What amazing processes go on inside super-athletes and couch potatoes alike? NOVA uses the latest medical imaging techniques to explore the body's incredible inner workings-with the help of Olympic ice skater Bonnie Blair, world record long jumper Mike Powell and others.
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00:00:00A production of WGBH Boston.
00:00:04Tonight on NOVA, superstar athletes push their bodies to the limit.
00:00:10Take an amazing journey inside to see what makes it all possible.
00:00:15Watch the body turn junk food into raw energy.
00:00:19Experience one climber's struggle to survive the onslaught of infection.
00:00:24Get up close and personal as sperm meets egg.
00:00:26Join us as we explore the universe within.
00:00:46Funding for NOVA is provided by Merck.
00:00:50Dedicated to pharmaceutical research.
00:00:53Committed to discovery.
00:00:54Improving health.
00:00:56Extending life.
00:00:58Merck.
00:01:00And Lockheed.
00:01:01America's aerospace company.
00:01:04Supporting math, science and engineering education for national technology leadership.
00:01:10Major funding for NOVA is provided by the Corporation for Public Broadcasting
00:01:14and by annual financial support from viewers like you.
00:01:17The human body.
00:01:27Driven by a great athlete's skill and dedication,
00:01:30the body is racing faster,
00:01:33jumping farther,
00:01:35reaching new heights
00:01:36all the time.
00:01:38But inside a web of complex mechanical, electrical, and chemical activity is constantly underway.
00:01:49Countless pieces working together in nature's most fantastic machine.
00:01:55With a tiny fiber-optic camera, an electron microscope, and cutting-edge computer graphics,
00:02:02techniques similar to those that first amazed the world in the miracle of life,
00:02:07NOVA now continues the journey through the incredible human machine.
00:02:11The trip reveals a whole universe within.
00:02:20Muscle and bone being built.
00:02:23Bursts of energy produced on a moment's notice.
00:02:27Invaders fought off.
00:02:30Precious new life created.
00:02:32This fantastic voyage begins with the story of a man who can fly.
00:02:39This fantastic voyage begins with the story of a man who can fly.
00:03:02This man is a champion.
00:03:11His name is Mike Powell.
00:03:13And he owns the world record in the long jump.
00:03:16In 1991, Mike soared 29 feet 4 1⁄2 inches, nearly 10 yards,
00:03:23breaking a record that had stood for more than 20 years.
00:03:25When I came to the stadium, I knew I was going to break the world record.
00:03:36I had thought about it all night.
00:03:38I had visualized the whole jump.
00:03:40I had even visualized what I was going to do to the crowd after I made the jump.
00:03:45So I went there with a purpose.
00:03:50Mike Powell is still the number one long jumper in the world.
00:03:53And while he still works hard to break records, his main focus now is to stay ahead of the competition.
00:03:59I used to be caught up on how far I was jumping because people would say,
00:04:03well, you didn't break the record.
00:04:05And I'm like, look, I broke the record once and the record was broken.
00:04:08Took 23 years for it to happen. It's not going to happen every day.
00:04:11So for me now, you know, I go for the win.
00:04:14When the wind is right, when the track is right, when the competition is right, when the crowd is right,
00:04:19when the ions in the air are right, when everything is perfect, I just try to get myself in the kind of shape where I can take advantage of the moment.
00:04:27The kind of shape Mike is in combines a smoothly functioning heart to pump oxygen-rich blood around the body.
00:04:35Large and pliant muscles to send him soaring high into the air.
00:04:39And beneath it all, a solid support system, the bones.
00:04:45To build the perfect long jumper, start with the 206 strong, light, dependable bones that form the human skeleton.
00:04:54Bones that are heavy enough to withstand a pounding and light enough to get airborne for a moment or two.
00:05:00Simplicity and strength in an elegant design.
00:05:05Outside the bone is hard and solid, but inside it's porous and light.
00:05:14It is a design often copied by architects when strong but lightweight construction is required.
00:05:21The electron microscope reveals the individual bone cells connected by thin, wiry tendrils.
00:05:28But bones are more than support structures.
00:05:37Inside they are alive, constantly building and rebuilding themselves.
00:05:48There are nutrient channels throughout the bone.
00:05:52Here is where the process of renewal takes place.
00:05:55Bone, when it is first built, is soft cartilage.
00:06:02As it thickens, it gets darker.
00:06:08But while new bone is being made, older bone is being destroyed.
00:06:13This is a bone eating cell at work.
00:06:17It is estimated that the skeleton is completely rebuilt every two years.
00:06:21After age 40, the bone eating cells begin to get the upper hand, making bones in older people more fragile.
00:06:32Not that Mike Powell has to worry.
00:06:36Yet.
00:06:37Now, I'm 30 years old, and 30 is not old by any means, but for a long jumper, it's what they call experienced.
00:06:47And I use that experience.
00:06:49Well, everything that I do in my training, I try to make sure that it is specific to what I do on the runway, and that's long jumping.
00:07:00All the weights that I do are very specific to running down the runway and jumping and landing.
00:07:06The running that I do is very specific to the kind of run that I do on the runway.
00:07:13With the pool, I do a lot of things in the pool concerning the long jump.
00:07:18I do underwater jumps, practicing my jump.
00:07:21I run in the pool and do drills in the pool.
00:07:25After the season's over, I may have three months off, but I play basketball.
00:07:28You know, I've been known for dunking, dunking on people and just dunking on anything.
00:07:39So I kind of get that residual effect year after year of training.
00:07:44So now my fitness level is at its highest because I just, it's like I've been training for 10 years now.
00:07:53Much of Mike's specialized training is geared toward the muscles.
00:07:57The moving parts that provide the body with the capacity for motion.
00:08:03All the muscles of Mike's leg are made up of elongated cells with energizing proteins
00:08:09that give them distinctive light and dark stripes.
00:08:16Skeletal muscle is enclosed in a membrane.
00:08:19At its ends, this forms the tendons, which attach muscle to bone.
00:08:28A cross section reveals the individual muscle fibers inside, like strands that make up a rope.
00:08:34Surrounding these fibers is a network of connective tissue, nerves and blood vessels.
00:08:40Closer up, we see a system of tiny vessels that store calcium ions needed to trigger muscle movement.
00:08:46In the fiber are the muscle proteins, actin and myosin.
00:09:00Shown as pink and white rods on the screen, these two proteins tug and pull each other.
00:09:19When repeated across the millions of cells that make up a muscle, this microscopic action gets the body moving.
00:09:30As an athlete, you have to know your body so well.
00:09:36My body now is at such a finely tuned level that I have to be careful with everything that I do.
00:09:43I can't run out and just go play basketball or go jump over a car like I used to.
00:09:49Because any little thing can throw it off.
00:09:51I just love you to be very precise about what you do.
