The upper respiratory tract includes. Human external respiration
To avoid unnecessary problems with the throat, you need to have at least a general understanding of the structure, functions and main diseases of the respiratory tract.
Structure of the respiratory tract.
The airways from the lungs to the outside begin with the smallest respiratory bronchioles in contact with the alveoli of the lungs. The bronchioles join together to form tiny bronchi. Consistently merging, these bronchi become larger and larger until they form two main bronchi, right and left, which connect and form the largest air tube in our body - the trachea (or windpipe).
Over 20 levels of bronchial division make up bronchial tree- closed air duct system with walls made of rings cartilage tissue, which become thicker as the bronchi enlarge. The top of this closed air duct made of cartilage is the larynx, formed by cartilage, and the entire system is called the lower respiratory tract. At the top of the larynx, the airway intersects with digestive tract. The air duct is protected from food entry by a special cartilage of the larynx - the epiglottis.
Above the larynx, the airway system is open, and the air ends up in the cavities of the pharynx, mouth, nose and sinuses. This is the space of the upper respiratory tract.
All airways are covered with epithelium. The abundant blood supply of the respiratory tract and the liquid secretion of the glands of their epithelium maintain the necessary parameters of temperature and humidity of the air penetrating into the lungs from the atmosphere. Everything from within Airways have a mucous membrane that filters and protects against pathogenic microorganisms, warming and humidifying the air coming from the environment.
Functions.
The main purpose of the respiratory tract is to deliver oxygen to the lungs and carbon dioxide from the lungs. But individual parts of the respiratory tract also have other functions. The nose is also an organ of smell. We eat and speak with our mouth. At the center of the respiratory tract is its most bizarre part - the larynx, the organ of voice production. The remaining parts of the respiratory tract can act as resonators, and the upper ones also form the timbre of the voice.
Major diseases.
Respiratory tract diseases are most often associated with damage to the mucous membrane. As the most common, they were named simply from the Greek or Latin name organ with the ending from the Latin word meaning inflammation. Rhinitis is inflammation of the nasal mucosa, pharyngitis is the pharyngeal mucosa, laryngitis is the larynx, tracheitis is the windpipe, bronchitis is the bronchi.
These diseases are not only similar in name, but also related to each other. Damage to the mucous membrane, as a rule, begins from above, with an almost harmless runny nose (rhinitis). Untreated inflammation can spread further to the pharynx. And then we say that the throat hurts. If slight hypothermia leads to a weakening of protection and increased activity of microorganisms, and treatment is insufficient, the inflammatory process can move from the upper respiratory tract deep into the body, affecting the larynx, trachea, bronchi, and can spread to the lungs and lead to pneumonia. This is why it is so important to maintain normal breathing through the nose and the health of the upper respiratory tract.
Breathing called a set of physiological and physical chemical processes, ensuring the body’s consumption of oxygen, the formation and removal of carbon dioxide, obtaining through aerobic oxidation organic matter energy used for life.
Breathing is carried out respiratory system, represented by the airways, lungs, respiratory muscles that control the functions nerve structures, as well as blood and cardiovascular system, transporting oxygen and carbon dioxide.
Airways divided into upper (nasal cavities, nasopharynx, oropharynx) and lower (larynx, trachea, extra- and intrapulmonary bronchi).
To maintain the vital functions of an adult, the respiratory system must deliver about 250-280 ml of oxygen per minute to the body under conditions of relative rest and remove approximately the same amount of carbon dioxide from the body.
Through the respiratory system, the body is constantly in contact with atmospheric air — external environment, which may contain microorganisms, viruses, harmful substances chemical nature. They are all capable by airborne droplets enter the lungs, penetrate the airborne barrier into the human body and cause the development of many diseases. Some of them are fast-spreading - epidemic (influenza, acute respiratory viral infections, tuberculosis, etc.).
Rice. Airway diagram
Air pollution poses a major threat to human health chemicals technogenic origin (harmful industries, vehicles).
