blodluftbarriär

A blodluftbarriär, often translated as blood-air barrier, is a vital physiological structure found in the lungs. It separates the air in the alveoli, the tiny air sacs where gas exchange occurs, from the blood in the capillaries, the smallest blood vessels. This barrier is extremely thin, typically less than a micrometer in thickness, which is crucial for efficient diffusion of gases.

The blodluftbarriär is composed of several layers. On the alveolar side, there is the alveolar epithelium, which consists primarily of type I pneumocytes, flattened cells that form the majority of the alveolar surface. On the capillary side, there is the capillary endothelium, a single layer of cells lining the blood vessel. Between these two epithelial layers lies a fused basement membrane, a thin layer of extracellular matrix. In some areas, the basement membranes of the alveolar epithelium and capillary endothelium may be fused, further reducing the diffusion distance.

The primary function of the blodluftbarriär is to facilitate the exchange of oxygen and carbon dioxide between the inhaled air and the bloodstream. Oxygen from the alveoli diffuses across the barrier into the blood, where it binds to hemoglobin in red blood cells. Conversely, carbon dioxide, a waste product of metabolism, diffuses from the blood across the barrier into the alveoli to be exhaled. The thinness and large surface area of the lungs, coupled with the efficiency of the blodluftbarriär, allow for rapid and effective gas exchange, which is essential for sustaining life.