The upper part of the respiratory system is made up of the nose and throat and structures associated with them. These include the sinuses (the air-filled cavities in the front of the skull) and the larynx, also known as the voice box. The upper respiratory system can be affected by a variety of disorders ranging from common complaints, such as nosebleeds, snoring, and laryngitis, to rare conditions such as cancers of the throat and larynx.
Disorders that affect the nose and the sinuses are covered first in this section. These conditions include nosebleeds, which are often a symptom of a minor injury but are sometimes due to a serious underlying disorder, and sinusitis, inflammation of the sinuses, which is usually caused by a viral infection such as the common cold.
Obstruction in the nasal passages may cause problems with sleep, and two such disorders, snoring and sleep apnoea, are covered here. Articles follow on common conditions that involve inflammation of the throat or larynx, such as pharyngitis, tonsillitis, and laryngitis. Finally, noncancerous growths in the larynx, known as vocal cord nodules, and cancers of the throat and larynx are discussed.
Infections that affect the nose and the throat are described elsewhere (see Infections and infestations), as is allergic rhinitis, a common disorder of the nose. Disorders of the nose and throat that are common in children, such as enlarged adenoids, are covered in another section (see Infancy and childhood).
For further information on the structure and function of the nose and throat, see Steam Inhalation.
The lower part of the respiratory system consists of the trachea, which divides into the two main bronchi and then into smaller air passages, and the lungs. The lungs can be damaged by many factors, such as inhaled smoke and dust, infections, and allergies. The resulting disorders vary in severity from mild conditions, such as a cough, to life-threatening illnesses, such as lung cancer.
This section starts with two common symptoms, cough and hiccups. More serious disorders of the airways are discussed next, including asthma, a common long-term disorder in developed countries.
Many common lung diseases, such as pneumonia and tuberculosis, are caused by infections. After discussion of these disorders, articles follow on disorders of the pleura. Occupational lung diseases are then covered.
The next article discusses primary lung cancer, one of the most common types of cancer in the world and the most likely to prove fatal. Lung cancer is almost always caused by smoking. The final articles cover acute, potentially life-threatening lung disorders, such as acute respiratory distress syndrome.
Lung diseases specific to children are dealt with elsewhere (see Infancy and childhood).
For more information about the structure and function of the lungs, see Steam Inhalation.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
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