Boiling Mud Pools

Where does mud boil?

            Have you heard of boiling mud? It is very unusual. Boiling mud is one of the side effects of volcanic activity. Hot water and gases form beneath the surface bubble through the mud, as a result, it looks like a pan of boiling porridge.

Boiling Mud Pool

            Boiling mud can be seen in a number of volcanic areas of the world. Volcanic gases such as sulphur, which creates heat and causes the boiling effect, usually gives the mud a foul smell. On the other hand, the associated minerals are said to promote healing and thus, mud pools are of the used as health centers.

            The Italian island of volcano is visited for curing rheumatism. Many people visit pools and springs of the volcanic plateau in North Island, New Zealand, which are used as health centers for healing diseases.

            Boiling mud is still found in areas where volcanoes have bee inactive for hundreds of years, such in the West Indian island of St. Lucia. This proves that volcanic activity is still going on deep beneath the earth’s surface.

The World’s Hottest and Coldest Places

Where are the world’s hottest and coldest places?

            The Sahara desert in Libya is the hottest place in the world. The highest temperature was recorded in September 1922, and it was 58 degree centigrade. Death valley, California, in the USA, recorded its highest temperature of 56.7 degree centigrade in July 1913.

World’s Hottest Place Sahara Desert

World’s Coolest Place  Antarctica

            The highest temperature recorded in the Sahara desert is due to long periods of sunshine. In eastern Sahara, 4300 hours of sunshine has been recorded in a year- an average of 11 hours 47 minutes per day. This long period of sustained heat raises the temperature to a very high level.

            The death valley of California, where temperatures up to 50 degree centigrade are very common; this area also being a desert.

            Antarctica is the coldest place in the world. In July 1983, Russian scientists measured a very low temperature of -89.2 degree centigrade at Vostok, the Russian research station in Antarctic. In Siberia, the lowest temperature was -68 degree centigrade recorded in 1892.

Types of Climates

How many kinds of climate are there?

            Changes in the weather, both on a day-to day and seasonal basis have puzzled man for ages. Climate is the average weather experienced in a region over a period of years. Climate depends on many factors such as the average temperature, rainfall, atmospheric pressure, wind directions, location, height above sea level and latitude of the place.

            Different kinds of climate are found in different parts of the world. Various instruments like the thermometer, barometer, rain gauge, etc. are used to study the climate, atmospheric pressure, wind speed and directions, rainfall, clouds, humidity, etc.

            After much study, the world has been divided into 12 major climatic regions. For convenience, these climatic regions have been grouped into three on the basis of their latitudinal positions and extent. These are the low latitude climatic zone, the mid-latitude climatic zone and the high latitude climatic zone.

Low Latitude Climatic Zone: This zone lies close to the equator, generally between the tropic of cancer and the tropic of Capricorn. It includes the humid tropical region, trade wind coastal region, tropical desert and steppe, tropical monsoon and savannah regions. The temperature in this region is very is high. The annual rainfall is heavy over most of the region, especially in the tropical areas.

Mid-Latitude Climatic Zone: This includes china type, west European type, Mediterranean, mid-latitude desert and the steppe region. The summers are not very hot, but the winters are very cold.

High Latitude Climatic Zone: It includes Taiga type, Tundra type, ice cap and high mountain type regions. In these places, temperatures are very low during the winter and frigid even during the summer. They generally lie beyond the Arctic Circle and the Antarctic Circle.

The 12 major subdivisions of climate within the zones given above are---

1.        Tropical wet

2.       Tropical wet and dry

3.       Highlands

4.       Desert

5.        Steppe

6.       Subtropical

7.        Subtropical moist

8.       Oceanic moist

9.       Continental moist

10.  Sub-arctic

11.  Polar

12.  Ice cap

            Climate affects the type of houses we live in, the clothes we wear, the food we eat and the type of transportation we use. In short, it has a major effect on our lives.

We Don’t Feel the Earth’s Motion

Why don’t we feel the earth’s motion?

