(HealthDayNews) -- Though it weighs less than a pound, the human heart provides enough energy in an hour to lift a one-ton, medium-size car one yard off the ground.

Actually, the human heart is two pumps: One sends 2,000 gallons of blood a day in a loop through the lungs to be oxygenated; the other sends an equal amount -- 50 million gallons in a lifetime -- through the rest of the body to distribute the oxygen, according to Anthony Smith, author of The Body. Human hearts, pumping an average 70 times a minute, will beat 2.5 billion to 3 billion times in a lifetime.

Only mammals and birds have two-part hearts, says Smith, who reports that the bigger the animal the slower the heartbeat. An elephant's 48-pound heart beats only about 25 times a minute; the mouse heart beats 600 to 700 times a minute; a canary 1,000 times. Last Updated: Jan-26-2004