[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.