What happens to our body in sleep?

Sleep is as important to the body as food, water or air. After a whole day's toil, both brain and body get tired. Sleep is necessary to restore energy and freshness to the tired organs and tissues of our body. It restores our vitality and refreshes us again.

Do you know how sleep comes to us and what happens to our body during sleep? According to scientific facts, there is a very complex area in the brain called "sleep centre". Calcium ions present in the blood, control this centre. When an optimum quantity of calcium is received by the "sleep centre", we get sleep. It has been observed from experiments on animals that they start sleeping when calcium is injected directly into the sleep centre. But if calcium is injected into the blood stream, this does not happen. So it seems that the sleep centre must first be "sensitized" by certain chemical substances, produced when we are tired, before it would react to calcium and put us to sleep. During sleep, the sleep, the sleep centre does two things. Firstly, it blocks off the brain so that we have no will-power or consciousness and secondly, it blocks all nerves leading from the brain so that our internal organs and limbs fall asleep.
In sleep, our body does many types of movements. A man on an average changes his sides 20 to 40 times during sleep in one night. Blood circulation continues during sleep. Heart beat slows down a little bit. The digestive system works normally. Liver and kidneys perform their functions. The effect of sound, liht, heat, smell etc. in sleep are the same on every sleeping person. During sleep, the body temperature is lowered by about one degree centigrade. During sleep the body cells are quietly engaged in getting rid of waste materials that have accumulated during the active part of the day.
How many hours a healthy person should sleep? The number of hours needed varies with individuals. the average adult needs from 7 to 9 hours of sleep. Boys and girls of 15 years of age need about 10 hours sleep each night. It is wise to form the habit of going to bed at the same time each night. If you have trouble in getting sleep. you should not take sleeping pills unless prescribed by the physician or medical practitioner.

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How long can man survive without food?

Like air and water, food is also essential for all living beings. From the smallest insects to the biggest animals-all need food for their survival. So much so that even plants and trees can not live for long without food. Most of us feel upset if we skip just one meal, and if we try to go without food for 12 hours we would really be uncomfortable.

Energy required for doing work is obtained from food. Cells and tissues damaged in working are repaired by it. It is very much needed for the growth and development of the body. In short, food is very essential for the proper functioning of the body.
Now the question arises how long can we survive without food? There are some animals which can store food in their bodies and live on it for a long time. It has been observed that the smaller and the more active is the animal, more rapidly it consumes its stored food. Warm blooded animals use up their stores of food in the body more quickly. A dog can survive without food for 20 days at the most. However, the bug is such a wonderful creature that it can survive without food for one full year.
But man cannot store food in his stomach. If he misses one meal, his condition is bad. Food is required to maintain the flow of blood. All the constituents of blood are obtained from food. The moment, the blood lacks nutritional materials, a signal, via blood, goes to the hunger centre of the brain and we start feeling hungry.
There are few examples of persons who survived for a very long time without food. Angus Warviern of Scotland survived without taking any food for 382 days i.e. from June 1965 to July 1966. During this period, he took only coffee, tea, water and soda water. One south African woman survived for 102 days on water and soda water only. Stefan Taylor of New Zealand remained alive for 40 days in 1970 on a daily intake of one tumbler of water only. These are some uncommon examples. Such people are endowed with exceptional power. Common man can at the most survive without food for a week.

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What is Regeneration?

Would it not be wonderful if people who lost an arm or a leg or even a finger in an accident could simply grow another one in its place? But in reality it does not happen in case of human beings. However, you will be surprised to know that there are some living beings in which a new limb

develops at the point from where the original limb has been lost. Development of a new part in place of a lost part is known as regeneration. Some creatures have the unique ability to regenerate their body parts. If small arm of a starfish is cut off or destroyed, it is regenerated. The hydra is also endowed with this wonderful capability of regeneration.
The ability of regeneration is different in different creatures. Living beings with complicated structures have lesser ability of regeneration. Man and other mammals have complex constitution. That's why they have lesser ability of regeneration. Because of lesser ability of regeneration, once our legs or hands are cut, they are not regenerated. Though in our body also, some type of regeneration takes place. For example, if the skin in any part of the body is burnt or cut, new skin comes up there again. Regrowing of wings of birds is another example of regeneration.
In some species new tissues grow from the surface of the wound and replace lost or damaged tissues. Sometimes, the tissues that an organism regenerates, are different from original tissues. The regenerated structure may be smaller than the original.