00:09:55Like for myself, I know when my heart's not beating right.
00:09:59I can tell when my heart's beating too fast.
00:10:01I'm going to have to try, I'm going to have to test it.
00:10:05A double action pump of ingenious design, the heart is the engine that drives the human machine.
00:10:11The heart and its network of blood vessels keep every part of the body supplied with a steady stream of life-sustaining oxygen.
00:10:24The oxygen enters the bloodstream through the lungs on either side of the chest.
00:10:30The heart takes in this oxygen-rich blood through the left atrium, the top left chamber.
00:10:35It flows down to the lower chamber, the left ventricle, and the ventricle pumps the blood up and out to the body.
00:10:46Emptied of oxygen, the blood returns to the heart through the right atrium, passing into the right ventricle, which pumps the blood back to the lungs.
00:10:54These tendons on the heart's inner walls are attached to muscles that contract to regulate the amount of blood flowing through the heart.
00:11:12Valves open and close. Blood enters and exits, creating a familiar rhythm.
00:11:17But what keeps the heart on the beat?
00:11:23Even when taken out of the body, an isolated piece of heart muscle will pump without any signals from the brain or the nervous system.
00:11:35Here's another.
00:11:40And another.
00:11:41But how can all these muscle cells, each capable of independent action, work together in the heart in perfect synchrony?
00:11:51The secret lies with the heart's spark plug, the sinoatrial node.
00:11:58Called the SA node, it is located at the top of the heart.
00:12:02Its signal is picked up by the AV node near the ventricles.
00:12:05Left to their own devices, the muscles of the heart will only beat about 40 times a minute.
00:12:14But the SA and AV node send out electrical impulses that synchronize the beating and boost the heart up to a more normal speed.
00:12:22About 70 beats per minute, 24 hours a day, 365 days a year.
00:12:35Here, we see the entrance to the coronary artery, where blood enters to fuel the heart muscle itself.
00:12:42Fully 10% of all oxygen taken in is used to keep the heart pumping.
00:12:48Any muscle can cramp if its oxygen supply is cut off.
00:12:53For the heart, the cramp means a heart attack.
00:12:57A devastating result of a blocked coronary artery.
00:13:00This is the top of the heart looking down through the aortic valve.
00:13:09Here is the entrance ramp for the blood's main highway.
00:13:13Oxygen rich blood is launched up and through the aortic arch.
00:13:19Setting out for every distant destination in the universe within.
00:13:25The first set of exits off the highway lead north.
00:13:28The opening on the right leads to the arms.
00:13:32While the two openings on the left will carry 15% of the body's blood supply to the brain.
00:13:39Passing this interchange, the road turns south.
00:13:43The two lights at the end of the tunnel lead toward the legs.
00:13:47The side roads above and below supply the abdomen.
00:13:50Blood that makes it all the way to the end of the road, the feet, branches into countless tiny vessels.
00:14:01The body's best attempt at keeping the toes warm on a cold winter's night.
00:14:05The hands too are shot through with tiny blood vessels.
00:14:13The fingertips are particularly well provided for.
00:14:17The electron microscope reveals another intricate net of blood vessels.
00:14:21This one supplying the tiny cochlea of the inner ear.
00:14:29Though only the size of a pea, this sound sensitive organ is one of our most important links to the outside world.
00:14:36What attracts me for me, I look at myself as like, almost like an entertainer.
00:14:54So, when I'm out there, I feel like I'm entertaining the crowd.
00:14:59So, as opposed to trying to block things out, I'm trying to encompass everything, bring everything in.
00:15:04Like, okay, everybody watch this over here. Watch what I'm about to do.
00:15:09Representing the USA, a two-time world champion in the long jump, ladies and gentlemen, this is world record holder, Mike Powell.
00:15:22Mike's machine is tuned and ready to follow the orders sent out by the brain.
00:15:28I think about trying to jump out of the pit.
00:15:31And after I get that emotional charge of how far I want to jump, I then just go through my technique.
00:15:39I have different phases, and I go through my walking phase, and my drive phase, and my sprint phase, and my takeoff phase, and then my jumping.
00:15:48And I visualize a whole jump in my head, and then I land, and then I hear the crowd, and then I go and I go do it.
00:15:56Mike decides to move. His brain sends a signal to the nervous system, setting into motion an amazing series of events.
00:16:09Here, a muscle cell appears as the dark streak running down the left side of the screen.
00:16:16The thin, hair-like structure to the right is a nerve. It reaches out to make contact with the muscle.
00:16:22In this electron microscope view, the nerve cell has been dyed yellow.
00:16:30The nerve is the brain's communication link to the muscles.
00:16:34The more points of contact between a nerve and the muscle, the more efficient the communication.
00:16:43When Mike decides it's time to go, his brain alerts the appropriate nerves.
00:16:48The nerve stimulus arrives at the muscle in the form of an electrical charge passed along through a chain of chemical interactions.
00:16:59The problem is to transform this electrochemical impulse into physical movement.
00:17:05It's a trick the body is constantly performing.
00:17:07In less than a thousandth of a second, the nerve impulse spreads across the surface of the muscle fiber and dives down into its interior.
00:17:19There, it releases stored calcium ions.
00:17:22These calcium ions instantly alter the chemical environment of the muscle.
00:17:28Just as lightning sends an electrical charge through the air, the calcium sets off a chain reaction, sparking the proteins actin and myosin to create movement in the muscle.
00:17:39And now for his last jump, Mike Powell.
00:17:48Jumping with a sore hamstring, Mike is not likely to break his record in this track meet.
00:17:54Going into the final jump, he's in fourth place.
00:17:57But even with his body in less than peak condition, a champion has his pride.
00:18:02I love competition, and I love to win, and that's a lot of motivation.
00:18:12And I have a good time at whatever I do.
00:18:16So I have fun when I train, I have fun when I compete, and I have even more fun when I win.
00:18:33The jump is over in the blink of an eye, but a look in slow motion reveals the champion at work.
00:18:40Muscles, bones, heart and mind working together to produce an explosion of power and grace.
00:18:47The human machine striving to perform at its peak.
00:19:02Doesn't matter hard!
00:19:08What are you doing by Kyle?
00:19:12Winner of the long jump, 26' 3 3 quarter's on his last step.
00:19:16Well, my jumping was ugly, and I won, but I still love Nova.
00:19:41Peace out.
00:19:46Fighting the elements every inch of the way, why would anyone want to scale a frozen
00:19:56waterfall hundreds of feet above the safety of solid ground?
00:19:59Oh, I think people climb it for a variety of reasons, but I think one of the great things
00:20:05we've discovered about ice climbing, in contrast to rock climbing or mountains in particular,
00:20:10is that the ice allows you the freedom to express yourself, to move where you'd like.