            Till a few hundred ears ago, it was believed that the earth was the centre of the universe and that the sun, the moon and the stars revolved round it. This belief was based on the assumption that the earth appears to be stationary, while the positions of the stars keep on changing. In 1545, Nicholas Copernicus, a polish astronomer suggested that the earth revolves around the sun. It was proved that the earth revolves around the sun and completes one revolution in 365 ¼ days. This period is called a year. Secondly, it also rotates on its own axis and takes 24 hours to complete one rotation.

Tidal Bulges from Moon and Sun

            If the earth is rotating and revolving at the same time, why don’t we feel its motion? The answer is that because of gravity, all the things situated on the earth including the atmosphere move with the earth and hence we cannot feel its motion. If you rotate a football with an ant on it, the ant will not feel that the ball is rotating.

            Exactly like the ant on the football, we are present on the surface of the earth and do not feel its movement.

            The biggest proof of the earth’s motion is the change in seasons. Seasons occur due to the earth’s revolution around the sun as well as due to its rotation on its own axis. Day and night are caused by the earth’s rotation on its axis. The portion of the earth which faces the sun experiences day, while the darker portion has night.

            If the earth did not rotate on its axis, the part of the earth facing the sun would always have day while the rest would have night forever. The earth’s axis makes an angle of 23 ½ degree with vertical. As a result of this, one pole faces the sun continuously for six months, and for the next six months, it does not. This explains the six-month duration of days and nights on the poles. All these observations confirm the motion of the earth round the sun, as well as on its own axis.

Inside the Earth

What is there inside the earth?

            Man has always bee curious to know as to what lies inside the earth. He tried digging and various other methods and finally, found an indirect method to know- through the study of earth quake vibrations or seismic waves. Studies reveal that our earth has three main layers- the outer surface on which we live is called the earth’s crust, below it is the mantle, and then comes the innermost part known s the core.

The internal structure of the earth

            The outer layer or the earth’s crust has two sub-layer-the first layer is the lighter one and is called Sima for silica-magnesium, while the second sub-layer is heavier than the first and is called Sial for (silica-aluminum). Thus, the earth’s crust is mainly composed of silica. Its depth varies form 16 kilometers to 50 kilometers on land and about 5 kilometers under the oceans. The volume of this crust is only 1% of the earth’s volume, while its weight is around 4% of the earth’s total weight. As we go deeper into the earth’s crust, the temperature increases.

            For every 35 meters in depth, there is an increase of about 1 degree centigrade in temperature. At a depth of 3 kilometers, the temperature is around 100 degree centigrade boiling point of water and at 50 kilometers; the temperature is 1,200 degree centigrade- hot enough to melt rocks.

            The second layer, which is below the crust, is called the mantle. It is 2,880 kilometers thick. It is mainly composed of silicon, magnesium and iron. The rocks in the mantle are denser than sial and sima. Its total volume is 84% of the earth’s volume. Its weight is around 67% of the earth’s weight.

            The innermost portion of the earth is called core which is made of high density solid materials. The core has two parts-outer core and inner cores. The outer core is liquid, and the inner core is solid. Its thickness is about 3482 kilometers. Its temperature is around 4800 degree centigrade. Its volume is 15% of that of the earth, while its weight is 32% of the earth’s weight. This solid core is surrounded form all sides by molten iron and nickel. Its temperature is around 3900 degree centigrade. The thickness of this molten mass is around 2.240 kilometers. The centre of the earth is some 6,336 kilometers form the earth’s surface.

The Earth’s Force of Gravity

What is the earth’s force of gravity?

            According to science, the earth attracts everything towards its centre. It is for this reason that fruits from trees or a ball thrown up into the air, all fall to the earth surface. This invisible force of attraction between the earth and any other body is called the force of gravity.

Gravitational pull keeps the moon revolving around the earth

            The centre of gravity of the earth lies in this center. Imagine what would happen if a hole is drilled in the earth form one side to the other, passing through its centre and a ball is dropped in this hole. The ball, in fact, will stop at the centre of the earth; it will not come out form the other side. The weight of a body will be more, if it is nearer the centre of the earth.

