What Is the Pathology of Lung Diseases?
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Lung Diseases - Classification, Diagnosis, Treatment, and Prevention

Published on Nov 02, 2022 and last reviewed on May 16, 2023   -  5 min read


The problems that lead to improper functioning of the lungs are lung disease. Read the article below to learn more about lung-related diseases.

Lungs form an important part of the respiratory or breathing system. The lung's main function is to take in oxygen from the air when the person breathes. Lungs pump oxygen in the blood and carry it to the heart.

How Are Lung Diseases Classified?

Lung disease is a term that involves airway-related diseases, lung tissue disorders, and issues with lung circulation. Lung diseases can be briefly classified into three types.

Airway Diseases: Occur due to the narrowing or blockage of tubes that carry oxygen and carbon dioxide in and out of the lungs. It includes asthma, chronic obstructive pulmonary disease, and bronchiectasis-like diseases.

Lung Structure-Related Diseases: These are the ones that occur due to inflammation of the lung tissue. Lungs lose the ability to expand fully, along with the ability for deep breathing. This includes sarcoidosis followed by pulmonary fibrosis.

Lung Circulation-Related Diseases: Occurs due to blood clots, and scar tissue is included in this category. The blood vessels lose the ability to carry oxygen. It includes pulmonary hypertension.

  • Asthma

Asthma is basically hypersensitivity or hyperresponsiveness to stimuli. One of the classic features is bronchoconstriction, the narrowing of the airways. The stimuli are in the form of dust, pollen, animal fur, or any specific food or drug. This stimulus is harmful and triggers the immune system. This leads to the narrowing of airways, followed by allergic reactions.

The immune system components generally consist of plasma cells or mast cells and immunoglobulin E, antibodies attacking cell types. Cytokine is a type of protein-based cell. Histamine is the chemical that dilates the blood vessels and causes allergic symptoms like sore throat, itchy eyes, and a runny nose. Prostaglandins and leukotrienes produce mucus and can cause an inflammatory reaction. They can lead to anaphylaxis which is an acute life-threatening reaction.

  • Chronic Obstructive Pulmonary Disease

The function of the lungs is the inhalation of air. This air is carried to the bronchial tube through the windpipe. It further passes small thin tubes called bronchioles to the air sacs called alveoli. Capillaries surround these air sacs. These capillaries facilitate the exchange of oxygen and carbon dioxide. When the air flowing in and out of the lungs decreases, it decreases the elasticity of lung tissue. This damages the air sacs, inflamed and thickened air sac walls. Increased production of mucus leads to clogging of the tubes. Increased mucus production leads to inefficiency of the cilia, a hair-like structure capable of removing mucus. This leads to prolonged coughing due to the retention of mucus. The symptoms of chronic obstructive lung disease are mentioned below.

Long-term cough.

Shortness of breath or dyspnea.

Blue fingernails.

Respiratory infections.



Tightness in the chest.

In severe cases, swollen faces and weight loss can be seen.

If the symptoms flare up, it can exacerbate emergency reactions.

  • Emphysema

Long-term damage to the air sacs decreases elasticity. It leads to decreased emptying capacity. Due to air trapping, the lungs cannot inflate adequately. This causes shortness of breath and fatigue-like symptoms.

  • Fibrosis

Fibrosis is the presence of damage and scarring in the lung tissue that causes difficulty exchanging oxygen. This decreases the working of the lungs. It presents symptoms like shortness of breath, dry cough, fatigue, weight loss, and muscle and joint pain. It is mainly caused by a reaction to occupational hazards, including inhalation of silica, asbestos, coal, hard metal dust, radiation damage due to chemotherapy as the treatment for cancer, and long-term consumption of medications like Methotrexate for cancer, Amiodarone for heart diseases, certain antibiotics, and anti-inflammatory medications.

  • Sarcoidosis

This happens when lumps of inflammatory cells called granulomas are formed. This leads to inflammation and scars, leading to fibrosis.

  • Pulmonary Hypertension

When the blood vessels narrow down, block, or destroy the lungs, it increases blood pressure. It shows symptoms like cyanosis, chest pressure, dizziness, swelling, palpitations, increased heartbeats, and fatigue. Lung hypertension can occur due to increased tension in the pulmonary artery, left-sided heart disease, valvular dysfunction, or blood clots.

How to Diagnose Lung Diseases?

The physician will ask about the history, signs and symptoms, and exposure risks. Following investigations can be carried out to confirm the diagnosis.

Chest X-rays can detect cancer, infections as well as chronic conditions.

A computed tomography scan shows the extent of damage and pattern in the lung tissue with the help of cross-sectional images of lung tissue.

A pulmonary function test or spirometry can detect the lung's air holding, diffusion, and capacity.

Pulse oximetry can measure oxygen saturation in the blood.

Stress tests will help denote lung function.

Arterial blood gas saturation measures the blood's oxygen and carbon dioxide levels.

A biopsy is done to test lung tissue to detect any abnormalities.

Bronchoscopy is a procedure where a tube is inserted with a camera to look at the inside of the lungs.

How to Treat Lung Diseases?

Treatment modalities aim at reducing the symptoms of the disease. Treatment prevents complications arising due to disease and improves the quality of life. The treatment plan may include the following:

Oxygen therapy and ventilation support are required to breathe efficiently and enhance the quality of life.

Glucocorticoids are steroid-based medicines that reduce inflammation in the airway.

Antibiotics can be prescribed for bacterial infections.

Antiviral medicines help against viral infections.

Bronchodilators are the medicine that helps to open the airways. Mast cell stabilizers, leukotriene modifiers, and antihistamines are the groups of bronchodilators. They relax muscles. They reduce inflammation and histamine production. They are available as inhalers for short-term and intraoral doses for long-term use.

Surgical treatment includes bullectomy, which involves the removal of large air spaces when air sacs collapse, surgical removal of diseased lung tissue, or transplanting the diseased lung with a healthy lung.

How to Prevent Lung Diseases?

Along with medications, other factors can be considered to prevent lung diseases and improve quality of life.

Getting timely vaccines to prevent flu-like symptoms.

Decrease potential exposure to irritants which can act as stimuli.

Maintenance of hygiene

Clean molds and animal fur. Maintain a dust-free environment. Use protective gear while entering dust-prone areas.

Increase lung function by maintaining a proper diet and exercise.

Avoid smoking as it decreases lung efficiency and decreases function.


Respiratory diseases can have some serious complications in patients. Lung diseases have increasing prevalence and health-related impact. Patient-doctor interaction, assessment, and treatment plan are vital in controlling lung diseases.

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Last reviewed at:
16 May 2023  -  5 min read




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