sundrythings:

    This drawing illustrates why birds have such efficient respiratory systems. The drawing is very simplified and you must realize birds have multiple air sacs throughout their bodies but it would have been too complicated to draw them all. This drawing also only shows a single “puff” of air as it travels in the system. In real life there would be a continuous stream of air into the system, not just one puff at a time.

    The first drawing shows the air on inspiration, traveling down the trachea and bypassing the lungs and going into the posterior air sac. The next shows expiration and the air going into the lugs, notice that the air sacs are all compressed at this point, pushing all of the air out of them and into the next section of the system. The third drawing is the next inspiration and the air flows into the anterior air sac and then on the final expiration the air leaves the system and is exhaled. Remember that the entire time this is happening there is a constant influx of air that circulates keeping everything oxygenated.

    Mammals can only process one breath at a time, having to exhale the entire volume of air before bringing in a new one. This is why birds can fly at such high altitudes and are able to keep their tissues oxygenated at such a high metabolic rate.

(Drawing from Dr. Lish)

May 28th / 17 notes