What gives you Flat Feet?

When you make wet footprints on the bathroom floor, you will see that there are blank patches in the middle between the toe marks and the heel marks. This is because the middle parts of the feet are raised off the ground by two sets of muscles, called the tibial and the peronal muscles which makes the arches of the feet.

If these muscles weaken, the feet spread out and the arches sink to the ground. The footprints are flat, with no gaps in the middle. This is called having flat feet, or fallen arches.

Sometimes people get flat feet because their jobs keep them standing around too much. Policewomen, waitresses and nurses often suffer from flat feet.

The cure is exercise which tighten up the muscles again. Supports to be put inside shoes are worse than useless. They make the muscles slacken, weaker instead of stronger.

When do Sounds Hurt?

Sounds hurt the ears when they register about 130 on the decibel scale. Decibels are units for measuring the loudness of sound. They show how strong the sound waves are.

The lightest sound - perhaps that of a butterfly landing - would register about zero on the decibel scale; the noise level of a house with the television turned on would be about 50; the din in a car factory would measure 95 or more; and some amplified pop music may be near the limit where the ears would be hurt.

Sound waves are formed by millions of molecules of air bumping and vibrating against one another. Weak sound waves move the eardrum only slightly, but strong ones cause it to respond violently and, in time, may damage hearing permanently. The waves get weaker the further they travel.

The word decibel was coined by scientists in honor of Alexander Graham Bell whose interest in sound waves led to the invention of the telephone.

What makes you feel dizzy?

Dizziness most commonly occurs when a person who has been moving around with speed stops suddenly. The sensitive liquid in the inner ear, which mainly controls balance, continues to move around for a time after the body has stopped. So the surroundings appear to be still in motion. However, it takes only a few seconds for the fluid and balance to settle.

This sensation, which is also called vertigo, may also occur to someone looking down from a height or on board ship. Here the cause is probably not so much physical as a nervous reaction which affects the fluid in the inner ear.

Why do we Become Sea Sick?

We become sea sick because our balancing organs, the labyrinthine portions of the inner ear, are disturbed by out of level movements, by sudden turning movements, and by sudden changes in movements in a straight line, either horizontal or vertical.

The three semicircular canals, filled with fluid are set on different planes in the ear. When sudden movements occur, each canal is affected differently. The nerve endings have no time to convey information to the brain so giddiness is likely to occur.

Nowadays, seasickness comes under the general heading of motion sickness, a name invented by Sir Frederick Banting in 1939, which includes the discomfort people feel while traveling in all kinds of vehicles.

Sea sickness may vary with individuals from slight uneasiness to complete transition. The symptoms are pallor, cold sweating, nausea and vomiting. People who have lost their ear labyrinths because of disease do not become sea sick. Others become resistant to it. We say they develop their "sea legs", but it would appear to be an adjustment of the central nervous system rather than the organs of balance. Some people find it helpful to keep their gaze firmly fixed on a steady object.

Why do we resemble our Parents?

We resemble our parents because of a complex of biological processes which we call heredity. Parents and children tend to be similar in many characteristics - structural, physiological and psychological. However, the young are not exact duplicates of their parents and usually differ in many traits. This difference we call variation.

The science of the study of heredity is called genetics, and the most famous name connected with it is that of Gregor Johann Mendel (1822-1884), and Austrian monk whose discoveries laid the foundation of the science.

Mendel studied plants, especially the garden pea and showed that inherited characteristics were the result of paired elementary units of heredity, which we now call genes. These he symbolized by letters. A characteristic of one parent, such as tallness, which appeared in the progeny to the exclusion of another, was said to be dominant. A characteristic which tended not to reappear was called recessive.

Later studies have shown that the genes are carried by structures called chromosomes. The human body begins with the union of two sex cells, and the body of a new born infant has some 200,000 million cells. These cells arise through the division of other cells. When they divide, their nuclei (or tiny central bodies) divide also by a remarkable process called mitosis.

During mitosis the nuclei resolve themselves into structures called chromosomes, which divide lengthwise. All body cells have true copies of all chromosomes that were present in the fertilized egg from which the body developed.

Why do we have Kidneys?

Our kidneys perform four functions, of which the most obvious is the ejection of waste materials containing nitrogen from the body. They also keep the acid-base balance of the blood constant, and regulate the volume of circulating blood and the fluid content of the body as a whole. Finally they regulate pressure relationships between the blood and the tissues.

The kidneys, bean-shaped and about four inches long, lie on the back wall of the abdomen just above the waist, one on each side of the spinal column.

Blood enters the kidney by the renal artery. Some of its plasma is filtered off and, after other processes, ends as urine. The rest leaves the kidney by the renal vein to return to the heart. The urine collects in the central activity (pelvis) of the kidney passes down to the bladder via a tube (ureter) and is finally expelled.

A human being can survive without kidneys for only two or three weeks. Nearly one-fifth of the blood pumped out of the heart goes through the kidneys. The kidneys thus regulate the body fluid - a fluid which Claude Bernard (1813-1878), the great French physiologist, called our "internal environment".

