[{"data":1,"prerenderedAt":824},["ShallowReactive",2],{"layer:body-systems:extend":3},{"layer":4,"contentHash":805,"dependencyHashes":806,"approval":817,"releaseId":823},{"schemaVersion":5,"conceptId":6,"locale":7,"depth":8,"revision":5,"title":9,"subtitle":10,"summary":11,"objectives":12,"estimatedMinutes":18,"plate":19,"blocks":40,"sourceIds":800,"reviewStatus":801,"authoring":802},1,"body-systems","en","extend","History, machines and weightlessness","Harvey's arithmetic, the stethoscope and ECG, three ways to image the body, artificial hand-overs, and bodies in orbit","Meet the arithmetic that proved blood circulates, the instruments that let doctors listen to and image a living body without cutting it, machines that rebuild a failed hand-over, what microgravity does to every system at once, and a few careers and open questions this topic leads to.",[13,14,15,16,17],"Reconstruct Harvey's arithmetic argument that blood must circulate rather than being made and consumed.","Compare a stethoscope, an ECG, an X-ray, ultrasound and an MRI by what each actually detects and is best for.","Explain how a dialysis machine and an artificial pacemaker each rebuild a specific hand-over from this topic.","Describe how microgravity affects the circulatory, skeletal, muscular and nervous systems together.","Connect this topic to real careers and to open questions that remain genuinely unanswered.",45,{"title":20,"rows":21},"Lesson plate",[22,25,28,31,34,37],{"label":23,"value":24},"Depth","Extend",{"label":26,"value":27},"Reading time","≈ 45 minutes",{"label":29,"value":30},"Prior knowledge","All earlier layers",{"label":32,"value":33},"Chapters","10",{"label":35,"value":36},"Labs","3: history match, imaging sort, dialysis anim",{"label":38,"value":39},"Big idea","A hand-over discovered once can sometimes be rebuilt",[41,45,51,54,83,98,104,129,135,140,143,163,168,173,176,219,223,244,262,300,305,308,342,354,358,381,386,389,414,426,430,443,448,451,487,491,496,499,510,525,530,534,539,542,546,550,571,576,579,595,599,604,607,635,638,678,774,790],{"id":42,"type":43,"markdown":44},"intro-extend","prose","Everything so far has explained how the body works, using knowledge that took centuries of careful, often risky, argument to establish. This layer steps back and asks three different questions: **how did anyone find any of this out**, **how do doctors watch it happening without opening you up**, and **what happens when a hand-over this topic relies on actually breaks — and can it be rebuilt with a machine?**\n\nIt closes by leaving the body's normal environment altogether: what happens when every system you have studied is suddenly weightless.",{"id":46,"type":47,"title":48,"eyebrow":49,"navLabel":50},"ch1","chapter","The idea that blood goes round","Chapter 01","1 Harvey and Galen",{"id":52,"type":43,"markdown":53},"galen-wrong","For roughly **1,400 years**, European and Islamic medicine largely followed the teaching of Galen, a physician of 2nd century CE: that blood was made continuously in the liver from food, travelled outward through the veins, and was *used up* by the body's tissues like fuel poured into a lamp. On this picture, blood did not circulate at all — it was made, spent, and made again.\n\nIt is a perfectly reasonable idea to have had with the tools available at the time, and it went almost unquestioned for longer than the entire span from Akbar's reign to today. Overturning it needed not a new instrument, but a new kind of argument: **arithmetic**.",{"id":55,"type":56,"title":57,"items":58},"timeline-circulation","timeline","From Galen to the electrocardiograph",[59,63,67,71,75,79],{"time":60,"title":61,"text":62},"c. 150 CE","Galen's liver-and-lamp model","Blood is made in the liver, travels outward through veins, and is consumed by the tissues. No circulation.",{"time":64,"title":65,"text":66},"1628","Harvey publishes De Motu Cordis","\"On the Motion of the Heart\": Harvey shows, mostly by arithmetic, that blood must circulate in a closed loop, pumped by the heart.",{"time":68,"title":69,"text":70},"1816","Laennec's stethoscope","A simple wooden tube, invented so a doctor need not press an ear directly to a patient — and it revealed heart and lung sounds clearly for the first time.",{"time":72,"title":73,"text":74},"1895","Röntgen discovers X-rays","A new kind of ray passes through soft tissue but not bone, producing the first images of a living skeleton without any cut.",{"time":76,"title":77,"text":78},"1903","Einthoven's electrocardiograph","Records the heart's own electrical signal from the skin's surface, turning each heartbeat into a readable trace.",{"time":80,"title":81,"text":82},"1977","First whole-body MRI scan","Magnetic resonance imaging produces detailed images of soft tissue using magnetism and radio waves, with no radiation at all.",{"id":84,"type":85,"title":86,"problem":87,"steps":88,"help":95},"we-harvey-arithmetic","worked_example","Harvey's arithmetic, redone in his own style","Harvey did not have a microscope good enough to see capillaries (they were found decades later). Instead he measured the volume of a beating heart, made a deliberately cautious guess at how much blood it pushed out per beat, and simply added it up over an hour. Follow his reasoning: suppose each beat pushes out a cautious 2 ounces (about 28.4 mL), and the heart beats about 4,320 times an hour. How much blood does that come to — and what does the answer imply?",[89,90,91,92,93,94],"Blood per beat: 2 ounces ≈ 56.8 mL.","Blood per hour: 56.8 × 4,320 = **245 litres in a single hour**.","Compare that with the whole body's blood supply, about 5 litres: 245 ÷ 5 = **about 49 times** the entire blood supply, pushed out by the heart in just one hour.","Compared with a typical body mass of 60 kg, that is 4.1 times the person's own body weight in blood, pumped in an hour.","No liver, however busy, could manufacture blood at anywhere near that rate, nor could the tissues possibly consume it that fast. There is only one way the arithmetic can work: **the same blood is going round and round, over and over**, not being made and destroyed once each.","This is the entire argument. Harvey never saw a capillary. He proved circulation by showing that any other explanation broke simple arithmetic.",{"simplerExplanation":96,"anotherExample":97},"Multiply the blood pushed out in one beat by the number of beats in an hour. The total is far more blood than a body even contains, so it must be reused, not freshly made each time.","It is the same style of reasoning as Understand's tennis-court check on lung surface area: take a repeated, widely believed claim, and simply do the sum.",{"id":99,"type":100,"variant":101,"title":102,"markdown":103},"nuance-harvey-missing-piece","callout","nuance","What Harvey could not see","Harvey's argument proved blood *must* travel from arteries back to veins somehow, to complete a circuit — but he could not see how, because capillaries are far too small for the microscopes of 1628. He guessed, correctly, that some kind of tiny connecting vessels must exist, and left the direct proof to whoever built a strong enough microscope.