Human Body Facts
The brain, the heart, and the incredible machine you live inside every day.
The Brain
100 billion neurons, unlimited storage capacity, and it uses more energy than any other organ.
4 reading levels: Rookie · Curious · Sharp · Expert
The Heart
It beats 100,000 times a day and pumps enough blood to fill a swimming pool every week.
4 reading levels: Rookie · Curious · Sharp · Expert
Bones & Skeleton
You were born with 300 bones, but adults only have 206. Where did the others go?
4 reading levels: Rookie · Curious · Sharp · Expert
Sleep & Dreams
Why we spend a third of our lives asleep: the stages of sleep, the science of REM dreaming, and what the brain does while the body rests.
4 reading levels: Rookie · Curious · Sharp · Expert