Knowledge about these pathways of impact on human health contributes to the adoption of legislative, anti-epidemic and other measures to protect against the effects of harmful factors atmosphere and preventing its pollution. This is possible subject to medical workers extensive explanatory work among the population, including the development of a number of simple rules of behavior. Among them are the prevention of environmental pollution, compliance elementary rules behavior during infections that must be vaccinated from early childhood.
A number of respiratory physiology problems are associated with specific types human activity: space and high-altitude flights, staying in the mountains, scuba diving, using pressure chambers, staying in an atmosphere containing toxic substances and excessive amounts of dust particles.
Functions of the respiratory tract
One of the most important functions of the respiratory tract is to ensure that air from the atmosphere enters the alveoli and is removed from the lungs. The air in the respiratory tract is conditioned, being purified, warmed and humidified.
Air purification. The air is especially actively cleared of dust particles in the upper respiratory tract. Up to 90% of the dust particles contained in the inhaled air settle on their mucous membrane. The smaller the particle, the more likely all penetration into the lower respiratory tract. Thus, particles with a diameter of 3-10 microns can reach bronchioles, and particles with a diameter of 1-3 microns can reach alveoli. Removal of settled dust particles is carried out due to the flow of mucus in the respiratory tract. The mucus covering the epithelium is formed from the secretion of goblet cells and mucus-producing glands of the respiratory tract, as well as fluid filtered from the interstitium and blood capillaries walls of the bronchi and lungs.
The thickness of the mucus layer is 5-7 microns. Its movement is created by the beating (3-14 movements per second) of the cilia of the ciliated epithelium, which covers all the respiratory tract with the exception of the epiglottis and true vocal cords. The efficiency of the cilia is achieved only when they beat synchronously. This wave-like movement will create a flow of mucus in the direction from the bronchi to the larynx. From the nasal cavities, mucus moves towards the nasal openings, and from the nasopharynx towards the pharynx. U healthy person per day, about 100 ml of mucus is formed in the lower respiratory tract (part of it is absorbed epithelial cells) and 100-500 ml in the upper respiratory tract. With synchronous beating of the cilia, the speed of mucus movement in the trachea can reach 20 mm/min, and in small bronchi and bronchioles it is 0.5-1.0 mm/min. Particles weighing up to 12 mg can be transported with the mucus layer. The mechanism for expelling mucus from the respiratory tract is sometimes called mucociliary escalator(from lat. mucus- slime, ciliare- eyelash).
The volume of mucus expelled (clearance) depends on the rate of mucus formation, viscosity and efficiency of the cilia. The beating of the cilia of the ciliated epithelium occurs only with sufficient formation of ATP in it and depends on the temperature and pH of the environment, humidity and ionization of the inhaled air. Many factors can limit mucus clearance.
So. at congenital disease- cystic fibrosis, caused by a mutation of the gene that controls the synthesis and structure of the protein involved in the transport of mineral ions through cell membranes secretory epithelium, an increase in mucus viscosity and difficulty in its evacuation from the respiratory tract by cilia develops. Fibroblasts from the lungs of patients with cystic fibrosis produce ciliary factor, which disrupts the functioning of epithelial cilia. This leads to impaired ventilation of the lungs, damage and infection of the bronchi. Similar changes in secretion may occur in gastrointestinal tract, pancreas. Children with cystic fibrosis need constant intensive care medical care. Disruption of the beating processes of cilia, damage to the epithelium of the respiratory tract and lungs, followed by the development of a number of other unfavorable changes in the bronchopulmonary system, is observed under the influence of smoking.
Warming the air. This process occurs due to the contact of inhaled air with the warm surface of the respiratory tract. The effectiveness of warming is such that even when a person inhales frosty atmospheric air, it heats up when entering the alveoli to a temperature of about 37 ° C. The air removed from the lungs transfers up to 30% of its heat to the mucous membranes upper sections respiratory tract.
Air humidification. Passing through the respiratory tract and alveoli, the air is 100% saturated with water vapor. As a result, the water vapor pressure in the alveolar air is about 47 mmHg. Art.