\n\nThat confirmation came a few decades later, when Marcello Malpighi examined a frog's lung under one of the first serious microscopes and actually saw capillaries carrying blood between artery and vein. Harvey's arithmetic and Malpighi's microscope are a good pairing to remember: sound reasoning can prove something is true well before anyone has the instrument to see it directly.",{"id":105,"type":106,"component":107,"componentVersion":5,"config":108,"objective":127,"textAlternative":128},"lab-match-history","interactive","match-pairs",{"prompt":109,"mode":110,"pairs":111},"Match each person to what they showed or built.","connect",[112,115,118,121,124],{"a":113,"b":114},"William Harvey","Proved blood circulates, mostly using arithmetic, in 1628",{"a":116,"b":117},"Marcello Malpighi","First saw capillaries under a microscope, confirming Harvey",{"a":119,"b":120},"René Laennec","Invented the stethoscope in 1816",{"a":122,"b":123},"Wilhelm Röntgen","Discovered X-rays in 1895",{"a":125,"b":126},"Willem Einthoven","Built a working electrocardiograph in 1903","Match five people from the history of understanding and imaging the body to what each one is remembered for.","Five names, five discoveries, in the order they happened.\n\n- **Harvey** (1628) ↔ proved circulation by arithmetic alone.\n- **Malpighi** (decades later) ↔ actually saw the capillaries Harvey's argument required.\n- **Laennec** (1816) ↔ invented the stethoscope.\n- **Röntgen** (1895) ↔ discovered X-rays.\n- **Einthoven** (1903) ↔ built the first practical electrocardiograph.\n\nNotice the gap between Harvey and Malpighi: proof by reasoning can arrive a long time before the direct evidence does, and good science treats that gap honestly rather than pretending the reasoning alone was the final word.",{"id":130,"type":131,"conceptId":132,"relation":133,"explanation":134},"conn-anatomy-harvey","connection","human-body-anatomy","related_to","Harvey worked out that the heart is a pump and blood circulates; exactly where the heart sits and its physical structure is covered in the anatomy topic.",{"id":136,"type":47,"title":137,"eyebrow":138,"navLabel":139},"ch2","Listening to the heart, and reading its signal","Chapter 02","2 Stethoscope, ECG",{"id":141,"type":43,"markdown":142},"stethoscope-ecg","Before 1816, a doctor who wanted to hear inside a patient's chest pressed an ear directly against it — awkward, and especially so, the story goes, when Laennec needed to examine a young woman and judged direct contact inappropriate. He rolled a sheet of paper into a tube instead, pressed one end to her chest and his ear to the other, and was startled at how much more clearly the heart sounds came through than with his ear alone. The modern **stethoscope**, little changed in principle since, simply channels and amplifies sound that was always there, using nothing but the physics of a tube.\n\nA stethoscope tells you a heart is beating and roughly how, but it cannot show you the **electrical** signal that triggers each beat — Understand's chapter on the heart never actually explained what makes the two sides contract together, in order, without you thinking about it at all. The heart contains its own tiny built-in pacemaker, a patch of cells that fires an electrical signal on a steady rhythm, and that signal spreads through the heart muscle in a fixed sequence, triggering the atria first and the ventricles a fraction of a second later — exactly the timed sequence from Understand's \"one heartbeat, in order\" chapter.\n\nThat electrical signal is small, but strong enough to reach the skin's surface, faint and spread out. Einthoven's **electrocardiograph (ECG)** was the first machine sensitive enough to pick it up reliably from the skin — with no cut, and no instrument entering the body at all — and draw it as a trace, one spike for each stage of the signal's journey through the heart.",{"id":144,"type":145,"caption":146,"columns":147,"rows":152},"table-listen-read","table","Two very different ways to check a heart, neither one cutting anything.",[148,149,150,151],"Method","What it actually detects","What it needs","What it cannot show",[153,158],[154,155,156,157],"Stethoscope","The sound of valves snapping shut (\"lub-dub\") and blood flow","A tube and a trained ear — no electricity, no screen","The heart's electrical signal, or its exact shape",[159,160,161,162],"Electrocardiograph (ECG)","The heart's own electrical signal, from sensors on the skin","Skin sensors and a machine to record and display the trace","Sound, or a picture of the heart's physical shape",{"id":164,"type":100,"variant":165,"title":166,"markdown":167},"aha-heart-electric","aha","The heart is its own electrician","Nerves, as Understand explained, carry electrical signals — but the heart's own beat-starting signal does not come from a nerve at all. A small patch of specialised heart-muscle cells generates it by itself, rhythmically, entirely automatically, which is exactly why a heart can be kept beating for a short time even disconnected from the body (in careful laboratory and transplant conditions), and why nerves and hormones only ever **speed up or slow down** a rhythm the heart was always going to keep on its own.\n\nAn ECG trace is a direct readout of that self-generated signal, and it is precisely because the signal is so regular that a doctor can spot an irregularity in the trace at a glance.",{"id":169,"type":47,"title":170,"eyebrow":171,"navLabel":172},"ch3","Three ways to see inside, without cutting","Chapter 03","3 Imaging",{"id":174,"type":43,"markdown":175},"imaging-intro","Röntgen's accidental discovery of X-rays in 1895 began a hundred-and-thirty-year project of building better and better ways to look inside a living body without opening it. Three methods, each using a completely different piece of physics, now do most of that work.",{"id":177,"type":178,"title":179,"prompt":180,"options":181},"explorer-imaging","explorer","Three windows into the body","Pick a method to see what it is built for.",[182,195,207],{"id":183,"label":184,"chain":185,"badge":191,"note":194},"xray","X-ray",[186,187,188,189,190],"Rays pass through the body","Bone blocks more than soft tissue","A shadow-picture forms","Bone shows pale, air shows dark","One quick, flat image",{"text":192,"tone":193},"Best for bone","yes","X-rays pass easily through soft tissue but are blocked more by dense bone, so a detector on the far side records a shadow picture: bone pale, soft tissue grey, air-filled lungs dark. Fast and inexpensive, which is why it is still the first choice for a suspected broken bone, but it uses a small dose of radiation and gives a flat, two-dimensional picture of a three-dimensional body.",{"id":196,"label":197,"chain":198,"badge":204,"note":206},"ultrasound","Ultrasound",[199,200,201,202,203],"Very