環(huán)球英語 — 681：Our Wonderful Blood
Voice 1
Welcome to Spotlight. I’m Adam Navis.
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And I’m Robin Basselin. Spotlight uses a special English method of broadcasting. It is easier for people to understand, no matter where in the world they live.
Voice 1
Eric was only sixteen years old when he got very sick. His parents took him to the hospital. A test showed that Eric had a blood cancer called leukemia. Leukemia causes blood cells not to clot, to not stick together like they should. If a person with leukemia is cut they may bleed and bleed. Their body cannot heal itself properly. Leukemia can also cause a body to attack itself. Normal blood keeps us healthy and strong. But when someone gets leukemia, it is as if their blood has become like poison.
Voice 2
Today’s Spotlight is on blood. Blood is an amazing part of our body. It is always moving and working. We talk about blood as a “river of life”. And this is not just nice language. Blood flows throw us like a river. It is the force of life within our bodies.
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Blood moves through us by the circulatory system. It is called the circulatory system because it is a kind of circle through the body. It begins in the heart. The heart pumps the blood through small tubes called blood vessels. The human body is full of blood vessels. If all blood vessels were put in a line, they would be over 100,000 kilometers long! Still, it only takes about twenty seconds for blood to reach every part of the body.
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The heart has to be strong to do this work. It needs to push about five to six liters of blood through the body. That is about eight percent of a person’s total weight. The heart is like an engine that moves the blood all around the body. And it is an engine that does not rest. It beats all day and all night. It starts while a person is still in his mother and continues for his whole life.
Voice 1
Blood does many important things for our bodies. When blood leaves the heart it goes to the lungs. The lungs then fill the blood with new oxygen. The blood carries this oxygen through the whole body. If the blood fails to bring oxygen from the lungs a person could die in just a few minutes. The lungs also remove waste from the blood, called carbon dioxide. Carbon dioxide is let out of our bodies into the air - through our breath.
Voice 2
Then the blood travels back to the heart. The heart pushes the blood out to the rest of the body. As it travels it does other things too. Blood takes other forms of waste to the kidneys. The kidneys separate the waste from the blood and release it out of the body in urine, liquid human waste.
Voice 1
Our blood also helps to defend the body from disease. It attacks viruses and harmful bacteria that enter the body. It also helps us to keep our body temperature normal. When the body works hard or is fighting a disease, its temperature rises. When this happens our blood vessels expand. This lets more blood flow through the body. The more blood that flows through the body, the cooler the body becomes. You can see this process when a person’s face turns red during exercise or when they are sick.
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Blood has four different parts. They are the plasma, red blood cells, white blood cells, and platelets.
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Plasma is important in three ways. First, plasma carries protein. Protein helps build the body’s tissues. Second, plasma has clotting factors. When we have a cut on our skin, plasma helps it to stop bleeding. Plasma makes sure that our bodies do not lose too much blood. Finally, plasma contains anti-bodies. Anti-bodies fight off disease. But anti-bodies do not have to fight alone. They work the second part of blood, the white blood cells.
Voice 2
White blood cells are like the army of the body. White blood cells attack bacteria, viruses, and small insects. They do this by attaching to them. After attaching, they destroy them. Some people do not produce enough white blood cells. These people have a hard time fighting off disease. They are often very sick.
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If white blood cells are the army of the body, then red blood cells are like the workers. Red blood cells carry the oxygen from our lungs to every other cell in the body. They give blood its red color.
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The final part of blood is the platelets. Platelets are another part that helps blood clot, or join together, when the body has an injury. When platelets mix with the air, they release a chemical. This chemical creates long string-like protein. These long strings gather red blood cells together. These are called scabs. They are what we see on the outside of our bodies while they are healing.
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Without blood, our bodies would not receive enough oxygen. Without blood, our bodies could not fight off disease. Imagine what would happen if we could not heal from small injuries on our own. We would be in the hospital all the time.
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Our circulatory system is very complex and helpful. And it is only one part of our bodies. Each part of our body works together to form an amazing machine. Most of the time we do not even notice all the things our bodies do for us. We just go about our lives. It is only when something goes wrong that we notice. Something like what happened to Eric.
Voice 1
Eric’s leukemia was bad. But another amazing thing about blood is that you can take blood from one person and put it in another person. This is a blood transfusion. Doctors took the sick blood out of Eric’s body. They replaced it with healthy blood. During his treatment Eric received over twenty-five liters of blood. Now, he has been healthy for three years. He has even been able to attend college. It was his blood that made him sick. But it was also blood that made him well again.
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