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The bronchi is an element of the respiratory system that belongs to the lower respiratory tract. Due to their structure, they are also referred to as the "bronchial tree". Their task is to allow air to enter the lungs and also to expel the substance on exhalation. How are bronchi built? Find out about the most common bronchial diseases.
The bronchi(Latinbronchi ; singularbronchus ) is an organ of the system the respiratory tract, resembling a branched tree. The main function of the bronchus is to allow air to flow to and from the lungs. The proper functioning of the bronchi is necessary to ensure gas exchange in the lungs. The most common bronchial diseases have an infectious background, however, neoplastic, genetic and inflammatory diseases can also develop in the bronchi. Find out how the bronchi are built, how the bronchi work, what tests enable the diagnosis of the bronchial condition and what are the most common bronchial diseases.
Bronchi - structure
The bronchi belong to the respiratory system, or more precisely - they are part of the lower respiratory tract. The bronchi begin where the trachea divides into two parts -right and left main bronchus . The bronchi then divide into an entirely tubular organ that we call the bronchial tree.
The bronchial treehas as many as 16 so-called generations of divisions, i.e. places of successive branching. The two main bronchi are divided into the lobar bronchi, leading to the corresponding lobes of the lungs.
Lobe bronchibranch intosegmental bronchiand those into even thinnersub-segmental bronchi. The end branches of the bronchial tree go into the tiniest elements of the respiratory tract - in the following order:
- bronchioles
- followed byalveoli
It can therefore be said that the bronchi allow the transfer of air from the trachea to the lungs during inspiration and from the lungs to the trachea during exhalation.
- Is the bronchial tree perfectly symmetrical?
It might seem so, but it's a wrong impression. The human chest is not symmetrical. On the left, much of the space is occupied by the heart muscle, resulting in only two lobes in the left lung andthree lobes on the right. For this reason, we have two lobe bronchi on the left and three on the right.
The main bronchi also differ from each other.Main left bronchusis longer, thinner and runs more horizontally. On the other hand, theright main bronchusresembles an extension of the trachea - it runs more vertically, is shorter and thicker. Contrary to appearances, this asymmetry is of great clinical importance - in the case of foreign body aspiration (aspiration), in most cases it will be found in the right bronchus.
Bronchi - functions
The main function of the bronchi is, of course, to transport air. This does not mean, however, that the role of the bronchi in the respiratory process is only passive. The functioning of the bronchi is well reflected in their microscopic structure. By examining a bronchial fragment under a microscope, we can find different types of tissue.
The bronchial skeletonis made of hard but flexible cartilage tissue.
The bronchial cartilageis covered from the inside by two membranes: muscular and mucous.
The muscle layeris responsible for constricting the bronchial wall. This function is especially useful in the coughing reflex, which is a protective reflex.
Contact of the bronchial wall with a foreign substance triggers a reflex that leads to a sudden contraction of the bronchial musculature. In combination with the stimulation of the respiratory muscles, a cough is produced which allows the airways to be cleared quickly. Unfortunately, the bronchial muscle can also be a source of disease problems - its excessive reactivity is the cause of breathlessness in bronchial asthma.
The bronchial mucosais equipped with components that allow it to perform specialized functions. One of them is a special type of epithelium -ciliary epithelium , also called snapshot. The cells of this epithelium have fine cilia that allow the purification of the inhaled air. The inhaled contaminants are captured on the surface of the cilia, which can move in a coordinated manner. This movement brings the pollutants back towards the upper respiratory tract.
The mucus produced by thebronchial glandsperforms a similar function. In addition to moisturizing the respiratory tract, the presence of mucus allows foreign substances and microorganisms to be suspended in it. In combination with the movement of the cilia and the cough reflex, the contaminated mucus can be discharged to the outside.
Bronchi - diseases
Bronchial diseases , especially infectious diseases, are relatively common. The bronchi can alsoconcern genetic, neoplastic and inflammatory diseases - the latter are a frequent result of smoking.
Various types of tests are used in the diagnosis of bronchial diseases. Traditional diagnostics begins with a chest X-ray, but better visualization of the bronchi is possible in computed tomography. When standard imaging tests are not enough, it may be necessary to perform bronchoscopy - an examination that involves examining the inside of the bronchus using a special camera.
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bronchitis
Bronchitis is a common ailment, especially in periods of increased incidence of infections. The most common cause of bronchitis is a viral infection that spreads through the continuity from the upper respiratory tract. Symptoms of bronchitis include cough, fever, weakness, and shortness of breath. Bronchitis is rarely caused by bacteria, so it shouldn't be treated routinely with antibiotics. In most cases, the disease is self-limiting. Patients are advised to rest, use antipyretics and symptomatic treatment of cough.
