When we are born, our brains are a third of the adult size. In just three months, babies’ brains grow to half the size they are going to be. An adult brain weighs about 1.5 kg. Your brain is like a very powerful computer. It needs oxygen to do its work. It uses a quarter of the oxygen and half of all the energy used by your whole body. It can stay alive for five to ten minutes without oxygen. Your brain has enough energy to turn on a light bulb.
oxygen: n. a gas in the air that we need to breathe
Unit 7
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