How COPD Affects Your Lungs

Chronic obstructive pulmonary disease (COPD) is an inflammatory disease of the lungs. It's a progressive and irreversible condition that often causes breathing problems. However, treatment and lifestyle changes can help alleviate symptoms and slow down the progression. Learn about COPD pathophysiology and how it affects lung function.


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COPD Conditions

The two main forms of COPD are chronic bronchitis and emphysema. Those who have COPD can have either form or a combination of both.

Chronic Bronchitis

Chronic bronchitis is the inflammation of the bronchial tubes (bronchi), which carry air to and from the air sacs (alveoli) in the lungs. Due to the inflammation, a buildup of mucus in the tubes develops, making it harder for your lungs to move air through them. Symptoms of chronic bronchitis can include:

  • Coughing
  • Shortness of breath
  • Wheezing
  • Chest tightness


Healthy air sacs are elastic and stretchy, allowing each sac to inflate with air when you breathe in and deflate when you breathe out. With emphysema, the walls that divide air sacs (and possibly the walls of air sacs) are damaged, causing the air sacs to lose their shape.

This damage can lead to the air sacs not inflating and deflating air properly, ultimately making it hard for the lungs to move oxygen in and carbon dioxide out of the body. Symptoms of emphysema can include:

  • Coughing
  • Wheezing
  • Chest tightness
  • Shortness of breath

The leading cause of chronic bronchitis and emphysema is smoking, but other risk factors include exposure to lung irritants like air pollution, age (typically those age 40 or older start to develop symptoms), and genetics.

Lung Structure

The chest cavity contains two lungs: one on the right side of the chest and one on the left side. Each lung is composed of different sections called lobes. The right lung has three lobes; the left only two. Each lobe is further divided into segments and lobules.

The space between the lungs that contains the heart, great vessels, and esophagus is called the mediastinum. A set of tubes, or airways, delivers oxygen to each section of the lung.

As you breathe, air enters your respiratory system through the openings of your nose (nares). It then passes through the nasopharynx (area of the throat behind the nose) and the oropharynx (area of the throat behind the mouth).

These structures make up the upper airways, which are lined with ciliated mucosa. This is a protective, moist tissue layer containing tiny hair-like projections (cilia) that help warm and humidify inhaled oxygen and assist in the removal of foreign particles and excess mucus.

Air continues through the larynx (voice-box)—a structure that connects the upper and lower airways—and then down through the trachea (windpipe), which connects the larynx to the bronchi. The bronchi are larger airways of the lungs that ultimately terminate into smaller airways called bronchioles. Together, the bronchi and bronchioles make up the bronchial tree.

The bronchioles end in alveolar ducts, which lead to alveolar sacs made up of millions of alveoli. The alveoli are the primary gas-exchanging structures in the lungs, where oxygen enters the blood and carbon dioxide is removed. All of these structures function together as your respiratory system.

The Purpose of the Lungs

The lungs are made up of spongy, elastic fibers that allow them to stretch and constrict when we breathe in and out, respectively. The purpose of the lungs is twofold: to deliver oxygen (O2) to the cells and tissues of the body and to remove carbon dioxide (CO2), the waste product of respiration, from the blood.

Oxygen, the body's most important nutrient, helps your body turn the food that you eat into energy, and, similar to car exhaust, CO2 is removed from your body every time you exhale.

Inflamed Lungs

COPD is not the only inflammatory condition that can affect the lungs. Inflamed lungs can develop due to infection or damage to lung structures as well. Inherited disorders like cystic fibrosis can also cause inflammation of the lungs, in addition to autoimmune conditions. Inflammation of the lungs caused by mild infections like the flu or injuries such as a rib fracture or puncture wound can often resolve with time and treatment.

However, for those who develop inflammation of lung structures due to ongoing smoking habits, exposure to irritants, or inherited disorders like cystic fibrosis, inflammation can become a chronic issue, and irreversible damage to lung structures can occur. This damage can lead to health complications as the lungs cannot effectively move oxygen in and carbon dioxide out of the body.


Chronic exposure to cigarette smoking is the number one cause of COPD, but repeated exposure to secondhand smoke, air pollution, and occupational exposure (to coal, cotton, grain) are also important risk factors.