            Similarly, the weight will be less if the body is away from it. This is why a body weighs more at the poles than at the equator, since the poles are nearer to the centre than the equator.

            Not only the earth, but all other planets have this force of gravity. As a matter of fact, every body in this Universe attracts the other body with its force of gravitations, and it is this force that keeps all the planets and stars in their places in the sky. It is this gravitational pull that keeps the moon revolving around the earth, and the earth revolving around the sun.

            Naturally, the moon also attracts the earth; tides in the seas are mainly due to the gravitational pull of the moon.

            Till the end of the 15^th century, it was assumed that if two bodies were simultaneously dropped from the same height in vacuum, the heavier body would hit the ground first.

            But this assumption was found to be baseless. The famous scientist Galileo Galilei was the first to prove that irrespective of their masses, all the objects dropped simultaneously form the same point in vacuum will reach the ground at the same time. He dropped one ball weighing 100 pounds and another of just half pound at the same time from the learning tower of Pisa, and demonstrated in the presence of thousands of people that both the balls hit the ground at the same time.

            Subsequently, Newton propounded the law of gravitation. According to this law, the force of attraction between two bodies is directly proportional to the product of their masses ad inversely proportional to the square of distance between them. It follows form this that the force of attraction will be doubled if the mass of one of the two bodies is doubled.

            On the other hand, if the distance between them is doubled, the force will be reduced to one-fourth of the initial value. The velocity of a freely falling body towards the earth increases by 9.8 meters or 32 feet every second. This is called acceleration due to gravity.

Geodesy

What is geodesy?

            Geodesy is the science of measuring the circumference of earth. When people came to know that the earth was round, they made use of geometry related to circles and angles. Nowadays, geodimeters can measure long distances very accurately by using light rays.

The traditional method used  by eratosthenes to calculate the circumstance of Earth

            The diagram shows how, in about 250 B.C., Eratosthenes measured the earth’s circumference. At noon in midsummer, the sun shone straight down a well at Syene, near Aswan in Egypt. At the same time in Alexandria, monument showed that the sun made an angle of 72 degrees.

            Using geometry, Eratosthenes knew that the angle at the centre of the earth would be the same. He calculated that the earth’s circumference was 46,300 kilometers.

            Eratosthenes was not very inaccurate in his measurements. In fact, the distance around the equator is 40,076 kilometers.

            Geodimeters are very useful and accurate devices for taking earth measurements.

Measure the Mass of the Earth

How do we measure the mass of the earth?

            When we wish to know the mass of an object, we weight it in a balance. The size of the balance varies with the size of the object to be weighed. The earth is a giant body and to think of a balance for weighting it, is almost impossible. Then, what is the way of measuring the mass of the earth?

            Scientists use Newton’s law of gravitation to determine earth’s mass. According to this law, there exists a force of attraction between any two bodies in the universe and this is dependent on the masses of the two bodies as well as on the distance between them. The force of attraction is directly proportional to the product of the masses of the two bodies, and inversely proportional to the square of the distance between them.

            An experiment is performed to determine earth’s mass with the help of the above mentioned law. In this experiment, a small metallic ball is suspended with the help of a thin thread. The position of this ball is accurately determined. Now a big lead ball weighing a ton is brought near this ball. The small ball is attracted towards the big ball due to the gravitational pull and as such it is slightly displaced form its initial position with respect to the big ball. The change in the position of the small ball is even less than one-tenth of an inch. This displacement is very accurately measured with the help of precision instruments. Using with the help of displacement in a formula of physics, the mass of the earth is calculated. The mass of the earth has been found to be 598x10¹⁹ (5980, 000,000,000,000,000,000) tones. 

Steps of Earth Formation

How was the earth formed?

