My Science School

          Before the discovery of anaesthetics, an operation used to be an agonizing experience for the patient. Even though different agents like herbs, gases, oils and drugs were used for relieving pain, the patient sometimes died from pain and shock. It was only with the discovery of modern anaesthetics that a major break-through was achieved in the field of surgery.

          An anaesthetic is a substance that causes a loss of sensation or feeling in the body. The history of its discovery is very interesting. In 1799, the British chemist, Sir Humphry Davy inhaled some ‘laughing gas’ (nitrous oxide) and found that it produced unconsciousness. Davy published this experience and in 1844 in the United States Horace Wells performed the first dental operation using nitrous oxide as an anaesthetic. Two years earlier, i.e. in 1842, the first painless operation had been carried out by Craw Ford W. Long, using ether as an anaesthetic. In 1847, chloroform was reported to have similar anaesthetic effect. At last surgeons had found a method of overcoming pain to carry out lengthy operations without undue haste. 

          Today, many new types of anaesthetics have been developed. Their application is of two types: local and general. Local anaesthetics are used to numb a particular part of the body. They act by blocking the transmission of electrical impulses along nerve cells, and are usually injected around the nerves that normally carry impulses from the area to be operated upon. The first of these anaesthetics was cocaine. This was superseded by another drug called procaine in 1905. Numerous drugs related to procaine such as lignocaine are nowadays used.

            General anaesthetics render the entire body unconscious. Nitrous oxide, ether and chloroform are included in this category, together with a more recently developed drug, halothane. Once inhaled, they act within seconds but recovery starts immediately after the drug is withdrawn. Halothane has been found to have side effects on liver. Now it has been replaced by ethrane.

          Under general anaesthesia, the patient’s respiration may be controlled externally. There are two reasons for this. First, general anaesthesia depresses the area of the brain that controls respiration. Second, for many operations the patient’s muscles need to be released which is achieved by giving a drug called curare.

          A person called an anaesthetist is trained to give proper amounts of anaesthetic to patients being operated for different ailments. At least one anaesthetist is always present in the operation room during the surgery.

 

In times of war, soldiers use special helmets to protect their heads. While driving a scooter, the riders often wear helmets to protect their heads against any injury. In many cities the governments have even made the helmets compulsory for riders. Do you know why the protection of head is necessary?

The most important part of our body, the brain, is located in the cranium under the protection of bones. The human brain is divided into three main parts: the cerebrum, the cerebellum and medulla oblongata. It controls all the important functions of the body – sight, taste, smell, hearing, touch, movements, memory, speech etc. Any damage to brain can disturb the proper body functioning.

Our brain is protected by the thick bone of the skull. Further a shock absorbing fluid cushions it against the blows of bumps. But if the blow is sharp or hard enough it can injure the skull. Thus to protect the brain from injuries it is essential to first protect the head.

Now the question arises what may be the consequences of head injuries?

A severe head injury due to an accident may cause brain hemorrhage which eventually may lead to death. The injury may damage the memory unit of brain by which a man can loose memory temporarily or permanently. It has been often seen that after having a severe injury of head people remain in coma for long periods.

If the brain tissues are damaged it may give rise to multiple sclerosis. Parkinson’s disease is caused by a disorder of brain chemistry which may result due to head injury. Brain injury may cause aphasia, a serious disorder of thought and communication. Apart from these effects many other disabling conditions can be generated by head injuries.

It is therefore essential to protect the head against injuries.

          More than 60 years back typhoid epidemics used to claim thousands of lives every year. But now, on account of research and advancement in medical science it has been largely controlled.

          Typhoid fever is an acute infectious disease caused by the typhoid bacillus. In medical terminology it is called bacillus salmonella typhosa. It enters the body via contaminated food, water, or milk and finally reaches the blood stream. It infects the blood and poisons the system. Among its main symptoms are fever, cough, headache, skin eruption, enlargement of the spleen, and a fall in the number of white cells. There may also be a loss of appetite. Persistent fever develops which gradually rises, reaching up to 39.4°C or 40°C. After a spell of one or two weeks it starts falling. In about 30 days, the temperature becomes normal.

          Formerly, the treatment was entirely symptomatic and supportive. After 1948 specific treatment with antibiotics was developed which proved to be very effective. Medicines like Chloramphenicol or Tetracyclines provide suitable antibiotic therapy. Cold sponge baths help to control the high fever. In some severe cases, the doctor may even go in for blood transfusion or infuse blood plasma. 

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          In fact, crying is the baby’s first sound message. It is the first attempt of the baby to communicate with the world around him. As the baby is unable to put its feelings and desires in words, it communicates by crying!

          It is a matter of common experience that newborn babies cry a lot during the first few months. As the baby starts growing up, there is a marked decline in this practice. By the time the baby is two years old, this habit is almost gone.

          It is interesting to note that this practice doesn’t just express wants and discomforts like hunger or illness. Normally the tears do not appear unless the baby is really distressed. 

          Most mothers are able to distinguish between cries indicating hunger, anger or pain. They are able to tell, with some degree of accuracy what the baby wants. For example, if a baby is hungry, it will continue to cry even when fondled. But if it is crying from boredom, it will stop crying when picked up or when moved to other interesting surroundings.

          Recent studies have shown that if a mother is sensitive in this regard, and responds accordingly, the baby will cry much less by the end of the first year as compared to one who is not. Knowledge of the basic food-stuffs essential to a growing child is necessary to become an ideal mother.

          By the age of four or five months most babies start making certain special sounds. These sounds are called  babblings. It has been observed that babies enjoy these sounds.

