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BODY OF KNOWLEDGE
The human body is a complex system of organs, muscles, bones, and electric impulses … which means there’s a lot of weird and cool stuff to learn about it.
It takes a team of about 300 different muscles
working together to get you to stand up (and
stay standing without falling flat on your face).
Blame them when you take a trip!
Boom-boom, boom-boom …
Over the course of a lifetime, your heart
will beat somewhere around 2.5 billion times.
There are exactly 206 bones in your body.
(We counted.) More than half of those are in
your hands, fingers, feet, and toes.
The reason your nose runs when you cry
really hard: Tears drain out of your eyes … and
into your nose. And then they come out your nose.
(With a bunch of other stuff.)
Think how cold you are when you forget your winter coat.
Now consider how cold you’d be without your skin.
Your skin weighs the same as four heavy winter coats.
Technically, urine is sterile and germ-free.
But you definitely shouldn’t drink it.
This fact stinks!
In just its first week of life, a newborn baby
will go through 80 diapers.
You’ve got a lot of growing up to do.
At birth, your brain weighed 3 ounces.
As an adult, it’ll weigh 3 pounds.
All that knowledge weighs a lot!
The hardest substance in your body
is the enamel on your teeth, even though
it’s one 1000th of an inch thick.
And that’s the tooth!
Looking sharper every day!
Fingernails grow at a rate of about
one 25th of an inch per week.
Every two weeks, your stomach produces
a new layer of protective mucus.
If it didn’t, it would digest itself.
Your stomach is its own worst enemy.
Hope you’re hungry:
In your lifetime, you’ll eat about 60,000 pounds of food.
That’s the equivalent weight of six elephants.
What’s the point?
The exact point where your nose meets your forehead
has a name. It’s called the nasion.
After being used for 10 years, a mattress doubles in weight.
Why? It gets loaded up with dust mites, mold,
dead skin cells, hair, and dried sweat.
Sweet dreams!
Hair grows incredibly slowly. It takes 30 days for
a human hair to grow just one half of an inch.
You grow, hair!
Care for some mouthwash?
The average person’s mouth is one of the most germ-infested places in the world. There are more germs in a mouth than there are on a public toilet seat.
Cold comfort:
It’s not the cold virus that makes
you feel awful—it’s your body fighting it off.
The immune system releases white blood cells to attack the virus and force it out, resulting in headaches and stuffy noses.
That’s sick! The stomach flu, a nasty virus that leads
to vomiting and diarrhea, isn’t really the flu.
It’s actually gastroenteritis.
You’ll never need eye mittens!
It’s impossible for your eyes to freeze
even when it gets really cold.
The salt in your tears prevents that from happening.
Don’t call them “eye boogers.”
That gunk that forms in your eyes
while you sleep is called rheum.
In your eyes, it’s a fine line between love and hate.
When you see someone you love, your pupils dilate,
or get larger. They also get bigger when you’re looking
at someone you really don’t like.
The white of your eye isn’t technically called
the “white of your eye.” It’s called the sclera.
Don’t blink … or do.
You blink about 15 times a minute. Over a lifetime,
that’s two years spent with your eyes shut!
That’s a big box of crayons!
The human eye can recognize 10 million different colors.
You may not even ever see them all.
You can’t even count that fast.
Your eyes move back and forth to take everything in
about 80 times a second. That’s about 4.6 million times a day!
The vast majority of people have blue eyes or brown eyes.
Only 2 percent of the human population has green eyes.
Let’s go green!
A blind man named Daniel Kish taught
himself echolocation. He hikes and mountain bikes
by listening for the echo of his tongue clicks.
Sounds amazing.
Tears are made up primarily of water and salt.
That means tears are almost exactly the same thing as urine.
Is that why people go to the bathroom when they need to cry?
Taking in the skin you’re in:
Every day, you inhale a lot of your own skin flakes.
About 700,000 of them, to be more exact.
The thickest skin on your body is the stuff
on the bottom of your feet. It’s three times thicker
than the skin on the palm of your hands.
And that’s no small feet!
Got a blister, mister?
If it’s a big one, it’s called a vesicle.
If it’s a small one, that’s a bullae.
Does something about this seem fishy?
There’s a rare condition called ichthyosis
that makes human skin appear scaly.
Get thee to a doctor!
In Medieval England, freckles were called “moth-patches.”
They were considered a serious health problem.
Do you dream in color? Apparently only 5 percent
of Americans do, with the rest dreaming in black and white.
Either way, we all dream in “weird.”
Don’t I know you from somewhere?
Your brain doesn’t invent new faces for people
in your dreams. They’re all faces you’ve seen
before—say, strangers on the street or people on TV.
Sleep like a grownup …
The average adult has four dreams a night.
They only have about one really bad nightmare a year.
If it takes you less than five minutes to fall asleep,
that means you’re sleep-deprived. Healthy sleepers
need about 10 to 15 minutes to head off to Sleepyland.
The sheep are counting!
Hair it is!
Even if you don’t have a lot of hair, your body
is still naturally cycling out old ones for new ones.
You lose about 50 to 100 hairs a day.
Imagine wanting green teeth …
Wealthy women in 16th-century Europe thought
it was fashionable to dye their teeth. In Italy,
the most popular colors were red and green,
while in Russia the favorite was black.
Stick your neck out!
