tissue structures capable of compressing and expanding. At the end of the exhalation, the strength of the elastic thrust of the chest is directed to the outside (in the direction of the expansion of the chest) and the maximum largest. When developing inhale, it gradually decreases. When inhale reaches 60-70% of its maximum possible value, the elastic rod of the chest becomes zero, and with further deepening, the inhalation is directed inside and prevents the expansion of the chest. Normally, the tensileness of the chest (C | K) is approaching 200 ml / cm of water. Art.

The total tensileness of the chest and the lungs (C 0) is calculated by formula 1 / s 0 \u003d 1 / C l + 1 / s of the GC. The average value of C 0 is 100 ml / cm of water. Art.

At the end of the calm exhalation of the magnitude of the elastic thrust of the lungs and the chest is equal, but are opposite to the direction. They equilibrate each other. At this time, the chest is in the most stable position called level of calm breath And take over the reference point for various studies.

Negative pressure in the pleural gap and pneumothorax

The chest forms a hermetic cavity, providing the insulation of the lungs from the atmosphere. Lightweight covers a leaf of visceral pleura, and the inner surface of the chest is a sheet of parietal pleura. The leaflets pass one into the other at the gate of the lung and between them the sliding space is formed, filled with pleural fluid. Often, this space is called pleural cavity, although the cavity between the leaves is formed only in special cases. The layer of fluid in the pleural gap is incredible and unpretentious and pleural sheets cannot move apart from each other, although they can easily slide along (like two glasses applied with moistened surfaces, they are difficult to separate, but it is easy to shift along the planes).

In conventional breathing, the pressure between the pleural sheets is lower than atmospheric; he's called negative pressure In the pleural slit.

The causes of the negative pressure in the pleural gap are the presence of elastic thrust of the lungs and the chest and the ability of the pleural leaflets to capture (sorbit) the gases molecules from the fluid of the pleural gap or air falling into it during the injuries of the chest or when punzing with therapeutic purposes. Due to the presence of negative pressure in the pleural gap, it is constant filtering a small amount of alveoli gases. Under these conditions, the sorption activity of pleural leaves prevents the accumulation of gases in it and protects the lungs from decay.

An important role of negative pressure in the pleural gap consists in holding the lungs in a stretched state even during exhalation, which is necessary to fill with them of the entire volume of the thoracic cavity determined by the sizes of the chest.

The newborn ratio of the volumes of pulmonary parenchyma and the chest cavity is greater than in adults, so at the end of the calm exhalation, the negative pressure in the pleural gap disappears.

In an adult, at the end of a calm exhalation, the negative pressure between the pleura sheets is an average of 3-6 cm water. Art. (i.e., 3-6 cm less than atmospheric). If a person is in a vertical position, the negative pressure in the pleural gap along the vertical axis of the body differs significantly (it changes by 0.25 cm water. Art. For each centimeter height). It is maximally in the area of \u200b\u200bthe tops of the lungs, so when you exhale, they remain more stretched and, upon subsequent breath, their volume and ventilation increase to a small extent. In the area of \u200b\u200bthe base of the lungs, the negative pressure value may approach zero (or it can even become positive in the case of loss of light elasticity due to aging or diseases). With its weight, light pressure on the diaphragm and the part of the chest adjacent to it. Therefore, in the field of base at the end of the exhalation, they are less extended. This will create conditions for their greater stretching and reinforced ventilation when inhaling, increasing gas exchange with blood. Under the influence of gravity to the base of the lungs, more blood flows, the bloodstream in this lung zone exceeds ventilation.

In a healthy person, only with a forced exhale, the pressure in the pleural gap can be more atmospheric. If the exhalation is performed with a maximum force in a closed space in a small volume (for example, a pneumotonometer device), the pressure in the pleural cavity may exceed 100 cm of water. Art. With the help of such a breathing maneuver, the pneumotonometer determines the power of the muscles of the exhalation.

At the end of a calm breath, the negative pressure in the pleural gap is 6-9 cm of water. Art., And with the most intensive breath, it can achieve greater magnitude. If the breath is carried out with a maximum force in the conditions of overlapping the respiratory tract and the impossibility of air intake into the lungs from the atmosphere, the negative pressure in the pleural gap for a short time (1-3 s) reaches 40-80 cm water. Art. With the help of such a dough and the device, the pneumogonometer determine the strength of the muscles inhale.