Due to the mixing of atmospheric and exhaled air, which has different contents of oxygen and carbon dioxide, a “buffer space” is created in the respiratory tract between the atmosphere and the gas exchange surface of the lungs. It helps maintain the relative constancy of the composition of alveolar air, which differs from atmospheric air more low content oxygen and more high content carbon dioxide.
The airways are reflexogenic zones numerous reflexes that play a role in the self-regulation of breathing: the Hering-Breuer reflex, the protective reflexes of sneezing, coughing, the “diver” reflex, and also affecting the work of many internal organs(heart, blood vessels, intestines). The mechanisms of a number of these reflexes will be discussed below.
The respiratory tract is involved in generating sounds and giving them a certain color. Sound is produced when air passes through the glottis, causing the vocal cords to vibrate. For vibration to occur, there must be an air pressure gradient between the outside and internal sides vocal cords. IN natural conditions such a gradient is created during exhalation, when vocal cords when talking or singing, they close, and the subglottic air pressure, due to the action of factors that ensure exhalation, becomes greater than atmospheric pressure. Under the influence of this pressure, the vocal cords shift for a moment, a gap is formed between them, through which about 2 ml of air breaks through, then the cords close again and the process repeats again, i.e. vibration of the vocal cords occurs, generating sound waves. These waves create the tonal basis for the formation of singing and speech sounds.
The use of breathing to form speech and sing is called respectively speech And singing breath. The presence and normal position of teeth are a necessary condition correct and clear pronunciation speech sounds. Otherwise, vagueness, lisp, and sometimes the inability to pronounce individual sounds appear. Speech and singing breathing make up separate item research.
About 500 ml of water evaporates through the respiratory tract and lungs per day, and thus they participate in the regulation of water-salt balance and body temperature. The evaporation of 1 g of water consumes 0.58 kcal of heat and this is one of the ways the respiratory system participates in heat transfer mechanisms. Under resting conditions, up to 25% of water and about 15% of the produced heat are removed from the body per day due to evaporation through the respiratory tract.
The protective function of the respiratory tract is realized through a combination of air conditioning mechanisms, protective reflex reactions and the presence of an epithelial lining covered with mucus. Mucus and ciliated epithelium with secretory, neuroendocrine, receptor, and lymphoid cells included in its layer create the morphofunctional basis of the airway barrier of the respiratory tract. This barrier, due to the presence of lysozyme, interferon, some immunoglobulins and leukocyte antibodies in the mucus, is part of the local immune system of the respiratory system.
The length of the trachea is 9-11 cm, the internal diameter is 15-22 mm. The trachea branches into two main bronchi. The right one is wider (12-22 mm) and shorter than the left one, and extends from the trachea at a large angle (from 15 to 40°). The bronchi branch, as a rule, dichotomously and their diameter gradually decreases, and the total lumen increases. As a result of the 16th branching of the bronchi, terminal bronchioles are formed whose diameter is 0.5-0.6 mm. This is followed by the structures that form the morphofunctional gas exchange unit of the lung - acini. The capacity of the airways to the level of the acini is 140-260 ml.
The walls of small bronchi and bronchioles contain smooth myocytes, which are located in them circularly. The lumen of this part of the airways and the speed of air flow depend on the degree of tonic contraction of myocytes. Regulation of the speed of air flow through the respiratory tract is carried out mainly in their lower sections, where the clearance of the paths can change actively. Myocyte tone is under the control of neurotransmitters of the autonomic nervous system, leukotrienes, prostaglandins, cytokines and other signaling molecules.
Receptors of the respiratory tract and lungs
An important role in the regulation of breathing is played by receptors, which are especially abundantly supplied in the upper respiratory tract and lungs. In the mucous membrane of the upper nasal passages, between the epithelial and supporting cells there are olfactory receptors. They are sensitive nerve cells having movable cilia that provide reception odorous substances. Thanks to these receptors and the olfactory system, the body is able to perceive the odors of substances contained in environment, availability nutrients, harmful agents. Exposure to certain odorous substances causes a reflex change in the patency of the respiratory tract and, in particular, in people with obstructive bronchitis may cause an asthma attack.
