It takes about 20 seconds for a red blood cell to circle the whole body.
102
Your thumb is about the same size as your nose.
124
Enamel is hardest substance in the human body.
61
The average sperm cell swims at 8 inches per hour.
76
Yawns are more contagious among people with closer relationships.
163
The average person's skin weighs twice as much as their brain.
131
The human brain is very soft, having a consistency similar to soft gelatin or firm tofu.
13