            Have you ever wondered how earth came in to existence? This unique planet came into existence around 4.6 billion years ago. Earth is the third planet forms the sun and the only planet on which life exists. Like the sun and the other planets, it was also formed out of dust clouds and gases. Would you believe that before taking its present shape, earth was a fireball? Earlier, earth revolved around the sun in the form of a hot spherical body. Thousands of years later, it gradually started moving away from the sun but still kept revolving around it. S it moved farther ad farther form the sun, the temperature of earth kept decreasing. As it started cooling, its outer layer changed into a crust. With the hardening of this crust, cracks developed in it and molten material from inside started coming out. Over a period of millions of years, this molten material gave birth to mountains and valleys.

Earth is 4.6 billion years ago

Earth is 1500 millions of years ago

Earth is 200 million years ago

Earth is Today

            As time passed, the thick layer of hot gases enveloping the earth started cooling and turned into clouds. These clouds rained on the earth continuously for a long time. Rainwater accumulated in the low-lying areas of the earth and these areas became the oceans as we know the today. With the passage of time, there were upheavals due to which its surface was raised high, or pressed down. This resulted in many volcanoes. Slowly, earth became calm and the seas and mountains took their definite shapes.

            Subsequently, around 570 million years ago, micro-organisms started developing on the earth. In the first 345 million years of earth’s existence, marine aquatic animals came into existence. As time passed, the aquatic animals also underwent changes.

            In the next phase of evolution, the great reptiles came into existence. And finally, around a million ears ago, man gradually evolved form lower two-legged species. Today, earth has the most favorable climate among all the nine planets, which is required for the sustenance of life. Had there been no atmosphere around the earth, human life would not have existed.

Pins and Needles

Why do we get pins and needles?

Numbness Pins and Needles

            Pins and needles refer to the tingling sensation we feel in our hands, feet, arms or legs when the blood begins to circulate gain in those areas, after being impeded for some time. For example, when we sit with our legs crossed on the floor for a long time, and then try to stand up, we sometimes get the feeling of numbness, as if the legs had fallen asleep. As the blood begins to flow again, a tingling sensation occurs due to the change. But why do we get this tingling sensation? We know that the blood flows freely through the blood vessels in our body, just as water flows freely through a stretched hose. Imagine what would happen if you bent the hose! Water would only trickle through. Similarly, blood is the transport system of our body and performs two important functions. It supplies food and oxygen to different parts of the body; as well s collects the poisonous wastes. When the flow is restricted; these poisonous wastes accumulate and block the nerve cells from carrying messages from the affected limb to the brain. This creates a feeling of numbness. When the limb is stretched again, the blood starts flowing, and this resumption of blood circulation causes the tingling sensation.

Touch and Pain

What are touch and pain?

            There are many nerve endings in the skin, which are sensitive to touch, pressure, pain, cold and heat. The brain receives the messages sent by the sense organs. The information received by the brain is analyzed to know what is happening at any point on the skin.

Receptors in our Skin

            The different receptors in the skin are shown in the figure. The pressure receptors 1. Are buried deep in the skin. Touch receptors 2. Are near the surface of the skin. Cold 3. And heat 4. Receptors are also near the surface of the skin. Pain receptors 5. are simply free nerve endings. Some areas of the skin have more sense organs than others. The fingertips, the tip of the nose, and the lips have large number of touch receptors.

            When you touch an object, more than one type of a receptor is stimulated. When you hole a glass of water, the receptors of touch, pressure and cold are stimulated, but holding a glass of water does not stimulate pain receptors. These require higher pressures or temperatures before they are stimulated in to sending signals to the brain.

Vitamins and Minerals

Why do we need vitamins and minerals?

            Just as carbohydrates, proteins, fats, inorganic salts and water are the essential ingredients of our food, vitamins and minerals are also necessary to keep our body free of none. Lack or deficiency of vitamins can cause many disorders and diseases like weak digestive power, impaired eyesight, general weakness, tiredness, dryness of skin, inflammation of gums, weakening of bones, beri-beri, rickets, etc.

Foods Rich in Vitamins and Minerals

            What are vitamins? The word ‘vitamin’ was coined in 1912, and is derived form the Latin word vita, which means life. In fact, vitamins are organic materials which are found in many food substances and are essential for the proper functioning of the body parts and organs. They are of many kinds and each vitamin has a separate role in keeping our body healthy.

