What is the process of movement of oxygen across the alveolar-capillary membrane called?

The movement of oxygen across the alveolar-capillary membrane is referred to as external respiration. This process specifically involves the exchange of gases between the air in the alveoli of the lungs and the blood in the capillaries surrounding them. During external respiration, oxygen from inhaled air diffuses into the blood within the capillaries, while carbon dioxide from the blood diffuses into the alveoli to be exhaled.

Understanding this process is vital for managing patients with respiratory issues, as it is a fundamental component of how the body acquires oxygen and eliminates carbon dioxide. The term "external respiration" directly points to the interactions occurring at the site of the lungs, highlighting its role in facilitating gas exchange that is essential for maintaining adequate tissue oxygenation and overall respiratory function.

In contrast, other terms like internal respiration refer to the exchange of gases at the cellular level, cellular respiration pertains to the metabolic processes within cells that use oxygen to produce energy, and oxygenation generally refers to the saturation of hemoglobin with oxygen in the blood, which is a result of successful external respiration but does not specifically describe the process across the alveolar-capillary membrane.