          It is not always possible to know why a baby cries. There are occasions when the baby is neither hungry, tired, uncomfortable, bored nor frightened but still keeps on crying. However, usually the baby’s cries are meant to communicate some message.

          When a person falls sick, the doctor often examines his pulse by placing his fingers on the wrist of the patient. What does this pulse indicate?

          By pulse we mean the regular throbbing of arteries caused by the successive contractions of the heart. During the action of the heart there is a pause. During this pause the wall of the aorta contracts. This contraction forces the excess blood to proceed along the arteries. This alternate expansion and contraction of the aorta produces a throbbing in the arteries. This throbbing which can be felt at many points in the body, through the skin, is called pulse.

          The pulse can be felt by placing fingers on the wrist over the radical artery. It can also be felt at the temples where we have temporal artery or at other places where an artery is near the surface. This sensation cannot be felt in the veins because the blood reaches them from the arteries by passing through the narrow capillaries.

          The nurse or a doctor asks the patient to put the arm in a relaxed position with the thumb turned upwards. Then the doctor feels the pulse. The beats are counted for one minute. Since the pulsations mean the heart contraction, the pulse tells us about the heart rate. The pulse rate depends on the blood requirement of the body. This rate indicates how fast the heart is beating and the state of pressure in the circulatory system. An irregular pulse may indicate some abnormality in the functioning of the heart.

          The number of pulsations per minute normally varies from 78 to 82 among women and from 70 to 72 among men. The pulse rate in children is much higher than the healthy adults. The normal rate for a seven-year old child is 90 beats per minute. A new born baby can have a pulse rate of 140. The old people can be in the 50-65 range of pulse rate. 

            The human body is a machine that needs energy to work. This energy is obtained from food materials through metabolism. These metabolic processes are carried on by activating agents or catalysts called enzymes. Let us see what enzymes are and what they do in our body.

             An enzyme is an organic catalyst produced by a living cell. All enzymes are proteins made up of long chains of amino acids. They combine with the substrate to form an intermediate compound. This intermediate compound is an unstable complex, and breaks down to yield the reaction product, plus the original enzyme.

             Enzymes are themselves synthesized by other enzymes derived from nucleic acids. An average cell contains about 3000 different enzymes. In order to function correctly, many enzymes require the assistance of related substances known as co-enzymes which are produced from vitamins in the diet.

             The human body literally contains hundreds of different enzymes. Many are contained within the cells, but some others, such as those used for digestive purposes, act outside cells in the gut itself. Enzymes are involved in almost every chemical reaction taking place in our body.

             Many physiological activities such as digestion, building up and breaking down of tissues, cellular respiration and muscle contraction depend on their action. The activity of an enzyme depends on the temperature, the degree of acidity or alkalinity (pH) and the substance upon which the enzyme acts. A single enzyme molecule is capable of bringing about the required changes on hundreds of molecules of the substrate in a few seconds.

             Enzyme action can be blocked by some poisonous substances such as mercury, lead or arsenic. The presence of such substances hinders the enzymes from forming intermediate complex with the substrate. Normal metabolism is thus prevented.

            Enzymes are classified into six major groups: Oxidases which bring about oxidation, transferases which bring about group transfer; hydrolases which speed up the process of hydrolysis; lyases that bring about group removal. Isomerases enzymes are responsible for isomerization and ligases for joining of molecules.

           Enzymes are not only important for our body, but are also very useful in industry, medicine and analytical chemistry. Although enzymes normally work inside living cells still they are capable of working outside the cell. They are used to convert starch into glucose and glucose into fructose. They are also used in cheese-making industry and for the production of semi-synthetic penicillin. Artificial sweeteners are also produced with their help. 

          The biological process of speech requires the amazing co-ordination of larynx, cheeks, tongues and lips to produce sound. A person, who stammers, lacks of such coordination.

          Technically stuttering or stammering is known as dysphemia. In one form, the speaker cannot utter a word clearly – spasms occur in the speech muscles and he gets stuck with the first sound. So instead of saying mother, he would say ‘m - m –mother’. 

          The speech development of children starts with associating sounds with persons and objects. It is closely related to the association of auditory and visual symbols. Speech involves coordination of many aspects of brain functions. These areas in the brain, particularly those concerned with aspects of speech, are located in the dominant hemisphere of right-handed persons and in either hemisphere of left-handed people. Disease of these parts of the brain leads to characteristic forms of stammering.

          In another form, the muscles in the tongue, throat and face get spasms, and despite the fact that facial muscles work to make sound, no words come out. The face gets twisted.

          Stammering rarely shows up before the age of four or five. It mostly occurs after puberty. It is more common in males than in females. According to studies, the ratio between males and females is 4:1.

          Doctors and researchers are yet in dark about the definite cause of this disorder. However it is often connected with a physical disorder or some emotional disturbance. In either case it can be corrected to some extent by special training in reading and speaking. The person is taught to read and speak slowly and carefully, and breathe regularly while speaking. Hereditary predispositions of stammering have been noted in many studies. In one study about 40% stutterers were found to inherit this disorder.

          The treatment is difficult and it demands much skill and sense of responsibility on the part of the therapist. No medicines have so far been discovered for its treatment. However psychotherapy and speechotherapy have been found quite effective. In this, attempts are made to overcome speech difficulties, this is particularly important in children.

          Prevention of stuttering may even be aided through parent counseling. Parents can take care of their children in such a way that they do not develop the habits of hesitation, or syllable repetition etc. Parental guidance has also been found quite effective in reducing the number of stutterers. A very controlled, guided and conscious approach on the part of the stutterer often helps to redress the problem.