My Science School

          Memory can be defined as the capacity to keep information available for later use. The process of memory can be divided in to the four aspects - learning, retention and forgetting, and retrieval. The initial storage of information is called learning, keeping the new information available is called retention, the loss of new information over a period of time is called forgetting and utilization of stored information is called retrieval.

            According to psychologists there are four kinds of learning. Classical conditioning is the simplest kind of learning. Ivan Pavlov studied it during the early 1900. He offered a dog food and at the same time rang a bell. The sight of food made the dog’s mouth water. Pavlov called this an unconditioned response because it was not learned. Soon, however, ringing the bell was enough to cause the dog’s mouth to water. This was called conditioned response. Classical conditioning is often called respondent learning.

            Another form of learning is called instrumental learning. Often a person learns to do something as a result of what happens after the person does it.

Multiple response learning is the third type and it takes place when a skill is learned. A sequence of simple things must first be learned. Using a typewriter is our kind of multiple-response learning. At first, a person has to type letter by letter. With practice, the person learns to type word by word or phrase by phrase.

            Fourth type of learning is insight learning. It means solving a problem through understanding how the different parts of a problem fit together. A simple example is that of a young child wanting to climb on the top of a table. The child may use a stool to get on to the chair and then use the chair to climb onto the table.

           There are two basic theories to explain the process how we memorise events. According to one theory, memory is said to be stored in the brain as a memory trace. When we learn or experience something, impulses are generated in the nerves of the brain. These impulses impart their effects in the brain in the form of a record. According to the other theory, sensations created by learning produce some permanent changes in the brain which remain there in the form of memory. According to some biologists, the R.N.A. (ribo-nucleic acid) present in the brain keeps the record of events. It has been observed that the quantity of R.N.A. present in the brain keeps on increasing from the age of three to the age of forty. During these years, the memory of the man also increases. The quantity of R.N.A. is almost constant from the age of 40 to 55 or 60. Therefore man’s memory is almost consent during this period. After the age of 60, the quantity of R.N.A. starts decreasing and so does the memory.

           The only effective way of remembering something is to repeat it many times Interest is very important. Boring things are much more difficult to remember than something that we understand and are interested in. Motivation or desire to do something is also important.

 

          Every man in this world wishes to live long and nobody wants to grow old. But this desire of man is never fulfilled. Growing old is a process that begins with birth itself and continues throughout the life.

          When the child is born, all the parts of his body are tiny. All the biological processes continue with a fast speed. As man grows older, biological changes take place in the body. These changes cannot be prevented. Old age is the culmination of these biological changes. Do you know which are the biological changes brought about by old age?

          With the advancement of age, biological processes slow down, due to which the strength and sensitivity of man also diminish. This is because of the fact that the rate of production of proteins in the body decreases. Changes in the enzymes are also responsible for aging process. With reduced physical activity, man starts losing weight, his eye sight becomes weak and hair go grey. All these are the signs of the old age.

         In old age, changes occur in all the cells and tissues of the body. The cells of kidneys, liver and intestines become weak. Blood vessels become old and consequently they are not able to carry blood and other nutrients adequately to all parts of the body. As a consequence aging increases. As the age advances, eyes, ears, skin, teeth and digestion become weak. Blood circulation becomes irregular. Finally life comes to an end.

          The rate of growing old may be different with different people but old age spares none. This is a definite biological change which cannot be prevented. However, with the help of nutritional food, pure environment and proper exercises, early onset of old age can be prevented.

           There are many theories regarding baldness. Some people treat baldness as the indication of the arrival of old age while some are of the view that bald men are intelligent. Baldness is also treated as a sign of richness. Some people think that bald men are fools. Whatever may be the significance of baldness, one thing is certain that by losing hair, man is deprived of his natural charm.

           Baldness or alopecia is mainly of two types: permanent and temporary. Heredity, age and male sex hormone (androgens) production are three main factors causing permanent baldness. Other causes of permanent baldness are scar producing skin diseases, injuries, inborn lack of hair development and severe injury to hair growing centers caused by chemical or physical agents. Disease of the scalp is one important cause of baldness.

           Temporary baldness may be due to high fever, typhoid, pneumonia, influenza etc. Hairs start falling due to weakness also. Baldness caused by disease and weakness can be cured by nutritive diets and tonics. X-rays, ingestion of meals and drugs, malnutrition, skin disease and endocrine disorders are some other causes of temporary baldness.

