Original subtitles

This athlete is a champion

of one of the world's most spectacular sports:

bull jumping.

This boxer survives being hit by a fist

travelling with the force of a third of a tonne.

And this man is hoping that surgeons will replace

his damaged limbs with another man's hands.

Can we Twitter that the surgery has started?

Their stories are part of your story...

the story of what makes you human.

Hidden deep beneath your skin is an extraordinary universe...

where billions of tiny powerhouses generate energy.

Where vast forests digest food...

and where the tiniest movements set off violent chain reactions.

This is a fantastic voyage through the most complex organism on Earth...

the human BODY

(?) Meet James ???

I deliver packages for a living. I'm a glorified postman.

James is a cycle courier,

one of the riskiest occupations in the world.

It's a fact there's danger about it, but...

that's what draws people to it. I suppose it's the adrenalyn factor.

Research has shown that cycle couriers

are three times more likely to be injured than those in other jobs.

And danger can come from any direction.

People aren't looking for cyclists so pedestrians will cross the road...

(? ) people will turn left on you, people will do U turns...

(?) ???

You're not in people's conscience.

You've got to expect things to happen.

James's life might be more hazardous than most.

But the fact is we all live in a hostile world,

a place full of unexpected threats.

how we defeat the environment

This programme will show you just how hard

your body has to work to keep you safe.

Because, as well as protecting you from the more obvious physical dangers...

it must shield you from potentially lethal solar radiation.

It must keep in check the 10 trillion bacteria that cover your skin.

It must deal ruthlessly with any invaders...

and, if things go wrong, immediately heal the damage.

Your body does all of this without your having to think about it.

And it works so effectively

that some of us will live for a hundred years or, perhaps, more.

I've got 21 great-grandchildren now.

I even have one great-great-grandchild.

Esther Turtle is in her hundreth year.

And she is in great shape.

In the morning, when I first get up, I do my yoga

to exercise every muscle in my body that I can think of.

And then I go up on the roof

where I take a walk for a half an hour without stopping.

So then I have a glass of orange juice, oatmeal and black coffee -

no sugar, no cream, no toast.

Over the last century, she's fought countless wars

against largely unseen enemies.

Well, as a child, I had all the usual diseases.

I had tonsillectomy and measles and chickenpox.

As I grew older, I had to have a hysterectomy at one point

and I had an appendectomy at another point.

And then about 15 years ago, I had breast cancer...

And I think that's about all the diseases I've had.

Esther leads a healthy life and has access to excellent medical care.

But perhaps the real reason she has lived so long is because, like you,

she has her own private army working for her around the clock.

Right now, as you watch this programme,

your immune system is fighting to keep you safe,

every single breath you take.

This tiny speck of dust is alive.

It's a fungal spore.

The air you breathe is filled with them.

Each spore is looking for a warm, moist home.

And it's just found one...

in your lungs.

Every minute, you breathe in a couple of spores just like this one.

Once it reaches a quiet corner of your lungs,

the spore implants and begins to grow.

Left unchecked, it would fill this entire chamber,

stopping oxygen passing from the air into your blood.

Within weeks, you'd be dead.

Fortunately, your body is armed and ready.

It unleashes macrophages,

prowling, remorseless, marauding killers.

They follow a chemical signal given off by the fungus.

The spore is doomed.

Unnoticed and unappreciated, the macrophage saves your life.

And it does this breath after breath, day in and day out.

But your body is not just protecting you from tiny, invisible things.

It's also designed to help you cope with more obvious threats...

like a fast-moving stick...

a huge hockey player...

or a hard object coming at you at nearly 100 miles an hour.

To survive in the fast-moving world of ice hockey,

you have to be able to react in an instant.

Professional goalkeeper Steve Lyle can react in less than a fifth of a second.

That's just the blink of an eye.

So how does he do it?

Even before his opponent hits the puck,

Steve is already beginning to work out where it might go,

based on his opponent's body position.

Then he has to work out how fast the puck is moving and where it's going.

His brain has to produce an action plan before it actually does anything.

All based on memories of previous occasions when he saved goals.

Then, finally, his brain tells his body what to do.

Everything up to now has been done entirely subconsciously.

It's only at this point that the goalie becomes consciously aware

that the puck has been hit.

