1. The stomach's digestive acids are strong enough to dissolve zinc. Fortunately for us, the cells in the stomach lining renew so quickly that the acids don't have time to dissolve it.

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2. The lungs contain over 300,000 million capillaries (tiny blood vessels). If they were laid end to end, they would stretch 2400km (1500 miles).

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3. A man's testicles manufacture 10 million new sperm cells each day - enough that he could repopulate the entire planet in only 6 months!

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4. Human bone is as strong as granite in supporting weight.. A block of bone the size of a matchbox can support 9 tonnes - that is four times as much as concrete can support.

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5. Each finger and toenail takes six months to grow from base to tip.

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6. The largest organ in the body is the skin. In an adult man it covers about 1.9m2 (20sq ft). The skin constantly flakes away - in a lifetime each person sheds around 18kg (40 lb) of skin.

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7. When you sleep, you grow by about 8mm (0.3in). The next day you shrink back to your former height. The reason is that your cartilage discs are squeezed like sponges by the force of gravity when you stand or sit.

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8. The average person in the west eats 50 tonnes of food and drinks 50,000 litres (11,000 gallons) of liquid during his life.

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