high-pitched sound sent in","Echoes bounce off internal surfaces","Timing and strength are measured","A live moving picture is built","No radiation at all",{"text":205,"tone":193},"Safe and live","A probe sends sound far too high-pitched to hear and listens for echoes bouncing back off internal surfaces — the same principle as the sound topic's echo lab, just at a far higher pitch. Because it uses sound rather than radiation, it is considered safe to use freely and can show movement live, such as a beating heart valve, but it struggles to see through bone or gas-filled gut.",{"id":208,"label":209,"chain":210,"badge":216,"note":218},"mri","MRI (magnetic resonance)",[211,212,213,214,215],"A strong magnetic field is applied","Radio waves excite atoms in the body","Atoms send a faint signal back","A computer builds a detailed image","Excellent for soft tissue",{"text":217,"tone":193},"Best soft-tissue detail","A very strong magnet and radio-wave pulses cause hydrogen atoms (abundant in water and fat throughout the body) to briefly emit a faint signal of their own, which a computer turns into an extremely detailed image, especially of soft tissue like the brain and muscles — where X-rays show almost nothing useful. It uses no radiation at all, first achieved as a whole-body scan in 1977, but the scan is slow, the machine is loud, and the strong magnet means no metal objects may enter the room.",{"id":220,"type":131,"conceptId":132,"relation":221,"explanation":222},"conn-anatomy-imaging","applied_in","Every one of these imaging methods exists to answer the anatomy topic's question — what is where — without a single cut.",{"id":224,"type":145,"caption":225,"columns":226,"rows":230},"table-imaging-compare","Choosing between the three, at a glance.",[148,227,228,229],"Uses radiation?","Best for","Typical limitation",[231,235,239],[184,232,233,234],"Yes, a small dose","Bones, quick checks","Flat image; soft tissue barely visible",[197,236,237,238],"No","Moving soft tissue, safe repeated checks","Cannot see through bone or gas",[240,241,242,243],"MRI","No (magnetism and radio waves)","Detailed soft tissue, brain, joints","Slow, loud, no metal allowed nearby",{"id":245,"type":246,"prompt":247,"options":248,"explanation":261},"predict-imaging-choice","prediction","A doctor suspects a child has broken a bone in their wrist after a fall. Which imaging method is almost always tried first, and why?",[249,252,255,258],{"id":250,"label":251},"a","MRI, because it gives the most detail of any method",{"id":253,"label":254},"b","Ultrasound, because it is completely safe",{"id":256,"label":257},"c","X-ray, because it is fast, inexpensive, and bone is exactly what it shows best",{"id":259,"label":260},"d","None — a doctor can always tell by touch alone","**X-ray.** It is quick, widely available, inexpensive, and bone — dense and mineral-rich — is precisely the tissue that blocks X-rays most strongly, so a break shows up clearly as a break in the pale bone shadow.\n\nMRI would show a broken bone too, and in far more soft-tissue detail than is needed here, but it is slower, far more expensive, and usually reserved for cases where soft tissue (ligaments, cartilage) also needs a careful look. Ultrasound is a poor match because bone mostly blocks sound waves rather than letting useful echoes through. Choosing the right imaging method for the right question is itself a skill, and \"the most advanced option\" is not automatically \"the right option.\"",{"id":263,"type":106,"component":264,"componentVersion":5,"config":265,"objective":298,"textAlternative":299},"lab-sort-imaging","sort-game",{"prompt":266,"bins":267,"items":272,"seconds":297},"Sort each imaging job by the method that suits it best.",[268,269,271],{"id":183,"label":184},{"id":270,"label":197},"ultra",{"id":208,"label":240},[273,277,281,285,289,293],{"id":274,"label":275,"bin":183,"why":276},"brokenwrist","A quick check for a possibly broken wrist bone","Fast, inexpensive, and bone is exactly what an X-ray shows best.",{"id":278,"label":279,"bin":270,"why":280},"heartvalve","Watching a heart valve open and close, live","Ultrasound builds a live moving picture with no radiation — ideal for something in motion.",{"id":282,"label":283,"bin":208,"why":284},"kneesoft","Looking closely at torn ligament tissue in a knee","Soft tissue detail like this is exactly where MRI outperforms X-ray.",{"id":286,"label":287,"bin":270,"why":288},"babycheck","A routine, repeated safety check with no radiation at all","Ultrasound uses sound, not radiation, so it is considered safe for frequent, repeated checks.",{"id":290,"label":291,"bin":208,"why":292},"brainscan","A detailed look at brain tissue with no radiation","MRI gives exceptional soft-tissue detail of the brain, using magnetism rather than radiation.",{"id":294,"label":295,"bin":183,"why":296},"boneage","A single quick image to check how a bone is growing","A one-off, fast, bone-focused image is again an X-ray job.",0,"Match six real imaging jobs to whichever of X-ray, ultrasound or MRI actually suits each one best.","Six everyday imaging jobs, three bins.\n\n**X-ray**: a quick check on a possibly broken bone, or a single image to check bone growth — fast, cheap, bone-focused.\n\n**Ultrasound**: watching a heart valve move live, or a routine repeated check where avoiding all radiation matters — safe, live, sound-based.\n\n**MRI**: torn ligament tissue in a knee, or detailed brain tissue — both jobs where fine soft-tissue detail matters more than speed or cost.\n\nThe game rewards matching the **job** to the **physics**, not reaching for whichever method sounds most advanced.",{"id":301,"type":47,"title":302,"eyebrow":303,"navLabel":304},"ch4","Rebuilding a hand-over with a machine","Chapter 04","4 Artificial hand-overs",{"id":306,"type":43,"markdown":307},"artificial-handovers-intro","This entire topic has been about hand-overs the body performs for itself, all day, without being asked. What happens when one of them genuinely stops working? In some cases, engineers have built a machine that steps in and performs the same job from outside the body — a hand-over, rebuilt.