00:20:14Being rather cautious about dropping ice and obviously not falling off, and that's the
00:20:20winter sport of ice climbing.
00:20:22Rob Taylor is one of the world's most experienced and adventuresome ice climbers.
00:20:28He scaled some of the world's highest peaks, but his favorite place to climb is Tuckerman
00:20:35Ravine in the White Mountains of New Hampshire.
00:20:37Well, the White Mountains are a pretty special place.
00:20:40I know a lot of people from the rest of the country would say they're tiny, because the
00:20:44highest peak here, Washington, is only 6,000 feet, but it's classified as having the worst
00:20:49weather in the world, and it has had the highest recorded wind value.
00:20:53So the snow blowing and the wind, avalanches, and part of all of the fun of it is making
00:21:00the right decisions and enjoying yourself being out in nature, if you're prepared for
00:21:04it.
00:21:05But if you're not, I mean, it's killed 102 people, so you need to use your wits and be
00:21:10careful and know when to turn back.
00:21:12Deb and I are going to head up into Tucks, and we're going to do the Tuckerman's Waterfall
00:21:18today.
00:21:19Even Rob would agree that knowing when to turn back is a lesson he learned the hard
00:21:23way, halfway up Africa's tallest mountain, Kilimanjaro.
00:21:29Back in 1978, I got this notion, just from a single picture of a friend of mine had, that
00:21:35there was a side of Kilimanjaro no one had ever climbed.
00:21:38So, in youth, one often does wild things, and I got the idea to go to this face, which
00:21:44is capped by this enormous 300-foot icicle, and we'd climb it.
00:21:50And things went actually quite well, up to 12,000, 13,000 feet vertical, the whole climb,
00:21:56until we got to the icicle, and when we arrived, the temperature was above freezing, it was melting.
00:22:03I made a mistake, and I went onto the icicle and climbed it.
00:22:09It got into a situation where it was just like oatmeal slapped onto a wall at home, a
00:22:15little child might throw.
00:22:17And no matter what I touched, it just started crumbling and falling away.
00:22:20And after some yards of making my way up, the ice above me and right directly in front of
00:22:26me broke off, hit me in the face, I flipped over backwards, came straight down, through
00:22:34the air, and actually smashed into the ledge, but kept going as I bounced off.
00:22:39Finally, I ended up at the end of the rope, and it pulled up taut.
00:22:42I looked through my legs, and there was the jungles of Africa 18,000 feet below.
00:22:51Then I looked down and realized that something was dramatically amiss, because instead of
00:22:56seeing the top of my boot laces, my foot was turned 180 degrees around, upside down, so
00:23:02that the actual sole and the climbing spikes were facing upwards.
00:23:07His climbing partner was below, anchoring the rope.
00:23:11Rob was lowered to the relative safety of a mountain ledge, where he first assessed the
00:23:15damage.
00:23:16I took my glove off and started to push my hand down into this area here and discovered
00:23:23not only had the outer leg bone, in fact, broken the skin here, but in fact was sticking
00:23:28out about six inches over the top of my boot, and I looked at the blood in my hand and realized
00:23:36I was in bad trouble this time.
00:23:40Somehow, Rob pushed the bone back in line and staunched the bleeding with bits of cloth.
00:23:46But inside his body, the battle was just beginning.
00:23:52Blood platelets rushed to the site of the injury and knit a web around the damaged cells.
00:23:58Eventually, the bleeding stopped.
00:24:04With the body's first line of defense, the skin was broken.
00:24:07The bacteria flooded in, quickly multiplying their number to become an invading army, bent on
00:24:13destruction.
00:24:47The bacteria was broken.
00:24:57More often, they engulf and devour their opponent whole.
00:25:00In this real-life footage, phagocytes are attacking and swallowing up bacteria.
00:25:22And here, the phagocytes are gathering to do battle with a deadly foe, an asbestos fiber
00:25:28caught in the lungs.
00:25:37The phagocytes, in fact, our entire immune system, is created from cells that originate
00:25:43in the body's munitions factory, the bone marrow.
00:25:48Within the marrow, stem cells divide and grow in different ways to form our many defensive
00:25:53weapons.
00:25:56Some are sent to the thymus for further development.
00:26:00And some grow to maturity here inside the bones, like the cells that grew into platelets and
00:26:06stopped the bleeding in Rob Taylor's leg.
00:26:11I took the leg and discovered by tying it up to the back of my harness.
00:26:20I'd pull it under tension, and then I used my good leg, this one, to go backwards downhill.
00:26:26So, in fact, that way, I hopped with my two arms and ice axes and the one good leg backwards
00:26:32over the next three days.
00:26:34Slowly, but surely, we made our way.
00:26:36We then decided that my partner would go down to the Shaga village, the tribe that lives
00:26:42at the base of Kilimanjaro, and get them to come up and help me get down.
00:26:46I got in my sleeping bag.
00:26:48My partner packed up, head off, and I waited for him to return with help.
00:26:57He didn't come back in a day.
00:26:58I actually didn't expect him to.
00:27:00It was a great distance to cover.
00:27:02But then it got into the second day and the second night, and I started to get nervous,
00:27:05because it started to snow.
00:27:07And that snowstorm turned into a blizzard.
00:27:12Into the third afternoon, I'd been waiting for day after day for help to come, and it
00:27:19just became clear that it wasn't going to.
00:27:24Food, you last for months.
00:27:27With the blood loss, unfortunately, though, that I'd had, and the infection that very
00:27:31slowly was starting, but most importantly, without water, it just came down to accepting
00:27:37the fact and facing that this time I was going to die, and there was nothing I was going to
00:27:42be able to do about it.
00:27:44It was not so much accepting it, but imagine you walk down a hole, and you arrive at the end.
00:27:51Well, that's death.
00:27:53It was lying there in the snow, the sheets of snow running across, and there, out of
00:28:00the snow, six Shaga tribesmen and a blonde Norwegian rescue.
00:28:06But to think of so many miles being able to be moved, it seemed impossible.
00:28:13The Shagas had an easy answer, and that was that they would pick me up and carry me on
00:28:16their backs, which they did day after day.
00:28:20Just about the most extraordinary human beings I've ever seen.
00:28:23The rescue team brought Rob down the mountain, but as the elevation dropped and temperature
00:28:30grew warmer, the infection in Rob's leg grew worse.
00:28:35The enemy began to overwhelm the body's defenses.
00:28:40With any infection, the phagocytes are the first to fight back.
00:28:45But often they can't do the job alone.
00:28:48If the invading forces are too overwhelming, the phagocytes will keep eating until they burst.
00:28:54The remains of this battle are part of what makes pus.
00:29:00Wave after wave of phagocytes fight and die, the heavy artillery comes into play.
00:29:05The large and unwieldy white blood cells called macrophages.
00:29:10These are basically giant phagocytes.
