What Is A Chronic Cough?

Chronic Bronchitis is often defined as a chronic cough. So, what is a cough anyway? What causes it to become chronic? Here’s what to know.

What is a cough reflex?

Lining your respiratory tract are a series of nerves. Lining your larynx, trachea, and upper airways are cough receptors. 1-3

So, say that along with air, you also inhale microscopic chemicals or particles. These are commonly called pollutants. These chemicals or particles make their way into your airway. At some point, these impact and make a landing.

They bind with cough receptors. These receptors, in turn, send signals via nerves to the cough center of your brain. 1-3

This cough center is in the brainstem of your brain. It then sends signals to various muscles. These muscles are called involuntary muscles. This is because you cannot control them. The involuntary muscles involved here are your inspiratory and expiratory muscles. When signaled to do so, inspiratory muscles contract, forcing you to take in a deep breath. Then expiratory muscles contract, generating a pressure as high as 300 mmHg. 1,3

This, in turn, forces air back up your airway. This force can reach speeds up to 500 miles per hour. The flow generated is so powerful it pushes your closed voice box open. This is what makes the sound of a cough. 1,3

What is the purpose of a cough?

Your cough is powerful enough to dislodge any chemicals or particles that lodge to your airway. More specifically, it’s powerful enough to dislodge any mucus stuck in your throat.

Mucus balls up and kill pathogens. It also balls up airway irritants. It is then brought to your upper airway by cilia. These are tiny hair-like structures that wave back and forth. They create an escalator of sorts that moves sputum to your upper airway. When this sputum gets stuck, it attaches to cough receptors and irritates these nerves. This initiates the cough reflex.

This helps push mucus up to your upper airway. Here, you can then swallow it, where it’s dissolved by your stomach juices. You can also expectorate it. Expectorate is a fancy way of saying spit it out.

So, technically speaking, your lungs are sterile. This means that they do not contain any germs that may cause infections like pneumonia. They also are free and clear of particles. This is important for your lungs to function normally. So, a cough is an important feature of your immune system. It’s essential for keeping your lungs sterile.

How does a cough become chronic?

Chronic bronchitis is defined as a chronic cough. It’s a cough that persists day after day after day. Some experts, such as those at the Mayo Clinic, say it’s a cough that lasts for three months or longer. So, what causes a person to develop a chronic cough?

Chronic inhalation of chemicals, such as those in cigarette smoke, causes an immune response. Immune cells treat these chemicals as pathogens. They secrete a series of chemicals. And this, over time, causes airways to become chronically inflamed.

This inflammation irritates goblet cells lining airways. So, they produce excessive amounts of mucus. To top this off, the normal mechanisms for bringing this mucus to your upper airway are damaged.

So, you inhale tiny chemicals or particles. Mucus balls them up. But, they are now unable to move upwards. So, this is what induces the cough reflex. Being that this condition is chronic, the cough becomes chronic as well. It becomes one of the initial symptoms of chronic bronchitis.

What to make of this?

You can have a chronic cough and not have COPD. For instance, post nasal drip due to allergies can also cause it. Asthma can cause it. Likewise, you can have chronic bronchitis without having COPD. But, many people with COPD have a chronic cough. And, that’s why we’re talking about it here.

And, while a chronic cough may be annoying, it rarely causes people to seek medical attention. But it probably should. Because, with a proper diagnosis and treatment, that chronic cough may improve over time. 1-3

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