"This programme contains scenes some viewers may find upsetting." "MICHAEL MOSLEY:" "This diver is able to swim in the depths of the ocean, without breathing." "This is "The Iceman"." "He can thrive where his flesh should freeze." "And this fireman is able to walk into flames hot enough to melt metal" "and walk out unscathed." "Their stories are part of YOUR story." "The story of what makes YOU human." "Inside you is a wonderful, hidden universe." "Covered with skin, which protects you against the harsh world outside." "Controlled by a brain, which is the most complex on the planet." "Even how you make another human involves unrivalled ingenuity." "This is a fantastic voyage through the most extraordinary survival machine on Earth." "Inside The Human Body" "Just existing for one minute feels like the simplest thing in the world." "Yet what goes on inside you every 60 seconds is wonderfully complicated." "Your body is doing a million different things to keep YOU alive and you're not even aware of it." "Your heart will beat 70 times driving five litres of blood around the 96,000 kilometres of your circulation." "Deep inside your bone marrow, each minute," "150 million red blood cells will be born." "And while you're sitting there, the 250 square metres of your gut are busy digesting the meal, you've just eaten." "Your body is amazing at adapting to any environment." "And this adaptability has enabled us to thrive in every corner of the planet." "Every minute of your life... ..depends on your body performing countless small miracles." "This film will show you how you do it." "First to Last" "Your survival depends on your body working hard to keep everything inside you balanced and stable, just so." "But to begin with, you need a lot of help." "This is Tyriece." "He's just been through a very traumatic minute." "The first minute after his birth." "For nine months, you were enveloped in the warm, comfortable, watery world of your mother's womb." "Your every need was taken care of." "As you lay immersed in a bath of amniotic fluid, your temperature was a comfortable 37 degrees." "You didn't have to eat for yourself you didn't even have to breathe for yourself." "Your mother's blood supplied you with oxygen so your own lungs weren't needed." "And because you didn't need your lungs, your body didn't bother sending blood to them but shunted it through a hole in your heart instead." "Then, suddenly, the tranquillity of the womb was shattered." "Well done." "He's coming." "There he is." "He is coming." "We can see his face." "Relax, nice and relaxed." "Nice and relaxed." "I can see my grandson!" "For April, the hard work of labour is almost over." "He's turning to face this way." "Can you feel him?" "Yeah." "There he is." " Say hello." " Wonderful." "But for baby Tyriece, the struggle for survival is just beginning." "As he emerges into the world, his body must take over from his mother's." "The shock of cold air and bright lights triggers your first breath." "But before Tyriece can take in oxygen, his heart has to connect with his lungs." "And to do this, the hole in his heart has to close." "As you draw your first breath, the airways of your lungs open and the drop in pressure causes blood to rush into them to pick up oxygen." "That oxygen-rich blood then flows to the heart for the very first time." "The pressure of this flood of blood pushes on a flap, closing the hole." "But sometimes it doesn't seal." "One in four of us has a hole in the heart and most will never know." "Your heart and lungs are now fully connected." "Your circulation is complete." "Finally got my boy." "Got what I've always wanted." "Over the moon." "Yeah." "So, you can take another breath and another." "From now on, without thinking, you will breathe around 16 times every minute." "You only really start thinking about breathing, when you stop." "Try it yourself." "Most people can manage around 30 seconds." "But this man can hold his breath for a whopping nine minutes." "Herbert Nitsch is a world champion at freediving." "Powered by a single breath, he can not only stay underwater for longer than seems humanly possible, but glide through the water with the freedom of a fish." "I find it always difficult to explain the sensations I have down there." "The quietness, the peacefulness." "That you are just floating, there is no gravity." "The fish or mammals in the water come right into your face, look at you." "I'm like... "OK, that's maybe even closer than I would want to, maybe."" "But they're just curious, because they think that you are one of them." "Before a dive, Herbert takes in as much air as he can." "But surprisingly, the key to success is not so much his lungs as his heart." "As Herbert plunges deep into the sea, the cold water on his face prompts something we all have, the dive reflex." "This reflex causes