Why do we hiccup?


          Whenever somebody hiccups, it is often remarked that he is being remembered by some one. Some people even go to the extent of saying that the person who is hiccupping has secretly eaten something. In fact all these sayings are myths. It is just a reflex action of the body by which the body protects itself. The question arises: why do we hiccup?



          Hiccups are short, sharp, and very sudden breaths of air which happen when our breathing muscles jerks, making us gasp. There is a diaphragm located between the chest and the stomach. While inhaling air this diaphragm goes down and presses the stomach due to which the lungs are filled with air; while exhaling air, the diaphragm goes up and the air comes out from the lungs. Thus the diaphragm goes up and down and the process of respiration continues incessantly without making any sound. The diaphragm functions like a piston. But sometimes, due to the formation of gas or increase of acidity in the stomach, the diaphragm gets irritated and as a result contracts suddenly. In such a situation, the air passing into the lungs experiences obstruction and makes a peculiar sound. This is nothing but the hiccup. Therefore it is a process by which the body tries to expel gas or undesirable food material out of the stomach so that respiration remains unobstructed. Shrinking of the diaphragm due to drinking or the growth of a tumour near it also causes hiccup. Hiccups can be caused by eating or drinking too much or too fast. It may also be a symptom of mineral disorders and brain-stem disease.



          Hiccups usually last for a few minutes and disappear if nothing is done about them. The best way to stop hiccup is to drink a glass of cold water because the cold water stops the irritation produced in the diaphragm and it resumes its normal movement. Hiccup can also be stopped by holding breath for a while. Sometimes the hiccup stops when one sees something frightening. If the hiccup does not stop even after a long time, it is advisable to consult a physician. Generally under such situations, doctors prescribe the inhaling of oxygen mixed with 5 to 10 per cent carbon dioxide. Chlorpromazine also suppresses hiccup. 


Why do we get tired?


          After a day’s work, we all get tired. Similarly we get tired after running, swimming or doing exercises. Do you know why we get tired after doing some work?



          When we do some work at a fast speed, our muscles do not get as much oxygen as they need. In such a situation to provide extra energy to the body, the glycogen stored in our muscles is transformed into lactic acid through the process of fermentation. The lactic acid reduces the working capacity of the muscles. This state of the body is known as muscle fatigue.



          The lactic acid acts as a poison for the muscles. If we can expel the lactic acid from the muscles by some process, they can again become fit for working.



          As a result of the muscular action some other substances called fatigue toxins are also produced in the body. Blood circulates these acids and toxins throughout the body because of which both the body and the brain get tired. Even when we do some mental work lactic acid and fatigue toxins are produced in the body and we get tired. Scientists have conducted many experiments in this field. A dog was made to work hard. And when it got tired and went to sleep its blood was transfused into an active dog’s body. This active dog also became tired and fell asleep. Similarly if the blood of an active dog is transfused to the body of a tired dog, it immediately becomes active.



          Fatigue is not only a chemical process but is a biological process too. It is a defence mechanism. This tells us as to when to stop work and give rest to the body. Fatigue cannot be removed fast. It is essential to give rest to the cells of the body to remove it. Sleep is a very effective means to remove fatigue. This repairs the damaged cells of the body. With the arrival of proper quantity of oxygen in the body through breathing, the lactic acid is reconverted into glycogen and we again start feeling fresh. Little rest also removes fatigue to some extent. The loss of glycogen due to fatigue is repleted to some extent by our food also. That is why a tired person feels very hungry.



 


What determines the sex of a child?

          When we look at the human race we find that it is divided in two sexes - male and female. The question arises: Why don’t all people belong to one sex? What causes some babies to be girls and others, boys? In other words, what determines the sex of an individual?



          A woman becomes capable of bearing a child after she starts menstruation. Between the 10th and the 18th days from the onset of menstruation, the reproductive organs of a woman produce an egg called ‘ovum’. During this period if a woman mates with a man, a sperm present in the semen of the man fertilizes the egg. The combination of the ovum of the female and the sperm of the male results in the formation of the embryo in the womb.



          The ova of the female and the sperms of the male contain sex chromosomes. The ova have only one type of chromosome called X chromosomes. But the sperms have two types of sex chromosomes called X and Y chromosomes respectively. The X chromosomes are slightly bigger than the Y chromosomes in size.



