The Gall Bladder is unusual among Yang Organs, because it does not receive, transform or transport digestate and waste products, but it stores bile. Bile is a pure (refined) substance, unlike the digestate and its products, which are impure substances.
Hence, since the Gall Bladder stores a pure substance, it resembles a Yin Organ. For this reason the Gall Bladder is included in the "Curious Organs".
It receives bile from the Liver and stores it, releasing it when needed during digestion (same as in Western biomedicine).
Smooth flow of bile aids Stomach and Spleen digestive functions.
When Liver Qi stagnates and bile does not flow smoothly, digestive signs such as nausea and belching occur.
Wood element (Gall Bladder and Liver) control sinews. Liver nourishes tendons with Blood, Gall Bladder provides Qi to ensure correct movement and flexibility of tendons. The influential point for tendons is Gall Bladder 34, i.e., on Gall Bladder channel.