A scan of the bladder probably using ultrasound (what they use on pregnant women) or x-ray maybe ☺
air bladders are on a bladder wrack for different reasons
im not 100% sure but i think they're the same thingGenerally they are, but there is also a gall bladder.
holds your water.
The bladder is an organ about the shape of a walnut (when healthy) that is responsible for holding and removing of urea (urine).