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Elderly adults are living longer, and causes of death are shifting. At the same time, autopsy rates are at or near their lowest in history.
The immune system needs 9.5 hours of sleep in total darkness to recharge completely.
In most cases, kidneys can recover from almost complete loss of function, such as in acute kidney (renal) failure.
There are over 65,000 known species of protozoa. About 10,000 species are parasitic.
Normal urine is sterile. It contains fluids, salts, and waste products. It is free of bacteria, viruses, and fungi.
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