00:29:13Like naval forces, macrophages are stationed in large numbers at strategic locations around the body.
00:29:20They capture the bacteria by lassoing them with protoplasm.
00:29:25The macrophage envelops the invader and breaks it into small pieces.
00:29:38Here is what an actual macrophage battle looks like.
00:29:51When we finally got down to the base, I was sweltering.
00:29:53It was about 100 degrees, even though it was the middle of the night.
00:29:56The doc came out from the hospital and he just sliced the trouser leg off.
00:30:00Then I looked down and for the first time got to actually see the leg, which I hadn't seen for nearly a week.
00:30:05And the kneecap was grey-purple.
00:30:08The toes had gone totally black.
00:30:10And this thing now was completely involved in gangrene.
00:30:15And he looked at me directly in the eye and was matter-of-fact and said,
00:30:22this leg has had it.
00:30:24I'm taking you into surgery and I'm taking it off eight inches above the knee.
00:30:28I obviously said there must be something you can do and argued back and forth and pleaded and then prayed.
00:30:41And he made it perfectly clear it was black and white, that he would give me 24 hours leeway.
00:30:48And if that 24 hour allowance would give me better feelings, but he knew the end result was going to arrive at the need to amputate the leg.
00:30:59Rob was fighting a war against hundreds of different bacteria.
00:31:04The massive invasion was too much for the simple defense offered by the macrophages.
00:31:09Rob needed the experts, T-cells that could identify different strains of invader
00:31:15and B-cells that could engineer antibodies, the specific weapons to fight them.
00:31:20The thymus, a small organ located between the lungs and above the heart,
00:31:25plays a pivotal role in the body's amazing ability to recognize an enemy.
00:31:32From before birth through puberty, large numbers of the same stem cells that gave rise to platelets, phagocytes and macrophages,
00:31:40migrate from the marrow inside the bone to the thymus.
00:31:44There they receive a higher education.
00:31:47Thymus cells, T-cells for short, stay here for years,
00:31:53packed like sardines, learning the art of self-defense.
00:32:02Exactly what goes on here is a mystery.
00:32:05But somehow the T-cells learn how to tell the difference between friend and foe,
00:32:10cells that belong to the body and those that do not.
00:32:14T-cells are specialists.
00:32:17Each type learns to recognize a different group of invaders.
00:32:26When graduates of the thymus training school are released,
00:32:29they immediately begin to patrol the body, searching out any suspicious-looking cell.
00:32:35Here, killer T-cells check out a body cell that may have been infected by a virus.
00:32:44If an infection is found, they will destroy the cell.
00:32:50In the case of an all-out attack, like the one on Rob's leg,
00:33:09a helper T-cells docks with a macrophage.
00:33:23The macrophage presents bits of the invader for the T-cells to analyze.
00:33:28This is what it looks like in real life.
00:33:43If the T-cell can recognize the peace of the invader, it sends the word out.
00:33:48A nearby B-cell, which can also recognize the invader, receives the message.
00:34:02Hormones activate, causing the B-cell to divide
00:34:06and to begin to produce antibodies of exactly the right type.
00:34:18An antibody is a Y-shaped missile made of protein.
00:34:24The tip is the same in all, but the two tail fins on the bottom
00:34:28are custom-built to match the protein structure of the invader exactly.
00:34:35It locks onto the enemy, robbing it of its ability to harm.
00:34:43The body never forgets an enemy,
00:34:45building up its repertoire of antibodies over the years.
00:34:49Familiar invaders are fought off quickly,
00:34:52but Rob Taylor was fighting the microbes of Kilimanjaro,
00:34:56foes his body had never seen before.
00:34:58B-cells can engineer antibodies to fit virtually anything.
00:35:03The question is whether the right antibodies will be produced in time
00:35:08to fight the growing infection.
00:35:10How the body is able to manufacture precisely
00:35:13the right antibody to match every new kind of invading organism
00:35:18is one of the miracles and mysteries of the universe within.
00:35:23Neutralized by the antibodies,
00:35:28the enemy bacteria is finished off by the phagocytes.
00:35:32But this process can take several days under the best of conditions.
00:35:35For Rob Taylor, conditions were the worst.
00:35:39The hospital was out of antibiotics.
00:35:42With 24 hours to save the leg, Rob's doctor had one hope.
00:35:47His thought was to use a technique from the 1800s, using painkillers in the lower leg.
00:35:52He bore six holes straight through the ankle joint and then put pipes through and began to attach garden hoses.
00:36:01And he ran hundreds of gallons of water through the three sets of hoses to try and move germs away by washing.
00:36:0824 hours later, he actually had seen improvement in the lower leg and decided day by day that he would watch.
00:36:21And if he could delay the amputation, he would.
00:36:24Six weeks later, the leg was still attached and he would call it a miracle.
00:36:28I would call it obviously that and a bit more because the shagas obviously did some pretty amazing things to save my life.
00:36:38It took Rob Taylor three years to rid himself of the last of 300 microbial infections.
00:36:46It was five years before he began to climb again, ten before he felt really good.
00:36:51He returned to Kilimanjaro in 1985, completing the climb he had begun so long ago.
00:37:00This time, his partners were the Shaga tribesmen who had rescued him.
00:37:09Today, he climbs as much as ever, but with a different perspective.
00:37:14I've come to appreciate over the years that when you take something for granted, and I mean walking or climbing,
00:37:23and I certainly climbed for years and enjoyed it, but then when it's taken away and you are given the gift back,
00:37:29each and every time I put the foot down onto the floor and walk or I'm back onto climbing,
00:37:36I begin to realize the sheer joy that it gives me.
00:37:38I begin to realize the joy that it gives me.
00:38:08Speed skating. The power, the grace, the controlled 30-mile-an-hour sprints around the track are the result of an unending series of demanding workouts.
00:38:21Here in Milwaukee, the United States speed skating team is preparing for another grueling season of competition.
00:38:27For five-time Olympic gold medalist Bonnie Blair, it will be the last.
00:38:31I'm definitely looking forward to the World Championships here in Milwaukee.
00:38:37You know, kind of my own home turf.
00:38:40Also, I feel that being able to kind of finish up at home is going to be a nice feeling.
00:38:47My whole family is going to be here, friends.
00:38:50I don't know how many they're expecting this time, so I'm definitely looking forward to it.
00:38:54Team training involves weightlifting.
00:38:56Torturous set of isolation exercises called plyometrics.
00:39:05And every other day, they spend the afternoon running up hills.
00:39:09All this activity takes a lot of energy.
00:39:21And at 5'4 and 130 pounds, Bonnie is hardly superhuman.
00:39:25So what's the secret of all that record-setting speed?
00:39:29Is she on a special diet?
00:39:32Space-age formula of vitamins and proteins?
