full transcript

From the Ted Talk by Sarthak Sinha: How a wound heals itself

Unscramble the Blue Letters

The lraegst organ in your body isn't your liver or your brain. It's your skin, with a surface area of about 20 square feet in adults. Though different areas of the skin have different characteristics, much of this surface performs similar functions, such as sweating, feeling heat and cold, and growing hair. But after a deep cut or wound, the newly healed skin will look different from the sidrurounng area, and may not fluly regain all its abilities for a while, or at all. To uanresdtnd why this happens, we need to look at the structure of the hamun skin. The top layer, called the epidermis, consists mostly of hardened cells, called keratinocytes, and provides protection. Since its outer layer is constantly being shed and renewed, it's pterty easy to repair. But sometimes a wound pettarenes into the dirmes, which contains blood vessels and the various glands and nerve endings that enable the skin's many functions. And when that happens, it triggers the four overlapping stages of the regenerative process. The first sgate, hemostasis, is the skin's response to two immediate threats: that you're now losing blood and that the physical barrier of the epidermis has been compromised. As the blood vessels tighten to mizinmie the bleeding, in a process known as vasoconstriction, both threats are averted by fmriong a blood clot. A special peirton known as fibrin forms cross-links on the top of the skin, preventing blood from flowing out and bacteria or pathogens from getting in. After about three hours of this, the skin begins to turn red, signaling the next stage, inflammation. With bnledeig under crntool and the barrier secured, the body sdens sepaicl cells to fight any pathogens that may have gotten through. Among the most important of these are white blood cells, known as macrophages, which devour bacteria and damage tissue through a process known as phagocytosis, in aoidditn to producing growth factors to spur healing. And because these tiny sedrlios need to travel through the blood to get to the wound site, the previously constricted blood vessels now expand in a process called vasodilation. About two to three days after the wunod, the proliferative stage occurs, when fibroblast cells begin to etenr the wound. In the process of collagen dpisioteon, they produce a fibrous protein called collagen in the wound site, forming connective skin tissue to racelpe the fibrin from before. As eaimerpdl cells divide to reform the ouetr leayr of skin, the dermis contracts to cosle the wound. Finally, in the fuorth stage of remodeling, the wound matures as the newly deposited collagen is rearranged and cervnteod into specific tepys. Through this process, which can take over a year, the tensile strength of the new skin is improved, and blood vessels and other connections are strengthened. With time, the new tissue can reach from 50-80% of some of its ogiinral healthy function, depending on the severity of the iianitl wound and on the function itself. But because the skin does not fully roveecr, scarring continues to be a major clinical issue for doctors around the world. And even though researchers have made significant sdtries in understanding the healing process, many fundamental myetsreis remain unresolved. For instance, do flsarbobit cells arrive from the blood vessels or from skin tissue adjacent to the wound? And why do some other mammals, such as deer, heal their wodnus much more efficiently and completely than humans? By finding the answers to these questions and others, we may one day be able to heal ourselves so well that sacrs will be just a mmroey.

