Chronic obstructive pulmonary disease (COPD) is a life-threatening condition that affects your lungs and your ability to breathe.

Pathophysiology is the evolution of adverse functional changes associated with a disease. For people with COPD, this starts with damage to the airways and tiny air sacs in the lungs. Symptoms progress from a cough with mucus to difficulty breathing.

The damage done by COPD can’t be undone. However, there are some preventive measures you can take to lower your risk of developing COPD.

COPD is an umbrella term for several chronic lung diseases. The two main COPD conditions are chronic bronchitis and emphysema. These diseases affect different parts of the lungs, but both lead to difficulty breathing.

To understand COPD’s pathophysiology, it’s important to understand the structure of the lungs.

When you inhale, air moves down your trachea and then through two tubes called bronchi. The bronchi branch out into smaller tubes called bronchioles. At the ends of the bronchioles are little air sacs called alveoli. At the end of the alveoli are capillaries, which are tiny blood vessels.

Oxygen moves from the lungs to the bloodstream through these capillaries. In exchange, carbon dioxide moves from the blood into the capillaries and then into the lungs before it’s exhaled.

Emphysema is a disease of the alveoli. The fibers that make up the walls of the alveoli become damaged. The damage makes them less elastic and unable to recoil when you exhale, making it hard to exhale carbon dioxide out of the lungs.

If the lung airways become inflamed, this results in bronchitis with subsequent mucus production. If the bronchitis persists, you can develop chronic bronchitis. You also can have temporary bouts of acute bronchitis, but these episodes aren’t considered to be the same as COPD.

The main cause of COPD is tobacco smoking. Breathing in smoke and its chemicals can injure the airways and air sacs. This leaves you vulnerable to COPD.

Exposure to secondhand smoke, environmental chemicals, and even fumes from gas burned for cooking in poorly ventilated buildings can also lead to COPD. Discover more COPD triggers here.

Serious symptoms of COPD don’t usually appear until the disease is more advanced. Because COPD affects your lungs, you may find yourself short of breath after minor physical exertion.

If you find yourself breathing harder than usual after a common activity, such as climbing stairs, you should see a doctor. Tests focused on your degree of respiratory health can reveal conditions such as chronic bronchitis and emphysema.

One of the reasons breathing becomes more challenging is because the lungs produce more mucus and the bronchioles become inflamed and narrower as a result.

With more mucus in your airways, less oxygen is being inhaled. This means less oxygen reaches the capillaries for gas exchange in your lungs. Less carbon dioxide is also being exhaled.

Coughing to try to help release the mucus from the lungs is a common sign of COPD. If you notice that you’re producing more mucus and coughing more to clear it, you should see a doctor.

As COPD progresses, many other health complications can follow.

Besides coughing, you may notice yourself wheezing when you breathe. The buildup of mucus and the narrowing of the bronchioles and alveoli may also cause chest tightness. These aren’t normal symptoms of aging. If you experience them, see your doctor.

Less oxygen circulating throughout your body can leave you feeling light-headed or fatigued. Lack of energy can be a symptom of many conditions, and it’s an important detail to share with your doctor. It may help determine the seriousness of your condition.

In people with serious COPD, weight loss also can occur as your body requires more and more energy to breathe.

One of the easiest ways to prevent COPD is to never start smoking or stop as soon as you can. Even if you’ve smoked for many years, you can start to preserve your lung health the minute you stop smoking.

The longer you go without smoking, the greater your odds of avoiding COPD. This is true no matter what age you are when you quit.

It’s also important to have regular checkups and follow the advice of your doctor. There are no guarantees when it comes to COPD. However, you can take steps to maintain better lung function if you’re proactive about your health.