Lung and Airway Disorders - Merck Manuals Consumer Version

Biology of the Lungs and Airways

To sustain life, the body must produce sufficient energy. Energy is produced by burning molecules in food, which is done by the process of oxidation (whereby food molecules are combined with oxygen). Oxidation involves carbon and hydrogen being combined with oxygen to form carbon dioxide and water. The consumption of oxygen and the production of carbon dioxide are thus indispensable to life. It follows that the human body must have an organ system designed to eliminate carbon dioxide from the circulating blood and absorb oxygen from the atmosphere at a rate rapid enough for the body’s needs, even during peak exercise. The respiratory system enables oxygen to enter the body and carbon dioxide to leave the body.
Symptoms of Lung Disorders

Disorders that affect the lungs and airways are called lung, respiratory, or pulmonary disorders. Among the most common symptoms of lung disorders are
Diagnosis of Lung Disorders

The respiratory system starts at the nose and mouth and continues through the airways and the lungs. Air enters the respiratory system through the nose and mouth and passes down the throat (pharynx) and through the voice box, or larynx. The entrance to the larynx is covered by a small flap of tissue (epiglottis) that automatically closes during swallowing, thus preventing food or drink from entering the airways. (See also Overview of the Respiratory System.)
Abscess in the Lungs

A lung abscess is a pus-filled cavity in the lung surrounded by inflamed tissue and caused by an infection.
- Abscess in the Lungs
  - Causes
  - Symptoms
  - Diagnosis
  - Treatment
Acute Bronchitis

Acute bronchitis is inflammation of the windpipe (trachea) and the airways that branch off the trachea (bronchi) caused by infection.
- Acute Bronchitis
  - Causes
  - Symptoms
  - Diagnosis
  - Treatment
Asthma

Asthma is a condition in which the airways narrow—usually reversibly—in response to certain stimuli.
Autoimmune Disorders of the Lungs

Diffuse alveolar hemorrhage is a syndrome of recurrent or persistent bleeding into the lungs, caused most often by an autoimmune disorder.
Bronchiectasis and Atelectasis

Bronchiectasis is an irreversible widening (dilation) of portions of the breathing tubes or airways (bronchi) resulting from damage to the airway wall.
- Bronchiectasis
- Atelectasis
Chronic Obstructive Pulmonary Disease (COPD)

Chronic obstructive pulmonary disease is persistent narrowing (blocking, or obstruction) of the airways occurring with emphysema, chronic obstructive bronchitis, or both disorders.
- Chronic Obstructive Pulmonary Disease (COPD)
- Alpha-1 Antitrypsin Deficiency
Environmental Lung Diseases

Environmental lung diseases are caused by harmful particles, mists, vapors, or gases that are inhaled, usually while people work. If the lung disease is due to inhaled particles, the term pneumoconiosis is often used.
Interstitial Lung Diseases

Interstitial lung disease (also called diffuse parenchymal disease) is a term used to describe a number of different disorders that affect the interstitial space. The interstitial space consists of the walls of the air sacs of the lungs (alveoli) and the spaces around blood vessels and small airways. Interstitial lung diseases result in abnormal accumulation of inflammatory cells in lung tissue, cause shortness of breath and cough, and have similarities in their appearance on imaging studies but are otherwise unrelated. Some of these diseases are very unusual.
Pleural and Mediastinal Disorders

The pleura is a thin, transparent, two-layered membrane that covers the lungs and also lines the inside of the chest wall. The layer that covers the lungs lies in close contact with the layer that lines the chest wall. Between the two thin flexible layers is a small amount of fluid (pleural fluid) that lubricates them as they slide smoothly over one another with each breath. The area containing the fluid is called the pleural space.
Pneumonia

Pneumonia is an infection of the small air sacs of the lungs (alveoli) and the tissues around them.
Pulmonary Embolism

Pulmonary embolism is the blocking of an artery of the lung (pulmonary artery) by a collection of solid material brought through the bloodstream (embolus)—usually a blood clot (thrombus) or rarely other material.
- Pulmonary Embolism (PE)
Pulmonary Hypertension

Pulmonary hypertension is a condition in which blood pressure in the arteries of the lungs (the pulmonary arteries) is abnormally high.
Rehabilitation for Lung and Airway Disorders

Pulmonary rehabilitation is the use of supervised exercise, education, support, and behavioral intervention to improve how people with chronic lung disease function in daily life and to enhance their quality of life.
Respiratory Failure and Acute Respiratory Distress Syndrome

Respiratory failure is a condition in which the level of oxygen in the blood becomes dangerously low or the level of carbon dioxide in the blood becomes dangerously high.
Sarcoidosis

Sarcoidosis is a disease in which abnormal collections of inflammatory cells (granulomas) form in many organs of the body.
- Sarcoidosis
Sleep Apnea

Sleep apnea is a serious disorder in which breathing repeatedly stops long enough to disrupt sleep and often temporarily decrease the amount of oxygen and increase the amount of carbon dioxide in the blood.
- Sleep Apnea
Tumors of the Lungs

Lung tumors can be