Open Cloze

The _______ organ in your body isn't your liver or your brain. It's your skin, with a surface area of about 20 square feet in adults. Though different areas of the skin have different characteristics, much of this surface performs similar functions, such as sweating, feeling heat and cold, and growing hair. But after a deep cut or wound, the newly healed skin will look different from the ___________ area, and may not _____ regain all its abilities for a while, or at all. To __________ why this happens, we need to look at the structure of the _____ skin. The top layer, called the epidermis, consists mostly of hardened cells, called keratinocytes, and provides protection. Since its outer layer is constantly being shed and renewed, it's ______ easy to repair. But sometimes a wound __________ into the ______, which contains blood vessels and the various glands and nerve endings that enable the skin's many functions. And when that happens, it triggers the four overlapping stages of the regenerative process. The first _____, hemostasis, is the skin's response to two immediate threats: that you're now losing blood and that the physical barrier of the epidermis has been compromised. As the blood vessels tighten to ________ the bleeding, in a process known as vasoconstriction, both threats are averted by _______ a blood clot. A special _______ known as fibrin forms cross-links on the top of the skin, preventing blood from flowing out and bacteria or pathogens from getting in. After about three hours of this, the skin begins to turn red, signaling the next stage, inflammation. With ________ under _______ and the barrier secured, the body _____ _______ cells to fight any pathogens that may have gotten through. Among the most important of these are white blood cells, known as macrophages, which devour bacteria and damage tissue through a process known as phagocytosis, in ________ to producing growth factors to spur healing. And because these tiny ________ need to travel through the blood to get to the wound site, the previously constricted blood vessels now expand in a process called vasodilation. About two to three days after the _____, the proliferative stage occurs, when fibroblast cells begin to _____ the wound. In the process of collagen __________, they produce a fibrous protein called collagen in the wound site, forming connective skin tissue to _______ the fibrin from before. As _________ cells divide to reform the _____ _____ of skin, the dermis contracts to _____ the wound. Finally, in the ______ stage of remodeling, the wound matures as the newly deposited collagen is rearranged and _________ into specific _____. Through this process, which can take over a year, the tensile strength of the new skin is improved, and blood vessels and other connections are strengthened. With time, the new tissue can reach from 50-80% of some of its ________ healthy function, depending on the severity of the _______ wound and on the function itself. But because the skin does not fully _______, scarring continues to be a major clinical issue for doctors around the world. And even though researchers have made significant _______ in understanding the healing process, many fundamental _________ remain unresolved. For instance, do __________ cells arrive from the blood vessels or from skin tissue adjacent to the wound? And why do some other mammals, such as deer, heal their ______ much more efficiently and completely than humans? By finding the answers to these questions and others, we may one day be able to heal ourselves so well that _____ will be just a ______.

Solution

  1. mysteries
  2. dermis
  3. memory
  4. protein
  5. deposition
  6. addition
  7. control
  8. replace
  9. largest
  10. minimize
  11. recover
  12. fully
  13. layer
  14. fourth
  15. surrounding
  16. types
  17. wounds
  18. close
  19. sends
  20. bleeding
  21. special
  22. stage
  23. scars
  24. original
  25. epidermal
  26. outer
  27. understand
  28. penetrates
  29. human
  30. wound
  31. fibroblast
  32. forming
  33. strides
  34. enter
  35. initial
  36. soldiers
  37. pretty
  38. converted

Original Text

The largest organ in your body isn't your liver or your brain. It's your skin, with a surface area of about 20 square feet in adults. Though different areas of the skin have different characteristics, much of this surface performs similar functions, such as sweating, feeling heat and cold, and growing hair. But after a deep cut or wound, the newly healed skin will look different from the surrounding area, and may not fully regain all its abilities for a while, or at all. To understand why this happens, we need to look at the structure of the human skin. The top layer, called the epidermis, consists mostly of hardened cells, called keratinocytes, and provides protection. Since its outer layer is constantly being shed and renewed, it's pretty easy to repair. But sometimes a wound penetrates into the dermis, which contains blood vessels and the various glands and nerve endings that enable the skin's many functions. And when that happens, it triggers the four overlapping stages of the regenerative process. The first stage, hemostasis, is the skin's response to two immediate threats: that you're now losing blood and that the physical barrier of the epidermis has been compromised. As the blood vessels tighten to minimize the bleeding, in a process known as vasoconstriction, both threats are averted by forming a blood clot. A special protein known as fibrin forms cross-links on the top of the skin, preventing blood from flowing out and bacteria or pathogens from getting in. After about three hours of this, the skin begins to turn red, signaling the next stage, inflammation. With bleeding under control and the barrier secured, the body sends special cells to fight any pathogens that may have gotten through. Among the most important of these are white blood cells, known as macrophages, which devour bacteria and damage tissue through a process known as phagocytosis, in addition to producing growth factors to spur healing. And because these tiny soldiers need to travel through the blood to get to the wound site, the previously constricted blood vessels now expand in a process called vasodilation. About two to three days after the wound, the proliferative stage occurs, when fibroblast cells begin to enter the wound. In the process of collagen deposition, they produce a fibrous protein called collagen in the wound site, forming connective skin tissue to replace the fibrin from before. As epidermal cells divide to reform the outer layer of skin, the dermis contracts to close the wound. Finally, in the fourth stage of remodeling, the wound matures as the newly deposited collagen is rearranged and converted into specific types. Through this process, which can take over a year, the tensile strength of the new skin is improved, and blood vessels and other connections are strengthened. With time, the new tissue can reach from 50-80% of some of its original healthy function, depending on the severity of the initial wound and on the function itself. But because the skin does not fully recover, scarring continues to be a major clinical issue for doctors around the world. And even though researchers have made significant strides in understanding the healing process, many fundamental mysteries remain unresolved. For instance, do fibroblast cells arrive from the blood vessels or from skin tissue adjacent to the wound? And why do some other mammals, such as deer, heal their wounds much more efficiently and completely than humans? By finding the answers to these questions and others, we may one day be able to heal ourselves so well that scars will be just a memory.

