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).
(A) hot air has a lower pressure than cold air, so hot air is drawn into the balloon by the partial vacuum inside it. (B) hot air has more inertia than cold air and doesn't accelerate easily. (C) the air pressure inside the balloon's opening is the same as the air pressure outside that opening.