The lungs can be affected by numerous pathologic processes, including inflammation (allergic, infectious, autoimmune, toxic), vascular insults, fibrosis, carcinoma, and changes resulting from cardiac or musculoskeletal problems. The functional consequences of the pathology can be divided into obstructive ventilatory functions and restrictive ventilatory functions.
Symptoms of lung disease include dyspnea, cough, and wheezing. Dyspnea develops when the demand for gas exchange exceeds the capacity of the respiratory system, as in hypoxemia or hypercapnia. Dyspnea may also reflect the increased work of breathing, as occurs in cases of airway obstruction or reduced compliance of the lungs or chest. Cough develops when mucus, inflammatory debris, or irritants stimulate the bronchi, causing reflex clearing expectoration, or when the lung parenchyma is infiltrated with fluid, cells, or fibrosis. Wheezing occurs when bronchospasm narrows the large airways and exhaled air is forced through narrowed passages.
Excerpted from BCSC 2020-2021 series: Section 1 - Update on General Medicine. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.