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Did you know?

Human neurons are so small that they require a microscope in order to be seen. However, some neurons can be up to 3 feet long, such as those that extend from the spinal cord to the toes.

Did you know?

About 600,000 particles of skin are shed every hour by each human. If you live to age 70 years, you have shed 105 pounds of dead skin.

Did you know?

Human stomach acid is strong enough to dissolve small pieces of metal such as razor blades or staples.

Did you know?

The average adult has about 21 square feet of skin.

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Sperm cells are so tiny that 400 to 500 million (400,000,000–500,000,000) of them fit onto 1 tsp.

These species are all at risk of extinction. These species are all at risk of extinction.
Map of the Moon by Johannes Hevelius from his Selenographia (1647), the first map to include the lib Map of the Moon by Johannes Hevelius from his Selenographia (1647), the first map to include the lib
CHD Risk Factors CHD Risk Factors
Factors Affecting Body Temperature Factors Affecting Body Temperature
Country of Birth of Authorized U.S. Immigrants Country of Birth of Authorized U.S. Immigrants
Locus control and developmental expression of human globin–complex genes Locus control and developmental expression of human globin–complex genes
Video: Chemical Changes

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