What process allows for gas exchange between blood and the alveolus?

The process that facilitates gas exchange between blood and the alveolus is known as alveolar gas exchange, which describes the specific exchange of oxygen and carbon dioxide within the alveoli of the lungs. During this process, oxygen from the inhaled air passes through the thin walls of the alveoli and enters the bloodstream, while carbon dioxide, which is a waste product of metabolism in the body's cells, moves from the blood into the alveoli to be exhaled.

Alveolar gas exchange is highly efficient due to the large surface area of the alveoli, the thinness of the alveolar walls, and the difference in partial pressures of the gases involved. Oxygen diffuses into the blood because its partial pressure is higher in the alveoli than in the deoxygenated blood arriving from the pulmonary circulation. Conversely, carbon dioxide diffuses into the alveoli because its partial pressure is higher in the blood than in the alveolar air.

While diffusion is a fundamental mechanism that underlies alveolar gas exchange, the term specifically refers to the process of moving oxygen and carbon dioxide through a concentration gradient, rather than the overall process of exchanging these gases in the alveoli. Therefore, alveolar gas exchange captures the complete nature of this critical respiratory function.