WHY DOES THE BLOOD GROUP VARY FROM PERSON TO PERSON?

BLOOD GROUP -

Even though the blood of all the human beings looks alike, in reality, it is not so. Our blood is mainly composed of red blood corpuscles, white blood corpuscles, platelets, and plasma. It has been observed from microscopic investigations that molecules of antigens found on the surface of red blood corpuscles are different in different people. Antigen molecules are a kind of proteins that stimulate the production of antibodies. It is this difference in the antigen molecules that give rise to different groups of blood.

In the year 1900, Dr. Karl Landsteiner discovered two kinds of antigen - `A' and `B' type. He was awarded the Nobel Prize for medicine in 1930 for this discovery. Blood containing 'A' type antigen was classified as A group, while that containing 'B' type as B group. Subsequently, it was discovered that the blood of some people contains both A and B type antigens. This type was classified as AB group. The blood that contained neither A nor B type antigens was called O group. Thus the blood of all human beings has been divided into four groups. Studies made till now have revealed the existence of more than 200 groups of human blood.

However, as far as the transfusion of blood to any patient is concerned, only the aforesaid four groups of blood are important. Before transfusing blood to any patient, it is essential to get his blood group tested. It is very essential to match the blood of the patient with that of the donor before transfusion. It has been found that the blood of even real brothers and sisters may not be of the same group. On the other hand, the blood of two individuals belonging to two different states may be of the same group.

If the wrong blood transfused to the patient, he can die, because antigens of different classes cannot combine with each other. However, the blood plasma of one individual can be given to another because it is the same in everybody. Landsteiner and Alexander S. Wiener discovered another important blood antigen in 1940. This additional factor is called the Rhesus antigen or Rh factor.

Rhesus antibodies do not occur in naturally blood groups - both for recipients and donors. 'AB' group is called the universal recipients whereas `O' is the 'universal donor.

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WHEN DID THE FIRST ALPHABET APPEAR?

ALPHABET -

The origin and development of any language can be traced back to the rudimentary symbols the primitive people used in their verbal interaction. These symbols, when used over a long period, take an established pattern thus giving rise to a new language, But the growth of a language does not stop at oral communication a script for writing is also to be developed. But when did the first alphabet that enabled man to express himself in writing?

The earliest people used pictures for writing which we call pictograph. The stone age people used this form in their writing. In pictograph, a particular sign represents an object such as a tree or a bird which in turn communicates a specific meaning or idea. Ideas could be communicated through picture writing in the sense that the picture of a bird might mean flying.

The ancient Egyptians also used picture writing. But this form had its limitations. It required thousands of pictures, which were also called characters, to symbolize a few things. This drawback of pictograph led to the discovery of signs that represented sounds used in verbal communication. These signs representing different sounds were grouped differently to form new words. But when did the sound-signs first appear which we now call alphabet?

About 3500 years ago, the Phoenicians in the eastern Mediterranean, invented the first alphabet. Later the Greeks and Romans developed their own alphabet which were improvements of the Phoenician script. In fact, the word 'alphabet' is derived from two words alpha (a) and beta (b) which were the first two letters in the Greek alphabet. The appearance of the alphabet made it easier to create thousands of words using a few alphabets. For example, there are only 26 letters in English alphabet but just imagine how many words we make out of these 26 letters. Pictograph lacked this advantage since one picture represented only one meaning or idea.

Now, most of the languages in the civilized world have their own alphabet but the number of letters in the alphabet and their pronunciation differ from language to language.

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WHY IS CUTTING OF NAILS AND HAIR PAINLESS?

NAILS AND HAIR -

You may have noticed that whenever any part of our body is cut, we experience tremendous pain but when we cut out our hair or nails, we do not feel any pain. Do you know why is it so?

We have, in all, twenty nails on our hands and feet. We do not experience any pain in cutting them because they are composed of dead cells. Nails are special structures of the body formes from the outer layer of the skin. They are made up of a hard material called keratin. Keratin is a kind of dead protein. The base of the nails is located inside the skin of the fingers. The skin beneath the nails is similar to that in other parts of the body, but it has flexible fibers. These fibers are attached to the nails and keep them in a fixed position. Generally, nails are thick but their roots in the skin are very thin. The portion near their roots is white and semi-circular. It is known as lunule. The fingernails grow at the rate of about 2 inches per year. Nails are very useful for our body. They help us in picking up things as well as in doing artistic work. They protect the fingertips too. For ladies, nails are an object of beauty.

Similarly, hair is also a filamentous structure made of keratin - a dead protein. The hair grows on our head about 13 millimeters each month. We have about 100,000 hairs on our head. the base of the hair - the root, as it is often called, is in the form of a round Bulb. About 50 to 100 hairs fall every day. Each hair usually lasts for about 3 years and then it falls. New hairs grow to replace the fallen ones. They grow out of pits in the skin and are called foliates. And, it is the shape of these follicles that make our hair straight, wavy or curly.

Men and women from very ancient times have practiced the custom of cutting and styling the hair. Hairdressing occupies a very important position in grooming and beautification in the present time.

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WHY DO SOME PEOPLE SNORE DURING SLEEP?

SNORING -

You must have definitely come across people who snore during sleep. Their mouth remains open and a peculiar sound comes out while breathing. Do you know why this happens?

Normally, people breath through the nose. But some people's nose remains blocked due to some reason. And thus they breathe through the mouth. Sleeping on the back can also make a person snore. When we are asleep and breath through the mouth, the air coming out causes our soft palate (tissue at the back and top of our mouth) to flutter back and forth. Thus, a strange sound of snoring is produced. Often this vibrations also causes cheeks, lips, and nostrils to vibrate which produces an even louder sound. When we are awake, the palate remains tight and, therefore, no such sound is produced.

