Respiratory disease is a medical term that encompasses pathological conditions affecting the organs and tissues that make gas exchange possible in higher organisms, and includes conditions of the upper respiratory tract, trachea, bronchi, bronchioles, alveoli, pleura and pleural cavity, and the nerves and muscles of breathing. Respiratory diseases range from mild and self-limiting, such as the common cold, to life-threatening entities like bacterial pneumonia, pulmonary embolism, and lung cancer.
The study of respiratory disease is known as pulmonology. A doctor who specializes in respiratory disease is known as a pulmonologist, a chest medicine specialist, a respiratory medicine specialist, a respirologist or a thoracic medicine specialist.
Respiratory diseases can be classified in many different ways, including by the organ or tissue involved, by the type and pattern of associated signs and symptoms, or by the cause (etiology) of the disease.
Inflammatory lung disease
Characterised by a high neutrophil count, e.g. asthma, cystic fibrosis, emphysema, chronic obstructive pulmonary disorder or acute respiratory distress syndrome.
Obstructive lung diseases
Obstructive lung diseases are diseases of the lung where the airways (i.e. bronchi, bronchioles, alveoli) become reduced in volume or have free flow of gas impeded, making it more difficult to move air in and out of the lung.
Chronic Obstructive Pulmonary Disease (COPD)
Chronic Obstructive Pulmonary Disease (COPD), which includes emphysema an example of an obstructive lung disease, is where the alveolae rupture causing air to be retained in the lungs and limit the available space during inhalation..
Asthma is an example of an obstructive lung disease, (and of an inflammatory lung disease).
Asthma attacks can be brought on by triggers, such as air pollution, tobacco smoke, factory fumes, cleaning solvents, infections, pollens, foods, cold air, exercise, chemicals and medications. Triggers are highly individual and may not be related to allergens. Many asthmatics are not allergic to common allergens such as mold, ragweed, dust or pollens. Asthma is a difficulty in breathing causing wheezing due to inflammation of bronchi and bronchioles, this causes a restriction in the airflow into the alveoli.
Restrictive lung diseases
Restrictive lung diseases (also known as interstitial lung diseases) are a category of respiratory disease characterized by a loss of lung compliance, causing incomplete lung expansion and increased lung stiffness. E.g. in infant respiratory distress syndrome (IRDS).
Respiratory tract infections
Infections can affect any part of the respiratory system. They are traditionally divided into upper respiratory tract infections and lower respiratory tract infections.
Upper respiratory tract infection
The most common upper respiratory tract infection is the common cold however, infections of specific organs of the upper respiratory tract such as sinusitis, tonsillitis, otitis media, pharyngitis and laryngitis are also considered upper respiratory tract infections.
Lower respiratory tract infection
The most common lower respiratory tract infection is pneumonia, a lung infection.[clarification needed] Pneumonia is usually caused by bacteria, particularly Streptococcus pneumoniae in Western countries. Worldwide, tuberculosis is an important cause of pneumonia. Other pathogens such as viruses and fungi can cause pneumonia for example severe acute respiratory syndrome and pneumocystis pneumonia. A pneumonia may develop complications such as a lung abscess, a round cavity in the lung caused by the infection, or may spread to the pleural cavity.