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How is the Rainbow formed?

During the rainy season you might have observed a bow shaped multicoloured strip in the sky. This is called rainbow. This strip has seven colours-red at the top and violet at the bottom. Other colours lie in between these two. How is the rainbow formed?
The sunlight which appears to be white is actually composed of seven colours. These seven colours are-Violet, indigo, blue, green, yellow, orange and red. The wavelength-wise distribution of these colours is called spectrum. After the rains, the atmosphere is full of small water-drops. When the white light coming from the sun enters these drops, its seven colours are separated. These rain-drops work like prisms. As the prism separates the seven colours of white light, these drops also sweparate the different colours. The separation of seven colours of the sunlight is called dispersion. These colours after being totally reflected from the back side of the rain drops come out as separate colours. When the rays of these colours reach our eyes, they give us the appearance of the rainbow. The rainbow is circular because the sun is also circular. Sometimes a second rainbow can also be seen. This is called secondary rainbow. This is fainter in comparison to the first one and the sequence of its colours is reversed i.e. violet colour occupies the upper most position while the red is the lower most. This rainbow is formed due to those rays which have been reflected twice inside the water drops. The rainbow is generally seen only when the sun is at our back and the cluster of water drops are in front of our eyes, i.e. when we stand in between the sun and the cluster of water drops. It is essential for the formation of the rainbow that the sun is shining after the rain. It is also essential that the sun, our eyes and the centre of the rainbow lie on the same straight line. To remember the order of colours in the spectrum, we should remember the word VIBGYOR. Each letter of this word represents one colour i.e. V for violet, I for indigo, B for blue, G for green, Y for yellow, O for orange and R for red.

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Why does the dog go mad?

 Dog is regarded as a faithful friend of man. But when it goes mad it is most dangerous. Biting by a mad dog leads to death if not treated properly. When a dog suffers from a disease called 'rabies', it goes mad. This disease is caused by a virus which is carried by the air or some wild animals and enters the dog's body through some cut or wound in its skin.
The virus is bullet shaped having a diameter of about 70 millimicron and a length of about 210 millimicron. It moves from the saliva-infected wound through sensory nerves to the central nervous system, multiply there and destroy brain cells. These viruses start showing their effect in 4 to 6 weeks' time. During this period the dog becomes lazy, suffers from fever and has no interest in food. When these viruses affect the brain, the dog gets excited. It growls and barks. saliva froths from the mouth. During this period, the dog can bite anybody. This is the stage when the dog is said to be mad. After such symptoms appear in the dog, it is likely to die within 3 to 5 days. When a mad dog bites a man, the viruses present in its saliva enter the man's body through the wound caused by the biting. Initially the victim experiences mental weakness and uneasiness followed by fever. Anxieties invade him. He suffers from lack of sleep and feels frightened. The muscles in the throat get slackened and he faces difficulties in swallowing food or drinking any liquid. He is afraid of water. That is why this disease is also called 'hydrophobia' which means 'fear of water'. The signs of this disease appear in the victim in one to three months from the time of dog-bite. If the dog has bitten at an upper part like the neck, mouth or head, it may take less time for the symptoms to develop. In cases of dog-bites, the affected portions should be immediately cleaned and arrangements made to start giving anti-rabies injections to the victim within three days of the bite. The dog should be watched for the next five days. If the dog does not die in that period, it should not be treated as a mad dog, and the treatment should be stopped since a mad dog must die within five days. A few years before, a daily injection of vaccine was given for 14 days or longer depending on the severity of rabies infection. In the early 1970s a new vaccine was tested. Now a days 7 to 10 injections are given, in case of a mad dog bite, to persons depending on the location of bite and number of bites on the body. The virus of rabies also attacks foxes, jackals, cats and rats. But they rarely transmit these viruses to human beings, because they have least contact with us.

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How do animals and plants survive in deserts?

