alveolsäckar

Alveolsäckar, also known as alveolar sacs, are tiny, thin-walled sacs found at the very end of the respiratory bronchioles in the lungs. They are the primary sites of gas exchange in the respiratory system. Each lung contains millions of these microscopic structures, which collectively form the alveolar portion of the lungs. The walls of the alveolsäckar are composed of a single layer of squamous epithelial cells, making them extremely thin. This thinness facilitates the efficient diffusion of oxygen from inhaled air into the bloodstream and the removal of carbon dioxide from the blood into the air to be exhaled. Each alveolär säck is surrounded by a dense network of capillaries, which are the smallest blood vessels in the body. This close proximity between the alveoli and the capillaries is crucial for rapid and effective gas transfer. The total surface area provided by all the alveolsäckar in the lungs is vast, estimated to be around 70-100 square meters, which is comparable to the size of a tennis court. This immense surface area maximizes the efficiency of oxygen uptake and carbon dioxide removal during respiration. Alveolar sacs are also lined with a thin film of fluid that contains a substance called surfactant. Surfactant reduces the surface tension of the fluid, preventing the alveoli from collapsing during exhalation.