Certified Transport Registered Nurse Certification Practice Exam

How is air exchange at the alveolar level primarily explained?

1. Henry's Law

2. Graham's Law

3. Dalton's Law

4. Charles' Law

The correct answer is: Henry's Law

Air exchange at the alveolar level is primarily explained by Henry's Law. This law describes how gases dissolve in liquids, stating that the amount of a gas that dissolves in a liquid is proportional to the partial pressure of that gas above the liquid. In the context of the alveoli in the lungs, as oxygen is inhaled and enters the alveolar space, the partial pressure of oxygen in the alveoli is higher than that in the surrounding pulmonary capillary blood. This difference in pressure drives the diffusion of oxygen into the blood, while carbon dioxide, with a higher partial pressure in the blood than in the alveolar space, diffuses into the alveoli to be exhaled. While other laws mentioned explain various gas behaviors, they do not specifically address the mechanism of gas exchange as clearly as Henry's Law in this biological context. For instance, Dalton's Law pertains to the partial pressures of gases in a mixture, and Graham's Law relates to the rates at which gases diffuse, while Charles' Law deals with the volume of gases in relation to temperature. None of these laws specifically outline the process of gas absorption and release at the alveolar and capillary levels as effectively as Henry's Law.