Respiratory System Conditions and Diseases


Lung disease has huge implications. Respiratory tract infections are common, and smoking air pollution, and environmental chemicals have led to huge increases in COPD rates. Lung cancer is the biggest malignant killer. Lungs are also secondarily affected in almost every dying patient, through pulmonary edema, atelectasis, or pneumonia.


  • obstructive
  • restrictive
  • acute lung
  • infectious/inflammatory
  • other lung

Obstructive diseases

Obstructive diseases are characterized by airflow limitations on lung function tests. Obstructions can result from airway narrowing or loss of elastic recoil. Important obstructive diseases include:

Restrictive Diseases

Restrictive, or diffuse interstitial diseases, are characterized by diffuse and usually chronic involvement of alveolar connective tissue. Important restrictive diseases include:

The array of restrictive pathologies all cause dyspnea, tachypnea, end-inspiratory crackles, and eventual cyanosis, without wheezing. Diffusing capacity, lung volume, and compliance all decrease.

Chest X rays show diffuse infiltration by small nodules, irregular lines, or ground glass shadows. Pulmonary hypertension and cor pulmonale may result. Advanced destruction leads to honeycomb lung.

Oxygen diffusion capacity and compliance decrease.

Alveolitis appears to be the earliest manifestation of all restrictive diseases, with most types of leukocytes accumulating in the interstitial and alveolar spaces. Interstitial or granulomatous inflammation can occur.

Pulmonary function tests can be used to distinguish these patterns.

Infectious Diseases of the Respiratory System

Infections are important causes and complications of respiratory disease. 100 million respiratory infections/year (Glass R, JAMA 2003) Coughs, colds, and antibiotics


upper airway tract infections

lower airway tract infections


Defense against respiratory infections include:

  • Nasal clearance, the glottal and laryngeal reflex, or tracheobrochial clearance reflex.
  • Respiratory secretions and mucociliary clearance operate within the lower airways.
  • Within the lungs, surfactant, alveolar clearance and the immunologic response.

Particulate trapping occurs throughout the respiratory system. Particles of various sizes are trapped in various locales:

  • > 10 μm: nose and upper airways
  • 3 to 10 μm: trachea and bronchi
  • 1 to 5 μm: terminal airways and alveoli
  • < 1 μm: in and out freely

Common bacterial pathogens:

Common viral pathogens:


Other Lung Conditions and Disorders

lung cancer

congenital lung problems

agenesis or hypoplasia

trachial or bronchial malformations

vascular anomalies