If we clean our nose and mouth before sleeping, snoring can be controlled to some extent. This increases the possibility of breathing through the nose rather than through the mouth. If one develops the habit of breathing through nose, the possibility of snoring is greatly reduced.

Breathing through the mouth is harmful to health. The germs of many diseases can enter directly into the mouth and causes disease. If we breathe through the nose, the hairs present in the nose do not allow these germs to enter into the body. It is, therefore, advisable to develop the habit of breathing through the nose.

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WHO WAS MICHAEL FARADAY?

MICHAEL FARADAY -

The great scientist Sir Humphry Davy was once asked by a friend to name his greatest discovery to which he replied ' Michael Faraday'. Faraday was then working as his assistant. Later his contributions in the field of electromagnetism and electrochemistry led to the invention of many things including dynamo and motor.

Born in 1791 in a poor blacksmith family, Faraday began his career at the age of 13 as an errand boy in a bookshop and moved along the pavements of London carrying and delivering newspapers. But his curious and inquisitive mind accompanied by hard work enabled him to reach great heights. His considerate employer in the bookshop taught him the art of book production. Thus Farady found an access to books and devoted his spare time to reading. He had always the inherent desire to achieve something great.

One day, Faraday got the opportunity to attend a lecture by Sir Humphry Davy. Faraday noted down his lectures and sent them to Sir Humphry along with suitable diagrams,. In return, Sir Humphry offered him the post of a laboratory assistant and Faraday served him for a long time. When Faraday got the opportunity to work on his own, his genius flourished. Chemistry was his first love and he invented stainless steel, liquid chlorine, new kinds of optical glasses, benzene etc. He also propounded the laws of electrolysis. He got instant fame when he ventured into the field of electricity. Oersted had earlier discovered that electricity could produce magnetic effects but Faraday started thinking of the reverse phenomenon. He thought if electricity could produce magnetic effects then there must be a way for magnetism to produce electricity. Later he invented the 'magneto-electric machine' that had a spinning disk became the forerunner of a dynamo. A dynamo converts mechanical energy into electrical energy. It consists of a powerful magnet and in between the poles of it, a suitable conductor (a coil) is rotated. The mechanical energy generated by rotation is thus converted into an electric current in the coil.

Faraday could not make money out of his inventions as he never bothered for money. Though at some stage of his life he earned a lot of money, he remained poor in his later days. He was generous, charitable and deeply religious. He died in 1867.

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DOES A BLACK CAT BRING BAD LUCK?

BLACK CAT  -

Have you heard someone telling you that a black cat crossing the road is a bad omen and you should not walk on the road if the cat has just passed by? Do you know why a cat in general and a black cat, in particular, is considered inauspicious?

Superstitions have taken various forms over the centuries but one of the most common superstitions that still prevails is that of the 'black cat'. Many people all over the world regard the site of a black cat as inauspicious.

The thought that a black cat is inauspicious in a mere superstition. This superstition goes back to a belief of thousands of years. The ancient Egyptians worshipped cats. They had a goddess called PASHT whose head resembled that of a cat. They believed that this goddess had nine lives. Whenever a black cat died in Egypt, its dead body was preserved as a mummy (the preserved corpse of a human being or animal). Remains of thousands of black cats have been recovered from a cemetery of Egypt. Killing a cat was then considered an offense, punishable with a death sentence. Thus people had a great fear of the sight of a black cat.

During the middle ages, witches and witch doctors always used the skull of a black cat to prepare mysterious medicines. As a result, people started thinking that a black cat brought bad luck and was a bad omen. People have believed in this superstition for many centuries. The truth is that no cat is inauspicious. The cat is a pet animal being domesticated from past 5,000 years.

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WHY DOESN'T FROZEN FOOD GET SPOILED?

FROZEN FOOD -

Have you ever wondered why we store perishable foodstuff in the freezer compartment of our fridge? It is because frozen food does not decompose for a long time and can be preserved for many months. There is an interesting fact about the discovery of the method of preserving food through low temperatures. In 1798, some explorers from Norway camped at the mouth of the river Lena in Northern Siberia. All of a sudden their dogs started barking aloud. When the explorers came out, they found the dogs digging in the snow. As they dug deeper they found the huge body of a dead mammoth. The flesh was dry. The explorers then hacked off a piece and cooked it. They found that it tasted like fresh meat. The last mammoths had died out about 30,000 years ago. This was a dramatic discovery. It meant that food could be preserved over such long periods. Since then, the man started preserving food at low temperatures.

What keeps food from getting spoiled at low temperatures? Food materials decompose because of the microscopic organisms called bacteria. At normal temperatures, bacteria flourish and multiply very fast and decompose the food. But at low temperatures, especially when the water present in the food material is frozen, the bacteria become inactive and stop growing. And thus, the frozen food can be preserved for a long time.

Nowadays, several techniques are being employed to preserve food materials. Among the important ones are the cold storage and freezing of foodstuffs. For the cold storage, many factors are to be kept in the mind. The type of food, the storage temperature and the amount of moisture in the storage room have to be taken into consideration. Cold storage temperatures range from 1Deg.C to 10 Deg.C. Freezing, however, is accomplished with dry ice (solid carbon dioxide), liquid air or nitrogen. Although freezing does not destroy the nutritive value of foods, some vitamins may be lost.

Domestic refrigerators are now widely used for food preservation. But, in a refrigerator, we can't preserve food for a long period. By using low-temperature techniques, great quantities of ice cream, frozen meat, fish, fruit, and vegetables are imported and exported throughout the world every year.

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