Page 275 - (DK) I Can’t Believe It! 2

TRUE OR FALSE? 273
ON THE At least 50%

MOVE MOVE MOVE MOVE of your body is
water. But how
much of each
organ is
An adult’s network of blood vessels is water?
100,000 miles
(160,000 km) long. That’s long
enough to wrap around the
world four times.

The fastest nerve signals can
LIVER
travel about 250 mph (402 km/h). 86%
That’s faster than a peregrine falcon
and a Formula 1 race car.

KIDNEYS
83%

FORMULA 1 CAR PEREGRINE FALCON NERVE SIGNAL
240 mph 242 mph 250 mph
(386 km/h) (389 km/h) (402 km/h) WATER IN THE BODY BRAIN
80%
GETTING

You are born with 300 SLEEPY
LUNGS
bones, but when you 80%
are fully grown you A hormone called melatonin peaks at night
have only 206. to make people feel sleepy.
Stirrup shown actual
size: 0.12 x 0.1 in
(3 x 2.5 mm)
HEART
The enamel of your teeth 33.3% 73%
is the HARDEST substance
in the body. It has no living YOU SPEND ABOUT ONE-THIRD OF YOUR LIFE ASLEEP.
cells, so your body cannot
A fingernail would grow about 90 ft (28 m) if it was never cut. repair it once it’s damaged. BONES
66.7% 22%
That’s about the length of four elephants.

Your feet have approximately
Teenagers don’t produce melatonin until 250,000 sweat
1am. This is much later than most adults,
which may be why it’s hard to get teenagers glands. They can make 1 pint
out of bed in the morning! (0.5 liters) of sweat each day.

US_272_273_309600_TOF_HumanBody.indd 273 19/12/17 3:49 pm