ABSTRACT
The lung’s only known essential function is to meet the organism’s need for oxygen. Because CO2 is much more soluble in water than O2, alveolar architecture that allows sufficient O2 uptake provides adequate elimination of CO2. The interesting and important relationship between O2 need and alveolar surface area is discussed fully and with great insight by Mortola in this volume. The tight match between O2 need and alveolar architecture may not bemet if alveoli fail to develop normally, as can occur in prematurely born babies (1-4). Even if alveoli have developed normally, the link between O2 need and the size, number, and surface area of alveoli may be broken if alveoli are destroyed; this occursmost commonly in patients with chronic obstructive pulmonary disease (5,6) and, with age, even in individuals who do not have lung disease and who may or may not be, or ever have been, smokers (see below). The loss of alveoli and lung function due to age alone is substantial and, to our knowledge, rarely considered as contributing to the burden of those with underlying cardiopulmonary disease.