What Steve is doing is something that you do instinctively

any time you are confronted by unexpected danger.

But reaction times are only part of the story.

You also rely on muscles.

You have 640 muscles that together make up 40% of your body weight.

Cristian Seraa relies on his muscles rather more than most of us do.

He's a champion of a truly terrifying sport.

He jumps over bulls for a living.

Cristian has no illusions about the dangers.

(in Spanish) One can fracture a bone, can end up in the cemetery,

or stay a year away, in bed.

His fragile body regularly goes head-to-head

with half a tonne of charging muscle.

So, every day, on his farm in eastern Spain, he hones his muscles.

In this form of bullfighting, known as recortes,

it's the men who risk their lives -

the bulls are unharmed.

But no less bad-tempered.

First in the ring are some of Cristian's competitors.

They're not allowed to use weapons or armour.

Instead, they rely on speed and agility to dodge a gruesome goring.

It's now Cristian's turn to enter the ring.

(?) As a champion "recortador",

he takes some of the greatest risks.

Risks that, even with all his experience, he finds scary.

(speaking Spanish) Fear is always present.

Fear keeps us safe.

It's good to be a little afraid.

Escaping uninjured will depend on how his muscles respond

in the next few moments.

We all have two different kinds of skeletal muscle fibres.

Just like a chicken, we have dark and white meat.

You use your dark, slow-twitch muscles for things like walking.

They work tirelessly for long periods of time,

so they need a constant supply of oxygen-rich blood.

But you also have white, fast-twitch muscles,

which allow you to react quickly.

And these are the muscles Cristian is about to use

to try and leap over the bull.

When you're dodging a bull,

you don't have time to burn oxygen for power,

so these fast-twitch muscles do something ingenious.

They reply on a rapid chemical reaction

that allows them to constrict four times faster than slow-twitch muscles...

which gives Cristian just enough time to escape.

(in Spanish) It is a feeling of power, of which I am superior to him.

My heart is filled with happiness.

I dance with the bull.

In some sports, muscles and reaction times aren't enough

to keep you out of danger.

Being hit with a force of up to a third of a tonne

means that getting damaged

is an occupational hazard for a boxer.

Fortunately, your body is incredibly good at healing injuries.

And that's something that boxer Johnny Greaves relies on...

because he gets hit a lot.

Get in close with this kid, cos he's tall, mate, you know what I mean?

Tonight, Johnny is fighting a man

who's three inches taller and five years younger.

I'm a professional opponent.

I fight week in, week out.

I get all the tough jobs

against all the up-and-coming boys, the good ticket sellers.

I basically get paid to fight and I do a good job.

For Johnny, boxing isn't just a sport, it's his livelihood.

I'm here primarily to pay my bills and to keep my kids OK,

so, obviously, that's the first thought in my mind,

is bringing home the bacon.

Johnny has fought in 53 professional fights.

But he's only won two of them.

He knows that tonight he's likely to get hurt.

Johnny works hard to avoid serious injury.

He ducks and dives, dodging punches.

He works at a frantic rate to keep himself a moving target.

But as Johnny tires, his defences begin to fail.

And then he gets injured.

The delicate blood vessels that wind through the fat cells under his eye

are destroyed by a punch.

As the vessels burst, blood cells rush out.

On the outside, the full extent of Johnny's injury is not yet obvious,

but a black eye is about to form.

What his body does next is normal and yet also utterly remarkable.

It begins to heal.

A repair crew is already on the way.

Travelling in the blood are some very special cell fragments.

Called platelets, they are there to stop the bleeding.

They extend arms that stick to each other

and form a net to catch the leaking blood cells.

This clot plugs the hole, and the bleeding stops.

But this is just the start.

Soon after the fight, Johnny's eye turns red and begins to swell.

It's caused by fluid seeping into the tissue around his eye.

The fluid is coming from tiny pores in the blood vessel.

This is not a sign of damage.

It's actually a rather clever form of defence.

The force of the flow would stop any infection in the wound

from travelling into the bloodstream

trapping it in the tissue instead.

Johnny's eye isn't just puffed up.

His bruise has now turned a lurid shade of purple.

The colour is the result of decaying blood cells

trapped outside the circulatory system.

Here, they can't survive.

Now, Johnny's body starts to clear up the mess.

