What is blood? It is the red liquid which comes out of your finger when you cut it because of not being careful.There are about 13 pints (品脱) of blood in a man's body. He can give a pfnt of blood at a time to a blood bank for the use o other man who may need it. A healthy body makes up the pint of blood quickly.
What does our blood do for us? It takes food to all parts of our bodies and takes waste away from them. All the parts of our bodies are made up of cells, these cells, which are very small, all need food all the time. The blood is like a stream.The cells take what they need out of the blood stream, as plants and fishes take their food out of water. The blood stream carries food and the oxygen which it has taken up in our lungs to all the cells in the body.
What makes the blood go on moving round the body in a stream? The heart sends it round. The heart keeps a stream of blood going all around the body and back again to itself. Everywhere the blood stream does two things: supplies the cells with food and oxygen and takes away waste. It is as if the blood kept the little fires in cells burning and took away the ashes.
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