Understanding How and Why Asthma Occurs

Pathophysiology is a word we used to describe how a disease alters the normal function of the body. It is derived from Greek prefix pathos, meaning "suffering," and the root phusiologia, meaning "natural philosophy."

In relation to a condition like asthma, this term would describe the ways in which the disease affects the normal function of the lung, such as:

• how the disease causes chronic inflammation of the airway passages; and 
• how the disease causes bronchoconstriction, the tightening of muscles around the air passages.

By contrast, pathogenesis (genesis meaning "origin") describes where the disease starts and the chain of events that occur in the course of that disease.

Within the context of asthma, pathogenesis describes the pathway by which the immune system abnormally responds to stimuli that cause chronic inflammation, and bronchoconstriction causing the hardening and thickening of the passageways, which causes further breathing restriction and in turn causes progressive damage to other parts of the body, such as cardiovascular system.

As such, pathophysiology describes how a disease alters a physiological process while pathogenesis describes how that disease progresses.

People with asthma are known to be hypersensitive to what we call triggers. What this means is that certain stimuli, such as dust or pollen, are incorrectly perceived by the immune system to be harmful.

In triggering a response, the body will release inflammatory chemicals as part of the normal immune process. These chemicals will, among other things, cause tiny blood vessels to expand so that defensive immune cells can flood the area of the perceived infection. When this happens in the lungs, the tissue itself will begin to swell and become inflamed.

At the same time, the body will produce excessive mucus as a protective barrier against the nonexistent threat, clogging the airways and obstructing respiration.

Chronic inflammation can lead to a process called airway remodeling in which the walls of the air passages begin to thicken and harden, the glands begin to enlarge, and the network of blood vessels proliferate abnormally. These sorts of changes to the lungs are considered irreversible and are associated with a worsening of symptoms.

During an asthma attack, the body's immune system reacts abnormally to stimuli. This triggers the release of histamines and other substances which inadvertently cause the airway passages to contract, restricting oxygen intake. This process, called bronchospasm, is further complicated by the obstruction of the passages by mucus, which causes both breathing difficulty and a chronic cough (to release the mucus).

Bronchospasm typically lasts for one to two hours. In some cases, however, the initial event can precede a subsequent attack anywhere from three to 12 hours later.

By understanding the pathophysiology of a disease, we can find the tools needed to either normalize the response or prevent it from happening. By understanding the pathogenesis of a disease, we can often find ways to avoid it, reverse it, cure it, or prevent it from progressing along the expected course.

And that's the important thing to remember about asthma: that while we don't have the means to cure it yet, we do know how to control its symptoms and to slow (if not entirely stop) its progression. In the end, the course of the disease is not inevitable and can be altered with the appropriate use of medications and lifestyle management. These include:

• taking your medications as prescribed;
• keeping your rescue inhaler near at hand;
• avoiding triggers that cause the attacks;
• getting vaccinated against the flu or pneumonia;
• addressing lifestyle choices to improve lung function, including diet and exercise; and
• visiting your doctor regularly to monitor your respiratory health and ensure your medications are correct.

Ultimately, the course of your disease is largely in your hands. By understanding the processes by which asthma symptoms occur and worsen, you can take the necessary steps to protect your respiratory health in the long run.