Incredible Human Machine Page #3

and nearly a billion times during the course

of his 30-year professional career.

There's no part of the human body

that likely sees these kinds of collision forces

and shearing stresses,

which is why vocal folds

essentially wear out over time.

lt's also why just months earlier damaged

vocal cords cancelled much of Aerosmith's tour.

Tyler could barely sing...

(Sings high note)

Just breathe.

..forcing him to undergo Zeitels'knife,

or laser, in this case.

Steven basically had a vocal bleed,

which is very common in performers.

Common, in fact, to many with the gift of gab,

from attorneys to telemarketers.

The laser surgery,

which Zeitels and his team pioneered,

works by sealing off damaged vessels

to stop the bleeding.

This is Steven Tyler's voice box

and these are his fragile blood vessels

disappearing.

He was able to just zap those blood vessels

so l go out there and sing

and hope for the best.

Now, as Steven heads on stage,

his finely tuned vocal cords spring into action.

(Guitar intro)

This is Steven Tyler outside...

Every time that l look in the mirror

- ..and in.

- Every time that l look in the mirror

All these lines on my face getting clearer

Every time we exhale,

we force air through our

two membranous vocal cords.

When we bring them together, they vibrate.

Dream on...

These vibrations produce sound,

much like a guitar string after it's been plucked.

Dream on...

Muscles open and close the chords

and change the sound's pitch.

During low notes, the chords are loose

and vibrate more slowly.

Dream on, dream on, dream on...

But for those falsettos...

(High-pitched) Dream on, dream on

His chords stretch to the limit

and vibrate virtually off the charts.

(Holds high note)

A surprisingly simple feat

for Tyler's pliable chords.

l mean, to go from,

(Gruffly) ''l woke up this morning

on the wrong side of the bed

And how l got to thinking

And all them things l said''

but it's in that voice.

And then, you know, of course...

(Higher) ''And l don't want to miss a thing''

is in that voice.

And then Dream On is:

(Falsetto) ''Dream on, dream on''

and they've asked me before,

''How do you sing that song every night?''

That's one of the easiest ones

for me to sing.

Go.

(Rising pitch)

As for what translates these vocal vibrations

into song

that happens much further up

in the throat, the mouth,

the tongue, and the nose.

These are what put the stamp

on human sound,

distinguishing the likes of Steven Tyler

from just about anyone else.

After some two hours of vocal gymnastics,

initial data reveal that Tyler's chords

crashed together more than half a million times,

and covered the equivalent of

more than six miles.

To read between the lines

(Wild cheering)

And there's no indication

they'll be wearing out anytime soon.

Thank you!

Dramatic as it may be, singing is a side effect

of a much more crucial process.

The real reason why air passes through

our mouths is breathing.

We wouldn't survive much more than

a couple of minutes if we didn't.

With every inhalation our noses or mouths

suck in about a pint of air

some 20,000 times a day.

We can follow it on itsjourney down the throat

past the voice box

and into the windpipe or trachea.

As it approaches the lungs,

air has a choice - left or right,

but both lungs lead to the same end.

The lungs'bronchi divide and divide into

thousands of smaller and smaller branches,

progressively filtering chemicals,

dust and smoke in the air,

until finally they come to an end

in this pouch-like ball called an alveolus.

More than 300 million of them

spread across each lung

with a combined surface area

roughly a third the size of a tennis court.

ln less than a second,

oxygen molecules exit the lungs here

through wallsjust one cell thick.

They'll then cross into a surging bloodstream,

be whisked throughout the body

and provide precious resources

to every one of our trillions of cells,

assuming air gets to this point.

The blue here shows how a healthy lung

empties oxygen into the bloodstream.

ln this smoker's lung,

oxygen can't empty nearly as well.

Then there's the exhalation.

Carbon dioxide.

The waste product of breathing

makes the opposite journey back out.

Another inhalation and our breathing apparatus

offers yet another gift,

with delightful or disgusting results.

With every new breath, our noses can

distinguish as many as 1 0,000 different odours.

Some pleasing...

..some not.

They can calm, caution,

or make our mouths water.

But the essence of any aroma,

from a day at the beach to fresh baked bread,

is pure chemistry.

lsobutyl acetate, vanillic acid and more than

300 different chemicals, for example,

come together to give chocolate

its unmistakable bouquet.

A rose by any other name

might be phenyl ethyl alcohol.

And once fish is past its prime,

it owes its stench to trimethylamine,

a by-product of the bacteria growing inside it.

Whatever the chemical

deep inside our noses,

there is a small patch of about 1 0 million cells

waiting to sniff it out.

These cells carry about a thousand

different kinds of receptors on their surfaces.

When the right odour chemical

meets up with the right receptor

an electrical signal gets sent to the brain,

and, finally, the incredible machine smells.

All in all, our respiratory systems

are ingenious multi-taskers,

sorting thousands of smells at each intake,

capable of making thousands of sounds

on the way out.

(Laughter)

But no matter how pleasant the by-product,

there is a higher calling to breathing.

Every breath we take delivers oxygen

to our trillions of power-hungry cells

and gets our hearts to pump.

(Heartbeats)

Every second of every day,

every cell in our body needs oxygen

to power its activities and survive.

More than a gallon of blood needs to travel

through some 60,000 miles-worth of arteries,

veins and capillaries.

And one little 1 0-ounce heart has the

Herculean task of driving the whole system.

lt begins with a heartbeat

which sends fresh, oxygenated blood

from the lungs streaming into the heart.

lf you stored up the power

from all the heartbeats in a day,

it could lift a car some 30 feet into the air.

The heart is a muscular pump to its core.

Even if it's removed,

it can still function all on its own.

lts genius lies in its cardiac cells -

millions of them all beating in tune.

But heart cells don't necessarily

have to be born in the heart.

These are stem cells

coaxed into beating by Dr Amit Patel

and his colleagues from

the University of Pittsburgh Medical Center.

Those cells had nothing to do with

becoming heart muscle.

But within less than a week,

we were able to train them

to become heart muscle.

Stem cells live in many tissues in our bodies,

standing by for maintenance and repair.

Unlike our other cells, stem cells can develop

into just about any kind of cell -

brain, muscle, bone, fat.

Almost anything you could possibly think of

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