Pathology

There exist a number of various pathologies associated with the alveolar structure, however, in this blog, only two will be discussed in detail. These include emphysema and pulmonary alveolar proteinosis, or PAP for short.

The first condition, emphysema, is characterized by the enlargement of the respiratory airspaces as a result of many destructive changes within the alveoli of the lungs. The basis for the classification of emphysema in an individual involves the localizations of lesions present on the acinus, which consists of 3 to 5 orders of respiratory bronchioles, alveolar ducts, and alveoli (2). There is a large loss of the elastic recoil in the lungs, due to the disruption of elastic fibers, and as a result of these changes, the compliance as well as the diffusing capacity of the lungs are greatly decreased (2). One major cause of emphysema includes exposure to cigarette smoke throughout life (2).

Figure 7: Normal Alveoli vs. Alveoli with Emphysema

(Retrieved from http://media-2.web.britannica.com/eb-media/04/100104-036-0E044846.jpg )

The second condition, called PAP, is caused by an oversecretion of surfactant within the alveoli of the lung, which subsequently causes a reduction in the oxygen that is able to diffuse across the alveoli and on into the pulmonary capillaries for transport to the body (5). It occurs in men more so than women, and symptoms generally include a dry cough, weight loss, and a shortness of breath (5). The exact cause of PAP is unknown in many cases, however, there does appear to be genetic link, which can be hereditary (5).

Figure 8: Lung Showing the Presence of Increased Amounts of Surfactant

(Retrieved from http://www.ajronline.org/content/vol176/issue5/images/small/05_AA1162_05A.gif)