          Baldness can be controlled to some extent through proper care of hair and a balanced diet. No successful drug or therapy has yet been developed to treat baldness. Don’t waste money on advertised patent medicines or so called, “cures”!

 

Just as carbohydrates, proteins, fats, inorganic salts and water are the essential parts of our food, vitamins are also necessary to keep the body in good health. Lack or deficiency of vitamins can cause many disorders and diseases like loss in digestive power, weakening of eye-sight, general weakness, tiredness, dryness of skin, inflammation of gums, weakening of bones, beriberi, rickets, etc.

What are vitamins? The word vitamin was coined in 1912 after the Latin word ‘vita’, which means life. In fact, vitamins are organic materials which are found in many food substances and are extremely essential for the proper functioning of the body. They are of many kinds and each vitamin has a separate role in keeping our body healthy. Twenty kinds of different vitamins have already been isolated, out of which six vitamins are most important. These are vitamins A, B, C, D, E, and K.

Vitamin A: Vitamin A is mainly found in milk, butter, cream, cheese, eggs, fish-oil, cabbage etc. It is very essential for the development of the body. Deficiency of vitamin A weakens eye sight and leads to night blindness. Vitamin A protects us from infections, skin diseases and many eye diseases.

Vitamin B Complex: Vitamin B consists of many water soluble vitamins of the same nomenclature. They are known by their chemical names. Their constitution and functions are also different.

Continue reading "Why are vitamins essential for us? "

          The normal body temperature of a healthy man is 98.4°F (37°C). Fever is a condition in which the body temperature rises above the normal. It is a common symptom of disease.

          The heat energy produced by the chemical reactions taking place inside the body is controlled by brain and skin. As long as there is no disease or malfunctioning in the body, the temperature remains 98.4°F. When germs of some specific disease attack the body, pyrogens are produced in the body cells. Consequently, the centres controlling the body temperature are affected and, as a result, body temperature starts rising. This rise in temperature is called fever. The first signs of fever are chills, loss of appetite and a feeling of weakness.

          Fever is a body mechanism that helps us in destroying the germs of diseases. During fever, some of the body organs start working fast and some physiological processes get accelerated. The rate of production of hormones, enzymes and blood cells increase considerably. These hormones, enzymes and blood cells start fighting the germs causing fever. During fever, blood circulation and respiration become faster. Both these processes help the body in getting rid of the poisonous germs present in the body. Fevers are often the symptom of a serious infection.

          There are various kinds of fever – malaria, typhoid, etc. Persistence of any fever for a longer period is not good. During fever, the internal parts become hot and there is deficiency of water causing the contraction of the capillaries of blood and urinary tracts. Protein accumulated in the body gets depleted. Disorder sets in the brain due to high temperature. It is, therefore, a big mistake on the part of anybody, if he or she ignores fever. Though fever is a physiological activity aimed at fighting any disease, it is extremely essential to seek immediate medical assistance once you get it.

A fracture is a break in a bone. Bones may break or fracture in several different ways. A simple fracture is one in which the two ends remain in position, and not much damage is done to the surrounding tissue. In a compound fracture, the broken bone sticks out through the skin. A comminuted fracture is a bone that has splintered or shattered. An impact fracture involves the ends of two bones rubbing each other. A greenstick is a partial break of a bone. In other kinds of fracture large blood vessels may be damaged or the bone ends may be smashed.

A fracture causes pain and inflammation in the area around it. Usually, when a fracture occurs, a doctor must set the bone right so that it may heal properly. A plaster cast is often applied to the limb with the fracture to assure proper healing.

The healing process begins when blood from broken blood vessels clots. After a few days the broken ends of the bone become soft and the space between them is filled with sticky ‘glue’ which contains bone forming cells.

Within two or three weeks, new soft bone tissues completely fill the gap between the broken ends. They slowly harden. The complete healing of a fracture may take several months. The only necessary condition is that the two broken pieces must be held in place for several weeks so that they can grow together properly.

Older people with brittle bones are most apt to get a fracture. Children tend to resist fracture.

             When your skin gets a cut, the broken blood vessels immediately become very narrow. This stops excessive bleeding and helps to keep germs out of the blood. Then substances released into the blood cause it to clot. The blood clot holds the edges of the wound together and hardens into a protective scab.