The remaining receptors of the respiratory tract and lungs are divided into three groups:
- sprains;
- irritant;
- juxtaalveolar.
Stretch receptors located in muscle layer respiratory tract. An adequate stimulus for them is stretching of muscle fibers, caused by changes in intrapleural pressure and pressure in the lumen of the respiratory tract. The most important function of these receptors is to control the degree of stretching of the lungs. Thanks to them functional system breathing regulation controls the intensity of ventilation of the lungs.
There is also a number of experimental data on the presence of collapse receptors in the lungs, which are activated when there is a strong decrease in lung volume.
Irritant receptors have the properties of mechano- and chemoreceptors. They are located in the mucous membrane of the respiratory tract and are activated by the action of an intense stream of air during inhalation or exhalation, the action of large dust particles, the accumulation of purulent discharge, mucus, and the entry of food particles into the respiratory tract. These receptors are also sensitive to the action of irritating gases (ammonia, sulfur vapor) and other chemicals.
Juxtaalveolar receptors located in the intestinal space of the pulmonary alveoli near the walls of the blood capillaries. An adequate stimulus for them is an increase in the blood supply to the lungs and an increase in the volume of intercellular fluid (they are activated, in particular, during pulmonary edema). Irritation of these receptors reflexively causes frequent shallow breathing.
Reflex reactions from respiratory tract receptors
When stretch receptors and irritant receptors are activated, numerous reflex reactions occur that provide self-regulation of breathing, protective reflexes and reflexes that affect the functions of internal organs. This division of these reflexes is very conditional, since the same stimulus, depending on its strength, can either provide regulation of the change in phases of the cycle calm breathing, or call defensive reaction. Afferent and efferent pathways of these reflexes pass in the trunks of the olfactory, trigeminal, facial, glossopharyngeal, vagus and sympathetic nerves, and the closure of the majority reflex arcs carried out in structures respiratory center medulla oblongata with the connection of the nuclei of the above nerves.
Self-regulation reflexes of breathing ensure regulation of the depth and frequency of breathing, as well as the lumen of the airways. Among them are the Hering-Breuer reflexes. Hering-Breuer inspiratory inhibitory reflex manifests itself in the fact that when the lungs are stretched during a deep breath or when air is blown in by artificial respiration devices, inhalation is reflexively inhibited and exhalation is stimulated. With strong stretching of the lungs, this reflex becomes protective role, protecting the lungs from overextension. The second of this series of reflexes is expiratory facilitation reflex - manifests itself in conditions when air enters the respiratory tract under pressure during exhalation (for example, with hardware artificial respiration). In response to such an effect, exhalation is reflexively prolonged and the appearance of inhalation is inhibited. Lung collapse reflex occurs when exhaling as deeply as possible or when injured chest accompanied by pneumothorax. It is manifested by frequent shallow breathing, which prevents further collapse of the lungs. Also distinguished Head's paradoxical reflex manifested by the fact that with intensive blowing of air into the lungs a short time(0.1-0.2 s) inhalation can be activated, followed by exhalation.
Among the reflexes regulating the lumen of the airways and the force of contraction respiratory muscles, available reflex to decrease pressure in the upper respiratory tract, which is manifested by contraction of the muscles that expand these airways and prevent them from closing. In response to a decrease in pressure in the nasal passages and pharynx, the muscles of the wings of the nose, the genioglossus and other muscles reflexively contract, displacing the tongue ventrally anteriorly. This reflex promotes inhalation by reducing resistance and increasing the upper airway's patency for air.
A decrease in air pressure in the lumen of the pharynx also reflexively causes a decrease in the force of contraction of the diaphragm. This pharyngeal-phrenic reflex prevents further decrease in pressure in the pharynx, sticking of its walls and the development of apnea.
Glottis closure reflex occurs in response to irritation of the mechanoreceptors of the pharynx, larynx and root of the tongue. This closes the vocal and supraglottic cords and prevents food, liquids and irritating gases from entering the inhalation tract. In patients who are unconscious or under anesthesia, reflex closure of the glottis is impaired and vomit and pharyngeal contents can enter the trachea and cause aspiration pneumonia.