A desert is an area where there is very little water and there is sand all around. Due to the scarcity of water, it is very difficult for animals as well as plants and trees to survive. Only those plants and animals which need very small quantities of water can survive in deserts.
There is a great variation in the temperatures of the days and the nights of deserts. Days are very hot, while nights are cool. To protect themselves from heat, during the day, the desert animals hide themselves in bushes. Whenever there is some rain, plants and animals store water inside their bodies. In deserts, you find many kinds of animals. Snails are found in abundance. American deserts have a kind of rat called 'pack rat'. A kind of animal named 'Jerboa' is found in the deserts of north Africa and Asia. Its hind legs are longer and it resembles the kangaroo. A variety of the wolf is also found in the Arab and African deserts. many kinds of lizards, owls, insects and ants are seen in derserts. All of these need very little quantity of water for survival because loss of water in the form of sweat and urine is very small. They excrete small quantities of urine which is very rich in urea nad uric acid. The camel occupies a very high position among the animals found in the deserts. It is also called the ship of the deserts. It survives on a diet of dry grass and thorny plants. There is a lot of fat accumulated in its hump and it is source of energy to the camel. It can survive without drinking water for several days. Water evaporates from its body at a slow rate. It can drink 25 gallons of water at one time. Its nose, ears and eyes are so constructed that they are not affected by sands. Mainly, two kinds of plants are found in deserts. One is shrub and the other is cactus. The shrubs have more of thorns and less of leaves. Because of lesser number of leaves, evaporation of water present in these plants is very slow. The trunk of cactus is thick and flashy. It has no leaves. It has only thorns. The upper layer of the trunk is very hard and hence water remains stored in the trunk. In some cacti, the ends of the thorns are pointed towards the earth. The dew drops deposited on these ends fall on the earth and thus moisture is maintained below the cacti. Their roots are also spread far and wide inside the earth. After long dry periods even if there is a little rain these roots immediately absorb water. The root of some cacti do not allow other plants to grow near them and thus the possibilities of more food and water increases.

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What is hypnotism?

Hypnotism is an art, with the help of which the mental state of a human being is so changed that he starts working according to the directions of the hypnotist. Man has been using hypnotic power since ancient times.
Previously, this was used to demonstrate some mysterious power, magic or miracles. Today, however, hypnotism is being studied in a scientific manner. This was started by Franz A. Mesmer, a doctor from Vienna. Hypnotism was known as 'mesmerism' for a long time after the name of Mesmer. The word 'hypnotism' was used for the first time in 1840 by James Braid, a surgeon from Scotland. This word has originated from the Greek word 'hypnos' meaning 'state of sleep'. In fact, a hypnotised person appears to be drowsing. His brain is so much influenced that he does any work according to the directions of the hypnotist. Hypnotic power is used over those persons only who are fully willing and ready to co-operate. Nobody can be hypnotised against his wishes. The person to be hypnotised is asked to sit in a dark room. The hypnotist then repeatedly tells his subject in a very calm voice to relax and sit comfortably. Thereafter, the subject is asked to concentrate his attention and focus his eyes on some object. When he gazes at that object for a long time, his eyes start getting tired. When this happens, he is asked to close his eyes. Now the subject is in a state of sleep. The hypnotist, at that moment starts giving his suggestions and directions to him. He is now hypnotised and does all that the hypnotist asks him to do. Hypnotism can make a person feel as if he is blind, deaf or dumb. It can make him shiver. Hypnotism can be used to frighten people. So much so that under the influence of hypnotism, a man can do things which he will never do in his normal state. When he regains his normal state, he forgets all that he did in hypnotised state. Hypnotism is being used very much these days in the treatment of patients suffering from various diseases. Dr. S. Del of England used to extract the teeth of his patients without putting them under anasthesia. Using this, he even operated upon the lungs of many people Hypnotism can also be used in removing mental anxieties.

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Why don't women have beard?