Scavenging macrophages sweep through the tissue

and gobble up the dying cells.

Inside the macrophages,

the chemical that gives blood cells their red colour, haemoglobin,

begins to break down.

It's this that gives the bruise its familiar cocktail of colours.

As the haemoglobin breaks apart,

it transforms into different-coloured chemicals.

Over time, the colour shifts

from green to yellow and finally to brown.

As the macrophages leave,

they draw the coloured chemicals away from the skin.

Healing is now complete.

Two weeks later, and Johnny is fighting fit once again...

so he can step back into the ring to earn his living.

Your body is brilliant at dealing with damage.

But prevention is always better than cure.

And when it comes to prevention,

the most impressive defence you have comes

from the largest organ in your body:

your skin.

Each centimeter of your skin is built from 10 million individual cells

and bristles with over a hundred hairs.

It acts as a formidable barrier against the threat of the outside world.

That's something that Jamie Donaldson is counting on.

OK, first step - identify the value of the last...

- Decimal... - Place.

She's a maths teacher, but she leads a double life.

Could this be simplified any more? Yes or no?

CHILDREN: No!

Jamie is about to run the equivalent of five marathons

in the hottest and driest place in North America -

Death Valley.

It's neat to see what the body is really capable of doing and

to prove that you can do a lot more than you think you can.

Here, temperatures can reach 56 degrees Celsius.

Water evaporates faster than almost anywhere else on Earth.

CROWD: Three, two, one, zero!

Jamie has entered the Badwater Ultramarathon.

She'll be running across this inhospitable environment

for over 24 hours non-stop.

And Jamie will be relying on her skin

to protect her from the brutal heat.

In the desert, you never really do know what is going to happen to your body.

It's extremely hot.

Jamie's greatest threat is dehydration.

Every step, the parched air

is trying to suck the moisture out of her body.

What stops her shrivelling up like a prune

is a substance made by the skin

that most of us casually wash away every morning.

At the base of every hair on your body is a tiny sebaceous gland.

It squeezes an oily substance called sebum

onto the surface of your skin.

It makes your hair greasy...

and gives you spots.

But this oil also makes your skin waterproof.

Waterproofing is essential in hot, dry climates...

because sebum doesn't just keep water out.

It also stops bodily fluids from evaporating into the desert air.

(?) As well as the heat, Jamie also has to contend with a ??? the sun.

Getting sunburned would seriously affect her chances of finishing the race.

So her dedicated sport group made sure

she's constantly covered and protected.

Ultraviolet radiation in the sun's rays

breaks down the DNA in skin cells.

Your skin responds by flooding the area with blood to repair the damage.

This heats up the skin and produces the familiar redness of sunburn.

But there can also be long-term damage.

By next morning, Jamie is still running.

She's covered 135 miles in record time.

(?) Alice ???, new women's record and...

(?)???, here's your medal.

Most of us have some control over how much

we expose ourselves to the sun's rays.

But there's another threat that we can never get away from.

Each square centimetre of skin has ten million bacteria camped out on it.

The tissues inside your body would provide a nice, juicy environment

if only they could get in.

What keeps them at bay is the way your skin cells lock together,

just like armour plating.

But your skin is also pushing outwards.

As new layers grow, the old surface layers peel away...

carrying a cargo of microbes with them.

But this also means you lose 30,000 skin cells every minute.

By this time next month,

you'll have replaced all the skin on your body.

Your skin is an absolutely fabulous barrier,

but, unfortunately, it does have holes in it.

Like your eyes... and your nose.

And these are very vulnerable to infection.

In particular,

viruses use our own defence mechanism - sneezing - against us.

A sneeze is all it takes for microbes to jump

from one person to another.

The main reason you sneeze

is to clear your nose of dust and other fine particles.

But as you blast out air at up to 100 miles an hour,

you also spray a fine mist of droplets

containing millions of microbes...

anything up to 12 feet away...

giving the microbes the perfect opportunity to find a new host.

If they do get inside you, your body quickly responds

by mobilising an army of white blood cells.

These are called phagocytes. They eat things.

In this case, they are packing little green blobs,

which are fake bacteria.

In just one tiny drop of blood

there are around 400,000 of these white cells.

And this is just a tiny fraction

of the forces your body can call on to fight infection.