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bronchial asthma
Asthma is an inflammatory disorder that is often (but not always) associated with an allergy. The essence of bronchial asthma is the excessive reactivity of the bronchial wall, causing bronchial muscle contraction and a feeling of breathlessness. Asthma typically progresses with periods of alternating worsening and relieving symptoms. In the treatment of bronchial asthma, two types of inhalation drugs are typically used: anti-inflammatory glucocorticosteroids and the so-called beta-mimetics that widen the bronchial wall.
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bronchial cancer
In everyday life we often come across the name "lung cancer". However, it is worth being aware that in many cases the starting point of this neoplasm is the bronchus. Squamous cell carcinoma is a type of cancer that is particularly common in large bronchi. The main factor in developing bronchial cancer is chronic cigarette smoking. The most common symptoms of bronchial cancer are cough, haemoptysis, shortness of breath, and weakness. Low-stage bronchial neoplasms give the best chance of recovery - then they can be completely surgically removed. Much worse prognosis concerns metastatic bronchial cancer, especially if there are metastases to other organs.
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bronchiectasis
Bronchiectasis is a condition in which the bronchial lumen is dilated excessively. The bronchi, instead of narrow tubes, resemble bloated balloons.Abnormal bronchial structure hinders gas exchange and cleaning of the respiratory tract. The main problem of bronchiectasis patients is recurrent infections, chronic cough, and massive bronchial secretions. Bronchiectasis can have a variety of causes - both congenital and acquired. Unfortunately, distended and damaged bronchi cannot be treated causally. There are, however, a variety of symptomatic treatments, such as infection prevention, physiotherapy to improve discharge of secretions, and - in the most severe cases - respiratory support with external devices.
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cystic fibrosis
Cystic fibrosis is a genetic disorder involving the abnormal functioning of the exocrine glands - the secretions they produce have a disturbed composition and are too dense. One of the effects of cystic fibrosis is the presence of a thickened, difficult-to-remove mucus in the airways. The secretion in the bronchi becomes the environment for microbial growth, which leads to frequent infections. Cystic fibrosis leads to the development of respiratory failure over time. Unfortunately, the genetic background of this disease prevents - so far - its causal treatment. The therapy includes rehabilitation breathing exercises, drugs that thin the mucus, and in some cases also lung transplantation.
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bronchopulmonary dysplasia
Bronchopulmonary dysplasia is a disease that mainly affects premature babies. Babies born before the physiological termination of pregnancy have immature lungs, therefore they often require respiratory support and oxygen therapy. Such therapy allows them to survive, but unfortunately it is also associated with long-term sequelae, which we call bronchopulmonary dysplasia. Disturbance in the development of bronchi and lungs in the early stages of a child's life results in their abnormal structure in the later stages of life. The bronchi of patients with bronchopulmonary dysplasia undergo remodeling, which hinders the proper air flow. Recurring infections are also a big problem. The effects of dysplasia are chronic, and the disease may lead to progressive respiratory failure over a long period of time.
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COPD
Although COPD is a chronic obstructive pulmonary disease, it also affects the bronchi. It leads to their narrowing, which significantly worsens breathing. It is necessary to take treatment that will slow down its development and reduce the symptoms.
Bronchial Testing
To check that the bronchi are functioning properly as well as thatnone of the previously discussed diseases occur, specialists may order the following tests.
- Physical examination - auscultation
This is one of the first tests that a doctor can perform in an office on a person with symptoms of respiratory diseases. Thanks to it, murmurs, wheezes, crackles, rattles and other abnormalities can be detected. To make a diagnosis, your doctor may order further tests.
- Chest X-ray
This type of radiological examination is also one of the basic tests in the diagnosis of bronchial diseases and other respiratory diseases. You can check if there are any abnormalities in a non-invasive way, but remember that this is not a very accurate examination and most often further diagnostics are required.
- Computed tomography of the chest
It is a precise examination that is performed in the case of suspected bronchial diseases, as well as their injuries. A specialist may order HRCT (high resolution) tomography, in the pulmonary embolism algorithm, or with administration of a contrast agent. In special cases, magnetic resonance imaging is also performed, which enables an accurate assessment of the state of the structures of the respiratory system.
- Spirometry
Thanks to spirometry, it is possible to check the proper functioning of the respiratory tract and lungs. You can, among others check ventilation, the reaction of the respiratory tract to external factors and the flow rate through the respiratory tract. The test may also take the form of exercise tests. Additionally, it can be performed with a histamine or methacholine provocation test.
- Bronchoscopy
This is a trachea and bronchus endoscopy. As a rule, it is a supplement to a chest radiograph. It allows not only the assessment of these elements of the respiratory system, but also the collection of specimens for histopathological examination, removal of secretions, pus and foreign bodies, as well as direct administration of drugs.
- Plethysmography
The test assesses the function of the lungs, which in this case is the total amount of air in them. It also allows you to assess the resistance to air through the respiratory tract, i.e. the degree of bronchial constriction (obstruction).