\n\nTwo examples make the idea vivid, because they rebuild two very different kinds of hand-over you met in this topic: one that moves a **substance**, and one that carries an **electrical signal**.",{"id":309,"type":310,"component":311,"componentVersion":5,"config":312,"textAlternative":341},"anim-dialysis","animation","process-steps",{"title":313,"diagram":314,"steps":315},"How a dialysis machine copies a nephron","none",[316,321,326,331,336],{"id":317,"label":318,"description":319,"highlight":320},"problem","The problem","If the kidneys can no longer filter the blood, waste and excess fluid build up in it, which — left unaddressed — is dangerous.",[],{"id":322,"label":323,"description":324,"highlight":325},"leave","Blood leaves the body","A tube carries blood out of the body to the machine, continuously, a little at a time.",[],{"id":327,"label":328,"description":329,"highlight":330},"membrane","Across a thin membrane","Inside the machine, blood flows on one side of a thin, purpose-built membrane, with a cleaning fluid on the other — the same thin-wall pattern as every hand-over in this topic.",[],{"id":332,"label":333,"description":334,"highlight":335},"cross","Waste crosses out by diffusion","Waste products drift from the crowded blood side to the clean fluid side, across the membrane, by simple diffusion — no living cells involved at all.",[],{"id":337,"label":338,"description":339,"highlight":340},"return","Clean blood returns","The cleaned blood is returned through a second tube, and the cycle repeats for as long as the session lasts.",[],"A five-step animation of blood passing through a dialysis machine, copying the kidney's own filtering hand-over.\n\n**1. The problem** — kidneys that can no longer filter the blood, so waste and excess fluid start to build up.\n\n**2. Blood leaves the body** through a tube, a little at a time, continuously.\n\n**3. Across a thin membrane** — inside the machine, blood runs along one side of a purpose-built membrane, with cleaning fluid on the other side. This is the same thin-wall design every natural hand-over in this topic uses.\n\n**4. Waste crosses by diffusion** — no pump forces it, no living cell does the work; waste simply drifts from the crowded blood side to the emptier fluid side.\n\n**5. Clean blood returns** through a second tube, and the whole cycle repeats for the length of the session.\n\nThe animation makes the comparison with a real nephron explicit: a thin membrane, a steep difference, and diffusion doing the actual crossing — engineered outside the body instead of grown inside it.",{"id":343,"type":85,"title":344,"problem":345,"steps":346,"help":352},"we-dialysis-time","How much of a week does dialysis actually take?","A typical dialysis routine is about 4 hours a session, 3 sessions a week. What share of an entire week does that come to?",[347,348,349,350,351],"Hours a week on the machine: 4 × 3 = **12 hours**.","Hours in a whole week: 24 × 7 = **168 hours**.","Share of the week: 12 ÷ 168 × 100 = **7.1%**.","So a machine, running only about 7.1% of the week, does a job a healthy pair of kidneys performs continuously, every minute of every day, without ever being switched off.","That comparison is not a criticism of the machine — it is a genuinely impressive piece of engineering — but it is a fair way to appreciate just how relentless the real, biological hand-over actually is, running unnoticed for a lifetime.",{"simplerExplanation":353},"Multiply hours per session by sessions per week, then divide by the total hours in a week (168), then convert to a percentage.",{"id":355,"type":100,"variant":101,"title":356,"markdown":357},"nuance-pacemaker","An artificial pacemaker rebuilds a different hand-over","A dialysis machine rebuilds the kidney's filtering hand-over. An **artificial pacemaker** — a small device, sometimes implanted permanently — rebuilds a completely different one: it takes over from the heart's own electrical signal-generating patch of cells, from Chapter 2, when that natural rhythm becomes unreliable.\n\nIt sends its own small, precisely timed electrical pulses to the heart muscle, standing in for the heart's built-in \"electrician\" much as a dialysis machine stands in for a kidney's filter — the same idea of rebuilding a specific hand-over, applied to an electrical signal instead of a filtered substance. Both machines are humbling in the same way: each one is bulkier, noisier or more limited than the tiny piece of the body it replaces, and both are still genuinely life-changing.",{"id":359,"type":360,"itemId":361,"prompt":362,"check":363,"hints":375,"feedback":378},"p-extend-dialysis","practice","body-systems.extend-dialysis","What does a dialysis machine actually copy from a healthy kidney?",{"kind":364,"options":365,"correct":374},"choice",[366,368,370,372],{"id":250,"label":367},"The lever action of a bone",{"id":253,"label":369},"The filter-across-a-thin-membrane hand-over, driven by diffusion",{"id":256,"label":371},"The electrical pacemaker signal",{"id":259,"label":373},"The stretch-and-recoil of an artery",[253],[376,377],"Which chapter of Understand covered kidneys?","What crosses at a nephron, and how?",{"correct":379,"incorrect":380},"Correct. It copies the filtering hand-over: blood on one side of a thin membrane, a cleaning fluid on the other, waste drifting across by diffusion.","The pacemaker copies the heart's electrical signal. Dialysis copies the **kidney's filtering hand-over** — a thin membrane and diffusion, done outside the body.",{"id":382,"type":47,"title":383,"eyebrow":384,"navLabel":385},"ch5","Every system, weightless","Chapter 05","5 Bodies in space",{"id":387,"type":43,"markdown":388},"microgravity-intro","Every system in this topic evolved on a planet where gravity constantly pulls blood downward, loads bones and muscles with body weight, and never once switches off. Send a person to the International Space Station, orbiting Earth at about 7.66 km\u002Fs and circling the planet roughly 16 times a day, and every one of those assumptions disappears within hours.",{"id":390,"type":391,"title":392,"items":393},"steps-microgravity","steps","What changes, system by system, in the first days",[394,398,402,406,410],{"title":395,"tag":396,"text":397},"Circulatory","a fluid shift","With no gravity pulling blood toward the feet, about 2 litres of fluid shifts toward the head and chest, causing a puffy face and the \"bird legs\" astronauts joke about.",{"title":399,"tag":400,"text":401},"Skeletal","height, briefly","The spine, no longer compressed by body weight, stretches slightly, and astronauts can gain up to about 5 cm in height for the duration of a mission.",{"title":403,"tag":404,"text":405},"Skeletal, long term","bone loss","Bones that normally bear weight lose mineral at roughly 1% a month without countermeasures — about 6% over a six-month mission.",{"title":407,"tag":408,"text":409},"Muscular","weakening","Muscles that would normally work against gravity all day, every day, have almost nothing to push against, and weaken measurably within weeks without deliberate daily exercise.",{"title":411,"tag":412,"text":413},"Nervous","balance confusion","The inner ear's balance sensors, built to sense \"down\", receive contradictory signals in freefall, which is part of why many astronauts feel motion-sick for the first day or two.",{"id":415,"type":85,"title":416,"problem":417,"steps":418,"help":423},"we-bone-loss-comparison","Comparing a month in orbit with a year of ageing","Without exercise countermeasures, an astronaut can lose bone mineral at about 1% a month. On Earth, a broadly comparable rate of bone loss in later life is often quoted as around 1% a year. Compare the two rates.",[419,420,421,422],"Turn