your heartbeat to slow by as much as 25% so you use less oxygen." "And the dive reflex does something more." "It priorities the brain and the heart's survival by switching off the more dispensable parts of the body." "After mere seconds, Herbert's body shuts off blood flow to his extremities." "First, his toes and fingers." "Then, his hands and feet." "And finally, his arms and legs." "Until all that remains is a circuit of blood flowing between his heart and his brain." "And that is what allows him to stay underwater for an incredible nine minutes." "What this really shows is how good your heart is at adapting to any environment." "Your heart is an exquisitely engineered pump, made of muscle." "And you can see the true elegance of this engineering if you slow it to a single beat." "Inside the cavernous chambers the muscles work together in perfect harmony." "These muscles never get tired and never stop working." "As your heart expands, blood flows from your body into its chambers." "Then an electrical signal storms through the heart causing it to contract," "forcing blood all the way through your body's vast network of vessels." "And to stop the blood flowing backwards, your heart needs valves." "As they slam shut, these valves make the familiar..." ""lub dub, lub dub"." "The soundtrack of your life." "These are the cells that control the beat of your heart." "They spontaneously create its rhythm." "And they have been doing this since long before you were born." "When you were just an embryo, merely three weeks old, they first started beating." "And from that moment these same pacemaker cells would stay with you for the rest of your life, never to be replaced." " Hi." " Stephanie Fuller." "Nice to meet you." " I'm Katlyn." " How are you?" "..." "They're so important that when they go wrong the consequences can be devastating." "So, tomorrow's the big day." "I don't know if we can call it the big day." "Katlyn Hagan was born with a heart defect which is causing some of her pacemakers to misfire giving her a dangerously irregular heartbeat." "She's here to meet leading heart surgeon, Stephanie Fuller." "There's a risk of death with heart surgery." "I hate saying it, it's not zero, but I have a great team and we'll take great care of you tomorrow, I promise you." "We'll do everything we can for you." "OK?" "Katlyn's biggest problem really stems from the abnormal pacemaker cells." "They are a risk for developing clots in the heart developing a stroke and continuing to have abnormal heart rhythms that eventually can cause her to have heart failure." "It's not just Katlyn's future that depends on the outcome of this operation." "She has a one-year-old daughter." "I'm very scared." "I... ..wanna make sure that I'm still living after my operation so I can be there for my daughter's growing up, and just live a normal life." " I don't know where my picture is." " OK." " It's right here." " Really thank you." "Just a little more sleepy medicine." "You're going to feel very warm and comfortable and very relaxed." "I'm scared." "We're going take very, very good care of you." "Everything's going perfectly." "Katlyn's heart is revealed." "In a healthy heart, the rhythm set by the pacemakers flows through the muscle as an electrical wave." "And this wave follows a precise sequence which controls the contractions." "But in Katlyn's heart some of the pacemaker cells are firing out of sequence making the electrical flow chaotic." "First, the surgeons must transfer the job of pumping blood to a machine." "When that's done, they can stop her heart." "Lean back on the cardio, please." "See it gradually slowing down, and as the fluid goes in, the heart gets a little whiter, because there's no blood going into it." "Without a heartbeat, Katlyn is in a hinterland between life and death." "Now the surgeons can begin to prune away the faulty pacemaker cells using a cryoprobe, which freezes them." "They have to be extremely careful only to freeze the cells which are misfiring." "It's very important that we make sure that we haven't destroyed the pacemaker cells that Katlyn very much needs to keep." "Katlyn has been without a pulse for nearly an hour." "I'm going to be coming off in just a second." "It's time to get her off the bypass machine and to reconnect her heart." "The hope is that when this is done her pacemakers will start to beat again all by themselves." "Her heart's starting to get blood right now." "So we're inflating the lungs." "As Katlyn's blood flows back into her heart, its warmth is enough to restart the pacemakers." "All right." "Come off." "Amazingly, this is all it takes to bring the rhythm back." "Looks good." "The operation was a great success." "Your heart's will to beat is incredibly strong." "And that's just as well, because it drives through your circulation something that is