            Twenty kinds of vitamins have so far bee isolated, out of which six vitamins are of crucial importance. These are vitamin 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 weakness eyesight and leads to night blindness. Vitamin A protects us form infections, skin diseases and many eye diseases.

Vitamin B complex: Vitamin B consists of several water-soluble vitamins of the same nomenclature. They are known by their chemical names. Their constitution and functions are also different. These are described below.

Vitamin B1 (thiamine): Vitamin B1 or thiamine’s found in yeast, germinated wheat and pork. Its deficiency leads to a disease called beri-beri and causes tiredness, weakness, breathing difficulties, indigestion, etc. vitamin B1 is lost if food is cooked with baking soda.

Vitamin B2 ( riboflavin): Vitamin B2 or riboflavin is mainly found in milk, eggs and liver, deficiency of vitamin B2 causes general weakness, skin diseases, and sores on tongue and cracks on lips. Eye is also affected; there is dimness in vision, redness or burning sensation in the eyes.

Vitamin B6 (nicotinic acid or niacin): Vitamin B6 or nicotinic acid or niacin is found in bigger proportion in yeast, grain chaffs, eggs, meat, kidneys and livers. This is also found in smaller quantities in flour, polished rice, fruits, green vegetables and milk.

Deficiency of vitamin B6 causes diseases

Called Pellagra: This causes mental tension, inflammation of tongue, gums and inner lining of the intestine. There is loss of appetite and the body becomes weak.

Vitamin B7: Vitamin B7 is found in eggs, meat, milk and green vegetables. Deficiency of this vitamin adversely affects the inner lining of stomach and intestines, thereby causing disorder of digestion.

Vitamin B12: Vitamin B12 is found in milk, meat, liver etc. by keeping the diet balanced; it can be obtained in sufficient quantity. Deficiencies of this vitamin can result in anemia, pains, toughness in arms, and partial paralysis. For the formation of red blood corpuscles, vitamin B12 folic acid ad vitamins C are essential. In case of a extreme anemic condition, it is injected into the body.

Vitamin C (ascorbic acid): Vitamin C or ascorbic acid is found in large quantities in orange, lemon, grape, tomato, pineapple, germinated pulses and green vegetables. Pears, bananas also have it.

Deficiency of vitamin C leads to pain in joints, and a disease called scurvy. Inflammation of gums, weakening of brain, lethargy, weakness, tiredness, pain in legs, loss of eyesight, appearance of blue scars on the body, and peeling of skin are also caused by its deficiency.

Vitamin D: Vitamin D is found in milk, butter, fish-oil, eggs, etc. the sunlight falling on the body also makes vitamin D under the skin. Deficiency of vitamin D causes a disease called rickets (weakening of bones).

Vitamin E: Vitamin E is found in grains and oils. It is also found in large quantity in onions. Deficiency of this vitamin badly affects skin, blood, brain and liver.

Vitamin K: Vitamin K is found in green leafy vegetables. Generally, the organisms present inside the intestines make vitamin K. it helps in clotting of blood on wounds. If we take a balanced diet containing fresh vegetables, fruits, eggs, milk, fish, beans, wheat and rice, we get all these vitamins. All these vitamins are also available in the form of tablets and capsules in the market. Minerals are also needed for good health. Iron is needed for blood pigment, hemoglobin. Calcium- found in milk and cheese- and phosphorus, which is present in most foods, are needed for the growth of healthy bones and teeth.

What is a Slipped Disc?

            We have many vertebrae in our spinal column. Between these vertebrae, discs of cartilage are sandwiched that act as cushions between the two bony surfaces of the adjoining vertebrae. When the cartilage becomes weak and bulges out form between its two vertebrae, it is known as a slipped disc. The slipped disc may no longer be an effective cushion, and the two vertebrae may rub against each other and pinch a nerve that is caught between them, causing intense pain known as lumbago.

Slipped Disc

            The inter-vertebral disc is a flexible pad consisting jelly like core surrounded by a fibrous cover. It lies directly in between two vertebrae ad acts as a shock absorber.

