Disorders of Respiratory System – Class 11 | Chapter – 17 | Biology Short Notes Series PDF

Disorders of Respiratory System: Respiratory disorder, or respiratory disease, is a term that encompasses a variety of pathogenic conditions that affect respiration in living organisms. Respiration makes gas exchange possible in higher organisms. The gas exchange involves taking oxygen into the body and expelling carbon dioxide. Respiratory disease occurs in the respiratory tract, which includes the alveoli, bronchi, bronchioles, pleura, pleural cavity, trachea and the nerves and muscles of breathing.

Types of Respiratory System Disorders

Respiratory system disorders affect millions of people worldwide. There are three main types of respiratory diseases:

Airway Disease

It affects the bronchial tubes which function by transporting oxygen and other gases in and out of the lungs. In airway disease, the passage for air is reduced, which is associated either with narrowing or blocking of bronchial tubes.

Lung Tissue Disease

Human lungs are covered by a thin tissue layer called the pleura. Due to certain viral or bacterial infections, the structure of the lung tissues is affected, which results in scarring or inflammation of the tissue that enables the lungs to expand normally and in turn, makes breathing difficult.

Lung Circulation Disease

This disorder occurs when the blood vessels of the lungs are coagulated, swollen or damaged. This affects the ability of the lungs to receive oxygen and release carbon dioxide. In extreme cases, this disorder may affect the functioning of the heart.

Causes of Disorders of Respiratory System

Respiratory diseases are caused due to exposure to pollutants, smoking, passively inhaling tobacco smoke, asbestos, radon, etc.

Respiratory Diseases

Following are the major respiratory disorders or diseases:


Asthma is a chronic disease which affects the bronchi and bronchioles of the lungs. It causes difficulty in breathing and is followed by severe cough, restlessness, cough and a wheezing sound while breathing.

Asthma might cause due to the following factors:

  • Cold air
  • Airborne allergens
  • Respiratory infections
  • Physical activity
  • Air pollutants

Chronic Obstructive Pulmonary Disease (COPD)

This includes all the respiratory diseases that cause breathlessness or the inability to exhale. It largely affects people who have been exposed to some sort of smoke. It is a very serious disease and worsens even if you stop smoking.


Emphysema is defined as a chronic disease, reduction of the respiratory surface due to damage to the lung alveolar walls. It is caused mainly by cigarette smoking. The main symptoms of emphysema include shortness of breath and cough. Emphysema might lead to a loss of elasticity of the lungs.

Emphysema may be caused by the following factors:

  • Dust
  • Chemicals
  • Air pollution
  • Smoking tobacco
  • Exposure to passive cigarette smoking

Occupational Respiratory Disorders

Occupational respiratory disorders are defined as any disorder which affects the respiratory system by long-term inhalation of chemicals, proteins, and dust. For instance, Asbestosis is caused by the inhalation of asbestos dust.

Occupational respiratory disorders might happen due to the inhalation of the following substances:

  • Fumes from metals.
  • Smoke from burning organic materials.
  • Sprays of varnish, paint, acids, and pesticides.
  • Dust from cotton, silica, coal, drug powders and pesticides.
  • Gases from industries. For instance, Ammonia, chlorine and nitrogen oxides.


It is the inflammation of the mucous membranes in the nasal sinus. The mucous membranes produce mucus that drains into the nasal cavities. Bacterial or viral infections or some airborne allergens cause the inflammation of the mucous membranes.

Lung Cancer

Lung cancer can develop in any part of the lungs. It occurs in the main part of the lungs. The treatment of lung cancer depends upon the type, location and its spread.

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By Team Learning Mantras