The bronchi are the two large tubes that carry air from your windpipe to your lungs. You have a left and right main bronchus in each lung. After the main bronchi, these tubes branch out into segments that look like tree branches. Many respiratory conditions, such as asthma or bronchitis, can affect your bronchi.


What are the bronchi?

Your bronchi (BRAWN-kai) are the large tubes that connect to your trachea (windpipe) and direct the air you breathe to your right and left lungs. They are in your chest. Bronchi is the plural form of bronchus. The left bronchus carries air to your left lung. The right bronchus carries air to your right lung. Your bronchi are an essential part of your respiratory system. As you breathe and your lungs expand, your bronchi distribute the air within your lung.


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What is the tracheobronchial tree?

The bronchi are part of the tracheobronchial tree. The tracheobronchial tree is where air passes to your lungs and exchanges gases (oxygen and carbon dioxide).

The tracheobronchial tree includes your:

  • Trachea, which starts in your neck.
  • Bronchi.
  • Bronchioles (BRAWN-key-ols), the lower portion of your bronchi.


What is your bronchi’s function?

Your bronchi carry air to and from your lungs. The bronchi also help moisturize the air you breathe and screen out foreign particles.

Your airways are lined with cells that create mucus. The mucus keeps your airways moist. It also traps bacteria, viruses, fungi and other particles to protect your lungs and prevent infection.

The bronchi are lined with cilia, tiny hairlike structures. The cilia help move mucus (phlegm) and particles out of your lungs. When you cough or swallow, the particles trapped in the mucus move out of your body or into your digestive tract, where your body can dispose of them.


How do your bronchi work with your respiratory system?

Your bronchi work with your respiratory system to help you breathe. When you breathe:

  1. Air passes from your mouth to your trachea.
  2. Your trachea divides into your left and right bronchi.
  3. The bronchi carry air into your lungs.
  4. At the end of the bronchi, the bronchioles carry air to small sacs in your lungs called alveoli. The alveoli perform your body’s gas exchange.

What is gas exchange?

When you breathe in, oxygen moves to your bloodstream. When you breathe out, you expel carbon dioxide. This process is known as gas exchange.

Gas exchange takes place in the alveoli in your lungs. You have about 480 million alveoli to do this vital job. Your bronchi are not involved in gas exchange — they only supply air to the alveoli.



What are the parts of the bronchi?

Your bronchi have two main (or primary, or first) parts:

  • Right main bronchus is a short, wide air passageway into your right lung.
  • Left main bronchus is a narrow, long passageway into your left lung.

Your right and left main bronchi are the widest portions of your bronchi. Then your bronchi divide into branches that get smaller and smaller starting with:

  • The lobar bronchi, which pass into a section (lobe) of your lungs.
  • The segmental bronchi, which pass through a segment of each lobe.
  • The bronchioles, which are the smallest segments of your bronchi.

What do the bronchi look like?

Your tracheobronchial tree looks like an upside-down tree with the trachea as the trunk and the bronchi representing the branches. The tubes of the right and left main bronchi divide into smaller segments as they move deeper into your lungs. Similarly, tree branches divide and get smaller and smaller, before ending in the leaves.

Where are the bronchi located?

You have bronchi throughout both lungs:

  • Primary (first) bronchiare the left and right main bronchi in the upper portion of your lungs.
  • Secondary bronchinear the middle of your lungs, also called lobar bronchi.
  • Tertiary (third) bronchiat the edge of your lungs (also called segmental bronchi), just before the bronchioles.

Conditions and Disorders

What conditions and disorders affect the bronchi?

Several conditions can affect your bronchi, including:

  • Asthma: Chronic inflammation in your airways that makes it difficult to breathe.
  • Bronchiectasis: When your bronchi widen and scar, causing you to cough up mucus.
  • Bronchitis: Inflammation or infection in your bronchi that may be short-term (acute) or long-lasting (chronic).
  • Bronchiolitis: A viral lung infection of the bronchioles.
  • Bronchopulmonary dysplasia: A breathing condition that occurs when an infant’s lungs do not develop properly.
  • Chronic obstructive pulmonary disease (COPD): A group of inflammatory lung diseases that can cause obstruction in airway flow, including bronchitis and emphysema.
  • Exercise-induced asthma: Airways that shrink when you exert yourself.

What tests check the health of my bronchi?

Depending on your symptoms, your healthcare provider may use pulmonary function tests to check the health of your bronchi and lungs. Other common tests include:

  • Bronchoscopy: Using a small, flexible tube with a camera to view inside your bronchi.
  • CT scans: Using special computers and X-ray images to look at your lungs from different angles.
  • Endobronchial ultrasound (EBUS): A type of bronchoscopy to diagnose inflammation or cancer.
  • Exhaled nitric oxide test: Measuring how much nitric oxide you exhale, which can tell providers if your bronchi are inflammed.
  • Spirometry: Measuring how much air you can hold and how forcefully you can exhale it.

How common are conditions that affect the respiratory system?

Certain respiratory conditions are among the most common illnesses worldwide. Approximately:

  • 334 million people have asthma.
  • 65 million people have COPD.
  • 10.4 million people have tuberculosis, an infection that attacks your lungs.


How can I keep my bronchi healthy?

To keep your bronchi, lungs and entire respiratory system healthy, you can:

  • Achieve and maintain a healthy weight for your sex, age and body type.
  • Avoid secondhand smoke.
  • Clean your home and change air filters regularly.
  • Exercise regularly to strengthen your heart and lungs.
  • Limit your exposure to air pollution.
  • Quit smoking.
  • Use protective gear such as a face mask if you are regularly around dust, allergens or chemical fumes.
  • Avoid respiratory infections by hand and oral hygiene, avoiding crowds during flu season, getting a yearly flu shot, and asking your doctor whether a pneumonia vaccine is indicated for you.

Additional Common Questions

When should I call my healthcare provider?

You should call 911 or go to your nearest emergency room if you experience any signs of respiratory distress. Signs of respiratory distress include:

  • Bluish, gray or pale color around or inside your mouth.
  • Chest retractions, when the chest appears to sink in with each breath.
  • Faster breathing with no known cause.
  • Grunting.
  • Nose flaring.
  • Sweating with no increase in body temperature.
  • Wheezing (a tight whistling sound while breathing out).

A note from Cleveland Clinic

The bronchi are the passageways that connect your windpipe to your lungs. You have two main bronchi in your right and left lungs that divide and branch off into smaller segments, like tree branches. At the end of your bronchi, the alveoli exchange oxygen and carbon dioxide. Many infections and conditions can affect the bronchi. But you can keep your bronchi and lungs healthier by avoiding smoke, chemicals, infections and air pollution.

Medically Reviewed

Last reviewed on 06/21/2021.

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