vital for life - oxygen." "The hard graft of carrying that oxygen is done by some of your smallest and most peculiar cells." "Their story begins deep inside the marrow of your bones." "Here, every minute of your life, 150 million red blood cells are produced by a dedicated factory." "The workers are specialised white blood cells affectionately known as nurse cells." "They carefully nurture each red blood cell for five days and then set it free." "As it's swept away in the bloodstream, it joins 25 trillion others whizzing around your body." "They're on a long journey." "If all the blood vessels in your body were joined, they'd stretch more than twice the way around the Earth." "Each cell travels through wide arteries spiralling off into smaller arterioles" "and then squeezing through tiny capillaries." "Here, in the smallest narrowest vessels, our cell does the job it's been created for." "It releases its payload of oxygen into your tissues." "It'll do this over and over again for the rest of its life." "But that life is short." "After four months of hard graft travelling the length and breadth of your body, your red blood cell begins to look rather knackered." "As it returns to the bone marrow where it was born, chemical changes on the aging cell attract the attention of the nurse cells." "But this time, their job is not to nurture but to destroy." "Every minute, 150 million red blood cells come to a sticky end." "But as fast as the old cells are destroyed, new cells are created." "So that you always have enough to keep up the balance of oxygen in your blood." "Here in the high altitudes of the Peruvian Andes, the air is thin and there is far less oxygen." "This lack of oxygen would make it hard for you to walk, climb or do any energetic activity." "Yet every year in June, people come here to take part in one of the highest pilgrimages in the world." "Carlos is one of the thousands of pilgrims who will climb for three days to reach the peak of Mount Sinakara." "Because at the peak, there is something that is very special to him - sacred ice." "The pilgrims believe that if they can reach it, it will answer their prayers." "Over many generations, their bodies have evolved a way of coping with the reduced oxygen levels." "Their blood contains higher numbers of red blood cells." "And so overall, it can hold more oxygen." "After two days walking the pilgrims have reached 5,000 metres and are close to their goal." "It's a time for energetic celebration." "At this altitude, the low oxygen levels would make it really uncomfortable for anyone who's not acclimatized." "But the most difficult part of the climb lies ahead." "Carlos is desperate to reach the sacred ice tomorrow so he can pray for the health of his daughter." "I have a daughter, her name is Jasmina," "she is five months old." "She could catch pneumonia" "when we bathe her in the mornings, because of the cold." "We don't have hot water or a shower." "We just have cold water." "I pray for her health." "The next morning, the pilgrims and their priests finally reach their destination." "At 5,500 metres, it's almost 1,000 metres higher than Mont Blanc - the highest mountain in western Europe." "Without the extra red blood cells," "Carlos would have struggled to make it here." "At last, he can pray for his young daughter's health." "Remarkably, in just three weeks your body would start to adapt to these conditions." "Even if you had never been at high altitude before, your body would soon start to create more red blood cells and your blood would temporarily become more like that of an Andean." "This balance is so vital for life because oxygen is a key ingredient in producing the thing that keeps you moving - energy." "You need energy for every single thing you do no matter how grand or how tiny." "And you get it by combining oxygen with one of the other essentials of life - food." "You might be surprised to know how little of that, you can survive on." "This is Debbie Taylor." "And this is what Debbie Taylor eats." "This is all Debbie Taylor eats." "This is lunch." "And this is dinner." "Now aged 31, for over a decade she's barely eaten anything else." "In the fridge, I have sausages." "I haven't had sausages since I was under 11 years old." "But I still cook them for other people." "I've never had a pepper, so I don't know what it tastes like and I don't want to either." "Not had grapes since I was at primary school, I should think." "There can't be any nice flavour in that, cos it's all rubbery, look." "It's probably really chewy on the outside." "I can imagine that getting stuck in your throat or something and it just gagging on it." "No matter the occasion, Debbie's diet doesn't deviate." "On Christmas Day, I won't eat the turkey or anything like that." "I'll leave that to the family." "I'll just eat a bag of crisps." "When we