The adult human brain weighs about 3 pounds (1,300-1,400 g).
99
Enamel is hardest substance in the human body.
61
Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
The average sperm cell swims at 8 inches per hour.
76
Oxygen, carbon, hydrogen and nitrogen make up 90% of the human body.
118
Your body is creating and killing about 2.4 million red blood cells per second.
17
Your heart will pump about 212 million liters in its lifetime.
26
When you take a step, you are using up to 200 muscles.
886