          When female sex cells are to be formed, the two X chromosomes of the female germ cell come together. They then split lengthwise, forming four X chromosomes. In the formation of male sex cells, the single X chromosome pairs with its smaller partner, the Y chromosome. Each of these chromosomes split lengthwise. The cell then contains two X chromosomes and two Y chromosomes. When this cell gives rise to four new cells - the sex cells - half will contain X chromosomes, the other half, Y chromosomes. If these two kinds of sperm are equally efficient in reaching and fertilizing the egg cells, we should expect the two kinds of fertilized eggs to be equally numerous. Half of these would have two X chromosomes (XX) and would develop into girls. Half would carry one X and one Y chromosome (XY) and would give rise to boys. As a matter of fact, male births are slightly more frequent than female births. The reason is yet not known. 





 

How are we able to speak?


          Of all the living beings only man can express himself in words. He is able to produce different types of sounds. Do you know how human beings produce sounds?



          Our throat has a hollow organ called the ‘sound box’ or ‘larynx’. It is, in fact, an enlarged part of the wind pipe. Its walls are made of cartilages and are lined with mucous membrane inside. The cartilage is made up of a very soft bony substance. The outer portion of our ears is also made up of this material. There are two vocal cords on the two sides of this box. Their movement is controlled by sixteen muscles. When air from the lungs passes through the vocal cords, they start vibrating. As a consequence of these vibrations, sound is produced.



          The sharpness, hoarseness and sweetness of sound depend upon the tension of the vocal cords. And this is controlled by the muscles. When the vocal cords are under higher tension, they can vibrate up to 1000 times per second, thus producing melodious sounds. In fact, more the number of their vibrations, sharper is the sound; and less the number of vibrations, the heavier is the sound. The rate of vibrations varies from person to person. That is why the pitch of sound is also different in different people. People with melodious voices have a better formed sound box as compared to others.



          When the child attains the age of 13-14 years, his vocal cords become thicker, as a result of which their frequency of vibrations is reduced. This lowers the pitch of the voice. Not only this, even our chest, stomach, tongue, lips, teeth, etc., are also involved in the production of sound. 


How do the ears detect sound?


          It is a well-known fact that different kinds of sounds are detected by our ears. On the basis of its structure, the human ear can be divided into three parts: external, middle and internal. Anything producing sound first vibrates. These vibrations set up a motion of sound waves in the medium through which the sound reaches our ear. The external ear has large surface and can receive maximum number of sound waves.



          When the sound waves hit the external ear, they are transmitted to the middle ear through a pipe. The middle part has the eardrum which starts vibrating when these sound waves hit it. Just behind the eardrum there are three small bones called hammer, anvil and stirrup. As the eardrum vibrates, these bones also start vibrating. These vibrations are transmitted to the cochlea. The cochlea is the part of the inner ear which acts like a spring. It is surrounded by a fluid. The fluid has the nerve endings. Due to the vibrations of cochlea the fluid also starts vibrating and as such activates the nerve endings. The activation of the nerve endings produce impulses which are taken to the brain by the auditory nerve and we hear the sound.



          Our ears can detect both feeble and intense sound with frequencies ranging from 20 Hz to 20,000 Hz. In order to keep the ears healthy, it is essential to clean them regularly. A waxy substance is produced in it which gets deposited on the eardrum if it is not cleaned. If this wax accumulates there it can lead to deafness. Therefore, we should take care of our ears and consult the ENT experts as soon as there is trouble in the ears.


How do female mammals produce milk?

               Apart from human beings, cow, buffalo, sheep, goat, etc. come under the category of mammals. Mammals are those living beings whose females produce milk to suckle their young. They are warm-blooded and have well-developed brains. They give birth to live Youngs and feed them with their own milk. They breathe air through lungs and their bodies are covered with hair. Do you know how the female mammals produce milk? 





               Milk in the female mammals is produced by ‘mammary glands’ which are located in the breasts. They are bag shaped and big in size. Shortly before the birth of her young, hormonal changes in the mother results in increased development of the mammary glands. They produce large drops of fat which when mixed with fluids present in the breasts become milk. Corpus luteum of the ovary also produces a hormone which helps in the process of milk production. Most of female mammals have teats or nipples from which the young can suck milk.



