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
Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
197
The largest cell in the human body is the female egg and the smallest is the male sperm.
682
It would take about 1,200,000 mosquitoes to fully drain the average human body of blood.
217
The human body contains over a billion miles of DNA.
147
The adult human brain weighs about 3 pounds (1,300-1,400 g).
99