Rhinobronchial reflexes arise from irritation of the irritant receptors of the nasal passages and nasopharynx and are manifested by a narrowing of the lumen of the lower respiratory tract. In people prone to spasms of smooth muscle fibers of the trachea and bronchi, irritation of the irritant receptors of the nose and even certain odors can provoke the development of an attack of bronchial asthma.
To the classics protective reflexes The respiratory system also includes the cough, sneeze and diver reflexes. Cough reflex caused by irritation of the irritant receptors of the pharynx and underlying respiratory tract, especially the tracheal bifurcation area. When implementing it, first there is short breath, then closing the vocal cords, contracting the expiratory muscles, increasing subglottic air pressure. Then the vocal cords instantly relax and the air stream passes through the airways, glottis and open mouth into the atmosphere at high linear speed. At the same time, excess mucus, purulent contents, some inflammatory products, or accidentally ingested food and other particles are expelled from the respiratory tract. A productive, “wet” cough helps cleanse the bronchi and performs drainage function. For more effective cleansing respiratory tract, doctors prescribe special medicines, stimulating the production of liquid discharge. Sneeze reflex occurs when the receptors in the nasal passages are irritated and develops similarly to the left cough reflex, except that the expulsion of air occurs through the nasal passages. At the same time, tear formation increases, tear fluid nasolacrimal duct enters the nasal cavity and moisturizes its walls. All this helps cleanse the nasopharynx and nasal passages. Diver reflex caused by fluid entering the nasal passages and manifests itself as a short-term stoppage breathing movements, preventing the passage of fluid into the underlying respiratory tract.
When working with patients, resuscitators, maxillofacial surgeons, otolaryngologists, dentists and other specialists need to take into account the features of the described reflex reactions that occur in response to receptor irritation oral cavity, pharynx and upper respiratory tract.
Respiratory system person- a set of organs that ensure respiration (gas exchange between inhaled atmospheric air and blood). All cells in the body must receive oxygen in order to convert it into energy nutrients food carried by the blood and regenerate.
Functions of the respiratory system
1. The most important function is gas exchange- supplying the body with oxygen and removing carbon dioxide or carbon dioxide, which is the end product of metabolism. Breathing in humans includes external and cellular (internal) respiration.
2. Barrier- mechanical and immune protection of the body from harmful components of inhaled air. Air containing various impurities in the form of inorganic and organic particles of animals and plant origin, gaseous substances and aerosols, as well as infectious agents: viruses, bacteria, etc. The purification of inhaled air from foreign impurities is carried out using the following mechanisms: 1) mechanical air purification (air filtration in the nasal cavity, deposition on the mucous membrane of the respiratory tract and removal from secretions; sneezing and coughing); 2) the action of cellular (phagocytosis) and humoral (lysozyme, interferon, lactoferrin, immunoglobulins) factors nonspecific protection. Interferon reduces the number of viruses that colonize cells, lactoferrin binds iron, necessary for the life of bacteria and due to this has a bacteriostatic effect. Lysozyme breaks down glycosaminoglycans cell membrane microbes, after which they become non-viable.
3. Thermoregulationbody
5. Smell
Lung tissue also plays an important role in processes such as: synthesis of hormones, water-salt and lipid metabolism s. In a richly developed vascular system lungs occurs blood deposition.
Physiology
The respiratory tract is divided into two sections: the upper airway (breathing) tract and the lower airway (breathing) tract.
Upper respiratory tract include the nasal cavity, nasopharynx and oropharynx.
Lower respiratory tract include the larynx, trachea and bronchial tree.
Nasal cavity
Nasal cavity, formed by bones the facial part of the skull and cartilage, is lined with a mucous membrane, which is formed by numerous hairs and cells covering the nasal cavity. Hairs trap dust particles from the air, and mucus prevents the penetration of germs. Thanks to blood vessels piercing the mucous membrane, air passing through nasal cavity, cleanses, moisturizes and warms. The nasal mucosa performs protective function, because it contains immunoglobulins and immune defense cells. On top surface The nasal cavity, in the mucous membrane, contains olfactory receptors. Through the nasal passages the nasal cavity is connected to nasopharynx. Oral cavity- This is the second way air enters the human respiratory system. The oral cavity has two sections: posterior and anterior.