Why do we have Wax in our Ears

Wax is deposited in our ear by special glands to prevent dust and similar foreign material from entering. The part of the ear that we can see as a projecting flap on the side of the head is called the auricle. Leading from it is a short tunnel, the external auditory meatus or earhole, which is closed at its inner end by a thin membrane called the eardrum, separating it from the inner ear.

This tunnel is lined with skin which, especially in men, carries hair and sebaceous glands, that is glands which produce an oily substance called sebum. The skin also contains specialized sweat glands (ceruminous glands) which secrete the brownish yellow wax.

Sometimes the glands secrete too much wax, and then it may collect in the external auditory meatus and deaden the hearing. As the ear is such a delicate instrument, the excess wax should be removed with a syringe by a doctor, although it can sometimes be softened by the application of warmed oil.

Why do we Grow Old

Scientists have evolved three main theories to explain why we grow old. The first concerns the loss of cells or of irreplaceable parts. Brain cells undoubtedly die off in their hundreds of thousands and cannot be manufactured again after a very infantile stage in human life.

However, this cannot be the complete explanation because people who suffer heavy damage to brain and body do not necessarily show the effects of ageing. Moreover, animals have totally different ageing rates, but suffer cell destruction at similar speeds.

A second theory concerns mutations or alterations. A dividing cell does not always divide correctly. All kinds of errors may creep in, aided by natural radiation. Sometimes the mutated cells may be harmful or put out of commission, with powerful effects on other cells, such as the endocrine glands or constituents of the blood. In the 1960s this theory was supported by the discovery that 10 percent of the cells of very old women had lost an X chromosome.

A third explanation, which is not now as widely believed, is concerned with the accumulation of unwanted chemicals. It is suggested that some vital substances can only be replaced at cell division and that a general decline in the rate of cell division could lead either to lack of needed substances or an excess of unwanted ones.

When was the first Blood Transfusion?

The first successful blood transfusion on record was performed in 1665 by Richard Lower. Using quills and silver tubes, he transferred the blood from the artery of one dog to the vein of another. Two years later, he transfused a man with the blood of a lamb. He gave a demonstration of this before the Royal Society in London and the incident is recorded in the diary of Samuel Pepys.

Richard Lower was able to perform these transfusions thanks to William Harvey who, in 1628, announced his theory of the circulation of the blood. Before Harvey, people had always realized that blood was vital to life, but they didn't know how it circulated in the body.

A vital development in blood transfusion came in 1900, when Karl Landsteiner demonstrated the different blood groups in human beings. After that, people were transfused with blood of their own group whenever possible.

Nowadays, blood transfusion saves many lives. People can be treated for shock by pumping plasma (the fluid part of the blood) into them. Large reserves of blood are necessary for open-heart operations, sometimes as much as 20 pints a patient.

Why do we Produce Saliva?

Saliva, the watery secretion produced in our mouths, has many functions. It moistens the mouth and tongue, making sure that the mucus membrane does not dry or crack. It also moistens our food so that it can be molded into an egg-shaped mass (or bolus) for swallowing, and it lubricates the bolus so that it can be swallowed easily.

By means of the enzyme ptyalin, which it contains, saliva begins the digestion of carbohydrates inside the food. Saliva also acts as a solvent to make tasting food easier for the taste buds are stimulated only by dissolved substances.

It is a cleansing agent, washing away particles inside the mouth. If salivation is stopped, for instance in the case of a high fever, the mouth becomes dirty and tastes and smells foul. If salivation slows down, our mouths feel dry and we know we need water.

Saliva is secreted in the three pairs of salivary glands. The largest of these are the irregularly shaped parotid glands which are packed tightly into a space between the ear and the top of the jawbone. The glands are encased in an inelastic covering and that is why they are extremely painful if they swell.

The next pair are the sub-mandibular glands which are egg-shaped and lie under the front of the jawbone, and the third pair, the almond-shaped sub-lingual glands, lie on the floor of the mouth between the tongue and the jawbone.

Why Do We Usually Get Measles or Chicken Pox Only Once?

We usually get measles or chicken pox only once because our bodies manufacture special chemical defences called antibodies. These antibodies are selective and are effective only against the particular microbe they have been formulated to fight. After the battle is won, the antibodies remain in the bloodstream, ready to repel another attack.

The antibodies are large complex protein molecules. One group, the antitoxins, act as antidotes, neutralizing the poisons that the microbes release into the body. The other group, the agglutinins, clump the microbes together so that they fall easy prey to the white blood cells, or leukocytes. These leukocytes develop in the bone marrow and are always present in the blood.

Some of them surround the infected area and quarantine it by making a wall with their own bodies. Within the barricade, the rest of them attack the microbes and eat them up. Like tiny amoebas, they crawl about and stretch out foot-like projections called pseudopods which they use to engulf bacteria and digest them. This explains their other name phagocyte or eating cell. Each phagocyte can eat about a dozen bacteria this way, a process called phagocytosis.