Reason why we feel dizzy after running in circles

Q. Why do we feel dizzy after running in circles?

A. Our brain performs the function of keeping our body balanced. Although our body sways from side to side much of the time while walking, running, bicycling or even standing the brain controlling any departure from the well balanced perpendicular pose keeps it from falling down. However, it needs some information in order to perform this work properly. It must have precise data in respect of imbalance – such as the direction and the extent of imbalance. Unless the brain has this information it can not issue appropriate instructions for regaining the balance. The ears provide this information.


Each person’s ears have a set of three hollow tubes filled with fluid that function like spirit-level, i.e. the fluid in the tubes maintains its level by flowing in the direction of the tilt to occupy the space created by the tilt. In order to understand the working of tubes take the example of a glass filled with water. So long the glass is standing upright on its base there is no problem but when it is tilted on one side the water is displaced towards that side to retain its horizontal level.

Similar action takes place in the semicircular tubes of the ear. As long as the head and torso are perpendicular the fluid in the semicircular tubes remains undisturbed. When the head tilts towards left, right, forward or backward, the liquid in the tubes is set in motion towards the direction of the tilt by the pressure. Very fine hair cells situated in the lower part of the tubes bend opposite to the flow. These hair cells function as sensors to gauge the flow of the fluid and by bending convey to the brain via the nerve cells that the body is not balanced. On receiving this information the brain immediately issues suitable commands to the legs, neck, arms, or the entire torso to carry out movements in a particular way so as not to fall down and to regain balance. The brain processes the data received from the ears and issues command signals to the limbs so quickly that the entire process of ‘watch out!’ appears normal. Even a powerful computer can not match this lightening speed.

The brain of the person who is pirouetting does not become dizzy. It is working as efficiently as before. The culprit is the fluid in the semicircular tubes which continue to shake for some time after the person has stopped pirouetting. Hair cells in the tube also take some time to come back in the original position but the brain acting on the misinformation commands the legs to plant themselves firmly. It is not the brain that trips but the legs that trip trying to position firmly on the ground.

More reading:
Dizziness (Wikipedia)

Harmfulness of overdose of vitamins

Q. Is overdose of vitamins harmful or the body just flushes out the excess substance?

A. When you go 10 times above the Recommended Dietary Allowance/RDA, a vitamin or mineral acts like a drug and may have side effects. For example, very high doses of vitamin A are extremely toxic, producing symptoms similar to brain tumor.

The fat soluble vitamins – A, D, E, and K – are the most dangerous in high doses because they are stored in the body. Two of these, A and D, have very clear toxicity. Large doses of vitamin K will cause clotting problems. With vitamin E, strangely enough, we have not seen any toxicity.

This is not to say that water soluble vitamins are safe at any dose. To be excreted in the urine, they must pass through the blood, and in that short time, they may have toxic effect. Vitamin B3 in very large doses causes palpitations, sweating and circulatory problems. And there’s evidence that excess of some vitamins, such as B6, may cause brain damage.

More reading:
Vitamin (Wikipedia)

Reason why we rub our eyes when tired

Q. Why do we rub our eyes when we are tired?

A. It’s because when we are tired, we don’t produce enough moisture our eyes need, and rubbing them stimulates the tear glands. They are called lachrymal glands, one of which lies above each eyeball. They continuously produce tears that are necessary to keep the eyes moist and clean. As you blink about 15 times a minute, the eyelid washes tears across the eye. Surplus tear fluid drains down the tear ducts to the nose.

If your eyes feel dry and itchy several times a day you might have dry eye syndrome. This may be because eyes do not produce enough tears or because your tears are evaporating too quickly. Some people naturally produce more tears than others, and those with lower tear production are more likely to have eye irritations. Persistent dryness may be caused by a thyroid condition called Hashimoto’s disease, or a glandular disease called Sjogren’s syndrome.

In most cases, however, dry eyes result from an inadequate fluid coming out of the lachrymal glands. This happens especially when you are tired. The best treatment is not to pick up kitchen knife and cut onions or have another viewing of tragedy-filled Titanic but to rub your eyes to activate the tear glands. Drinking plenty of water throughout the day might also help to keep your eyes lubricated.

