What is primarily exchanged at the alveolar-capillary membrane?

At the alveolar-capillary membrane, the primary exchange involves oxygen and carbon dioxide. This membrane is crucial for the respiratory process, facilitating the transfer of gases between the air in the alveoli and the blood in the capillaries. When air enters the lungs, oxygen diffuses from the alveoli into the bloodstream, where it binds to hemoglobin in red blood cells for transport throughout the body. Simultaneously, carbon dioxide, which is a waste product of cellular metabolism, diffuses from the blood into the alveoli to be exhaled. This efficient exchange is essential for maintaining proper oxygen levels in the body and removing carbon dioxide, thus supporting cellular respiration and overall metabolic function.