the space rate into a yearly rate for comparison: 1% a month × 12 = **12% a year**, if it continued unchecked.","Compare with the Earth ageing rate: 12 ÷ 1 = **12 times faster**.","So, without the daily resistance exercise routines the ISS actually requires, weightlessness would age an astronaut's bones roughly twelve times faster than ordinary ageing on Earth.","This is exactly why ISS astronauts spend a couple of hours almost every single day using resistance and treadmill machines specially designed to push and pull against their muscles and bones the way gravity ordinarily does for free — exercise is not optional fitness there, it is a medical necessity standing in for gravity itself.",{"simplerExplanation":424,"anotherExample":425},"Multiply the monthly rate by 12 to get a yearly rate, then divide by the Earth rate to compare them directly.","It is the same kind of \"how many times more\" comparison this topic has used throughout — the tennis-court lung, the bacteria ratio, the exercise oxygen multiple — applied to a completely different question.",{"id":427,"type":131,"conceptId":428,"relation":133,"explanation":429},"conn-gravity-micro","gravity","Why bones, muscles and fluid distribution depend on gravity in the first place is explored fully in the gravity topic; this topic covers what happens to the body's systems when that pull is removed.",{"id":431,"type":246,"prompt":432,"options":433,"explanation":442},"predict-astronaut-return","After six months on the ISS without full countermeasures, an astronaut returns to Earth. Which of these would you expect on landing day?",[434,436,438,440],{"id":250,"label":435},"Nothing at all — the body adjusts instantly back to normal",{"id":253,"label":437},"Difficulty standing and walking steadily at first, as weakened muscles, bone and balance systems all readjust to gravity together",{"id":256,"label":439},"Only their eyesight would be affected",{"id":259,"label":441},"They would be permanently unable to walk","**Difficulty standing and walking steadily at first.** Every system this chapter described adapting to weightlessness now has to re-adapt to gravity all at once: weakened muscles must push against body weight again, bone that has lost some mineral must bear load again, and balance sensors that recalibrated to weightlessness must recalibrate back. Astronauts are typically supported as they take their first steps back on Earth and go through weeks of guided rehabilitation, with the great majority recovering the great majority of their fitness over the following months.\n\nIt is a striking demonstration, at large scale, of the whole topic's theme: nothing in the body works in isolation, and a stress on one system (gravity's sudden return) shows up as an effect across several systems at once — muscular, skeletal and nervous together, exactly as running for a bus did back in Discover.",{"id":444,"type":47,"title":445,"eyebrow":446,"navLabel":447},"ch6","People whose job is one of these systems","Chapter 06","6 Careers",{"id":449,"type":43,"markdown":450},"careers-intro","Almost everything in this topic is somebody's daily work. A short, honest tour of a few of those jobs, without pretending any one of them is the \"best\" or only path into this subject.",{"id":452,"type":145,"caption":453,"columns":454,"rows":458},"table-careers","A handful of careers connected to body systems.",[455,456,457],"Career","Mostly works with","A typical task",[459,463,467,471,475,479,483],[460,461,462],"Doctor (general or specialist)","Any system, or one in particular","Working out which system a symptom is coming from, and treating it",[464,465,466],"Physiotherapist","Muscular and skeletal systems, and nerves","Helping an injured muscle, joint or nerve pathway recover strength and movement",[468,469,470],"Dietician or nutritionist","Digestive and endocrine systems","Planning what and how much a person should eat for their needs",[472,473,474],"Sports scientist","Circulatory, respiratory and muscular systems together","Measuring how an athlete's body responds to training, like the pulse and breathing data in Investigate",[476,477,478],"Radiographer","Any system, via imaging","Operating X-ray, ultrasound or MRI equipment and producing clear images for a doctor to read",[480,481,482],"Biomedical engineer","Any system that can be assisted by a machine","Designing devices like dialysis machines, pacemakers and artificial limbs",[484,485,486],"Immunologist \u002F microbiologist","The immune system and germs","Studying how the body defends itself, and how vaccines can be designed",{"id":488,"type":100,"variant":101,"title":489,"markdown":490},"nuance-many-paths","There is no single \"body systems\" job","Notice how differently these careers actually spend their days — some talking with patients, some in a laboratory, some designing hardware, some analysing data from a sports team. What connects them is not a single skill but a shared foundation: understanding how the body's systems work and hand over to each other, which is exactly what this whole topic has been building.\n\nNone of them require deciding on a career at age eleven. They are here to show that the ideas in this topic are not only exam material — they are the daily working knowledge of a great many real jobs, in medicine, sport, engineering and research.",{"id":492,"type":47,"title":493,"eyebrow":494,"navLabel":495},"ch7","Puzzles: use the numbers you already have","Chapter 07","7 Puzzles",{"id":497,"type":43,"markdown":498},"puzzles-intro","Every puzzle below reuses a number already established somewhere in this topic. None of them need new facts — only the same kind of careful, step-by-step arithmetic Harvey used four hundred years ago.",{"id":500,"type":85,"title":501,"problem":502,"steps":503,"help":508},"we-puzzle-tanker","The heart versus a water tanker","A small water tanker used to supply a school holds about 5,000 litres. At a resting cardiac output of 5 litres a minute, how long would it take your heart to pump a tanker's worth of blood — and how does that compare with how long it takes to pump your own five litres of blood once round?",[504,505,506,507],"Time to pump 5,000 L at 5 L a minute: 5,000 ÷ 5 = **1,000 minutes**, which is 1,000 ÷ 60 ≈ **16.7 hours**.","Time to pump your own 5 L once round: 5 ÷ 5 = **1 minute**, matching the 'about a minute per lap' figure from Understand.","So a tanker's worth of blood is not a strange, oversized target — it is simply about a thousand times your own blood volume, pumped at the same steady rate your heart uses every single minute, all day.","The heart never notices the difference between 'pump five litres once' and 'pump five litres, a thousand times over' — it simply keeps doing the same job, one beat at a time, for as long as it is asked to.",{"simplerExplanation":509},"Divide the tanker's volume by the pumping rate to get minutes, then convert minutes to hours by dividing by 