00:39:34One thing that people have kind of always teased me about is usually day competitions, I always have a peanut butter and jelly sandwich.
00:39:43And, you know, that's just been something that's worked well for me.
00:39:47I enjoy that.
00:39:49That's probably one of my favorite lunch foods anyway.
00:39:51So, you know, when you are at a competition, sure, you're going to have some nerves.
00:39:55And so you have to find something that's going to sit well with you in your stomach.
00:39:57And that's important.
00:39:59And to me, a peanut butter and jelly sandwich is what works best.
00:40:03For a jolt of energy, there's nothing quite like the sugar and carbohydrates in Bonnie's snack.
00:40:08They're very close in structure to the fuel the body uses, glucose.
00:40:13But a quick fix will only last about 20 minutes.
00:40:16To make it through her day, Bonnie needs a huge amount of energy, stockpiled for use a little at a time.
00:40:22The way the human body manages this is to convert everything we eat into a few basic components.
00:40:30Instant and storable energy, vitamins, nutrients and waste.
00:40:36In a process never to be discussed at the dinner table, here's what happens after we chow down.
00:40:43The first stage of digestion is simple.
00:40:47Moistened by the saliva of the mouth, muscle contractions move the food down the gullet toward the stomach.
00:40:55Here, whatever we've taken in will be turned into something more manageable.
00:41:02Although it doesn't look it, the stomach is a muscle, a smooth muscle.
00:41:07It flexes over and over again, slowly squeezing whatever we've eaten into pulp.
00:41:12Depending on the food, this process can take up to several hours.
00:41:22While enzymes help break the food apart, industrial-strength acid surges in from a thousand tiny jet streams along the stomach wall.
00:41:30A closer look reveals the microscopic glands that manufacture more than three quarts of gastric juice a day.
00:41:41It's a powerful brew, mostly made up of hydrochloric acid, a substance that can turn metal to mush.
00:41:53What keeps the gastric juice from eating the stomach itself?
00:42:01The answer lies in the shiny reflections on the surface.
00:42:05They are part of the mucous membrane.
00:42:07The thin, protective layer that not even hydrochloric acid can penetrate.
00:42:26Salt, alcohol and certain other foods can.
00:42:31And too much of any of them may result in an ulcer.
00:42:33The burn marks on this stomach wall show what the acid can do if the protection of the mucus is stripped away.
00:42:41While stomach ulcers have most often been blamed on diet and stress, recent studies indicate certain bacteria can also be the culprits.
00:42:50A healthy stomach can break down just about anything we serve it up.
00:42:55I'm actually lucky that I'm not too regimented. I'm not too picky about what I eat.
00:43:01Being an athlete, you do try to like to get a lot of carbohydrates in.
00:43:04So, you know, some pastas.
00:43:06But I also grew up being a younger meat and potatoes type person.
00:43:11So, you know, I like my meat and potatoes.
00:43:12I'm not a real big vegetable eater, but I do have something green every day.
00:43:18And, you know, whether I chase that with milk or whether it's a salad, which I enjoy, then that's okay.
00:43:24But sometimes I have to chase those vegetables with milk.
00:43:28I like to snack on chips and probably like candy bars like Snickers or something like that, ice cream.
00:43:34So I love chocolate chip cookies.
00:43:36Actually, I probably like the dough better than the actual cookies, but those are my favorites.
00:43:40Might not sound all that healthy, but then maybe I come back with yogurt and that's better.
00:43:49If you think Bonnie's diet sounds good, be prepared to train as hard as she does to burn it all off.
00:43:54Thoroughly massaged, the sandwich is passed down the disassembly line to the duodenum, the top of the small intestine.
00:44:07Here, it gets a rinse as intestinal juice, pancreatic juice, and the bile are all added.
00:44:13The dirty looking bile is really a cleanser, manufactured by the liver and shot in from the gallbladder.
00:44:20It breaks large globules of fat into fine digestible droplets and helps pancreatic juices neutralize acids from the stomach.
00:44:34The gallbladder concentrates and stores the bile until it is needed.
00:44:39If the concentration gets too great and is made up of too much cholesterol, gallstones can result.
00:44:45These are gallstones, old bits of cholesterol, bile salts, and pigments that rolled around together until they collect it into little balls.
00:44:55They're not a real problem until they get stuck in the bile duct.
00:45:00Then, until they pass, they become the source of excruciating pain and usually a resolution to eat less fat.
00:45:07By the time our meal reaches the small intestine, it has been turned to soup.
00:45:18From here, useful nutrients will be taken up by the body, while muscle contractions draw the fiber, other undigested substances, and water into the large intestine.
00:45:29The journey through the large intestine can take up to 12 hours.
00:45:35Needed fluids and water are removed, along with most of the bile that was added.
00:45:40The bile that remains accounts for the brown color of human waste.
00:45:43These are bacteria, feasting on our food remains.
00:45:55These helpful microbes produce vitamins and consume leftover nutrients and oxygen, causing intestinal gas in the process.
00:46:02Under regular conditions, 25% of human waste is made up of these friendly bacteria.
00:46:19The process of the body taking what it needs from the food we eat is called absorption.
00:46:25This takes place here, back in the small intestine, where the body soaks up the good stuff for distribution.
00:46:30But bacteria are also present in the small intestine.
00:46:37How does the body absorb nutrients while screening out the bacteria that could be dangerous in other parts of the body?
00:46:47These tiny finger-like projections that line the small intestine walls are called villi.
00:46:53Like a super-absorbent rag mop with filter attached, the villi are able to soak up the nutrients and leave the bacteria behind.
00:47:04Here's how it works.
00:47:06On the top, each villus finger are six-sided cells, one ten-thousandth of a millimeter across.
00:47:11The bacteria are too big to fit between these tightly knit fibers, but glucose and other nutrients easily slip through.
00:47:23Here at the cell surface, tiny greenish fat globules float right in.
00:47:28Enzymes, here looking like red jelly beans, turn complex sugars into simple sugars that can be pulled into the cell through openings in the cell membrane, seen here as cups on the cell surface.
00:47:42Now it's on to the bloodstream.
00:47:49Some of the sugar goes directly to the muscles, but that can only power us for brief spurts.
00:47:55The rest needs to be stored for when we need it.
00:47:59Bonnie's snack is now being put to use.
00:48:01Her sandwich, the yogurt, and a few crispy tortilla chips have been broken down.
00:48:07The high-octane fuel pulled from them, glucose, powers her every stride.
00:48:13But it takes more than raw fuel to make a champion.
00:48:16I've been real lucky to be able to work with the men on our team, and they've been very hopeful to be, in a sense, bring me to speeds that I would never be able to go on my own.
00:48:26Being able to skate behind them, skate in their draft, has been a very big plus for me.
00:48:32You know, I'm lucky that my boyfriend's in the sport, and I can be his shadow.