             Meanwhile white blood cells called neutrophils rush to the wound and begin to engulf the invading germs of dangerous bacteria. Then larger white cells called monocytes appear and engulf more germs, together with any debris. Any germs that escape are dealt with by a third kind of white cells called lymphocytes. These recognize germs as being ‘foreign protein’ or antigens. Then they start the production of antibodies, which are protein substances that stop germs working.

                      In the lower layer (the dermis) of the skin, special cells called fibroblasts move into the wound and start producing new tissues. These new tissues are essential for the healing of the wound. In the upper layer (epidermis), the cells around the wound start multiplying and filling the gap. When the process of new skin tissue development beneath the scab is nearly complete, the scab falls off. In this way the wound gets healed. 

             During the past two decades bio-engineers have developed a number of artificial substitutes for diseased tissues and organs. Some of these, such as, kidney dialyzers are external devices. Other such as plastic heart valves and artificial blood vessels are implanted inside the body, replacing the diseased or damaged ones. Two devices - the dialyzer and artificial heart valves are of special interest.

           The artificial kidney or dialyzer performs the function of removing wastes from the blood of a person whose kidneys do not work properly. It is an external device and patient needs dialyses twice a week. With this machine a person can be kept alive for years.

            In April 1969, Dr. Denton A. Cooley of St. Luke’s Episcopal Hospital in Houston placed a Dacron and silastic heart (artificial heart) into a dying man. Three days later a cadaver heart became available and was used to replace the artificial device. The next day the patient died. Some 13 years later, at the university of Utal medical centre, an artificial heart powered by a 170 kilogram external system, was implanted in the chest of 62 years old Barney Clark. He died 112 days later of multiple organ collapses. The heart was in perfect working condition.

        In 1984-1985, several artificial heart implants were performed in the United States and Sweden. Good life spans have been achieved but against a tremendous cost.

       Artificial teeth have been used by humans for a long time very successfully.

       The heart, the lung, the liver, the kidney, the adrenal glands and cornea can be transplanted from one human being to another. Success rate of transplantations of human organs is much higher than that of artificial parts.

 

 

 

            In many stories it is told that animals can talk like us. But this is our imagination only. Amongst all the living beings, man is the only creature on earth who can communicate with the help of words or speech. This is because of the higher development of our brain. Because of a less developed brain, animals have not been able to originate words or a language to express their feelings. Hence they can’t talk like we do.

            It is a well-established fact that the animals too feel happiness, sorrow, fear, love, affection, hostility, hunger, thirst or protective needs etc. as humans do. Because they are incapable of expressing their feelings in words, they express or communicate to each other or to humans, with the help of certain gestures and sounds, which may or may not be familiar or understood by us. You might have seen when a cat goes near a group of birds, all the birds start chirping very loudly in a peculiar way. They actually express their fear that they may be caught by the cat. Similarly a dog expresses its anger by barking and its feelings of flattery by wagging its tail. A monkey demonstrates its anger by making peculiar sounds.

              Bark is the protective outer covering of tree branches, trunks and roots. Bark has three layers. The outer layer called periderm is made of dead cells, such as cork. Periderm is usually thick. It protects the tree against weather, insects and diseases. The middle cortex layer is made of living, non growing cells. The innermost phloem brings food made in the leaves, down to the roots. The periderm of some trees has small openings called lenticels. Lenticels allow gases such as oxygen and carbon dioxide to enter and leave the plant.

             As wood is laid down inside a shoot, a layer of cells near the outer side begins to divide and produce cork cells. The walls of these cells soon get heavily thickened with a waterproof substance. The cells die and form bark.

           Over the years the bark is constantly added to form the inside of the tree. So as the diameter of the twig, branch or trunk increases, the waterproof barrier is maintained. But the outer bark often splits and cracks or becomes flaky.

           As already mentioned, the bark protects a tree from the weather and sudden temperature changes. It contains substances that repel insects and resist fire. Bark often has commercial uses. The actual cork comes from the bark of the Mediterranean cork oak. The drug Quinine is obtained from the bark of Cinchona trees and Cinnamon comes from the bark of the Cinnamon tree. Cough medicines and many other useful substances are also obtained from the bark.