60.",{"id":511,"type":360,"itemId":512,"prompt":513,"check":514,"hints":519,"feedback":522},"p-extend-puzzle1","body-systems.extend-puzzle-alveoli","If a pair of lungs has about 300 million alveoli and one breath uses a fixed one-thousandth of them for a fresh exchange, how many alveoli (in millions) does that one breath actually reach?",{"kind":515,"answer":516,"tolerance":517,"unit":518},"number",0.3,0.1,"million alveoli",[520,521],"Divide the total number of alveoli by 1,000.","Then convert the answer back into millions.",{"correct":523,"incorrect":524},"Right: 300,000,000 ÷ 1,000 = 300,000, which is **0.30 million alveoli** — still an enormous number for one ordinary breath.","300,000,000 ÷ 1,000 gives the count for one breath; divide by 1,000,000 again to express it in millions.",{"id":526,"type":100,"variant":527,"title":528,"markdown":529},"careful-puzzle-scope","careful","What this \"one-thousandth\" puzzle is, and is not","The one-thousandth figure in that puzzle is invented purely to make a clean arithmetic exercise — it is not a measured fact about real breathing, and the layer says so plainly rather than dressing up a made-up number as science. Real gas exchange involves the great majority of alveoli on almost every breath, refreshed continuously as air moves in and out.\n\nThe habit worth keeping from this puzzle is the arithmetic, not the specific number: dividing a huge quantity down to a per-event share, and converting comfortably between millions and plain counts.",{"id":531,"type":532,"prompt":533},"reflect-extend-open","reflection","This topic answered a great many questions with hard numbers. Three it has not, because nobody fully has yet: how sleep turns a day's experience into long-term memory; why reflex speeds vary between equally healthy people; whether damaged tissue could one day be grown in a lab instead of needing a machine like dialysis.\n\nPick one. Write down what evidence would actually convince you of an answer, as if you were the scientist trying to find out.",{"id":535,"type":47,"title":536,"eyebrow":537,"navLabel":538},"ch8","A pulse sensor on your wrist","Chapter 08","8 Wearable heart-rate",{"id":540,"type":43,"markdown":541},"wearable-intro","Many modern fitness bands and smartwatches claim to measure your pulse without a single wire touching a blood vessel directly, using nothing but a tiny light and a light sensor pressed against the skin. The trick connects two topics you might not expect to meet in the same sentence: **blood** and **light**.\n\nEvery time your heart beats, a small pulse of extra blood arrives in the capillaries under the skin, and that blood absorbs a little more light than the skin around it does an instant later, when the pulse has passed. A small LED shines light (commonly green) into the skin, and a sensor right beside it measures how much bounces back. That reflected light dims very slightly with every heartbeat, and counting those tiny dims gives a pulse reading, once every second or so, with no wire touching blood at all.",{"id":543,"type":100,"variant":101,"title":544,"markdown":545},"nuance-wearable-limits","Why a wearable pulse reading can wobble","This method, called photoplethysmography, depends on light passing cleanly through skin into blood and back out again. Anything that gets between the sensor and steady blood flow — the band worn too loosely, dark tattoo ink under the sensor, cold hands (less blood near the skin surface), or moving your arm hard during exercise — can throw the reading off, which is exactly why a fitness band's heart rate sometimes jumps around unrealistically during a fast sprint or a mis-fitted strap.\n\nAn ECG, from Chapter 2, reads the heart's electrical signal directly and does not have this problem, which is why hospitals still use ECG rather than a wrist-worn light sensor when real precision matters — a good example of a newer, more convenient technology not automatically replacing an older, more direct one.",{"id":547,"type":131,"conceptId":548,"relation":221,"explanation":549},"conn-light-wearable","light","A wearable pulse sensor works by shining light into the skin and measuring how much bounces back — light absorption and reflection, applied to a body-systems problem.",{"id":551,"type":360,"itemId":552,"prompt":553,"check":554,"hints":565,"feedback":568},"p-extend-wearable","body-systems.extend-wearable","How does a typical wrist-worn fitness band estimate your pulse?",{"kind":364,"options":555,"correct":564},[556,558,560,562],{"id":250,"label":557},"By listening for the heart sounds, like a stethoscope",{"id":253,"label":559},"By measuring the heart's electrical signal, like an ECG",{"id":256,"label":561},"By shining light into the skin and measuring how the reflection dims slightly with each heartbeat",{"id":259,"label":563},"By counting your breaths",[256],[566,567],"Think about what a small LED on the underside of a fitness band is for.","It is optical, not electrical.",{"correct":569,"incorrect":570},"Correct. Extra blood arriving with each heartbeat absorbs slightly more light, so the reflected light dims in time with the pulse — no wire near blood needed.","It uses light, not sound or electricity: blood arriving with each beat absorbs a little more of the light shone into the skin, and the sensor detects that tiny, repeating dip.",{"id":572,"type":47,"title":573,"eyebrow":574,"navLabel":575},"ch9","Vaccination, working at national scale","Chapter 09","9 Vaccination at scale",{"id":577,"type":43,"markdown":578},"vaccination-scale-intro","Understand's immune chapter explained how a vaccine works for one body: showing the immune system a harmless version of a germ so it builds the memory in advance. Extend it to an entire country and the same idea becomes one of the largest public health achievements in history.\n\n**Smallpox**, a severe and often fatal disease, was declared eradicated worldwide by the World Health Organization in **1980** — the only human disease ever wiped out completely, achieved through a sustained global vaccination campaign. **Polio**, which can cause permanent paralysis, saw its last recorded case in India in **2011**, and India was certified polio-free by the WHO in **2014**, following a vaccination campaign that reached hundreds of millions of children, repeatedly, across the entire country.",{"id":580,"type":56,"title":581,"items":582},"timeline-vaccination","Vaccination at national and global scale",[583,587,591],{"time":584,"title":585,"text":586},"1980","Smallpox eradicated","The World Health Organization declares smallpox eradicated worldwide, the first and so far only human disease eliminated entirely through vaccination.",{"time":588,"title":589,"text":590},"2011","India's last polio case","The last case of wild poliovirus in India is recorded, the result of a sustained, repeated national vaccination effort.",{"time":592,"title":593,"text":594},"2014","India certified polio-free","The WHO certifies India and the wider South-East Asia region free of wild polio transmission.",{"id":596,"type":100,"variant":165,"title":597,"markdown":598},"aha-vaccination-scale","The same immune trick, multiplied by hundreds of millions","Every individual vaccination is the small, personal event Understand described: one immune system shown a harmless preview of a germ. What made smallpox eradication and India's polio-free status possible was doing that same small event, reliably, for almost everyone, again and again, over years — turning a single body's immune memory into a barrier the germ could no longer cross anywhere in a population.