What is Asthma?

Learn what asthma is and what causes it.

Rob Lamberts, MD
5-minute read
Episode #32

“Burning” something involves combining it with oxygen – a process which releases energy stored in the substance.  That’s what happens to wood in the fireplace and gas in the car. In the body, the cells combine oxygen and glucose releasing energy, water and carbon dioxide. The water is, well, water, but the carbon dioxide is toxic to the cell, and so is carried away by the bloodstream to the lungs, where it leaves the blood and is exhaled.

Why am I telling you this? It turns out that both intake of oxygen and output of carbon dioxide are really important to your body. Without oxygen, your cells can’t burn glucose and so are without energy. They suffocate. Too much carbon dioxide in your blood will make your blood acidic, and that causes all sorts of problems. The oxygen is like fuel for your car, which is necessary for it to function, whereas the carbon dioxide is like the toxic gasses released when fuel is burned; if you don’t get rid of them, everyone in the car gets sick or dies.

What Causes Asthma?

In asthma, the tubes that bring oxygen to the lungs, called bronchi, get inflamed and spasm, so that they are narrower than they should be. That affects exhaling more than inhaling because you increase the pressure in your chest cavity when you breathe out. That increased pressure pushes the bronchi closed even more. The result is a prolonged exhalation, often with a high-pitched sound called a wheeze. Let me say that again: wheezing is a high-pitched sound that happens when a person breathes out. That is why asthma is sometimes called an obstructive lung disease.

Why Do Bronchi Become Inflamed?

So why do the bronchi get inflamed? Respiratory infections, allergies, cold air, air pollution, and smoke are some of the more common causes of inflammation. A person with asthma has an increased response to these things, causing more inflammation than normal, as well as a spasm of the muscles in the bronchi. That means that what gives most of us a cough will result in wheezing in an asthmatic.

What are the Symptoms of Asthma?

Some people with mild asthma have a persistent cough only--that’s their only symptom. I’ve seen people who come in a few times each year with a cough and even mild wheezing end up having mild asthma. Other people with asthma get short of breath after a small amount of exercise. They avoid symptoms by simply avoiding exercise.

Wheezing isn’t Always Asthma

Not all wheezing is caused by asthma. Certain viruses can cause wheezing in non-asthmatics. The most notorious of these is the Respiratory Syncytial Virus, or RSV, which causes wheezing and shortness of breath and hospitalizes many young children and infants each year. Hospitalization with RSV is associated with a higher future risk of asthma, but it doesn’t guarantee it.

Exposure to smoke and to caustic chemicals like chlorine can cause the bronchi to spasm, resulting in wheezing. Though this wheeze can be life threatening, it doesn’t represent asthma.

Finally, there is a condition known as Chronic Obstructive Pulmonary Disease, or COPD, which causes significant wheezing and shortness of breath. COPD, which includes the terrible condition called emphysema, is caused by cigarette smoking, which permanently destroys lung tissue.  I’ll cover this in a future article.


Please note that all content here is strictly for informational purposes only. This content does not substitute any medical advice, and does not replace any medical judgment or reasoning by your own personal health provider. Please always seek a licensed physician in your area regarding all health related questions and issues.