- Do you know that letter? - Yes.

Rowan O'Brien is three years old.

He should be at school, but he's feeling unwell.

What letter's that one?

- Muh! - That's it. That's it.

He's got the flu.

No, that's not right.

No. 1, 2, 3, 4, 5...

Inside him, his body is about to engage in all-out war

with one of the most infectious viruses on the planet.

Flu viruses start by attacking the tissue at the back of your throat.

But strangely enough,

it's not only the virus that will make you feel ill,

it's also your own immune system.

Your body's first response to infection is fever.

The flu virus thrives

at your normal body temperature of 37 degrees Celsius...

so you raise your temperature by a few degrees.

It's just enough to slow the infection down.

Meanwhile, an army of phagocytes flood the infection site.

They have come to feast on their enemies.

But instead of destroying the viruses,

the fighters are themselves infected

and are forced to self-destruct.

As their bodies pile up, they form the basis of your snot.

Rowan's symptoms are getting worse.

You're a little bit hot.

It's a sign the battle inside him is hotting up.

His body has launched a second wave of attack -

the killer Ts.

They home in on the throat cells that have been infected by the virus.

They administer the kiss of death,

destroying the viruses inside.

But this approach has its cost.

The killer Ts are causing heavy collateral damage.

Rowan is feeling the effects.

He's got a really sore throat.

Despite everything, the virus remains undefeated.

Now, your immune system tries a completely different approach.

Instead of trying to destroy the virus head-on,

it releases a cloud of Y-shaped antibodies.

These are specifically produced to destroy this strain of virus.

They coat the viruses, making them stick together.

Now, they are easily swept up.

Rowan finally starts to feel better.

And with his energy restored,

he can go back to doing what three-year-old boys do best.

As well as working hard to protect you from infection,

the human body is very versatile

when it comes to dealing with other medical emergencies.

It can mend damaged nerves,

plug leaking blood vessels,

regenerate broken bones,

heal your skin

and repair ripped muscles.

Your body is so adaptable, it can even be encouraged

to accept and repair part of someone else's body.

Buns.

Let's see...

Put the buns right here.

Richard Edwards is a chiropractor.

He has a loving wife and family, and considers himself a lucky man.

He doesn't even know what food is!

But five years ago, Richard was caught in a freak accident.

It really is hot, guys.

He found himself trapped in a burning vehicle.

Everything was on fire behind me.

My electrical system had burnt up, and I couldn't unlock my door.

I couldn't even manually lift up the lock.

I was having trouble breathing

and I quickly looked over to the passenger side

to see if it was unlocked, so maybe I could get out that way,

and as soon as I looked over to the passenger door,

I remember seeing the window on the passenger side,

it just exploded into several thousands of pieces of glass,

and I'd already started... burning alive.

Every time I open one of these things, the heat,

- that blast from the heat... - Yeah, I know.

is a memory of...

the moments in the truck, but...

The heat from the fire left 30% of his body severely burnt.

With medical help, most of his injuries have now healed,

but his hands were too badly damaged.

OK, guys.

He can't button buttons.

He can't do his zipper very easily.

I have to look around the rest room and find a guy that I think is,

maybe the most, or the least... masculine...

and ask, "Would you mind unzipping my pants for me?"

This fire has really put a stop to my life.

I want to be able to go back to work and grab an X-ray

and separate one sheet of X-ray from another

and talk to patients about how I can help THEM again instead of...

checking out of life like I have done for the last couple of years.

Richard has decided to undergo a radical operation.

It will push his body's ability to heal to the absolute limit.

A very unusual package is being delivered

to a hospital in Louisville, Kentucky.

With just a few hours' notice, Richard is rushed to the hospital.

He's about to have a double hand transplant.

His hands will be cut off and replaced with someone else's.

97 over 54 is his blood pressure.

It's the first time something as radical as this has ever been attempted.

OK, so have you guys decided who's going on what team to start?

The operation will be masterminded by Dr Warren Breidenbach.

There'll be four teams working simultaneously at one point.

There'll be two teams on each of the arms that we're preparing,

that is the patient himself,

and there'll be two teams working on the arms that have come from the donor.

The new hands have come from someone who died in the last 15 hours.

It's a race against time to connect them to Richard's blood supply

before they begin to deteriorate.