\n\nThis is why vaccination campaigns emphasise reaching **everyone**, not just most people: a germ that can still find enough unprotected bodies to pass between can keep circulating indefinitely, however many people are already protected.",{"id":600,"type":47,"title":601,"eyebrow":602,"navLabel":603},"ch10","Capstone: design an artificial hand-over","Chapter 10","10 Design capstone",{"id":605,"type":43,"markdown":606},"capstone-intro","This topic opened with a single idea: hand-overs, not organs, are what keep a body alive, and every real one follows the same three-rule pattern — a thin barrier, a huge surface, and a steep difference to drive movement. Chapter 4 showed that pattern rebuilt as a machine, for the kidney's filtering job.\n\nAs a closing exercise, use exactly that pattern to design your own artificial hand-over, on paper, for a system this topic has not already rebuilt for you.",{"id":608,"type":391,"title":609,"items":610},"steps-capstone-design","A design brief: build an artificial hand-over",[611,615,619,623,627,631],{"title":612,"tag":613,"text":614},"1. Pick a hand-over","from this topic","Choose one this topic covered that has not already been rebuilt as a machine here: the alveolus, the villus, or the nerve-to-muscle junction are all good choices.",{"title":616,"tag":617,"text":618},"2. State what must cross","and in which direction","Name the exact substance or signal, and whether it needs to cross one way or both ways at once, as oxygen and carbon dioxide do at the alveolus.",{"title":620,"tag":621,"text":622},"3. Design the barrier","as thin as you can justify","Decide what your barrier could realistically be made from, and explain why thinner is better for your chosen crossing.",{"title":624,"tag":625,"text":626},"4. Design the surface","as large as you can justify","Decide how your design multiplies surface area — folding, branching or bundling many small units, as the body does.",{"title":628,"tag":629,"text":630},"5. Create the difference","that drives the crossing","Explain what keeps one side \"crowded\" and the other \"empty\", so your substance or signal keeps moving without needing to be pushed.",{"title":632,"tag":633,"text":634},"6. Name a limitation","honestly","Every real machine in Chapter 4 was bulkier, slower or more limited than the body part it copied. Say what yours would struggle with.",{"id":636,"type":532,"prompt":637},"reflect-capstone","Using the six-step brief above, design an artificial version of the alveolus, the villus, or the nerve-to-muscle junction (pick one). Write a short paragraph for each of the six steps.\n\nThen compare your design with the real thing it is copying: what did the real body already solve more elegantly than your design manages, and why might that be? There is no single correct design — the value is in applying the three-rule pattern deliberately, the way an engineer actually would.",{"id":639,"type":640,"title":641,"terms":642},"glossary-extend","glossary","Words for this layer",[643,646,649,652,655,658,662,666,670,674],{"term":154,"meaning":644,"example":645},"A simple instrument that channels chest sounds to a listener's ear, invented by Laennec in 1816.","Still built on the same basic idea over two centuries later.",{"term":159,"meaning":647,"example":648},"A machine that records the heart's own electrical signal from sensors on the skin.","Invented in working form by Einthoven in 1903.",{"term":184,"meaning":650,"example":651},"A kind of ray, discovered by Röntgen in 1895, that passes through soft tissue more easily than through bone.","Used to image broken bones quickly.",{"term":197,"meaning":653,"example":654},"Imaging using echoes of very high-pitched sound, with no radiation.","Can show a beating heart valve moving live.",{"term":240,"meaning":656,"example":657},"Magnetic resonance imaging: a strong magnet and radio waves produce detailed images of soft tissue, with no radiation.","First achieved as a whole-body scan in 1977.",{"term":659,"meaning":660,"example":661},"Dialysis","A machine that filters waste and excess fluid from the blood outside the body, standing in for failed kidneys.","Copies the kidney's thin-membrane, diffusion-driven hand-over.",{"term":663,"meaning":664,"example":665},"Pacemaker (artificial)","A device that generates electrical pulses to keep a heart beating on a steady rhythm.","Stands in for the heart's own built-in electrical signal.",{"term":667,"meaning":668,"example":669},"Microgravity","The near-weightless condition of an orbiting spacecraft, where gravity's pull is not felt because the craft is continuously falling around the Earth.","Astronauts on the ISS float because they, and the station, are in constant freefall.",{"term":671,"meaning":672,"example":673},"Photoplethysmography","Estimating pulse by shining light into the skin and measuring how the reflected light dims slightly with each heartbeat.","How most wrist-worn fitness bands measure heart rate.",{"term":675,"meaning":676,"example":677},"Eradicated (a disease)","Wiped out completely, everywhere, with no cases left anywhere in the world.","Smallpox, declared eradicated by the WHO in 1980.",{"id":679,"type":680,"title":681,"questions":682},"quiz-extend","quiz","Check yourself: history, technology and space",[683,696,709,722,735,748,761],{"itemId":684,"prompt":685,"options":686,"correct":253,"why":695},"body-systems.extend-q-harvey","What kind of evidence did Harvey mainly use to prove blood circulates?",[687,689,691,693],{"id":250,"label":688},"A microscope image of capillaries",{"id":253,"label":690},"Arithmetic — comparing blood pumped per hour with the body's total blood volume",{"id":256,"label":692},"An X-ray of the heart",{"id":259,"label":694},"A stethoscope recording","Harvey had no microscope capable of showing capillaries. He showed that the volume of blood pumped per hour vastly exceeds the body's total blood supply, which only makes sense if the same blood is reused — circulating.",{"itemId":697,"prompt":698,"options":699,"correct":253,"why":708},"body-systems.extend-q-ecg-vs-steth","What can an ECG detect that a stethoscope cannot?",[700,702,704,706],{"id":250,"label":701},"The sound of the valves",{"id":253,"label":703},"The heart's own electrical signal",{"id":256,"label":705},"Blood pressure directly",{"id":259,"label":707},"The size of the heart","A stethoscope hears