Chronic inflammation plays a major role in COPD pathophysiology. Smoking and other airway irritants cause neutrophils, T-lymphocytes, and other inflammatory cells to accumulate in the airways. Once activated, they trigger an inflammatory response in which an influx of molecules, known as inflammatory mediators, navigate to the site in an attempt to destroy and remove inhaled foreign debris.

Under normal circumstances, the inflammatory response is useful and leads to healing. In fact, without it, the body would never recover from injury. In COPD, repeated exposure to airway irritants starts an ongoing inflammatory response that never seems to shut itself off. Over time, this process causes structural and physiological lung changes that get progressively worse.

As inflammation continues, the airways constrict, becoming excessively narrow and swollen. This leads to excess mucus production and poorly functioning cilia—a combination that makes airway clearance especially difficult. When people with COPD can't clear their secretions, they develop the hallmark symptoms of COPD, which include a chronic productive cough, wheezing, and dyspnea.

Finally, the build-up of mucus attracts a host of bacteria that thrive and multiply in the warm, moist environment of the airway and lungs.


The main goal of COPD treatment, no matter which type of COPD, is to improve quality of life, slow the progression of the disease, control COPD symptoms, and prevent COPD worsening.

No other factor carries more weight in slowing COPD progression than smoking cessation. Other treatment options include antibiotics (for those with evidence of bacterial infection), inhaled bronchodilators, corticosteroids, aerosol therapy, pulmonary rehabilitation, oxygen therapy (for hypoxic patients), flu shots, and sometimes, especially those with end-stage COPD, surgical intervention.


As cigarette smoking is the leading cause of COPD, the best method for preventing COPD is to stop or never start smoking. In addition, avoiding exposure to lung irritants like secondhand smoke, air pollution, and environmental or occupational chemicals and dust can decrease your chances of developing COPD. Some ways to avoid irritant exposure include:

  • Staying indoors when an uptick in air pollution occurs
  • Not allowing smoking in your home and workplace
  • Using physical and respiratory protective equipment such as masks, gloves, and goggles if exposed to occupational chemicals

A Word From Verywell

COPD is often preventable. Though it can be hard to quit smoking, there are ways to quit smoking if you do. Also, try your best to avoid lung irritants. If you learn you have COPD, talk thoroughly with your doctor about the many treatment options available that can manage symptoms and slow down the progression.

Frequently Asked Questions

  • What are the four stages of COPD?

    The Global Initiative for Chronic Obstructive Lung Disease (GOLD) devised a classification system for COPD severity:

    • Stage 1: Mild
    • Stage 2: Moderate
    • Stage 3: Severe
    • Stage 4: Very Severe
  • How is COPD diagnosed?

    Tests commonly used to diagnose COPD include functional lung tests, a chest x-ray, and blood tests. Your healthcare professional will also review your symptoms and your and your family's medical history.

  • How long can you live with COPD?

    Life expectancy with COPD depends on factors like age, overall health, and the severity of the condition. A system known as the BODE index calculates possible life expectancy from measures of body max index (BMI), airway obstruction, dyspnea, and exercise tolerance.

10 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. MedlinePlus. COPD.

  2. MedlinePlus. Chronic bronchitis.

  3. MedlinePlus. Emphysema.

  4. National Cancer Institute. Anatomy of the lung.

  5. National Cancer Institute. Nasopharynx.

  6. Kids Health from Nemours. Your lungs & respiratory system.

  7. National Heart, Lung, and Blood Institute. COPD.

  8. Vijayan VK. Chronic obstructive pulmonary diseaseIndian J Med Res. 2013;137(2):251–269. PMID:23563369

  9. Fernandes FLA, Cukier A, Camelier AA, et al. Recommendations for the pharmacological treatment of COPD: Questions and answersJ Bras Pneumol. 2017;43(4):290–301. doi:10.1590/S1806-37562017000000153

  10. Global Initiative for Chronic Obstructive Lung Disease. Pocket guide to COPD diagnosis, management, and prevention.

By Deborah Leader, RN
 Deborah Leader RN, PHN, is a registered nurse and medical writer who focuses on COPD.