It takes about 20 seconds for a red blood cell to circle the whole body.
102
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.
73
It would take about 1,200,000 mosquitoes to fully drain the average human body of blood.
217
For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515
The average sperm cell swims at 8 inches per hour.
76
Staying awake for 17 hours is the same for your body as drinking 2 glasses of wine.
193
Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
It takes twice as long to lose new muscle if you stop working out than it did to gain it.
127