Kidneys are a filter system. The main job of the kidneys is to remove waste from the blood and return the cleaned blood back to the body. Each minute about one litre of blood ï­ one-fifth of all the blood pumped by the heart - enters the kidneys through the renal arteries.
The volume of helium in the balloon has been estimated as being able to lift a total load, including the balloon material and the structure beneath it, of 65 pounds (29 kg) at sea level and 48 pounds (22 kg) at 8,000 feet (2,400 m).
To make the balloon bigger (hypertrophy), one can either add more water to the balloon, thereby stretching it to its maximum capacity (increase cell volume) or one could theoretically add more rubber (balloon material) to make the overall size of the balloon larger (increase in contractile protein).