               At present there are about 4400 living species of mammals grouped into 19 orders and about 120 families. They, of course, differ from one another in their bodies, shapes, sizes and habits. Most of them live on land but some live in water and air also. For example, the whale is a mammal which lives in water. And the bat is also a mammal which flies in the air. They exist in different climatic conditions - hot, cold, dry or humid. Most mammals give birth to less than 10 young a year. Humans usually have only one baby at a time.


Why is the blood red?


          Generally a normal person has 4 to 5 litres of blood in his body. This blood keeps on circulating in the arteries, veins and capillaries. The blood of all men and women, all over the world, is red. And this colour has no relationship with the colour of the skin. Do you know why the blood is red?



          To answer this question we have to understand the composition of blood. Our blood has four major constituents - plasma, white blood corpuscles, red blood corpuscles, and platelets. More than half of the blood in human body is plasma only. It is a thick fluid of yellow colour. It contains proteins, antibodies, fibrinogen, carbohydrates, fats, salts, etc. Proteins help in the growth of the body. Antibodies kill the harmful bacteria and neutralize the toxins secreted by them. Fibrinogen helps to stop bleeding from cuts.



          The white blood corpuscles are much less in number. They have a size of about .01 mm. There is one white blood corpuscle for every 700 red blood corpuscles. They protect the body from germs of diseases by fighting against them.



          Platelets are very small in size - about 0.002 mm. One cubic millimetre of blood contains 150,000 to 400,000 platelets. They are especially helpful in the clotting of blood.



          The red blood corpuscles give the blood its colour. They are saucer shaped and have a size of approximately .008 mm. These cells carry oxygen from one point to another in the body. They contain a pigment called haemoglobin whose colour is red and which, in fact, makes the blood red. Haemoglobin is made up of iron and proteins. Each cubic millimetre of blood in a healthy woman has about 4.5 million red blood corpuscles. On the other hand one cubic millimetres blood of man has 5.5 million red cells. Shortage of the red blood corpuscles leads to anaemia. As soon as blood passes through lungs oxygen is absorbed by these particles and carried throughout the body. Every red cell lives for about 4 months and then breaks up mostly in the spleen. Old red cells are destroyed in the liver and elsewhere at the rate of 2 million cells per second. New red cells are always being formed to replace the worn out cells.



 


Why do tears come out while weeping?


          Whenever somebody weeps, tears come out from eyes. Do you know why it happens?



          We blink our eyes - like the stage curtains - by means of muscles. The movement of the eyelids is so fast that it does not disturb our vision. The blinking of the eyes is an involuntary action. This takes place every six seconds throughout our life.



          In each eye, there is a ‘tear gland’ located at the outer corner of the eye. There are small tubes or ducts which carry the tears to the upper eyelids and from there they are taken out of the eyes by other ducts.



          Every time we blink our eyes, some fluid comes out through the openings of the tear ducts. This keeps the eyes lubricated and prevents them from drying. When we weep, more fluid comes out through openings of the ducts in the form of tears. It is a reflex action that occurs without our control.



          Sometimes tears come out even when we laugh a great deal. That is because, when we laugh, the muscles squeeze the tear glands, due to which tears begin to flow out.



          When we cut onions, tears can come out of our eyes. In fact, the onion gives off an irritating volatile substance. When it reaches our eyes tears are produced to protect the eye from irritation. The tears ‘wash’ the irritating substance away. The same thing happens with smoke.



          Some sad news also produces tears by reflex action. This happens only when we do not have words to express our feelings.


What makes people sneeze?


          There are many stories and superstitions connected with sneezing. Some people take sneezing as a sign of luck while some others regard it as a bad omen. In our country, sneezing in front of a person when he is leaving his house is considered inauspicious but sneezing at his back is considered a good sign. The Romans thought that a person expelled evil spirits when he sneezed. Primitive people believed that sneezing was a sign of approaching death. When anyone sneezed, people said, “God bless you”, because it was considered a sign of danger. In fact, all these ideas came up due to superstitions. They do not have any truth in them.