00:48:37Even sometimes he likes to be my shadow.
00:48:40It's been said I've been one of the better technical skaters in the sport, so a lot of times then he likes to skate behind me just for the technical aspects,
00:48:48where I like to skate behind him for more of the speed aspects of the sport.
00:48:51So it's kind of nice to be able to have your best friend there with you all the time.
00:48:58Going through all the workouts day in and day out, be there to support you, help you when things are going wrong,
00:49:06and pat you on your back when things are going right.
00:49:10Perfect.
00:49:12I'm just not sure.
00:49:13Back inside the body, this is the liver, the largest single organ we have, the regulator of our energy needs.
00:49:29This is where proteins, fats, and carbohydrates not put to immediate use are sent.
00:49:34Centrally located above the intestines and below the diaphragm, the liver is a multifunction workhorse.
00:49:42It's a storage battery, recycling center, health club, and detox unit all rolled into one.
00:49:51The liver is made up of a forest of blood vessels that connect millions of tiny working units.
00:49:56These working units preserve the body's delicate chemical balance, making the liver one of the most complex and well-run factories on earth.
00:50:10The moment the digested sugars from Bonnie Sandwich enter the liver, they are met by teams of enzymes, here imagined with mechanical arms.
00:50:18The enzymes grab onto the glucose molecules and assemble them in a chain called glycogen.
00:50:29These chains, connected together, form balls of glycogen, the body's pep pills.
00:50:35They're stored in the liver and throughout the muscles.
00:50:39Between meals, the liver converts the glycogen back to glucose and releases it into the bloodstream to supply the body's energy needs.
00:50:46The steady flow of glucose is essential, not only for champion athletes, but for all of us.
00:50:55The brain, for example, runs entirely on glucose.
00:50:58Too much or too little can have effects ranging from minor disorientation to coma or even death.
00:51:04The liver is also able to manufacture many different proteins.
00:51:17These boost muscle and bone growth and give blood the ability to clot.
00:51:21The liver's protein factories, here lit up like spaceships, are called ribosomes.
00:51:35The snake-like ribbons flowing toward them are messenger RNA molecules, each one carrying the blueprint for the assembly of a single protein.
00:51:43In a fantastic display of assembly line engineering, building blocks called amino acids are hooked together in a precise order to form long protein chains.
00:51:55Inside the ribosome, the protein chains are further processed into a stable form that will allow them to perform their assigned tasks in the body.
00:52:14A million proteins are produced every minute.
00:52:31With the new protein complete, it's time for the rollout, out of the liver and into the bloodstream for distribution.
00:52:40For the blood, the liver serves as both health club and detox unit.
00:53:00It constantly checks for levels of cholesterol and poisons of many types.
00:53:03If there is too much cholesterol in the blood, the liver removes the excess, recycling some of it into bile.
00:53:11The bile and some leftover cholesterol are then shipped to the gallbladder.
00:53:20And here's the detox unit.
00:53:23These beautiful crystals are benzopyrene.
00:53:26They're found in cigarette smoke and car exhaust.
00:53:28Getting a good look at a poison like this, the liver sets up a machine shop, engineering an enzyme to clean up the toxic spill.
00:53:39It can do this for many dangerous substances, up to a point.
00:53:47You know, sometimes I can have, like, one beer and it's weird.
00:53:50I don't know whether it's just being an athlete or what.
00:53:52It feels like it goes right into my legs.
00:53:55And my legs feel funny from that.
00:53:58You know, so that's sometimes where, you know, that's something you almost try to tend to stay away from a little bit,
00:54:05especially during, you know, a major, especially during a heavy competition season.
00:54:12Under normal conditions, the body can process a small amount of alcohol with no problem.
00:54:16The trouble starts when things are taken to excess.
00:54:25A few drinks and an empty stomach can have an immediate negative effect.
00:54:29The alcohol gets past the mucous membrane and kills some cells in the underlying blood vessels, causing bleeding to occur.
00:54:36Aspirin and excessive amounts of salt can do the same thing.
00:54:48Seen under the electron microscope, the damage to the stomach wall appears devastating.
00:54:54But the body has an answer for these everyday assaults.
00:54:58The undamaged cells surrounding the injury rally to the cause, stretching out their tendrils until they reach one another,
00:55:09making a healthy net over the damaged area.
00:55:13This quick repair process takes about 30 minutes to complete, if it's not needed too often.
00:55:18In the liver, these lobes are in more serious trouble.
00:55:29Weakened by virus or parasites or the long-term effects of alcohol,
00:55:33they are unable to process all the food that is entered.
00:55:38Instead, the food turns to fat, here tinted blue.
00:55:42The fat fills the liver lobe until the cells burst.
00:55:54The dead lobe is replaced by simple connective tissue,
00:55:58and some of the liver's working capacity is lost.
00:56:03The surviving liver cells must do even more.
00:56:06If they too are overstressed, more cells will die.
00:56:12Cirrhosis sets in.
00:56:15Unchecked, the connective tissue will be all that is left.
00:56:21When too much of the liver goes, we go with it.
00:56:25Because there's nothing in the body, and nothing we can build, to replace it.
00:56:29These Japanese engineers tried to design a chemical plant that would work like the liver.
00:56:33But as they discovered, the chemical engineering carried out in the liver is more advanced than anything modern technology can offer.
00:56:41An enormous factory would be needed just for the energy distribution system.
00:56:46And handling the toxins was just overwhelming.
00:56:50The healthy liver takes care of us, day in and day out.
00:56:54And like the champion athlete, who makes everything look easy, its astounding abilities are sometimes overlooked.
00:57:03I never got involved in the sport of speed skating, you know, to be able to make money out of it.
00:57:08I knew that that was going to be very slim, few and far between.
00:57:11I got into the sport of speed skating because I love what I'm doing.
00:57:16I love that crack of the gun.
00:57:19The thrill of competition.
00:57:20I look forward to it.
00:57:21I'm never scared of it.
00:57:23But now I'm getting to the point where I want to kind of go on and do other things in my life.
00:57:27And I'm looking forward to that as well.
00:57:29You ready?
00:57:46Ready.
00:57:48One minute.
00:57:50And begin.
00:57:52Karen Hatchett-Pavlin is in training.
00:57:53Once one of America's elite track and field athletes, Karen is now preparing for the biggest event of her life.
00:58:03The birth of her first child.
00:58:06Although there's no medical evidence that being in shape leads to a smooth delivery, Karen is convinced she has a big advantage going in.
00:58:15Trying to visualize it.
00:58:16Being in good condition means being in tune with your body and being able to listen to and respond to whatever your body is telling you.
00:58:25Being in good shape really, really has given me that kind of advantage, hopefully. We'll see.
00:58:34Okay. Concentrate. Focus back in.
