Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
Your heart will pump about 212 million liters in its lifetime.
26
The average sperm cell swims at 8 inches per hour.
76
Stress can result in more headaches as a result of the body rerouting blood flow to other parts of the body.
92
When you take a step, you are using up to 200 muscles.
886
The adult human brain weighs about 3 pounds (1,300-1,400 g).
99
The average person's skin weighs twice as much as their brain.
131
The human body contains over a billion miles of DNA.
147