What is the process called when gases exchange between the air in the lungs and the blood?

The process of exchanging gases between the air in the lungs and the blood is known as external respiration. This involves the inhalation of oxygen-rich air into the lungs, where oxygen diffuses across the alveolar membrane into the bloodstream. Simultaneously, carbon dioxide, which is a waste product of metabolism in the body, diffuses from the blood into the alveoli to be exhaled. This exchange is crucial for maintaining the oxygen levels necessary for cellular functions and removing carbon dioxide effectively from the body.

In contrast, internal respiration refers to the exchange of gases between the blood and the body's tissues, cellular respiration is the metabolic process where cells use oxygen to produce energy from glucose, and metabolic respiration encompasses broader energy-producing processes within cells. These definitions help clarify why external respiration specifically describes the lung-blood gas exchange process.