More reading:
Lacrimal gland (Wikipedia)

Reason why the entire surface of a plane is not painted over

Q. Why the entire surface of the passenger planes is not painted over? Why the nose of the plane is black?

A. There are a number of reasons why the entire surface of a passenger plane is not painted over. Firstly, ordinary oil-paint will not serve the purpose. Sometimes the plane is on the runway of an airport in the temperature of 50◦ Celsius and after a few minutes it is flying at the altitude of 30,000 feet above the sea level where the temperature is below the freezing point. Therefore, specially made polyurethane paint is used and it is very expansive. The job of painting takes up almost two weeks and during this time the plane remains unused. The loss of revenue on this account is substantial. As a result the cost of painting only 1/3 surface of a jumbo jet is a whopping $ 24,000 approximately. Moreover, almost 500 liters paint is necessary to paint 1/3 surface. This amounts to a permanent increase of half a ton in the payload. The engines have to work so much more and consume additional fuel. A plane traveling from Delhi to Kochi would burn up to half a ton more fuel to carry this extra load. Imagine the overall costs involved in painting the entire surface of the plane!

The reason for leaving the plane’s nose unpainted is quite different. The nose is fabricated from carbon alloy that is black in color. It houses radar scanner to capture the data regarding weather. The disc antenna for radar inside the nose can swing 30◦ to the right or left. As black colored carbon metal absorbs reflected radio waves better it is left unpainted.

However, most of the passenger planes made today are painted fully.

Cause and cure of hiccups

Q. What causes hiccups and how they can be cured?

A. Hiccups are caused when our diaphragm – a large muscle across the chest – starts contracting in jerks, instead of moving smoothly up and down. To stop hiccups, one has to shock the diaphragm back to its normal movements. There is no sure-fire cure for hiccups, but some things that can work include a good scare, drinking water while someone plugs your ears, eating a spoonful of crushed ice, sucking a slice of lemon and holding your breath for a few seconds.

More reading:
Hiccup (Wikipedia)

Reason why we have deciduous and permanent sets of teeth

Q. Why do we have two – deciduous and permanent – sets of teeth?

A. Around the age of six or seven years, our teeth start to loosen, eventually falling right out. These are what we call milk teeth. Their termination is not a cause for alarm, but rather, a natural process. Soon new teeth replace the ones that are lost. In fact, the deciduous teeth help the permanent teeth erupt in their normal position. Certain of the lower vertebrates, such as sharks and mud puppies, continuously produce new teeth. But most mammals have only two sets. It seems that as you go up on evolutionary scale, there is loss in capacity to replace teeth, scientists say. On the other hand, the teeth become more specialized. For example, in lower organisms, teeth are designed primarily for grabbing and slashing, while in higher animals, they are also adapted for chewing and grinding.

It has been known that in humans the first set of teeth do more than just allow a child to chew. They play a role in stimulating and guiding the growth and development of jawbones and permanent teeth. One of the biggest fallacies is the belief that because deciduous teeth are temporary, they are not important. If a child loses milk teeth prematurely, by accident or because of decay, his jaw and permanent teeth are likely to develop improperly. Prolonged treatment may be needed to set them right.

Another reason for our two sets of teeth is that there is not enough room in a child’s small mouth for the full set of permanent teeth – there are only 20 deciduous teeth, compared with 28 or 32 permanent teeth present in adults.

How do the deciduous teeth know just when to fall out? The beginnings of our second set of teeth are already present below the gum line at birth. During early childhood, the permanent teeth develop and start to push through the jaw towards the mouth’s interior. As they move, they cause the roots of the deciduous teeth to dissolve. Without the roots to hold them firmly in place, the deciduous teeth become wobbly and simply fall out.

More reading:
Deciduous teeth (Wikipedia)
Permanent teeth (Wikipedia)

Effect of rusting on weight of iron

Q. Does iron increase in weight when it rusts?

A. The answer is yes and no. Let’s consider the yes part first. What happens when iron rusts is that the outside of it, which is exposed to the air, corrodes or oxidizes. A certain amount of oxygen of the air is added to the iron. This oxygen, like everything else, has weight, and its weight (actually relative atomic mass of 15.9994) must be added to that of the iron itself when the iron is rusty. Therefore, the answer to the question must be yes. Iron increases in weight. But as everyone knows, the rust, or oxide of iron, is friable; a Latin word which means that it crumbles easily.

Now the answer which is clearly no. The rust will crumble away under the influence of water or wind or anything else rubbing against the iron. Therefore, the iron object will lose not only the oxygen that it has taken into itself, but also the part of the iron which has combined with oxygen. So the material made of iron, when it rusts, loses weight. The whole piece crumbles into red dust eventually. This is very serious, of course, for it means that the object loses its strength. And if an iron and steel bridge were allowed to decay in this fashion, it would soon break. That is one reason why such a bridge is painted to protect the iron from the air.

More reading:
Rust (Wikipedia)
Iron (Wikipedia)