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Latihan shadowing: How The Immune System ACTUALLY Works

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  1. The human immune system is the most complex biological system we know after the human brain and yet most of us never learn how it works or what it is.0:00
  2. Your immune system consists of hundreds of tiny and two large organs.0:12
  3. It has its own transport network spread throughout your body.0:17
  4. Every day it makes hundreds of billions of fresh cells organised like an army with soldiers, captains, intelligence officers, heavy weapons and crazy suicide bombers.0:20
  5. It's not some sort of abstract entity.0:32
  6. Your immune system is you.0:35
  7. Your biology protecting you from the billions of microorganisms that want to consume you and from your own perverted cells that turn into cancer.0:38
  8. It's so manifold that it's impossible to cover in one video so we'll make a series looking at different aspects of it.0:46
  9. Today, what happens when your body is invaded and your first lines of defences are engaged in a fight for life and death?0:53
  10. It's been a normal day when suddenly the world explodes and an asteroid rips the sky open.1:11
  11. Countless alien life forms invade, ready to destroy cities and infrastructure and eat civilians.1:18
  12. Or this is what your cells experience.1:25
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  1. You look at your bleeding thumb that you just cut on a dirty twig in the park.1:28
  2. How annoying.1:34
  3. But inside the wound a horrible catastrophe has happened.1:35
  4. There are dead cells and blood and dirt everywhere.1:39
  5. Even worse, countless bacteria invade the warm caverns between your helpless cells to explore their new home, steal your resources and poop everywhere.1:42
  6. Immediately, the first stage of your defense kicks in.1:53
  7. The cells that survive the impact or are hurt or dying scream in panic, releasing an onslaught of chemical alarm signals that awaken your immune system.1:57
  8. The first cells to show up are macrophages.2:07
  9. If an average cell with the size of a human, a macrophage would be the size of a black rhino.2:11
  10. A stoic cell in principle, but you wouldn't want to annoy it.2:17
  11. Bacteria do annoy them.2:22
  12. Within seconds, the large cells attack and begin killing them without mercy.2:25
  13. They stretch out parts like the arms of an octopus and grab the bacteria to swallow them whole and digest them alive.2:30
  14. A macrophage can eat 100 bacteria before it's exhausted.2:38
  15. But there are too many enemies, so the macrophages call for reinforcements.2:42
  16. In your blood, hundreds of thousands of neutrophils pick up their signals and move to the battlefield.2:47
  17. Neutrophils are intense suicide warriors that only live to kill.2:53
  18. They're so enthusiastic about killing that they kill themselves a few days after birth, so they don't have time to accidentally destroy your body from the inside.2:58
  19. As soon as neutrophils arrive, they begin vomiting deadly chemicals at bacteria or devour them.3:08
  20. They are so careless in their attacks that they are causing real damage to your own cells, but collateral damage is not their concern now.3:15
  21. Or ever.3:23
  22. Some neutrophils go so far to push their suicide button and explode, casting wide and toxic nets made from their own DNA filled with deadly chemicals that trap and kill3:25
  23. bacteria.3:36
  24. Sometimes they can continue fighting after that, even though they're sort of dead already.3:38
  25. This is how much fun they have killing.3:43
  26. While the battle rages, your blood vessels let fluid stream into the battlefield like a dam opening up towards a valley.3:46
  27. You notice this as inflammation, your thumb swells up a little and gets red and warm.3:53
  28. The fluid brings a silent killer into the battle zone, millions of complement proteins, a sort of automated liquid weapon that stuns and kills bacteria by ripping holes into them.3:59
  29. We made a whole video explaining them in detail.4:10
  30. We're reaching a crossroad now.4:13
  31. If things go well, your first line of defense kills the invaders quickly.4:15
  32. But sometimes the enemies are too strong and would overwhelm your defenses eventually, which means certain death for you, the human.4:20
  33. This is the hour of the dendritic cell.4:28
  34. Your immune system's intelligence officer.4:30
  35. While your soldiers were bashing in heads, it was collecting samples by ripping bacteria into tiny parts and covering itself in it.4:34
  36. Like a soldier decorating itself in the guts of a dead enemy.4:42
  37. The cell leaves the battlefield and enters the superhighway of your immune system that connects all your tissues with your immune headquarters, your lymph nodes.4:47
  38. The dendritic cell coming from the battlefield is looking for a helper T -cell, which is a sort of all -purpose commander cell within your immune army.4:56
  39. But not any helper T -cell, one that happens to have just the right weapon for the bacteria that infected your wound.5:05
  40. So it goes around and rubs itself, still covered in bacteria parts, against every helper T -cell it meets.5:12
  41. Most T -cells are a bit disgusted and not interested, but after a few hours, something clicks.5:19
  42. A helper T -cell recognizes the bacteria parts.5:26
  43. This cell is the weapon that's needed right now.5:30