          According to physiology sneezing is just an involuntary reflex action. It is an explosive expiration through the nose and mouth stimulated by irritation in the nasal epithelium. It occurs when the nerve endings of the mucous membrane of the nose get irritated. This happens when we get cold. It can also be caused by the foreign bodies that somehow manage to get into the nose. Again, even allergies produce irritation. The act of sneezing is an attempt by the body to expel air to get rid of the irritating substances. Sometimes sneezing also occurs when our optic nerve is stimulated by a bright light. During the act of sneezing, our whole body gets a jerk because the air comes out with a great speed - around 160 kms per hour. The whole body vibrates and the eyes get automatically closed. After the sneeze, the body becomes fresh and light. Some people put snuff (powder of tobacco leaves) in their nose and create artificial sneezing. This is harmful for the body.


How is urine formed in our body?


          We have two bean-shaped glandular organs in the lumbar region of the abdominal cavity which are called kidneys. They are reddish brown in colour. Each kidney is approximately 11 cms long 5 cms wide and 2.5 cms thick. Each of them weighs about 150 gms. Do you know what functions the kidneys perform in our body?



          The main function of the kidneys is to purify our blood by removing the impurities from it. They work as filters. Not only this, the kidneys maintain proper proportion of every constituent in the blood. If sometimes the level of sugar, salt or, water in blood, exceeds the normal level, the kidneys excrete the excess amount from it. They also regulate the formation of urine according to the exigencies of the situation and thus do not allow the blood to become extra thick or thin. The undesirable acids and bases of the blood come out of the body as urine.



          Each kidney has millions of coiled capillaries. Blood enters the kidney through the renal artery and passes through these capillaries and the dissolved impurities are filtered out. The purified blood returns to the lungs. About 200 litres of blood pass through the kidneys everyday. The impurities removed from the blood pass from the kidneys to a bag where they are stored for some time. This bag is known as the bladder. When the bladder is sufficiently filled, one feels the urge to empty it. We pass urine primarily to empty this bladder. Normally an ordinary person passes 1.5 litres of urine in one day.



          Any disorder or damage in the kidneys is very dangerous for the body. If the kidneys become defective, impurities in blood go on increasing and have poisonous effects on the body. If somebody’s kidneys stop functioning, the person dies within a few days. It is, therefore, absolutely essential to have proper treatment of any defect or disease of the kidneys. It is necessary to take proper quantity of food in order to keep them healthy. Excessive eating compels the kidneys to work more to expel more excretory materials and thus the chances of any damage to the kidneys increase. To keep the kidneys healthy, we should take eight to ten glasses of water everyday. 


Why do some people snore during sleep?

          It is often seen that some people snore during sleep. Their mouth remains open and a peculiar sound comes out while breathing. Do you know why some people snore?



          Normally, people breathe through nose. But some people’s nose remains blocked due to some reason. And thus they breathe through mouth. In fact, snoring is the stertorous respiration of certain persons during sleep.





          When we are asleep and breathing through 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 is produced which is called snore. Often this vibration 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 nose rather than through mouth. If one develops the habit of breathing through nose the possibility of snoring becomes less.



          Breathing through mouth is harmful for health. The germs of many diseases enter directly into the mouth and can cause diseases. If we breathe through 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 nose.



 


How do we breathe?


          Breathing is essential for all living beings. Men, animals, birds, insects and plants - all need oxygen which they get from the air through respiration. However, different creatures breathe differently. Some breathe through lungs, while some others breathe through skin. For example, the earthworm breathes through its skin. Do you know how man breathes and what happens in the body during the process of respiration?



          Man inhales air through the nose or mouth. The nose and mouth are joined in the back of the mouth in an area called pharynx. The air inhaled goes to the lungs through the wind pipe. There are two lungs in our body - one each on the left and right of our chest. They are made up of tissues shaped like soft bags. Each lung has millions of air sacs which get filled and enlarged when air is inhaled. When it is exhaled they contract.



          The energy-releasing process which utilizes the oxygen and produce carbon-dioxide is termed as ‘tissue respiration’ or external respiration. In man, external respiration is the process whereby air is breathed from the environment into the lungs to provide internal respiration.



