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The familiar sounds of your heart are made by the heart's valves as they open and close.
The largest baby ever born weighed more than 23 pounds but died just 11 hours after his birth in 1879. The largest surviving baby was born in October 2009 in Sumatra, Indonesia, and weighed an astounding 19.2 pounds at birth.
Before a vaccine is licensed in the USA, the Food and Drug Administration (FDA) reviews it for safety and effectiveness. The CDC then reviews all studies again, as well as the American Academy of Pediatrics and the American Academy of Family Physicians. Every lot of vaccine is tested before administration to the public, and the FDA regularly inspects vaccine manufacturers' facilities.
Prostaglandins were first isolated from human semen in Sweden in the 1930s. They were so named because the researcher thought that they came from the prostate gland. In fact, prostaglandins exist and are synthesized in almost every cell of the body.
Egg cells are about the size of a grain of sand. They are formed inside of a female's ovaries before she is even born.