parabronkiene

Parabronchi are a unique anatomical feature found in the respiratory system of birds. They represent a crucial component of the avian respiratory system, which is highly efficient compared to that of mammals. Unlike the lungs of mammals which are tidal, meaning air flows in and out through the same passages, the avian respiratory system is unidirectional. This unidirectional flow is facilitated by the presence of parabronchi.

These structures are essentially thin-walled, tubular air capillaries that are the primary site of gas exchange. They are arranged within the avian lung parenchyma, forming a complex network. Air entering the bird's respiratory system passes through a series of air sacs, which act as bellows, and then flows through the parabronchi. This flow pattern ensures that fresh, oxygenated air is constantly passing over the gas exchange surfaces, maximizing oxygen uptake.

The parabronchi are so named because their arrangement and function are analogous to bronchi, but they are more specialized for gas exchange. The highly branched nature of the parabronchi, combined with a dense capillary network surrounding them, creates an enormous surface area for efficient oxygen diffusion into the bloodstream. This advanced respiratory system is thought to be an adaptation for the high metabolic demands of flight.