alveolar-capillary membrane

The alveolar-capillary membrane is a thin barrier in the lungs where oxygen enters the blood and carbon dioxide leaves. It separates tiny air sacs called alveoli, filled with fresh air, from the surrounding blood vessels called capillaries. This membrane is incredibly thin, allowing gases to diffuse quickly—oxygen from the air into the blood, and carbon dioxide out of the blood into the alveoli to be exhaled. Its efficiency is essential for proper breathing and oxygen delivery to the body's tissues. Any damage or thickening of this membrane can impair gas exchange and affect breathing.