go away on holiday" "I usually pack a suitcase, a hand luggage, full of the crisps that I eat, my flavour." "because sometimes you'll find that they don't sell them abroad so I have to take them with me." "Debbie's unusual eating habit began as an effort to lose weight." "I mean, I know crisps are carbs, but at the end of the day" "I'm not eating meat with it and gravy and all the, you know, vegetables." "It petrifies me, the thought of eating a meal." "With such a singular diet, there's a price to pay from a lack of vitamins and minerals." "The hair is really bad, nails don't grow, skin's colour is awful." "Sometimes you can't sleep." "Teeth, as well, are another thing." "They..." "When you brush them, they bleed... a lot." "Despite the long-term problems, a diet of just crisps gets Debbie through her busy working day." "My job is a housekeeper in a hotel." "It is a very energetic job, physical job." "It may seem surprising, but in terms of energy alone, Debbie's crisp diet is no problem." "And that's because the human digestive system is very efficient at squeezing all it can out of any food including crisps." "After chewing, your food drops into an expandable bag of acid, also known as your stomach." "The pulverised pieces then pass into your small intestine where they get broken down even further." "Here, there's a carpet of finger-like projections, called villi." "And on top, smaller versions called microvilli." "Together, they increase the surface area of your gut to that of a tennis court." "In the small intestine, any carbohydrates you've eaten are rapidly taken up and converted into a simple sugar - glucose." "This glucose is carried in your blood to your tissues which contain a network of tiny power stations, called mitochondria." "Here, the glucose is finally combined with oxygen to produce precious energy." "And this is what powers everything you do." "Every minute of your life, your body is working furiously to keep you going." "It ensures that everything is just so." "Your heart beats at the right speed to drive the right amount of oxygen through your blood" "to combine with the food you eat, to make the required amount of energy." "But that is not the end of the story, because there is another delicate balancing act that your body has to perform if you are to stay alive." "For these elite firefighters in Texas their body's ability to regulate temperature, is a matter of life and death." "And the way they do it is by sweating." "Sweating is a part of the game when it comes to firefighting." "I've seen guys actually pour sweat out of their boots." "They've taken their T-shirts and they wring the sweat out." "If I couldn't sweat, I couldn't go in and do what I need to do." "I couldn't be a firefighter." "When your body starts to overheat, it stimulates sweat glands deep down within your skin" "to produce a tiny bead of sweat." "Each bead must then work its way to your skin's surface." "And it's here that sweat performs its magic." "As it evaporates into the air, it takes heat with it." "This is how your body keeps its cool and keeps you alive when things hot up." "Today, Fire Chief David Herr is running a test to find out exactly how much a firefighter sweats when doing a high-temperature rescue." "Firefighter Mario Rodriguez has the dubious honour of being the test subject." "First, he's weighed naked." "By comparing his weight before and after the test, they can calculate how much sweat he has lost." "He swallows an electronic pill containing a thermometer which will monitor his core temperature to see how much it varies from the normal 37 degrees." "The fire is set and its temperature is also measured." "I have a good angle on the fire, a good reading." "Currently getting 1,200 degrees." "At this temperature, aluminium melts." "Before he goes in, Rodriguez kits up." "The suit should protect him from the flames and the worst of the heat." "Firefighter Rodriguez, hold on." "His core temperature is checked." "It's now just over 37 degrees Celsius." "You're starting to warm up already." "You know what your task is." "Let's get going." "Be safe." "All that stands between Rodriguez and certain death, is his suit and his ability to sweat." "The temperature has just rocketed by 1,200 degrees." "Yet, if his temperature were to increase by just a few degrees, that could have devastating consequences." "An increase of just four degrees would leave him confused and unconscious." "A rise of seven degrees would kill him." "After 45 seconds in the fire, Rodriguez is poaching in his own juices." "It was real hot." "My bones and all my joints starting burning." "Just the heat, just gotta get out of there and get some cool air." "Stand by, let me get your core temperature reading." "Despite everything he's been through, his core temperature has risen by just one degree Celsius." "Now