大學(xué)英語(yǔ)綜合教程學(xué)生用書 The Brain

[00:00.00] The Brain [00:03.29]The brain is the most complicated part of the human body, [00:09.85]and yet less is known about it than any other part. [00:15.60]It is quite small(a normal hunman brain weighs about one kilogram), [00:22.65]and a bigger brain does not mean a better brain. [00:28.60]The surface area of the cortex(the outside part) [00:34.46]is more important than the actual size of the brain. [00:40.62]Over the centuries,the cortex has grown, [00:45.87]and it is now deeply folded in order to provide a larger surface [00:53.21]area without requiring a greater total volume. [00:59.48]The brain receives information [01:04.13]from the outside world through the Sensory System. [01:09.88]This information is gathered through the eyes, [01:15.62]the nose,the ears,the mouth and the surface of the body. [01:22.00]It is then stored in the memory which has a tremendous capacity. [01:28.95]In fact,scientists do not fully understand how the memory works [01:37.10]but they have not shown that there is any limit [01:42.03]to the amount of information that the human brain can store. [01:48.67]Also,it appears that the information is never lost. [01:55.02]Very old people often remember incidents from their childhood [02:02.25]which have not come to their minds for sixty to seventy years. [02:08.52]If we have stored something in our memory,it is there. [02:14.87]But can we get it out again to use it? [02:20.12]That is the difficulty. [02:24.38]Some of the information we receive only goes into the Short Term Memory; [02:32.82]We only keep this information for a minute or two,then we lose it. [02:41.28]Schoolchildren in class often seem to use only the Short Term Memory [02:49.04]if they are not interested in the subject. [02:54.29]Shoolteahcers have a description for this, [03:00.04]saying that things go"in one ear and out the other". [03:06.59]But if a child is interested, [03:11.24]he puts the information in his Long Term Memory,and he never loses it [03:18.50](though,of course,there are times when he cannot recall it). [03:25.17]The brain sends instructions to the body through the Motor System. [03:32.61]This tells the arms and the legs to move, [03:38.07]the eyes to focus,the hands to open and close, [03:44.42]the jaw to move up and down,etc. [03:49.46]Through the Motor system [03:53.30]we can even control our breathing for a short time.but not for long. [04:00.04]It is very difficult,however,to make the body do something that is bad for it. [04:07.88]Try to cut yourself with a knife,nor burn yourself with a match, [04:15.03]and you will find it is very difficult to do. [04:20.18]There is a third system which the brain controls, [04:25.53]but not consciously;this is called the Homeostatic System. [04:31.80]Through this system the brain tells the heart how fast to beat, [04:38.44]it tells digestive system how much food to absorb, [04:44.81]and it tells the glands in the body when to sweet,salivate,etc. [04:52.36]This we cannot normally control,though some fakirs, [04:58.50]or Hindu mystics,in the East have claimed that [05:03.75]they can control parts of the Homeostatic System. [05:09.99]So the brain is a complex and delicate part of the human organism, [05:17.44]and in addition to the three systems that have been mentioned, [05:23.60]the brain is able to work in special ways. [05:29.04]It can use the information that is stored in it to think creatively, [05:35.99]allowing the human race to make astonishing scientific, [05:42.23]artistic and technical progress. [05:47.09]It will be a long time before a computer is invented [05:52.94]that can do this because imagination is a very difficult thing [05:59.89]to build into integrated circuits and silicon ships.

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