Okey-dokey. That arm is ready to shake, rattle and roll...

To give Richard's body the best chance of accepting the new hands,

both the donor's blood type and bone structure

were matched to his.

Did we Twitter that the surgery has started?

Both donor hands are on the table. Preparing for bone work.

It's going to be a long night, everybody.

The first thing they do

is prepare Richard's damaged hands for amputation.

His nerves and blood vessels need to be carefully preserved.

Let me have the knife.

The same is done to the vessels in the donor arm.

Hand is being scraped and sterile dressing.

Don't throw any of those veins away, ok?

Save the veins as though they're gonna work.

Once his hands are off, there is no going back.

The donor arm came off at 5.30.

So, we're five-and-a-half hours now,

so, we wanna try to get some blood into it.

Very carefully, the new hands are attached,

vessel by vessel, nerve by nerve.

- Nerve, I need nerve. - Ok, nerve.

Surgeons are now preparing the arteries.

Next, 54 bones and 56 muscles have to be connected

so that Richard will be able to control his new limbs.

- Find the motor branch. - Yes.

Dissect it back in here, connect it to that.

After 18 hours of painstaking surgery,

the new hands are attached.

Hand looks pretty pink.

Everything looks good.

Pretty cool, huh?

The patient is now in recovery.

Our first double hand trasplant is complete!

Signing off for the day. Thanks for following along.

Just ten hours after surgery,

Richard sees his new hands for the first time.

It will take months for his body to complete

this remarkable repair job.

- Thanks, Doctor. - You're welcome!

You can go ahead and let this go down.

But astonishingly,

Richard is already able to take control of someone else's hands.

Let's go ahead and get him moving.

Pull that down. That's good and strong.

Pull that down.

That's pretty strong.

Remember the one we tightened up? It's good and strong.

Pull it down, little finger.

That's strong.

It's amazing.

I'm very thankful to have a new pair of hands.

I've waited a long time for this.

Now and for the rest of his life,

Richard will have to take drugs to suppress his immune system

and prevent his body rejecting the new, alien hands.

Yep, I think it looks excellent.

But if the drugs work...

his bones will fuse together with the bones of the new hands.

They will join as one.

Blood will flow from his body into the donor tissue.

And the nerves of his body will grow, connect and control

what were once a stranger's hands.

Three months later, Richard is trying out his new accessories.

Back to the tough stuff!

He's gained some sensation in his new fingers,

and these hands are already changing his life.

It hits us, I think, every single day about how amazing,

how miraculous it is to have a brand-new set of hands on me.

When we thought I was...

never going to be able to have another set of hands,

I had to live with what I had.

His body is beginning to take full control of them.

They really look like they belong and fit to him.

Oh, yeah, they feel like my hands...

in... in every way.

- She loves them. - These are his hands to me and...

At least I can see that in her eyes!

Look at the wrist. The wrist...

Richard's recovery is impressive.

- Ooh, nice catch! - "Bet she won't get that."

A real tribute to his own resilience

and to the skill of his medical and surgical team.

I can hold her hand again.

- Now I can do it. - All right.

We are, each and every one of us, biological marvels,

able to adapt to a challenging world.

Although we have our differences,

we are fundamentally all the same.

We smile using the same muscles.

We see the world with the same eyes.

We have the same hearts...

which work around the clock to keep us alive,

tirelessly pumping blood,

picking up oxygen from our lungs

and transporting it to every cell in our body.

We have such remarkably efficient life-support systems

that we can survive on water and just a small amount of food.

And that nourishment feeds the most complex brains that have ever existed.

Each of our brains has 100 billion cells

that are constantly processing a mass of information,

rushing in through our senses.

We all began the same way,

when a precious egg and a single sperm came together,

creating a new individual:

you.

As our hearts began to beat, we grew from a tiny embryo...

into the 100 trillion cells that make up every one of us.

I played with Humphrey Bogart and Leslie Howard...

And your body is so well put together

that with a little careful maintenance it can last a hundred years or more.

Just like Esther Turtle.

Subtitles by Red Bee Media Ltd

E-mail subtitling@bbc.co.uk

reviewed/corrected for this release by: Tio Beto from Brazil

tiobetonh@gmail. com ... =Peace Through Anarchy=...