The familiar sounds of your heart are made by the heart's valves as they open and close.
Did you know?
The human body produces and destroys 15 million blood cells every second.
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Pregnant women usually experience a heightened sense of smell beginning late in the first trimester. Some experts call this the body's way of protecting a pregnant woman from foods that are unsafe for the fetus.
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Bacteria have flourished on the earth for over three billion years. They were the first life forms on the planet.
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Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.
Ground cover and colour such as shown here in (a) white sand
black sand
Sand bathing.
This Native American depiction of the Sand Creek Massacre, painted on a buffalo hide, shows the Indi
Rackstraw Downes, Presidio in the Sand Hills Looking East with ATV Tracks and Water Tower.