            If the bulge of the disc is to one side, it may press on a nerve branch of the spinal cord. In this case, the person will feel pain in the area connected by that nerve, such as the leg or arm. It the bulge pushes straight back into the spinal cord itself, the person may feel pain in the back, neck or chest.

            In case of a problem of slipped disc, one should consult an orthopedic surgeon. In acute cases, the surgeon will remove the disc and fuse the two vertebrae together, sacrificing some flexibility in the patient’s back in return for relief from pain.

What Protects our Eyes?

            Eyes are the most delicate organs used for seeing and need protection. There are many parts that protect the eyes, like the eyelids, eyelashes, eye brown and eye tears. Tears kill germs that invade the eyes.

Human Eyes

            The eyelids, eyelashes and eyebrows protect the eyes form dust and other harmful objects. Eyelashes form rows of stiff hairs around each eye.

            Our eyelids have muscles by which eyes can be closed. The eyelid muscles help to close our eyes by reflex action and help to protect them form dust particles and bright light.

            Any dust or dirt that gets lodged in our eyes is wiped aside to the comer of our eyes when we drink, helped by few drops of tears form the lachrymose ducts that secrete tears.

            The eyebrows forms two long patches of protective hairs above our eyes. They help to trap sweat tricking down form the forehead, while the bony bulge of the brows saves the eyes form impact with any large objects that come too close to our eyes.

            These three natural mechanisms protect our eyes.

What are the Different Methods of Birth Control?

            The human population is going up by leaps and bounds and the developing countries are the worst affected. This is giving rise to shortages of food, shelter and water. The potential threat of a population explosion made family planning a national issue in many developing countries.

            In the developed courtiers, just the opposite was true- family size became smaller to meet the demands of a hectic industrial life but this did not happen in the poorer countries. Several birth control methods have been developed over the years to control population.

            The testes- the sex gland of a man- produce sperms, while ovaries- the ova. When the male sperm combines with the female ovum inside a woman’s body, a new life begins to grow. Birth control methods are used to prevent the combination of the egg with the sperm. These have been divided into three broad categories: natural methods, spacing method and terminal methods.

            Natural methods are those which do not involve the use of any drug. These are

1.        The rhythm or safe period method and

2.       Coitus interrupts.

The rhythm method is based on the avoidance of

Sexual inter course during the unsafe period or the days when there is a possibility of the egg meeting the sperm. Women normally produce one ovum every month. If the male sperm does not enter the vagina at the time, then pregnancy can be avoided. The safe period is counted basing on the days of the regular menstrual cycle of 28 days.

            11 days before the expected date of commencement of menstruation are considered safe; the 8 days proceeding these 11 days are full of risk. The 8 days before this risk period are considered safe. Since the regularity of monthly period varies from woman to woman, the safe period varies accordingly.

            The second natural method, coitus interrupts, involves interrupting sexual intercourse before the man ejaculates the semen. Withdrawing the penis for the vagina before discharge prevents the semen from entering the woman’s body. This method is, however, very risky, and said to be psychologically unhealthy.

            Spacing methods include the barrier contraceptives, which prevent the viable sperm either form entering the vagina or from reaching the uterus, thus leaving them unable to swim up the fallopian tube and fertilize an ovum. These methods involve the used of: 1. Condom, 2. Diaphragm, 3. Intra-Uterine Devices (IUD), 4. Oral Contraceptive Pills and 5. Spermicides. All these methods are good for delaying or gap between the children, as simply stopping their use easily reverses their effects.

Intra-Uterine Device 

Condom

            A condom is an extremely thin rubber sheath unrolled on the erect penis before doing sex. As it covers the penis, sperms cannot go inside the woman’s body. A condom can not be reused. Similarly, a diaphragm is a thin rubber can shape like a dome, which is placed in a woman’s again before intercourse. This closes the opening to the womb and hence prevents the meeting of male and female cells.

            Again, intra-uterine devices are placed inside the uterus so that sperm is not allowed to meet ovum. Lippies loop and copper-T are the most commonly used IUDs in India.

