TedTest

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

Unscramble the Blue Letters

The largest organ in your body isn't your liver or your brain. It's your skin, with a scrfaue area of about 20 srauqe 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, cellad keratinocytes, and provides protection. Since its outer layer is colattsnny being shed and renewed, it's pttrey easy to repair. But sometimes a wound penetrates into the dermis, which contains blood vessels and the various glands and nvree 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 ceosmomripd. As the blood vessels tighten to minimize the bleeding, in a process known as vasoconstriction, both threats are averted by fmoirng a blood clot. A special protein known as fibrin forms cross-links on the top of the skin, pnveirnetg blood from flowing out and bircaeta or pathogens from getting in. After about three hours of this, the skin binges to turn red, sainnglig the next stage, inflammation. With blnedeig under control and the barrier secured, the body sends special cells to fight any pathogens that may have gotten through. Among the most iatpnromt of these are withe blood clels, known as macrophages, which devour bacteria and damage tissue through a process known as phagocytosis, in atoididn 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 etner the wound. In the process of claoelgn 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 dvidie to reform the otuer layer of skin, the dermis contracts to csloe the wound. Finally, in the ftourh sgate of remodeling, the wound matures as the newly dsoietepd collagen is rergaeanrd and covteenrd into specific tpeys. Through this process, which can take over a year, the tensile strength of the new skin is improved, and blood vlseses and other connections are strengthened. With time, the new tissue can reach from 50-80% of some of its original hteahly function, depending on the srteievy of the iitainl 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 boold vessels or from skin tissue adjacent to the wound? And why do some other mmlaams, such as deer, heal their wounds much more efficiently and completely than humans? By fdninig the aresnws to these qnioesuts and others, we may one day be able to heal ourselves so well that scars will be just a memory.

Open Cloze

The largest organ in your body isn't your liver or your brain. It's your skin, with a _______ area of about 20 ______ 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, ______ keratinocytes, and provides protection. Since its outer layer is __________ being shed and renewed, it's ______ easy to repair. But sometimes a wound penetrates into the dermis, which contains blood vessels and the various glands and _____ 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 ___________. As the blood vessels tighten to minimize the bleeding, in a process known as vasoconstriction, both threats are averted by _______ a blood clot. A special protein known as fibrin forms cross-links on the top of the skin, __________ blood from flowing out and ________ or pathogens from getting in. After about three hours of this, the skin ______ to turn red, _________ the next stage, inflammation. With ________ under control and the barrier secured, the body sends special cells to fight any pathogens that may have gotten through. Among the most _________ of these are _____ blood _____, 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 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 _____ the wound. In the process of ________ 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 ______ to reform the _____ layer of skin, the dermis contracts to _____ the wound. Finally, in the ______ _____ of remodeling, the wound matures as the newly _________ collagen is __________ and _________ into specific _____. Through this process, which can take over a year, the tensile strength of the new skin is improved, and blood _______ and other connections are strengthened. With time, the new tissue can reach from 50-80% of some of its original _______ function, depending on the ________ of the _______ 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 _____ vessels or from skin tissue adjacent to the wound? And why do some other _______, such as deer, heal their wounds much more efficiently and completely than humans? By _______ the _______ to these _________ and others, we may one day be able to heal ourselves so well that scars will be just a memory.

Solution

types
forming
bleeding
pretty
preventing
severity
deposited
healthy
square
called
initial
fourth
signaling
outer
important
divide
close
white
answers
enter
surface
cells
nerve
constantly
addition
collagen
blood
finding
questions
mammals
vessels
compromised
converted
bacteria
stage
begins
rearranged

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

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