Frequently Occurring Word Combinations

ngrams of length 2

collocation frequency
blood vessels 5
outer layer 2
fibroblast cells 2
skin tissue 2

Important Words

  1. abilities
  2. addition
  3. adjacent
  4. adults
  5. answers
  6. area
  7. areas
  8. arrive
  9. averted
  10. bacteria
  11. barrier
  12. begins
  13. bleeding
  14. blood
  15. body
  16. brain
  17. called
  18. cells
  19. characteristics
  20. clinical
  21. close
  22. clot
  23. cold
  24. collagen
  25. completely
  26. compromised
  27. connections
  28. connective
  29. consists
  30. constantly
  31. constricted
  32. continues
  33. contracts
  34. control
  35. converted
  36. cut
  37. damage
  38. day
  39. days
  40. deep
  41. deer
  42. depending
  43. deposited
  44. deposition
  45. dermis
  46. devour
  47. divide
  48. doctors
  49. easy
  50. efficiently
  51. enable
  52. endings
  53. enter
  54. epidermal
  55. epidermis
  56. expand
  57. factors
  58. feeling
  59. feet
  60. fibrin
  61. fibroblast
  62. fibrous
  63. fight
  64. finally
  65. finding
  66. flowing
  67. forming
  68. forms
  69. fourth
  70. fully
  71. function
  72. functions
  73. fundamental
  74. glands
  75. growing
  76. growth
  77. hair
  78. hardened
  79. heal
  80. healed
  81. healing
  82. healthy
  83. heat
  84. hemostasis
  85. hours
  86. human
  87. humans
  88. important
  89. improved
  90. inflammation
  91. initial
  92. instance
  93. issue
  94. keratinocytes
  95. largest
  96. layer
  97. liver
  98. losing
  99. macrophages
  100. major
  101. mammals
  102. matures
  103. memory
  104. minimize
  105. mysteries
  106. nerve
  107. newly
  108. occurs
  109. organ
  110. original
  111. outer
  112. overlapping
  113. pathogens
  114. penetrates
  115. performs
  116. phagocytosis
  117. physical
  118. pretty
  119. preventing
  120. previously
  121. process
  122. produce
  123. producing
  124. proliferative
  125. protection
  126. protein
  127. questions
  128. reach
  129. rearranged
  130. recover
  131. red
  132. reform
  133. regain
  134. regenerative
  135. remain
  136. remodeling
  137. renewed
  138. repair
  139. replace
  140. researchers
  141. response
  142. scarring
  143. scars
  144. secured
  145. sends
  146. severity
  147. shed
  148. signaling
  149. significant
  150. similar
  151. site
  152. skin
  153. soldiers
  154. special
  155. specific
  156. spur
  157. square
  158. stage
  159. stages
  160. strength
  161. strengthened
  162. strides
  163. structure
  164. surface
  165. surrounding
  166. sweating
  167. tensile
  168. threats
  169. tighten
  170. time
  171. tiny
  172. tissue
  173. top
  174. travel
  175. triggers
  176. turn
  177. types
  178. understand
  179. understanding
  180. unresolved
  181. vasoconstriction
  182. vasodilation
  183. vessels
  184. white
  185. world
  186. wound
  187. wounds
  188. year