Pharynx
Pharynx is a tube that originates in the nasal cavity. The digestive and respiratory tracts intersect in the pharynx. The pharynx can be called the link between the nasal cavity and the oral cavity, and the pharynx also connects the larynx and esophagus. The pharynx is located between the base of the skull and the 5-7 vertebrae of the neck.
It concentrates a large number of lymphoid tissue. The largest lymphoid formations are called tonsils. Tonsils and lymphoid tissue play a protective role in the body, forming the Waldeyer-Pirogov lymphoid ring (palatine, tubal, pharyngeal, lingual tonsils). The pharyngeal lymphoid ring protects the body from bacteria, viruses and performs other important functions. IN nasopharynx open like this important formations, How eustachian tubes connecting the middle ear ( tympanic cavity) with the pharynx. Ear infections occur through swallowing, sneezing, or simply from a runny nose. Long course otitis is associated specifically with inflammation of the Eustachian tubes.
Paranasal sinuses- these are restricted air spaces facial skull, additional air tanks.
Larynx
Larynx- a respiratory organ connecting the trachea and pharynx. Located in the larynx voice apparatus. The larynx is located in the area of 4-6 vertebrae of the neck and is attached to the hyoid bone with the help of ligaments. The beginning of the larynx is in the pharynx, and the end is a bifurcation into two tracheas. The thyroid, cricoid, and epiglottic cartilages make up the larynx. These are big unpaired cartilages. It is also formed by small paired cartilages: corniculate, sphenoid, arytenoid. The connection between the joints is provided by ligaments and joints. Between the cartilages there are membranes that also serve as a connection. Located in the larynx vocal folds, which are responsible for the voice function. The epiglottis is located in the larynx before inhalation into the trachea. It closes the lumen of the trachea during the act of swallowing and moving food or liquid into the esophagus. During inhalation and exhalation, the epiglottis opens the trachea and closes the esophagus to move the respiratory mixture in the desired direction. Directly below the epiglottis is the entrance to the trachea and vocal cords. This is one of the narrowest places in the upper respiratory tract.
Trachea
Next, the air enters trachea, having the shape of a tube 10-14 cm long. The trachea is reinforced with cartilaginous formations - 14-16 cartilaginous half-rings, which serve as a frame for this tube, which does not allow air to be retained during any movements of the neck.
Bronchi
Two large ones arise from the trachea bronchus, through which air enters the right and left lungs. Bronchi are the whole system airway tubes forming the bronchial tree. The branching system of the bronchial tree is complex, it has 21 orders of bronchi - from the widest, which are called “main bronchi,” to their smallest branches, which are called bronchioles. Bronchial branches are entangled with blood vessels and lymphatic vessels. Each previous branch of the bronchial tree is wider than the next, so the entire bronchial system resembles a tree turned upside down.
Lungs
Lungs consist of shares. Right lung consists of three lobes: upper, middle and lower. In the left lung there are two lobes: upper and lower. Each lobe, in turn, consists of segments. Air enters each segment through an independent bronchus, called segmental. Inside the segment, the bronchial tree branches, and each of its branches ends in alveoli. The exchange of gases takes place in the alveoli: carbon dioxide is released from the blood into the lumen of the alveoli, and in return oxygen enters the blood. The exchange of gases or gas exchange is possible due to the unique structure of the alveoli. The alveolus is a vesicle, covered with epithelium on the inside and richly enveloped on the outside. capillary network. Lung tissue has a large number of elastic fibers that ensure stretching and collapsing of the lung tissue during the act of breathing. The act of breathing involves the muscles of the chest and the diaphragm. The unhindered sliding of the lung in the chest during the act of breathing is ensured by the pleural layers that cover the inside of the chest (parietal pleura) and the outside of the lung (visceral pleura).