            Spermicides are chemical contraceptives like jelly cream and foam tablets, which kill the male sperms, deposited in the woman’s body during intercourse. They are used only 15 minutes before the intercourse.

            Oral contraceptives are birth control pills; they keep the egg from moving out of a woman’s ovary, and thus prevent her from becoming pregnant. These pills contain estrogen and progesterone hormones, thus maintaining them at a constant high level. As a result, ovulation is not triggered, and without an ovum, pregnancy cannot occur.

            Terminal method, popularly known as sterilization, is an extremely effective method of contraception because it is permanent. In males, it is called vasectomy where the sperms are prevented from leaving the testes by cutting and tying the vas deferens- the tube that carries the sperm from the testes to the urethra.

            In females, it is called Tubectomy; here the surgeon closes the fallopian tubes along which the egg cells pass to reach the uterus. With the help of the different birth control methods, one can have as many children as desired and also achieve a suitable gap between the births- normally recommended as three years.

Why do We Need to Exercise?

            Our body works like a machine continuously till we die. To keep this machine fit, regular exercise is needed. A general fitness crated by routine practice helps person to remain healthy.

Exercise keeps us fit and healthy

            A person, who does not do any exercise, converts only a small amount of food into energy and may become overweight. The muscles become weak without exercise, while blood circulation is slower.

            Regular exercise makes the muscle stronger and improves their tone. Well toned muscles help in proper functioning of organs. Muscle movement helps to speed up blood circulation.

            Exercise not only strengthens the muscles, it improves the amount of oxygen intake-when the breathing becomes deeper, greater quantities of oxygen and nutrients reaches all parts of the body, and waste products are flushed out quicker.

            There are many kinds of exercise that one can take. British walking is one of the best exercises. Yoga is a excellent way to calm the mind while toning up the body. For younger people, more active variations can be swimming, jogging, and aerobics, and tai chi, cycling, playing games and even supervised exercise in a gymnasium. These are some of the several options available for taking regular exercise, and keeping the body fit and mind alert.

How does Our Nervous System Function?

            Whatever it is the heat from a candle or fire that is sensed by you or the pain when a pin pricks your finger, it is all because your nerves are passing the messages to the brain. The nervous system is a network of nerve cells called neurons that send information to and from all parts of the body to the brain. The messages are in the form of electrical signals or nerve impulses. They travel through the cells and are passed on to the other cells. The body has millions of nerve cells linked together to make up the nervous system. The human brain itself contains about ten thousand million nerve cells.

Nervous System in our body

            The human nervous system is divided into two parts- the central nervous system and the peripheral nervous system. The central nervous system comprises the brain and the spinal cord, whereas eh nerve cells and nerve fibers at the periphery. The tough bones of the skull protect the bran, and the bones of the spinal column protect the spinal cord.

            There are two kinds of nerve cells or neurons- sensory neurons and motor neutrons. Sensory neurons carry messages form distant parts of the body towards the brain.

            These relate to pain, temperature, pressure and other messages from the sense organ. The motor neurons carry messages to the muscles, telling them to contract; and to the glands, telling them to produce secretions. The nerves of the central and peripheral nervous system are a mixture of sensory and motor neurons traveling together.

            The nervous system can also be divided on the basis of the nature of work of the neurons. If the nerves are all concerned with conscious sensations, it is called the voluntary nervous system. They carry out orders given by the brain that are directed by will. When we want to walk, write or talk, we use the neurons of the voluntary system. The neurons of the autonomic system help in carrying out the routine activities we do not normally think about. The autonomic system regulates the heartbeat, respiration, digestion, blood pressure, and other unconscious activities.

            The autonomic nervous system has two main divisions- the sympathetic and parasympathetic systems. Their activities balance each other. Nerve impulses in the sympathetic system tend to increase the rate of heartbeat and the blood pressure. On the other hand, the impulses in the parasympathetic system tend to have the opposite effect. Under different conditions each system takes control of the unconscious activities. With the help of prescribed physical exercises, training and to some extent will power, it is possible to control some of the activities of the autonomic nervous system.