he's weighed again to see how much sweat he's lost." "You're at 207 now." "So that looks like you lost three pounds of body weight." "Three pounds equals 1.4 litres of sweat." "That's three times more than you would lose in an average day." "Thanks to all that sweating, Rodriguez was able to maintain his core temperature despite the extreme heat of the fire." "It's important to keep your body at 37 degrees because this is the optimum temperature for the chemical processes that keep you alive." "But coping with the cold requires an entirely different strategy." "These are the frozen wastes of Iceland." "And this is Wim Hof also known as "The Iceman"." "Cold is a noble force." "It ignites beautiful feelings within." "It's so majestic, I feel a king." "I want to show the forgotten language of the cold." "To explore how Wim endures the cold, he's agreed to spend the afternoon in an industrial fridge." "His friend, Henny, who's not used to the cold, will act as a comparison." "A thermal camera measures their skin temperature to see whether Wim is better at keeping warm." "Henny starts off well." "But after a while he starts to show signs that his body's defences are struggling." "When you get cold, your skin goes pale as it redirects blood away from the surface." "Tiny piloerector muscles pull up your hairs, so they stand erect." "You see this as goose bumps." "The hairs trap a layer of air that insulates your body like a wafer-thin duvet." "But in reality, goose bumps are pretty useless at keeping you warm." "I'm not comfortable." "I don't stay any much longer in here, I think." "Finally, Henny starts to shiver." "It's his body's attempt to generate heat by making his muscles move." "But shivering, too, is ineffective." "Using large amounts of energy to generate precious little heat." "Shivering is a sign that Henny's starting to fade." "But Wim is fine." "One hour in this fridge and still warm." "That counts for something, huh?" "A cold beer." "Strangely enough, the thermal camera shows there's no difference in skin temperature between Wim and Henny." "It must be something going on inside that's keeping Wim warmer." "I quit." "After an hour and four minutes, Henny can't stand it any more." "Wim, however, is still happy." "But sitting naked in a fridge is child's play compared to what Wim does next." "He's about to take a swim in this lake." "The water here is just above freezing - two degrees Celsius." "Wim intends to stay in for 15 minutes." "That would kill most people." "Yet Wim believes that everyone has the potential to do what he does." "There is a natural ability in everybody to neutralise the cold." "It's about nothing abstract, it's no hocus-pocus, it's the mind." "Anybody can do what I do." "It is trainable." "Water looks clear, good." "Inviting, attractive." "Powerful." "Inviting me to come in and to take part." "The first minute in ice-cold water is the most dangerous." "Your body goes into a panic-like cold shock which can trigger a heart attack." "But it has no effect on Wim." "I don't feel the cold." "I feel the power, yes." "I don't feel the pain, because I am stronger than the pain at that moment." "Repeated exposure has changed Wim's threshold for withstanding cold and pain." "He no longer feels the shock." "Instead, he's able to endure it and stay calm." "Even to enjoy it." "# Is everybody happy?" "#" "# Is everybody fine?" "#" "It's a privilege to be here." "Look at this." "Diamonds!" "Five minutes in, and he's still going." "Looks like a dinosaur." "Whales." "Monsters." "After ten minutes, there's a new danger." "The cold starts to chill the thinnest parts of your body - your arms and your legs." "Nerve impulses slow down, so they no longer trigger your muscles to contract." "Most people come to a grinding halt which makes them vulnerable to drowning." "But not Wim." "Because he's adapted to the cold, he keeps swimming vigorously and this helps him generate heat to keep him going." "I feel charged, actually." "Sort of charged." "I feel like a bit electric." "Yeah, electrified." "After 15 minutes, swimming in ice-cold water, he emerges." "Wim has survived an experience that would kill most of us." "A testimony to the body's amazing ability to adapt to almost unimaginable extremes." "Since your early days in the womb when your heart first began to beat." "Your body has been working round the clock to keep you alive and ticking." "It ensures that everything inside you is nicely balanced." "Producing just the right number of blood cells to carry oxygen to your tissues." "And keeping your tissues at just the right temperature." "So you can generate just the right amount of energy to keep you going." "The extraordinary adaptability of the human body gives each and everyone of us the potential to thrive in every corner of our planet." "Subtitles by JohnCoffey_09"