00:58:37For husband and coach Rob Pavlin, training for this event is very different from when he coached Karen at the track.
00:58:43And I was really able to detach myself from her at that moment that she was just somebody who was running that needed encouragement and sometimes needed to be encouraged softly and sometimes needed somebody to tell her just to go run and stop complaining and just get it done and so we can get out of here.
00:58:58But now it's like, you know, when she says to me, look, I'm really tired. Can we, you know, I just melt. I mean, because it's now it's our experience instead of just her experience. And that's a big change.
00:59:08It's a connection.
00:59:09Oh, God, feel that. You feel an arm there or something.
00:59:15As Karen and Rob prepare for the big event, their baby is nearing the completion of a process that began nine months ago with a single cell.
00:59:25Okay, come on. Let's go back.
00:59:27A woman is born with all the egg cells that she will ever have. There are about a million of these primitive cells called oocytes. By puberty, this amount is reduced to 400,000. Over the course of the fertile years, only 400 eggs will grow to maturity. 400 chances to make a baby.
00:59:49Here, with the addition of a ring of supportive nurse cells, an oocyte has developed into a follicle. Several follicles are created each month, but only one continues to develop into a mature egg.
01:00:04Every oocyte and every sperm carries the unique combination of genes that make up our inherited characteristics. Here, the egg is collecting all of its genes in a little sack. The sack is then broken down and dissolved.
01:00:23The gene pool divides in half, and one part is pushed out of the egg. Out of 46 chromosomes, 23 are left, the mother's share of a child's biological inheritance.
01:00:41The eggs are held in the woman's ovaries, the almond-shaped organs connected to the uterus by the fallopian tubes, or oviducts.
01:00:56The man's reproductive cells are found inside the 300 feet of coiled passageways within the testicles.
01:01:05At birth, they are immature, lacking tails.
01:01:08Beginning at puberty, the sperm matured, at a rate as high as 1,000 a second.
01:01:17The dark blue rods are the 46 chromosomes, the man's genetic identity.
01:01:23But as this primitive sperm divides, two cells are created, each carrying just 23 chromosomes.
01:01:31The sperm now grow tails, to help navigate the long trip to the egg.
01:01:36When the 23 chromosomes contained in any one of these sperm, combined with the 23 chromosomes of a mature egg, the result will be a new combination of 46.
01:01:48The blueprint for a completely new human being.
01:01:51In the ovary, the monthly process of ovulation is about to begin.
01:01:58First, a single follicle expands like a bubble on the surface of the ovary.
01:02:04The bubble ruptures, and the egg's nurse cells are propelled out, seeming to lay out a protective carpet for the egg.
01:02:12These are the first pictures of ovulation ever photographed.
01:02:18The egg is gently caught by the frilled edges of the fallopian tube, and led into the narrow channel leading to the uterus.
01:02:38At first, tiny muscle contractions in the fallopian tube push the egg along its way.
01:02:46But then, the cilia take over.
01:02:49Millions of microscopically fine hairs that slowly sweep the egg along.
01:02:53So slowly, in fact, that it takes four days for the egg to reach the uterus, longer than it can survive on its own.
01:03:03If a baby's to be made, the sperm will have to join the egg here in the fallopian tube during the brief period when fertilization is possible.
01:03:12The sperm arrive on the scene during sexual intercourse at the moment of ejaculation.
01:03:22At male orgasm, typically several hundred million sperm are ejaculated into the woman's vagina.
01:03:29They have a common goal. Get to the egg and fertilize it.
01:03:34Only one, if any, will succeed.
01:03:42Millions of sperm die at the first pass, destroyed by the vagina's protective acidic environment.
01:03:50The survivors continue up to the cervix, the entry gate to the uterus and egg beyond.
01:03:59If a woman is not ovulating, the secretion barrier of the cervix spells doom for the sperm.
01:04:05There is zero chance of getting past it.
01:04:07Folds in the mucous membrane trap the sperm, and they struggle to escape for up to three days before they die.
01:04:24But during the few days of ovulation each month, with the mature egg waiting,
01:04:28the impenetrable gate of the cervix opens ever so slightly.
01:04:33Sperm are still trapped by the thousands, but a few find the microscopic channels created in the secretion barrier by the release of estrogen.
01:04:43The surviving sperm are halfway home.
01:04:47They push on through the uterus up to the entrance to the fallopian tube.
01:04:50Of the 300 million that began, perhaps a few thousand remain.
01:04:57Now, within striking distance of their target, they prepare to do what they've come for.
01:05:02Fertilize the egg.
01:05:06Just past the fallopian tube entrance, the surviving sperm suddenly stop and rub themselves against the cilia.
01:05:12It is possible that this is the moment when a covering of protein molecules on the sperm surface are stripped off.
01:05:19With the covering removed, the sperm, for the first time, are ready to deliver their chromosomes, fertilizing the egg.
01:05:27So close and yet so far.
01:05:30Of the thousands that make it as far as the fallopian tube, only a few hundred reach the egg.
01:05:34When they get there, they encounter the final and most imposing barrier of all, the egg's protective shell.
01:05:43On the cellular level, this dense cement-like ring is the equivalent of a castle wall 30 feet thick.
01:05:51Special measures are called for.
01:05:56Arriving at the egg, enzymes carried in the sperm's body rush to the surface and form a chemical battering ram.
01:06:02The chromosomes remain in the sperm head, but the tail, powered by energy capsules called mitochondria,
01:06:11changes its motion from regular waves of movement to quick, strong, whip-like lurches.
01:06:20An amazing effort.
01:06:22But without the cooperation of the egg, it probably wouldn't be enough.
01:06:26The support cells that now make up the wall of the egg are changing shape, weakening the wall just enough to draw the sperm in.
01:06:41The sperm keep trying, the explosive energy of their tails driving them along.
01:06:45Most of the remaining sperm die in this last attempt to penetrate the egg.
01:06:52Finally, success.
01:06:55A single sperm has broken through.
01:06:59Instantly, a burst of electrical activity changes the surface of the egg, making it totally impenetrable.
01:07:06300 million sperm set out.
01:07:13One made it to the finish line.
01:07:17The sperm continues to move for a short time while inside the egg, and then its tail drops off.
01:07:23The sperm's head slowly starts to swell until it is 200 times its original size, preparing to combine its genes with those of the egg.
01:07:36The two large, round structures hold the ingredients for a new human being.
01:07:42Half the genes from the woman, half from the man.
01:07:45Now, the moment of fertilization.
01:07:49The two pools of genes appear here as the two interlocking circles.
01:07:54They fuse with immense power.
01:07:56United, we dissolve into the egg, and the blueprint for a new individual is set.
01:08:03A combination of inherited characteristics unique in all the world has been created.
01:08:15Almost immediately, the egg divides itself into two identical cells.
