Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
When you get goosebumps and your hair stands, the hair helps to trap air, making you feel warmer by keeping in your body heat.
46
The human brain doesn't stop developing until about 25 years old.
102
Every year your body replaces 98% of your atoms.
119
The human brain uses approximately as much energy as a 10 watt light bulb.
120
Your heart will pump about 212 million liters in its lifetime.
26
After age 30, the brain begins to lose about 50,000 neurons per day - shrinking the brain .25% each year.
55
An average heart beats 100,000 times a day, pumping some 2,000 gallons of blood through its chambers. Over a 70-year life span, that adds up to more than 2.5 billion heartbeats.
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