This film shows advanced sarcoid, scarring of the lungs (the light streaking), and cavity formation (the dark areas in the upper right side of the picture).

Acute conditions are severe and sudden in onset. This could describe anything from a broken bone to an asthma attack. A chronic condition, by contrast is a long-developing syndrome, such as osteoporosis or asthma. Note that osteoporosis, a chronic condition, may cause a broken bone, an acute condition. An acute asthma attack occurs in the midst of the chronic disease of asthma. Acute conditions, such as a first asthma attack, may lead to a chronic syndrome if untreated.

Chronically low blood levels of oxygen may lead to pulmonary hypertension (high blood pressure in the lungs), and possibly to cor pulmonale. Cor pulmonale is also called right-sided heart failure, and is characterized by enlargement of the right ventricle. Treatment targets the underlying illness and may include supplemental oxygen, a low-salt diet or calcium channel blockers.

Air is breathed in through the nasal passageways, travels through the trachea and bronchi to the lungs.