Bronchi: anatomy, function and treatment


The bronchi are the airways that travel from the trachea to the lungs and then branch into smaller and smaller structures until they reach the alveoli, small sacs that exchange oxygen and carbon dioxide in the lungs.

Although the bronchi primarily function as airways, they also play a role in immune function. Several different diseases can affect the bronchi, such as bronchitis , asthma, chronic obstructive pulmonary disease (COPD), and lung cancer.

Treatment is tailored to the specific condition and ranges from medication to surgery.


The bronchi are made up of cartilage, smooth muscle, and mucous membranes. Collectively, the trachea and bronchial structures are known as the tracheobronchial tree or simply the bronchial tree .

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The junction between the trachea and the bronchi begins at the level of the fifth thoracic vertebra. At the bottom of the trachea is a cartilaginous ridge called the keel. The carina is essentially divided into two main bronchi; The right bronchus enters the right lung and the left bronchus enters the left.

Cartilage is what prevents the bronchi from collapsing during inhalation and exhalation. While the trachea and upper bronchi contain C-shaped cartilage, the smaller bronchi have cartilage 'plates'.

As the bronchi divide into smaller (subsegmental) bronchi, the amount of cartilage decreases and the amount of smooth muscle increases.

The vessels no longer contain cartilage as they are divided into bronchioles, terminal bronchioles, respiratory bronchioles, alveolar sacs and finally into alveoli , where oxygen and carbon dioxide are exchanged .

The tracheabronchial tree is lined with a mucous membrane made up of epithelial cells, goblet cells that secrete mucus, and hair-like projections called cilia that move foreign particles up and out of the airways.

Right main bronchus: The right main bronchus is shorter and more vertical than the left, it is about 2.5 cm long and divides into smaller bronchi to enter the three lobes of the right lung.

Due to the angle at which the bronchi enter the lungs, absorbed (inhaled) fluids are more likely to enter the right lung. For example, aspiration pneumonia occurs most often in the right lower lobe.

Left main bronchus: The left bronchus is smaller and longer than the right main bronchus (approximately 5 cm or 1.5 inches). This , in turn, divides into two secondary lobar bronchi, which enter the two lobes of the left lung.


The bronchi primarily function as a conduit for air from the mouth and windpipe to the alveoli and back to the body. Therefore , the body's tissues receive oxygen and carbon dioxide can be expelled from the body. …

Because the bronchi bring in air from outside, potentially exposing the lungs to infectious agents, they are lined with mucous membranes. This mucus layer is an important "barrier" to inhaled pathogens that can help prevent the spread of infections .

Related conditions

Numerous diseases can affect the bronchi. Some of them affect other areas of the lungs, while others are limited to the main bronchus and small bronchi.

The chase of foreign objects

If you accidentally inhale a foreign object, it often gets stuck in one of your bronchial tubes. People who have problems eating and swallowing, such as after a stroke, tend to inhale food.

People who are unconscious, for example during an operation that requires general anesthesia , are at risk of vomiting and aspiration. (This is why people are advised to fast before surgery.) Inhaled substances can attract bacteria and cause aspiration pneumonia.

Acute bronchitis

In acute bronchitis, a viral infection usually begins in the nose or throat and then infects the cells of the bronchial tubes, causing them to swell. Common symptoms of bronchitis include coughing, which is often accompanied by spitting up and wheezing.

Chronic bronchitis

Chronic bronchitis causes inflammation of the bronchioles, causing a persistent accumulation of mucus in the lungs (compared to acute bronchitis). Symptoms include chronic cough and predisposition to bacterial infections; breathing becomes more and more difficult over time.

Most cases of chronic bronchitis in the United States are caused by long-term smoking. Long-term exposure to secondhand smoke, air pollution, and chemical fumes can also be important.


Chronic bronchitis is one of the manifestations of chronic obstructive pulmonary disease . Emphysema , in which the alveoli are affected, often accompanies bronchitis. COPD is a serious disease that can lead to lung cancer and is often fatal.


Asthma is a condition characterized by narrowing of the bronchi (bronchospasm), which in turn prevents the passage of air from the environment to the alveoli of the lungs .

Asthma attacks are often triggered by allergies, exercise, or irritants.