sound; an ECG records the heart's self-generated electrical signal from sensors on the skin.",{"itemId":710,"prompt":711,"options":712,"correct":253,"why":721},"body-systems.extend-q-imaging","Why is X-ray usually tried first for a suspected broken bone, rather than MRI?",[713,715,717,719],{"id":250,"label":714},"X-ray shows more soft-tissue detail",{"id":253,"label":716},"X-ray is faster and cheaper, and bone is exactly the tissue it images best",{"id":256,"label":718},"MRI cannot be used on bones at all",{"id":259,"label":720},"X-ray uses no radiation, unlike MRI","X-ray is quick, inexpensive and shows dense bone very clearly. MRI gives more soft-tissue detail but is slower and more expensive — better suited to different questions.",{"itemId":723,"prompt":724,"options":725,"correct":256,"why":734},"body-systems.extend-q-dialysis2","A dialysis machine mainly copies which hand-over from this topic?",[726,728,730,732],{"id":250,"label":727},"Alveolus to blood",{"id":253,"label":729},"Nerve to muscle",{"id":256,"label":731},"Blood to kidney filter",{"id":259,"label":733},"Muscle to bone","It copies the kidney's filtering hand-over: blood against a thin membrane, waste crossing by diffusion into a cleaning fluid.",{"itemId":736,"prompt":737,"options":738,"correct":253,"why":747},"body-systems.extend-q-space","Why do ISS astronauts need to exercise for a couple of hours almost every day?",[739,741,743,745],{"id":250,"label":740},"To pass the time",{"id":253,"label":742},"Because without gravity loading their muscles and bones, both weaken and lose mineral rapidly",{"id":256,"label":744},"To keep the spacecraft balanced",{"id":259,"label":746},"Exercise is not actually necessary in space","With no gravity to push or pull against, muscles weaken and bone loses mineral at a rate many times faster than ordinary ageing on Earth. Daily resistance exercise substitutes for gravity's constant load.",{"itemId":749,"prompt":750,"options":751,"correct":256,"why":760},"body-systems.extend-q-wearable2","What actually changes, and is measured, by a wrist-worn optical pulse sensor?",[752,754,756,758],{"id":250,"label":753},"The heart's electrical signal",{"id":253,"label":755},"The sound of the heartbeat",{"id":256,"label":757},"How much light reflected from the skin dims with each pulse of extra blood",{"id":259,"label":759},"Body temperature","Extra blood arriving with each heartbeat absorbs slightly more light; the sensor detects that small, repeating dip in reflected light.",{"itemId":762,"prompt":763,"options":764,"correct":253,"why":773},"body-systems.extend-q-vaccine-scale","What made India being certified polio-free in 2014 possible?",[765,767,769,771],{"id":250,"label":766},"A single vaccination given to every citizen once",{"id":253,"label":768},"Repeated, sustained vaccination reaching hundreds of millions of children over years",{"id":256,"label":770},"Polio disappeared naturally without vaccination",{"id":259,"label":772},"A new antibiotic","It took a sustained, repeated national vaccination campaign reaching hundreds of millions of children, applying the same individual immune-memory trick at enormous scale.",{"id":775,"type":776,"title":777,"points":778},"cheat-extend","summary","Cheat sheet",[779,780,781,782,783,784,785,786,787,788,789],"**Harvey (1628)** proved circulation with arithmetic: blood pumped per hour vastly exceeds total blood volume, so it must be reused, not made fresh.","**Malpighi** later confirmed it by actually seeing capillaries under a microscope — reasoning first, direct evidence afterward.","**Stethoscope (Laennec, 1816)** hears heart sounds; **ECG (Einthoven, 1903)** reads the heart's own electrical signal — two different signals, two different instruments.","**X-ray (1895), ultrasound and MRI (1977)** each use different physics (radiation, sound echoes, magnetism) and suit different questions; more advanced is not automatically better for a given case.","**Dialysis** rebuilds the kidney's filtering hand-over outside the body; an **artificial pacemaker** rebuilds the heart's own electrical signal — two machines copying two very different hand-overs.","**Microgravity affects every system at once**: fluid shifts toward the head, the spine lengthens slightly, bone loses mineral roughly 1% a month without exercise, muscles weaken, and balance sensors get confused.","Many careers — doctor, physiotherapist, dietician, sports scientist, radiographer, biomedical engineer — work with these systems every day, from very different angles.","Real open questions remain: how sleep builds memory, why reflex speeds vary between people, and whether lab-grown tissue could one day replace machines like dialysis.","**Wearable pulse sensors** shine light into the skin and detect the tiny dimming caused by extra blood arriving with each heartbeat — light and circulation, in one device.","**Smallpox was eradicated worldwide in 1980; India was certified polio-free in 2014** — the same individual vaccine-memory trick, repeated at national and global scale.","The capstone design task reuses the whole topic's central pattern — thin barrier, big surface, steep difference — to build a new artificial hand-over on paper.",{"id":791,"type":792,"sourceIds":793},"sources-extend","sources",[794,795,796,797,798,799],"body-systems-britannica-history-medicine","body-systems-britannica-dialysis","body-systems-nasa-humans-in-space","body-systems-britannica-cardiovascular","body-systems-britannica-nervous","body-systems-who-immunization",[794,795,796,797,798,799],"needs_review",{"generatedBy":803,"notes":804},"claude-code","Draft generated locally; pending owner review.","d5f12f0bb07ba1a711b6d13c3ec822a0c6f66fe4f8d54a719387e65910e0d780",{"component:match-pairs@1":807,"component:sort-game@1":808,"component:process-steps@1":809,"logic:practice":810,"source:body-systems-britannica-cardiovascular":811,"source:body-systems-britannica-dialysis":812,"source:body-systems-britannica-history-medicine":813,"source:body-systems-britannica-nervous":814,"source:body-systems-nasa-humans-in-space":815,"source:body-systems-who-immunization":816},"2a8ee4ac87460b4e1175a4bb13c96b03d577db06dde95670eb7fcfe4ad787899","b164f45a2c8ca08f26c450768ff0231e113e9fe45381eddb34dc6d0548596c38","c2f918c426383c50d52939054780add1488f3f282c9d1a965c3a38345ddcb265","3d6b0fe1b15255975a32b0fcd94e8019bc959ad45cbf12e136e86149549c6878","8b7278004bfe64d7ad3e369fbfa62cada6c2ca19bdda240520d8cb96569d40a7","f84d9e2a5ffc9a1351da1e245ac71000e5564ac0ac9c1bebb262fab02e1b1b64","fe1a4e43d20072580424c152ced7e693b4b96fbd453bddd8de4a914b2f062c9e","07d4488afad056b326893d48a8ecd74894b1e87c5b23c8f0bbd1268b77fdf252","02b80a915fbee98479fc55757f037cca24b091dd7844fee0cb6a54fb141040f2","9b61cc1683dd013de90da0ab1067e4bd122ff090c0383f4d64355890022d25e0",{"state":818,"reviewer":819,"selfReview":820,"reviewedAt":821,"method":822},"approved","The library owner",true,"2026-09-20T10:18:37.581Z","owner_bulk","preview-7e1cbbcc4f",1789899598884]