01:08:31These daughter cells are the first of the billions to come that will culminate in the birth of a single new human being.
01:08:39Or maybe more.
01:08:45A combination of inherited characteristics.
01:08:49Mother-to-be Karen Hatchet Pavlin is an identical twin.
01:08:53Like Karen, her sister Kim was also once a track star.
01:08:58Today, Kim is an investment banker, and Karen is an account executive for Xerox.
01:09:05Like many twins, Karen and Kim are close.
01:09:08Sometimes they believe they can even sense what the other is experiencing.
01:09:11It just had a very, very strange feeling when she called.
01:09:16And I remember Rob was away.
01:09:18And I just knew she was pregnant.
01:09:21I just knew it was it.
01:09:23And it just convinced me to just go ahead and take the test and find out.
01:09:28And she was right.
01:09:30We were really excited.
01:09:31Yeah.
01:09:32So you knew before Rob knew.
01:09:35He's not supposed to know that.
01:09:41Being twins, we always wondered if Kim was having this baby with my husband, if the baby would look a lot alike or if they would be, look like twins or obviously they would look like brother and sister.
01:09:55Because we're genetically the same.
01:09:58So it's an interesting thing.
01:10:01It's an interesting experiment for, maybe not us, but somebody to do.
01:10:10Much of who we are as people is determined by our genes.
01:10:14Eye color, hair color, looks, even some personality traits.
01:10:17And all of this is set in the first moments of pregnancy, when maternal and paternal genes fuse together.
01:10:30In the first few days of pregnancy, the egg cells continue to divide as they slowly float down the fallopian tube toward the uterus.
01:10:38Sometimes, about once every 300 pregnancies, this group of identical cells may divide in half.
01:10:48Identical twins, like Karen and Kim, are the result.
01:10:55Fraternal twins develop when two eggs escape the ovary and are fertilized by separate sperm.
01:11:03By day four, the egg finally reaches the uterus.
01:11:06Now, a startling change takes place.
01:11:10The cells begin to differ from one another.
01:11:13Within the egg, a dark colored blastocyst develops.
01:11:17This ball of cells is preparing to leave the egg behind and move on to the next stage of development.
01:11:22In this process, never before seen on film, the blastocyst shakes the egg like a baby chick about to hatch.
01:11:37After a moment, it succeeds in freeing itself.
01:11:40Once the healthy blastocyst has separated from the egg wall, it floats freely in the uterus.
01:11:51Close up, the blastocyst shows its makeup.
01:11:53The light round cells on the lower right will become the placenta, the dark mass on the upper left, the embryo, which will grow in nine months into a new baby.
01:12:08Day five, and the blastocyst finds its way to the uterine wall.
01:12:11Its sticky surface helps it adhere, and the blastocyst implants itself.
01:12:20Sometimes, the process doesn't work just right, and the body is quick to respond.
01:12:25Here, three round chromosome sacs lie inside a fertilized egg.
01:12:34This occurs rarely, when two separate sperm have both managed entry to the egg.
01:12:41Because of the extra half set of chromosomes, this egg could never develop into a normal human being.
01:12:48The body recognizes the problem, and the egg is rejected.
01:12:52These early miscarriages often occur so quickly and automatically,
01:12:57that the woman hardly has a chance to register that she has been pregnant at all.
01:13:05Day 21, three weeks after fertilization.
01:13:10Clear as glass, the developing heart begins to beat.
01:13:14Blood cells appear, running backwards and forwards in newly constructed blood vessels.
01:13:25Their thin walls providing the developing tissues with oxygen.
01:13:28At four weeks, the heart beats on, ever stronger.
01:13:46The beginnings of a head and face have appeared.
01:13:49This is the start of an eye.
01:14:04The liver takes shape to the left of the heart, the spinal column below.
01:14:09The embryo of almost any animal that has a backbone, from a fish to a tiger to a human being, looks just like this at this early stage of development.
01:14:22But now, in the human embryo, millions of years of evolution are compressed into a few short months.
01:14:35Four weeks, the embryo is four millimeters long.
01:14:38The arms appear as narrow protrusions.
01:14:41This part will grow into a hand.
01:14:43Five weeks, primitive fingers have become apparent.
01:14:55The frog-like webbing between the fingers gradually recedes.
01:15:04Week 16, hands and face are clearly recognizable.
01:15:08The fetus floats in the uterus, surrounded by a protective fluid sac.
01:15:18This flexible coil is the umbilical cord.
01:15:25The umbilical cord belongs to the fetus, but it is connected to the placenta.
01:15:30The vital link between fetus and mother.
01:15:33The placenta, firmly rooted to the uterine wall,
01:15:36is made up of an astonishing network of blood vessels.
01:15:41From the early stages of pregnancy, everything the fetus needs to survive and grow,
01:15:46passes from the mother to the fetus, through the placenta.
01:15:51In this animated view, the mother's blood, carrying nourishment for the fetus,
01:15:56passes through tiny holes into the placenta's many chambers.
01:16:00What look like trees inside so many boxes are really the branched endings of the fetus's umbilical cord,
01:16:10the villi.
01:16:14The mother's blood must stay separate from the fetus.
01:16:17So how is the fetus nourished?
01:16:20A closer look reveals the secret.
01:16:22The surface of the villi is made of a selectively permeable membrane, a strainer.
01:16:31It allows nutrients from the mother in, but keeps her blood out.
01:16:36The nutrients seep through the membrane into the fetus's blood supply.
01:16:39This system protects the fetus from some harmful substances,
01:16:45but cannot keep alcohol, certain drugs, and some viruses from passing through.
01:16:50This view shows what the process looks like inside the body.
01:16:55Mother's blood shooting into the exchange chamber and bathing the villi,
01:16:59dangling down on either side of the screen.
01:17:01This animation shows the mother's antibodies surging along with the blood into the exchange chamber.
01:17:18For nine months, the fetus is protected and nourished in this way.
01:17:24And it grows, readying itself for a new life in the world outside the mother.
01:17:32This is an ultrasound picture of the heartbeat just before birth.
01:17:40Now, 18 hours into labor, the baby's condition is carefully monitored,
01:17:46and Karen's endurance is put to the test.
01:17:51Contraction begins, right? Here it comes.
01:17:55Deep breath. Breathe out.
01:17:58Breathe out.
01:18:01Good.
01:18:02Another one.
01:18:03Speak again.
01:18:04Speak again.
01:18:07One more, come on. Stay with it.
01:18:13Good job.
01:18:16Another one. Stay with it.
01:18:17Hi there, little guy. Hi.
01:18:34How are you doing there? How are you doing in there, little baby?
01:18:37Ha, ha.
01:18:38Ha, ha, ha.
01:18:40Transcription by CastingWords
01:19:10Transcription by CastingWords
01:19:40Improving Health, Extending Life
01:19:44Merck
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