When considering external respiratory mechanics, also takes into account transpulmonal pressure - the difference between air pressure in alveoli and pressure in the pleural gap.

Pneumothorax Call air intake in the pleural gap, leading to the falling of the lungs. Under normal conditions, despite the action of elastic thrust forces, the lungs remain straightened, since due to the presence in the pleural slot liquid, the pleura sheet cannot be disconnected. When entering the pleural aircraft, which can be compressed or expanded in the volume, the degree of negative pressure in it decreases or it becomes equal to atmospheric. Under the action of the elastic forces of the lung, the visceral leaflet will be filled with parietal and lungs decrease in size. Air can enter the pleural slot through the hole of the damaged chest wall or through the message of the damaged lung (for example, with tuberculosis) with the pleural slit.

Elastic lung thrust- The force with which the lungs seek to squeeze.

It arises due to the following reasons: 2/3 elastic lung thrust is due to surfactant - surface tension of the liquid, lining alveoli, about 30% -elastic lung fibers and bronchi, 3% -tonous smooth muscle bronchi fibers. The strength of elastic thrust is always directed with the outside inside. Those. The magnitude of the extensibility and elastic thrust of the lungs is strongly influenced by the presence of an intrastallyolar surface surfactant - Substances, which is a mixture of phospholipids and proteins.

The role of surfactant:

1) reduces the surface tension in the alveols and thus increases the extensibility of the lungs;

2) stabilizes the alveoli, prevents the sticking of their walls;

3) reduces the resistance of the diffusion of gases through the Alveol wall;

4) prevents the alvetol edema by reducing the size of the surface tension in the alveoli;

5) facilitates the lighting of the lungs at the first breath of the newborn;

6) contributes to the activation of phagocytosis by alveolar macrophages and their motor activity.

Pnemothorox

End of work -

This topic belongs to the section:

Physiology of breathing

Spirometry method of measuring exhaled air volumes using a device of spirometer .. Spirography of the method of continuous registration of exhaled volumes and .. Pneumatic philchography methods of continuous registration of the bulk speed of inhaled and exhaled streams ..

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All the themes of this section:

Physiology of breathing
Breathing is one of the vital functions of the body aimed at maintaining the optimal level of redox processes in cells. Breathing - complex

External breathing
External breathing is carried out cyclically and consists of a phase of inhalation, exhalation and respiratory pause. A person has the frequency of respiratory movements on average equal to 16-18 in one minute. External breathing

Negative pressure in the pleural gap
The chest forms a hermetic cavity, providing the insulation of the lungs from the atmosphere. Lightweight covers the visceral pleural sheet, and the inner surface of the chest - parietal pl

Pulmonary volumes and tanks
With a calm breath, man inhales and exhales about 500 ml of air. This volume of air is called respiratory volume (up to) (Fig.3).

Transport gas blood
Oxygen and carbon dioxide in the blood are in two states: in chemically associated and dissolved. Transfer of oxygen from alveolar air to blood and carbon dioxide from blood in Alveolar

Oxygen transport
From the total amount of oxygen, which is contained in arterial blood, only 5% dissolved in plasma, the rest of the oxygen is transferred by the red blood cells in which it is in chemical

Bicarbonate buffer
From the above gas exchange reaction it follows that their flow at the level of lungs and tissues turns out to be multidirectional. Than in these cases, the focus of the formation and dissociation of odds is determined

Types of HB compounds
Hemoglobin is a special chromoproteide protein, due to which red blood cells perform a respiratory function and maintain blood pH. The main function of hemoglobin is the transfer of oxygen and partially carbon

Basic regulation systems of acidic alkaline equilibrium in the body
Acid - alkaline equilibrium (KRCH) (acid-based balance, acid-chicken condition (KSH), acidic - basic equilibrium) is the constancy of the concentration of H + (protons) in liquid

Respiratory regulation
Like all systems in the body, breathing is regulated by two main mechanisms - nervous and humoral. The basis of nervous regulation is the implementation of the reflex of Goering Charker, which