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COPD 101: What Is Chronic Bronchitis?

Chronic bronchitis is the inflammation of your bronchial airways. It’s a gradually progressive disease causing symptoms such as coughing, sputum production, chest tightness, shortness of breath, and wheezing. Here’s what to know.

What happens in healthy lungs?

Air travels into your nose or mouth. It then passes through the pharynx at the back of your mouth and nose. Then it travels down your larynx, which includes your voice box. It then travels down larger airways called bronchi and smaller airways called bronchioles. It’s these bronchial air passages that become inflamed.1-2

This inflammation is normal. It’s a good response. It’s meant as a defense mechanism to keep you healthy.

So, let’s say you inhale a respiratory virus. It’s job is to enter airway cells and turn them into virus making factories.3 Thankfully, infected cells release chemicals that act as messengers that say, “Hey! Invaders are here! Come help us!”

What is acute bronchitis?

Your immune system responds. It sends immune cells to the rescue. These cells cause airway inflammation. Again, this is all good. Inflamed airways secrete extra mucus. Viruses get stuck in the mucus. They are killed and balled up in it.4-5

Lining airway cells are cilia. These are fine-hairlike structures that line airways. There are literally millions of cilia. They work together like the bristles on a broom to sweep mucus to the back of your throat.2

As mucus collects there it may trigger your cough reflex. This is what makes you cough or clear your throat. Mucus is now called sputum. You can swallow it and it will be destroyed by stomach juices. Or, you can spit it out and completely rid it from your body.2,6

Inflammation in response to viruses is acute. This means it’s happening right now. It will go away when the viruses are gone. This usually takes around 10 or so days. Although, sometimes, symptoms may persist for up to 90 days. This is a natural mechanism for keeping your lungs healthy.4,7

What is chronic bronchitis?

So, this is similar to acute bronchitis. But, it’s a response to noxious substances in the air you are inhaling. These noxious substances are in cigarette smoke. They may also be in fumes, vapors, or dusts in the air at your work. They may also be in outdoor air pollution.2,7-10

These noxious substances irritate cells. They may damage cells. These cells send out messengers. They say, “Hey! There’s something in here bothering us!”

Your immune system hears the call for help. It sends immune cells to the rescue. They cause airway inflammation. But, this inflammation does not go away. Why? It’s because you continue inhaling the noxious substance day after day and year after year. This makes the inflammation permanent. It becomes chronic.2

Chronic inflammation is damaging to cells. In turn, cells try to repair themselves. Repeated efforts at damage and repair ultimately causes scar tissue. A combination of inflammation and scar tissue makes airway walls abnormally thick. This acts to obstruct the flow of air through them. This causes airflow limitation. It can cause chest tightness, shortness of breath, and wheezing.2

Now, your body thinks it can help all this. So, what it does is tell goblet cells and mucus glands to replicate. So, over time, you develop large numbers of these specialized cells and glands. Also, they end up becoming abnormally large. They end up secreting abnormal amounts of mucus.2

At the same time cilia are destroyed. This makes it difficult for airway cells to move mucus to your upper airway. Mucus that makes it up triggers your cough reflex. Mucus that doesn’t make it up may block airways. This acts to further obstruct airways. This too can make you feel short of breath.

What to make of this?

What I just explained is chronic bronchitis. It’s clinically defined as a cough that doesn’t go away. It’s defined as a cough that persists for 3 consecutive months and 2 consecutive years. Coughing is usually the first symptom observed. It’s often brushed off to being out of shape or to aging. For this reason, chronic bronchitis usually isn’t diagnosed until after the age of 45. Sometimes it’s not diagnosed at all.2, 9, 11

The good news is there are lots of treatments for this on the market today. These treatments can slow the progression and allay any symptoms you feel. Learning what treatments work best for you entails working with your doctor and getting a proper diagnosis.

This article represents the opinions, thoughts, and experiences of the author; none of this content has been paid for by any advertiser. The COPD.net team does not recommend or endorse any products or treatments discussed herein. Learn more about how we maintain editorial integrity here.

  1. Scanlan, Craig L., et al., editors, “Egan’s Fundamentals of Respiratory Care,” Sixth Edition, 1995, Mosby pages 198-207
  2. Weinberger, Steven E., Barbara A. Cockrill, Jess Mandrel, Principles of Pulmonary Medicine," 6th Edition, Elsevier, pages 64-66, 91-94, 281
  3. Alcamo, Edward I, “Fundamentals of Microbiology,” 5th Edition, Addison Wesley Longman, Inc., pages 323-348
  4. “Bronchitis, “Cedars-Sinai,” https://www.cedars-sinai.edu/Patients/Health-Conditions/Bronchitis.aspx, accessed 11/30/18
  5. Felner, Kevin, Meg Schneider, COPD For Dummies,” 2008, NJ, Wiley Publishing, pages 10-12, 40
  6. Kasper, et al., editors, “Harrison’s Principles Of Internal Medicine,” 19th edition, 2015, McGraw Hill, page 243
  7. “Bronchitis,” Mayo Clinic, https://www.mayoclinic.org/diseases-conditions/bronchitis/symptoms-causes/syc-20355566, accessed 11/20/18
  8. Andreoli, Thomas e., et al., editors, “Andreoli and Carpenter’s Cecil Essentials of Medicine,” 8th Edition, 2010, Saunders Elsevier, page 216
  9. COPD Guidelines, “Global Initiative For Obstructive Pulmonary Disease,” 2018, https://goldcopd.org/wp-content/uploads/2017/11/GOLD-2018-v6.0-FINAL-revised-20-Nov_WMS.pdf, accessed 10/9/18

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