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The familiar sounds of your heart are made by the heart's valves as they open and close.
During the twentieth century, a variant of the metric system was used in Russia and France in which the base unit of mass was the tonne. Instead of kilograms, this system used millitonnes (mt).
The human body produces and destroys 15 million blood cells every second.
A cataract is a clouding of the eyes' natural lens. As we age, some clouding of the lens may occur. The first sign of a cataract is usually blurry vision. Although glasses and other visual aids may at first help a person with cataracts, surgery may become inevitable. Cataract surgery is very successful in restoring vision, and it is the most frequently performed surgery in the United States.
Approximately 70% of expectant mothers report experiencing some symptoms of morning sickness during the first trimester of pregnancy.