When the walls of the bronchi are left with irreversible scars, they can thicken, causing mucus to accumulate and become a breeding ground for bacteria. Lung function declines over time.

Bronchiectasis is commonly associated with other medical conditions such as COPD, cystic fibrosis, and recurrent cases of pneumonia .


Bronchiolitis is caused by a viral infection, most commonly respiratory syncytial virus (RSV). The bronchioles swell and fill with mucus, making it difficult to breathe. Babies under three months are the most susceptible to this disease .

A rare and serious type of bronchiolitis called obliterative bronchiolitis (also known as "popcorn lung") is a chronic form of the disease that mainly affects adults.

Bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) can occur in newborns (usually premature babies) who are being treated with oxygen or a ventilator for another breathing problem.

The large amounts of oxygen and pressure used in these treatments can overstretch the alveoli, causing inflammation and damage to the lining of the airways. In some cases, BPD can have lifelong consequences.

Bronchospasm occurs when the airways narrow or narrow, causing wheezing and shortness of breath. Bronchospasm is a symptom of many conditions that affect the airways, including asthma, seasonal allergies, and COPD.

Bronchogenic carcinoma

Bronchogenic carcinoma is an older term for cancer that occurs in the bronchi and bronchioles. The term is now used synonymously with lung cancer of all types. Non-small cell lung cancer is the most common, causing 80% to 85% of cancers.

This type of lung cancer is more common in nonsmokers, women, and young adults. Small cell lung cancer   it is responsible for approximately 15% of lung cancers. These lung cancers tend to be aggressive and cannot be found until they have metastasized (spread to other parts of the body).

Bronchopleural fistula

A bronchopleural fistula is an abnormal passage (sinus tract) that develops between the bronchi and the space between the membranes that line the lungs ( pleural space ).

It is a serious complication often caused by surgery for lung cancer, but it can also appear after chemotherapy, radiation therapy, or an infection. Bronchopleural fistula is a rare but dangerous disease that leads to death in 25% to 71% of cases .

Diagnostic procedures

The following general imaging tests are used to diagnose bronchial problems.


A chest X-ray is usually the first procedure used to obtain images of the lungs. X-rays are helpful in identifying causes of aspiration, pneumonia, and lung tumors.


During bronchoscopy , a tube called a bronchoscope is inserted through the mouth into the bronchial tubes.

A bronchoscopy may be performed to evaluate symptoms such as a persistent cough or coughing up blood, but it can also be used to treat certain conditions, such as bleeding in the airways or removal of a foreign body.

Endobronchial ultrasound

Endobronchial ultrasound examines the deeper tissues of the lungs, behind the walls of the bronchi .

If a tumor is found, a needle biopsy can be performed under the guidance of an endobronchial ultrasound, which allows obtaining tissue from the tumor without the need for an open lung biopsy.

Treatment and rehabilitation

Because there are so many different types of conditions and diseases that can affect the bronchial tubes, treatments vary widely, from medications to surgery.


These medications help relax the muscles around the airways, making it easier to breathe by widening the airway openings. They are the mainstay of asthma treatment and are usually delivered through a nebulizer or spacer inhaler.


These medications reduce and / or prevent inflammation of the lungs. They help reduce airway inflammation and mucus production. Like bronchodilators, they can be given using a nebulizer or spacer inhaler.

Bronchitis often clears up on its own or can be treated with over-the-counter medications that thin the mucus. Antibiotics are generally prescribed when a bacterial infection affects the bronchial tubes.

Oxygen therapy

When bronchial disease results in low blood oxygen levels, supplemental oxygen is often required, either temporarily in an acute condition or permanently, such as in a chronic disease such as COPD.

Oxygen therapy is performed in hospitals, but it can also be used with household equipment. Oxygen is usually given through an oxygen cannula (nasal cannulae) or a mask.

Airway cleaners

Portable devices, including oscillating positive expiratory pressure (PEP) devices and intrapulmonary percussion ventilation (IPV), can help dissolve mucus.

Thoracic Physiotherapy (CPT)

CPT is a mucus-thinning technique that involves patting the chest in some way. Firecrackers and electronic vests are now available to help with this technique .

Cancer treatment

People with lung cancer may receive radiation therapy, chemotherapy, surgery, and / or immunotherapy, depending on the stage and extent of the cancer.

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