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The familiar sounds of your heart are made by the heart's valves as they open and close.
In most cases, kidneys can recover from almost complete loss of function, such as in acute kidney (renal) failure.
In the United States, congenital cytomegalovirus causes one child to become disabled almost every hour. CMV is the leading preventable viral cause of development disability in newborns. These disabilities include hearing or vision loss, and cerebral palsy.
The Babylonians wrote numbers in a system that used 60 as the base value rather than the number 10. They did not have a symbol for "zero."
It is believed that the Incas used anesthesia. Evidence supports the theory that shamans chewed cocoa leaves and drilled holes into the heads of patients (letting evil spirits escape), spitting into the wounds they made. The mixture of cocaine, saliva, and resin numbed the site enough to allow hours of drilling.