    The ways of nature are peculiar. Some living beings have hair on their bodies, while some others have wings on them. Broadly speaking, mammals have hair on their bodies, while birds have wings. Hair preserve the body-heat and protect the body from being burnt by the
scorching heat of the sun. It also helps us in realising the sensation of physiacal touch.
    Now the question is: why do men have beards, and women do not? This can be understood as follows.
    When a child is born, he has only fur like hair on the body. As he grows, hair become harder. Boys and girls reach puberty at the age of 11 to 13 years. There is faster growth of sex glands at this age. In man, the testes or other sex glands, produce a group of sex hormones known as 'androgens'. In woman, the ovaries or other sex glands, produce another group known as 'estrogens'. The function of the androgens is to regulate secondary male sex features such as the growth of facial and chest hair and deepening of the male voice at puberty. The function of the estrogens is to regulate secondary female features, such as the change in the size of breasts at puberty and the menstrual cycle. There are various other changes in men and women broyght about by these hormones. For example female body becomes soft and tender whereas, male body turns hard and strong. A special group of estrogens is called the 'progestrogens'; they are responsible for the regulation of pregnancy. Hence women do not have beards due to the absence of androgens.

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How do we lose our memory?

    Some people lose their memory after some accident or on hearing some tragic news.Such people forget their past and even fail to recognise their close friends and relatives.So much so they even forget their names.In psycholgy this disease is called 'amnesia'.
    Amnesia is caused by many factors.Head injury, metal shock, extreme tiredness, ill-effects of medicines, surgery of brain, phychological processes, old age
and after effects of drinking are some of the reasons which reduce or completrly destory memory.What ever may be the redsons causing amnesia,its effects on brain is almost the same in each case.Memory is said to be the brain as a"memory trace".What makes up this trace is not known. According to one theory each experience sets up an oscillating pattern or wave of electrical excitation in a group of cells. Each learning experience generates its own pattern of excitation. A given neuron may participate in thousands of separate memories but its removal will not diminish any of them.
    Memory is considered a three-part system. Sensory information store (SIS), short-term memory (STM) and long term memory. The SIS forms an instant, but very temporary, storage of every piece of information that come in. Information can last for only about three tenths of a second in the SIS. If it has not been selected and transferred to short-term memory within this time, it fades away.
    Short-term memory is used for carrying information a person needs for a few seconds, but can afford to forget later. Two characteristics of short term memory prevent its use as a permanent information store. First concentration is required to maintain a particular piece of information in it. Second, it is able to store only six or seven items such as a seven digit telephone number.
    For any information to be permanently stored, it has to be passed from short-term to long-term memory by the mechanism of rehearsal.
    The long-term memory has virtually unlimited capacity. It allows a person to remember events that have happened years before. Permanent memory takes place through structural changes in nerve cells, caused by patterns of electrical activity in these cells.
    When somebody suffers from amnesia, he forgets events either preceding it or following it. It can last for weeks, months or for years. There are people who have lost memory for life. When memory is restored, one remembers all the forgotten things but forgets every event which took place during the period when one had lost memory. One thing is however certain that in spite of the restoration of memory, some aftereffects do remain, thereby weakening the memory. In cases involving loss of memory, assistance of psychiatrists should be obtained immediately. Normally old age weakens memory, but sometimes peptic ulcer, high blood pressure, asthma etc. also affect memory.

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Why can't animals talk like us?

    In many stories,it is told that animals can also talk like us.But they do not talk like us.Amongst all the living beings,man is the only creature who can communicate with one another with the help of words.Even though,it is a fact that animals do not talk with one another with help of words.Even though,it is a fact that animals do not talk with one another like us,yet they also express their happiness, sorrow, fear etc.
with the help of certain gestures and sounds. you might have seen that when a cat passea by a group of birds,all the birds start chirping very loudly in apeculiar way. They actually express their fear of being caught by the cat.Similarly,the dog expresses its anger by barking and flattery by wagging its tail.The moneky also demonstrates its anger by making peculiar sounds.
    Do you know why animals cannot talk like us?This is because the brain of animal is less developed in comparison to the human beings.It is a fact that feelings are generated in the animals-but they lack words to bring them out So they are incapable of expressing their feeling in some language.They do it by some gestures and sounds.These feeling clearly bring out their love ,affection,anger,hostility etc .They have their own language of expresssing their hunger,thirst or protective needs.Even through they may not utter a sound,they continue uninterrupted communication between themselves.
    It may be pointed out here than ever today,we do not use language for saying everything.Instead ofsaying 'yes' or 'no' on many occasions,we shake our head or signal with hand to communicate our approval or disapproval.We can conclude that due to lesser development to their brain in comparision to ours, animals have not been able to develop words and language to express their feelings Hence they can't talk like us.

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