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
Oxygen, carbon, hydrogen and nitrogen make up 90% of the human body.
118
Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
197
The human brain uses approximately as much energy as a 10 watt light bulb.
120
The human body contains over a billion miles of DNA.
147
Dogs can be trained to identify the scent of lung cancer long before symptoms develop.
190
The largest cell in the human body is the female egg and the smallest is the male sperm.
682