Human ( gas exchange between inhaled atmospheric air and circulating through pulmonary circulation blood).
Gas exchange occurs in the alveoli lungs, and is normally aimed at capturing from inhaled air oxygen and release into the external environment formed in the body carbon dioxide.
An adult, at rest, makes an average of 14 respiratory movements per minute, but the respiratory rate can undergo significant fluctuations (from 10 to 18 per minute). An adult takes 15-17 breaths per minute, and a newborn baby takes 1 breath per second. Ventilation of the alveoli is carried out by alternating inhalations ( inspiration) and exhalation ( expiration). When you inhale, it enters the alveoli atmospheric air, and when you exhale, air saturated with carbon dioxide is removed from the alveoli.
Normal calm inhalation is associated with muscle activity aperture And external intercostal muscles. When you inhale, the diaphragm lowers, the ribs rise, and the distance between them increases. Normal calm exhalation occurs in to a large extent passively, while actively working internal intercostal muscles and some abdominal muscles. When you exhale, the diaphragm rises, the ribs move down, and the distance between them decreases.
According to the method of expansion of the chest, two types of breathing are distinguished: [ ]
Structure [ | ]
Airways[ | ]
There are upper and lower respiratory tracts. The symbolic transition of the upper respiratory tract to the lower is carried out at the intersection digestive and respiratory systems in the upper part of the larynx.
The upper respiratory tract system consists of the nasal cavity ( lat. cavitas nasi), nasopharynx ( lat. pars nasalis pharyngis) and oropharynx ( lat. pars oralis pharyngis), as well as partially the oral cavity, since it can also be used for breathing. The lower respiratory tract system consists of the larynx ( lat. larynx, sometimes referred to as the upper respiratory tract), trachea ( Old Greek τραχεῖα (ἀρτηρία) ), bronchi ( lat. bronchi), lungs.
Inhalation and exhalation are carried out by changing sizes chest by using. During one breath (in calm state) 400-500 ml of air enters the lungs. This volume of air is called tidal volume (BEFORE). The same amount of air enters the atmosphere from the lungs during a quiet exhalation. Maximum deep breath is about 2,000 ml of air. After maximum exhalation, about 1,500 ml of air remains in the lungs, called residual lung volume. After a quiet exhalation, approximately 3,000 ml remains in the lungs. This volume of air is called functional residual capacity(FOYO) lungs. Breathing is one of the few functions of the body that can be controlled consciously and unconsciously. Types of breathing: deep and superficial, frequent and rare, upper, middle (thoracic) and lower (abdominal). Special types of respiratory movements are observed when hiccups And laughter. With frequent and shallow breathing the excitability of the nerve centers increases, and with deep stimulation, on the contrary, it decreases.
Respiratory organs[ | ]
The respiratory tract provides connections between the environment and the main organs of the respiratory system - light. Lungs ( lat. pulmo, Old Greek πνεύμων ) are located in chest cavity surrounded by bones and muscles of the chest. In the lungs, gas exchange occurs between atmospheric air that has reached pulmonary alveoli(lung parenchyma), and blood, flowing through the pulmonary capillaries, which ensure the flow oxygen V organism and removal of gaseous waste products from it, including carbon dioxide. Thanks to functional residual capacity (FOYO) lungs in alveolar air, a relatively constant ratio of oxygen and carbon dioxide content is maintained, since FOE is several times greater tidal volume(BEFORE). Only 2/3 of the DO reaches the alveoli, which is called the volume alveolar ventilation. Without external breathing human body can usually live up to 5-7 minutes (the so-called clinical death), followed by loss of consciousness, irreversible changes in the brain and its death (biological death).
Functions of the respiratory system[ | ]
In addition, the respiratory system is involved in such important functions, How thermoregulation , voicing , sense of smell, humidification of inhaled air. Lung tissue also plays an important role in processes such as hormone synthesis, water-salt and lipid metabolism. In the abundantly developed vascular system of the lungs, blood is deposited. The respiratory system also provides mechanical and immune protection from environmental factors.