Every bone in the body eventually stops growing.
The last to do so is the collarbone.
Ouch! There are pain receptors all over the body.
One square centimeter contains about 200 pain receptors.
Everybody into the gene pool!
DNA is microscopic and takes up a small percentage
of the room in a cell. If you put all the DNA in
the human body together, it would fit inside
a space about the size of an ice cube.
What an air hog!
The brain is the single biggest consumer of oxygen.
It uses a quarter of all the oxygen in the body.
Burn your tongue? No need for a bandage.
The tongue is the fastest-healing part of the human body.
The choice is yours:
Smiling requires the use of 17 muscles.
Frowning needs 43 muscles.
Your own private ocean inside …
Not only is blood mostly water, but the plasma
is almost as salty as ocean water.
Baaaad blood?
The first successful blood transfusion took place in 1667.
A French doctor named Jean-Baptiste Denys injected
sheep’s blood into a 15-year-old boy.
Drink up!
Your blood is 83 percent water,
your brain is about 75 percent water, and
your bones are about a quarter water.
Time to bone up …
The strongest bone in the human body is
the thigh bone. It’s actually stronger than concrete.
Lights out!
Until the 20th century, humans slept about
10 hours a night. Today we only sleep an average
of seven. What happened? The development of electricity
allowed us all to stay up later.
If you have metal tooth fillings and chew aluminum foil,
it can generate a two-volt electrical current.
But please don’t try this at home.
Twins aren’t always born in quick succession,
or even on the same day. The longest time
between two twins being born was 87 days.
Oh, baby!
About one in every 2,000 newborn babies
is born with at least one tooth already above the gums.
Now that’s a baby tooth!
Happy birthday, and happy Tuesday.
More babies are born on Tuesdays
than on any other day of the week.
The nose knows the difference.
Just as everyone has a unique fingerprint, we all
have a unique (if barely detectable) scent.
Even identical twins have different scents.
People are taller when they wake up than
when they go to bed. Gravity pulls you down
a little bit over the course of the day.
Good morning, and my, have you grown!
Stand tall!
Stretch your arms out from side to side.
The distance from fingertip to fingertip
is the same as your height.
Everybody farts, every day. In fact, most people
let out enough gas each day to fill up a small balloon.
Probably doesn’t qualify for your science fair project, though!
My, you have good taste in makeup!
Every time a person applies lipstick, they wind up
swallowing a little bit. Over the course of a lifetime,
the average woman will consume four pounds of lipstick.
Sensitive information: There’s a medical condition
called synesthesia. It mixes up senses, meaning people
can see sounds, feel colors, or taste music.
Incoming …
Messages are sent from the nerves on your body
to the brain—where they’re processed—at a speed
of about 200 miles an hour!
Ever wonder exactly how many calories you need
to eat every day? The rule of thumb is that it’s the number
of your weight in pounds multiplied by 11.
Math can be delicious!
Feel the burn!
Your brain requires very little energy to operate.
It uses about 1/10 of a calorie per minute to function.
According to studies of astronauts who have spent
a lot of time in space, fingernails and toenails
grow more slowly in space than they do on Earth.
So does a manicure cost less on Mars?
Transplants of most body parts are now possible.
You can even get a fingernail transplant.
Just don’t bite ’em—the transplant often comes from a toenail.
Not everything is meant to be shared …
According to a survey, 10 percent of Americans
say they’ve picked someone else’s nose.
Pick me!
The finger used the most for nose picking
(at 65 percent) is the index finger.
The least popular choice: the thumb (16 percent).
There’s no single illness called “the cold.”
Each year, many strains makes lots of people sick—about
100 different viruses are usually going around at one time.
That’s something to sneeze at.
What a flake! Over your life,
you’ll shed about 40 pounds of skin.
It comes off one flake at a time.
There’s enough iron in your body to make a nail.
There’s enough aluminum to make a piece of foil large
enough to wrap a cheeseburger.
Are you a robot?
Your tongue needs moisture to work. If your tongue
is completely dry, your taste buds won’t function.
Water! Water!
Skip the finger workout …
There aren’t any muscles in your fingers, except
the tiny arrector pili muscles that help make the hair
on your fingers stand out straight. All finger movement
is controlled by muscles in your arms.
You’ve got a lot of nerve … literally.
If you’re average, there’s a total of about
46 miles of nerves in your body.
The Incredible Shrinking Brain is a true story.
Over the course of your lifetime, your brain
does slowly shrink. It will decrease from its
peak mass by about 15 percent.
Mosquitoes are more attracted to you if
you’ve recently eaten a banana.
Yellow-no!
The longest recorded sneezing fit was 978 consecutive days.
Gesundheit! Gesundheit! Gesundheit …
Now hear this!
The part of your ear that sticks out isn’t really
where you hear. The hearing functions go on in the middle ear and the inner ear, which are safely stored inside the head.
Small but mighty!
The three smallest bones in the human body are
all located inside the middle ear. The stapes, malleus,
and incus put together could fit on top of a penny.
What is the purpose of earlobes? Scientists still aren’t really sure.
They’re just hanging around.
Add it all up and the average adult doesn’t laugh
all that much. Laughter totals about six minutes a day.
Make it your mission to change that with wacky facts
from this book! Keep reading.…
Copyright © 2018 by St. Martin’s Castle Point