Why do We Have Belly Button?

            Belly button is the little dent that we have in the belly. Though it does not serve any purpose in our daily life, yet it is a matter of interest to know what it is and why we have it in our body.

Belly Button

            Before birth, a baby in its mother’s womb passes through the embryo and fetus stages. In these stages, its abdomen is connected to mother’s body by a long tube called the umbilical cord. A fetus needs to survive and grow during the pre-birth phase of nine months, during which it is supplied with nutrition from the mother’s body through this cord. Oxygen and food from the mother’s blood are carried to it through the vein, and the wastes are excreted through the two arteries in the umbilical cord. The cord is attached to the baby’s body at spot where the belly button is formed after the birth.

            After the child is born, the role of the umbilical cord ends because the child can now eat, drink, breathe and get rid of the body’s waste by itself, using its own organs. Hence, at the time of delivery, the cord is carefully cut off as close to the belly as possible by the doctor. It does not hurt the other or the baby. The tiny stump of the cord that is left after cutting off the long umbilical cord dries within a week and falls off, leaving a scar or a dent on the abdomen. This forms the navel or the belly button.

Why do We Need Rest?

            A normal person sends about 8 hours daily, or one-third of the lifetime in sleeping. Nobody knows exactly why we sleep, but it is essential for both the mind and the body the duration of sleep depends on a person’s age, health and the type of work he or she does during the day.

Sleeping

            Rest is required to make the body and mind fresh and keep them healthy. A newborn baby sleeps nearly all day. The child wakes up only at feeding time. A young child sleeps for about 12 hours a day. An adult generally needs a sleep for about 8 hours a day. After sleep, one feels refreshed and energetic.

            Someone who does not take rest for 36 hours at a stretch becomes irritable and tired. If he manages to stay awake without collapsing for over 60 hours, he may begin to see and hear things that are not there.

            Hence rest is a must for every one to keep the body and mind active and alert.

What Causes a Reflex Action?

            If you accidentally touched a hot stove, what would you do? You would immediately jerk your had away even before you have had time to think about it. This action is called a reflex action. A reflex action is an automatic nervous action, in which a stimulus causes a rapid and totally involuntary response. In this case, the hot stove is a stimulus, and the jerk is the response.

Reflex Action

            Reflexes such as the pupil reflex are quite common. When a bright beam of light hits a person’s eye, his pupil automatically becomes smaller, i.e., it contracts. When the light is taken away and his eyes are shaded, the pupils return to their normal size. In this example, the light is the stimulus and the reaction of the pupil is the response.

            Reflex actions re of two types- unconditioned ad conditioned. Unconditioned reflex actions re exemplified by the reflex tests of the physician. When a doctor tests a person’s reflexes, he makes sure that the different parts of his nervous system are functioning properly.

            One reflex action frequently tested is the knee-jerk action. In this, the doctor lightly strikes an area just below the kneecap with rubber hammer. This cases the lower part of the leg to jerk upward suddenly. This is because the nerve impulses move via the spinal cord directly to the leg muscle and are not controlled by the brain.

             Conditioned reflex actions are a result of particular internal or external stimuli. The Russian physiologist Ivan Pavlov and his associates popularized such conditioning process. Pavlov believed that whenever there was a response to a particular stimulus, a kind of reflex was established in the brain. However, most psychologists today believe that the mechanism of learning is much more complicated than what was explained by him.

            Now the question arises- what cause a reflex action?

            To explain it in simple terms, four basic processes are involved in a reflex action. These are- reception, conduction, transmission, and response. The stimulus is received by receptors nerve ending. Energy from the stimulus is changed into nerve impulses and carried from the receptor to the central nervous system. The nerve impulses are then sent to the motor nerves. The motor nerves control muscle action, causing the muscles and gland respond. Most reflex actions, however, are much complicated and also involve other parts of the nervous system, like the brain. More than 90% of all our actions are performed by our nervous system, through reflex actions.