Gas exchange [ | ]
Gas exchange is the exchange of gases between the body and the external environment. Oxygen is continuously supplied to the body from the environment, which is consumed by all cells, organs and tissues; The carbon dioxide formed in it and a small amount of other gaseous metabolic products are released from the body. Gas exchange is necessary for almost all organisms; without it it is impossible normal exchange substances and energy, and, consequently, life itself. Oxygen entering the tissues is used to oxidize the resulting products long chain chemical transformations carbohydrates, fats and proteins. In this case, CO 2, water, nitrogen compounds are formed and energy is released, which is used to maintain body temperature and perform work. The amount of CO 2 formed in the body and, ultimately, released from it depends not only on the amount of O 2 consumed, but also on what is predominantly oxidized: carbohydrates, fats or proteins. The ratio of the volume of CO 2 removed from the body to the volume of O 2 absorbed during the same time is called respiratory quotient, which is approximately 0.7 for the oxidation of fats, 0.8 for the oxidation of proteins and 1.0 for the oxidation of carbohydrates (in humans, with mixed food, the respiratory coefficient is 0.85–0.90). The amount of energy released per 1 liter of O2 consumed (caloric equivalent of oxygen) is 20.9 kJ (5 kcal) during the oxidation of carbohydrates and 19.7 kJ (4.7 kcal) during the oxidation of fats. Based on the consumption of O 2 per unit time and the respiratory coefficient, the amount of energy released in the body can be calculated. Gas exchange (and therefore energy expenditure) in poikilothermic animals (cold-blooded animals) decreases with decreasing body temperature. The same dependence was found in homeothermic animals (warm-blooded) when thermoregulation is turned off (under conditions of natural or artificial hypothermia); When body temperature rises (overheating, certain diseases), gas exchange increases.
When the ambient temperature decreases, gas exchange in warm-blooded animals (especially small ones) increases as a result of increased heat production. It also increases after eating, especially rich in proteins(the so-called specific dynamic action of food). Gas exchange reaches its greatest values during muscle activity. In humans, when working at moderate power, it increases after 3-6 minutes. after its start it reaches a certain level and then remains at this level throughout the entire period of work. When operating at high power, gas exchange continuously increases; soon after reaching the maximum for this person level (maximum aerobic work), work has to be stopped, since the body’s need for O 2 exceeds this level. In the first time after work, an increased consumption of O 2 remains, which is used to cover the oxygen debt, that is, to oxidize metabolic products formed during work. O2 consumption can increase from 200-300 ml/min. at rest up to 2000-3000 during work, and in well-trained athletes - up to 5000 ml/min. Accordingly, CO 2 emissions and energy consumption increase; at the same time there are shifts in the respiratory coefficient associated with changes in metabolism, acid-base balance and pulmonary ventilation. Calculation of the total daily energy expenditure for people of different professions and lifestyles, based on the definitions of gas exchange, is important for rationing nutrition. Studies of changes in gas exchange under standard physical work used in occupational and sports physiology, in the clinic for assessment functional state systems involved in gas exchange. The comparative constancy of gas exchange with significant changes in the partial pressure of O 2 in the environment, disturbances in the functioning of the respiratory system, etc. is ensured by adaptive (compensatory) reactions of the systems involved in gas exchange and regulated by the nervous system. In humans and animals, gas exchange is usually studied under conditions of complete rest, on an empty stomach, at a comfortable ambient temperature (18-22 °C). The amounts of O2 consumed and the energy released are characterized by BX. Methods based on the principle of an open or closed system are used for research. In the first case, the amount of exhaled air and its composition are determined (using chemical or physical gas analyzers), which makes it possible to calculate the amounts of O 2 consumed and CO 2 released. In the second case, breathing occurs in a closed system (a sealed chamber or from a spirograph connected to the respiratory tract), in which the released CO 2 is absorbed, and the amount of O 2 consumed from the system is determined either by measuring an equal amount of O 2 automatically entering the system, or by reducing the volume of the system. Gas exchange in humans occurs in the alveoli of the lungs and in the tissues of the body.