  44. The dendritic cell is overjoyed and activates the helper T -cell.5:33
  45. Okay, wait.5:38
  46. How come your immune system has a cell that has a weapon against the specific bacteria that infected you?5:39
  47. Well, your immune system has a perfect weapon against every possible disease in the universe, against the Black Death, the Coronavirus, or an infection that will emerge in 100 years5:46
  48. on Mars.5:56
  49. We'll talk about this a bit more in the next video because it's very complex.5:58
  50. So for now, just know that you have billions of unique helper T -cells that each have weapons against every possible enemy.6:02
  51. After the right T -cell is activated, your second line of defense awakes and rises like a teenager that needs to get up on a school day, very slowly.6:09
  52. Your heavy weapons are incredibly effective, but they're not fast.6:20
  53. The activated helper T -cell begins to clone itself over and over again.6:25
  54. One becomes two, two become four, until there are thousands of them.6:30
  55. Now they split into two groups.6:34
  56. The first group quickly moves to help out your soldiers.6:36
  57. At the battlefield, things are getting out of hand.6:40
  58. A tired macrophage is ready to give up.6:43
  59. After fighting for days, it just wants to go to sleep, like many of its buddies have done already.6:46
  60. But now the helper T -cells arrive.6:52
  61. One of them comes to the tired macrophage and whispers something using special chemical signals.6:55
  62. In a heartbeat, the demoralized soldier feels fresh again.7:00
  63. But there's something else.7:05
  64. A hot, white anger.7:06
  65. The macrophage knows what it needs to do.7:09
  66. Kill.7:12
  67. Invigorated, it throws itself against the enemies once again.7:13
  68. All over the battlefield, this begins to happen.7:18
  69. Meanwhile, the second group of helper T -cells was working on activating another line of defense, B -cells, your antibody factories.7:21
  70. Antibodies are protein superweapons that look like tiny crabs with two pincers to grab enemies.7:30
  71. Just like the helper T -cells, there are B -cells in your body that are able to make just the right antibodies for every possible enemy.7:36
  72. And the helper T -cell is looking for exactly these B -cells.7:43
  73. After a day or two, the right B -cell is found and begins to clone itself.7:47
  74. As soon as enough clones have been made, each B -cell begins pumping out up to 2 ,000 antibodies per second.7:52
  75. About a week after you injured yourself and bacteria invaded, your second line of defense finally arrives in full force.7:59
  76. The tiny army begins to saturate the battlefield, pinching and stunning desperate bacteria.8:07
  77. The antibodies clump them together and make them unable to move or fight, while your soldiers massacre the defenseless victims.8:13
  78. The tide is turning fast.8:21
  79. As the last enemies are cleaned up, your soldiers realize they are no longer needed and begin to kill themselves to save resources.8:24
  80. But not all of them.8:31
  81. A few helper T -cells remain and turn into memory cells.8:33
  82. They will guard the tissue for years, making sure the same bacteria will never again gain a foothold here.8:37
  83. Similarly, a few B -cells will stay alive and keep producing a low amount of antibodies, making you immune against this bacteria, maybe for the rest of your life.8:44
  84. One day you wake up and notice that the wound has grown over and left nothing but a faint red mark.8:54
  85. You were completely unaware of the drama your cells had to deal with.9:01
  86. For you, the whole ordeal was a slight annoyance, while for millions of cells, it was a desperate fight for life and death.9:05
  87. But this is just the beginning of the epic story that unfolds inside you every day and is told in full in Immune, a journey into the mysterious system that9:15
  88. keeps you alive, written by Philip Depma, the founder and head writer of Quartz -Kazakh.9:24
  89. The book is a beautifully illustrated deep dive into the immune system, the most important thing you don't know enough about that will forever change how you think about your9:29
  90. body.9:38
  91. Written to be as simple and fun as possible, it's been an ongoing passion project for almost a decade because the immune system is just about the most amazing and9:39
  92. fascinating topic there is.9:47
  93. So go on a journey and get to know your own body, from mystery organs, murder universities, to the largest library in the universe.9:49
  94. Explore how incredibly vast your immune system is and how it actually works, how it fights enemies from cancer to HIV or just the flu.9:57
  95. Learn how you can boost it and if that's actually a good idea.10:07
  96. The book will be out in six weeks and it would mean the world to us and Philip if you could pre -order it.10:11
  97. Pre -ordering is super important in the world of books and in contrast to games we can guarantee that it's actually finished and there will be no day one patch.10:16
  98. There's a link in the description.10:26
  99. This is the end of a decade long personal journey and we'd love to see what you think.10:28
  100. Thank you for watching.10:33

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Tingkat CEFR
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Kata yang perlu diketahui
microorganisms, demoralized, antibody, pincers, awakes, crossroad
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