          The oxygen which is inhaled is circulated throughout the body by the blood. It oxidizes the food materials. During this process of oxidation, carbon-dioxide, water and other substances are produced. The same carbon-dioxide comes out when we breathe out. When we do some physical work or exercise, we need more energy. For the production of more energy we need more oxygen. That is why, the rate of breathing becomes fast when we do any hard work or physical exercise.



          Normally, a newly born child breathes 60 times per minute. A 15 year old child breathes 20 times a minute and an adult 16 to 18 times. The rate of breathing is faster in adults than in old people. The process of breathing is controlled by the respiratory centre in the brain. This centre is sensitive to the amount of carbon dioxide in the blood. If there is an increase in carbon dioxide such as during exercise, this centre sends signals to control breathing. As a result the person breathes faster. 


Why does the human skin have different colours?

          All over the world people of different races have skin of varying colours? For example, people in the northern Europe have white skin whereas those in the western Africa have black skin. People in the south-east Asia have yellowish skin. In fact, it is difficult to categorize the colours of people’s skin. Do you know why people have skin of different colours? 





          The colour of the human skin depends mainly on three ‘pigments’ or ‘colouring materials’ found in the body. The first of these is called ‘melanin’ which is a brown substance. If concentrated, it appears black. The second is called ‘carotene’ which is a yellow substance. And the third is called ‘haemoglobin’ which is the red pigment of the blood. In the absence of these pigments the skin’s colour will be creamy white. The mixture of these three in different proportions produces the different colours of the skin. A man having more melanin will have dark complexion while the man having more of carotene will have yellowish skin. Melanin and carotene are found in the deep epidermis in all skin types.



          The tissues of the body produce more melanin when exposed to the ultraviolet rays in sunlight. That is why the colour of the skin of the people who live in tropical regions is very dark. When we work in the sun light continuously for a few days, our skin becomes dark. People living in the colder countries have white skin, because their skin contains smaller quantities of melanin. The deficiency of these pigments in the body produces white spots on the body. This disorder is called ‘leucoderma’.



          The colour of the skin depends partly on the amount of blood circulating through the dermis and the texture of the dermis. Since the texture varies considerably in different people, the light that falls on the skin is not always reflected in the same way. 


What is roundworm infestation?


          Roundworms or Nematodes as they are named are among the commonest and most widely distributed of invertebrates. Although best known as parasites of man and his domestic animals, a majority are free-living. The free-living and plant parasitic forms are usually microscopic but animal-parasitic species are long and thin, tapering at each end. The outside of its body is covered with a thin cuticle. They look something like earthworms. Do you know how they manage to enter our body?



          The roundworms generally lay eggs on the exposed eatables like fruits, vegetables, sweets, etc. If we eat these fruits or vegetables without washing they reach our intestines. When the eggs reach there they hatch and the roundworms come out.



          The roundworms live happily in our intestines. Here they get a lot of food on which they thrive. As a matter of fact, they eat up a large part of the food we eat. That is why a person afflicted by them starts becoming weak gradually. These worms have thick and tough skin on which the digestive juices do not have any effect.



          If the growth of roundworms in the intestines is not checked in time, their presence can be disastrous. Fortunately, we have many medicines today which can kill them easily. A person afflicted by them should immediately consult a doctor.



          A person afflicted by roundworms excretes thousands of eggs everyday in his stool. If our habits are unhygienic, some of these eggs are carried to open fields, where from they reach fruits and vegetables. When we eat such things without washing them properly they get inside our body.



          Compared to adults, children have more complaints of roundworms. It is because children play in the open, and are careless about sanitary habits. If eatables and our hands are properly washed before eating, the possibility of getting roundworms becomes negligible. 


Why does the blood group vary from person to person?


          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 antigen 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 gives rise to different groups of blood.



          In the year 1900 Dr Karl Land Steiner 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. All blood groups are inherited.



          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, so 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 castes may be falling in the same group.



          If the wrong blood is transfused to a patient, he can die, because antigens of different classes cannot combine with each other. However, blood plasma of one individual can be given to another because it is the same in everybody.



          Another important blood antigen was discovered in 1940 by Landsteiner and Alexander S. Wiener. This additional factor is called the Rhesus antigen or Rh factor.



          Rhesus antibodies do no occur naturally but may develop in unusual circumstances.