Why do people get allergies?

An allergy is any condition in which a person reacts in a hyper- sensitive or unusual manner to any substance or agent. The range of allergies is very broad and people may react to various foods, drugs, dusts, pollens, fabrics, plants, bacteria, animals, heat, sunlight and many other things. If a person develops asthma, it is usually the result of an allergy.

Whenever a foreign material invades the tissues, the body reacts to fight against it. The body produces certain materials called antibodies which combine with the foreign material and render it harmless. But should it enter the body a second time, the antibodies are torn away from the body tissues to attack the substance. This causes a chemical substance called histamine to be released, which in turn produce the disorders which are symptoms of an allergy.

Fact:
In spring and early summer some people suffer from an allergic reaction to certain plants and pollens. This is called hay fever and can give the symptoms of a heavy cold.

Why do some people get asthma?

Asthma is not a disease but a symptom of some other condition. When a person suffers from asthma, he finds it hard to breathe because there is an obstruction to the flow of air in and out of the lungs.

What causes asthma?

The cause may be an allergy, an emotional disturbance, or atmospheric conditions. If a person develops asthma before he is 30 years old, it is usually the result of an allergy. He may be sensitive to pollens,dust, animals, or certain foods or medicines.

Children, especially tend to develop asthma from food allergies. These are often caused by eggs, milk, or wheat products. People who have asthma are often put on special diets to eliminate or minimize contact with these food products.

Fact:

People can develop allergies to many different foods. One of the most common is to dairy related products.

Why do we awaken from sleep?

Everybody has strange experiences with sleep. Sometimes we can't wait to go to sleep and other times we just can't seem to get to sleep. What is actually wake us up is something that scientists find hard to and seeing and feeling and carrying on mental activities of all sorts, we use up a lot of energy. So the brain and other nerve centers need a rest.

Sleep clears away our tiredness and when we wake up we feel rested. The most probable reason is that while we are asleep our body still feels hungry, cold or even damp, or we may experience an emotion such as fear. These feelings stimulate our brain and cause us to wake up. Of course we may wake up simply because we have had enough sleep!

Fact:
Even while the body sleeps, its nerve systems are active, continuously monitoring and adjusting the internal processes, and checking the outside world for danger. The heart never stops, but beats slower while at rest.

Why Do We Dream?

Why do people dream?
All our dreams have something to do with our emotions, fears, longings, wishes, needs, and memories. But something on the 'outside' may influence what we dream. If a person is hungry, tired, or cold, his dreams may well include these feelings. If the covers have slipped off your bed, you may dream you are on an iceberg.

There are people called psychoanalyst who have made a special study of why people dream. They believe that dreams are expressions of wishes that did not come true. In other words, a dream is a way of having your wish fulfilled. During sleep, according to this theory, our inhibitions are also asleep.

Fact:

Daydreaming is actually a form of dreaming, only it is done while we are awake. Night dreaming is done while we are asleep. That is the only difference between them, since both are done when the dreamer is so relaxed that he pays no attention to what goes on around him.

Why are some frogs poisonous?

Not all frogs are poisonous but some have developed a venom that they can use should they come under attack from predators. The common toad contains a poison that it exudes through its skin if attacked. Dogs and cats commonly experience this poison, however they seldom suffer serious effects. It does teach them,however, to avoid these amphibians. Cane toads are very large toads which contain a drug capable of causing hallucinations if eaten. The skin of some frogs and toads contain poisons which are among the most powerful known to humans.

Fact:
The South American arrow frog is extremely poisonous. It advertises this danger by being very brightly coloured.

(1) Blue poison arrow frog (2)poison arrow (3)Yellow-headed Poison Arrow

Why do Salmon go upstream to spawn?

Salmon have a natural instinct to return to the place they were born to lay their eggs ( to spawn ). This is a safe place to, usually a quiet area of a river, where young salmon upstream can grow. The adult salmon stop feeding when they first reach fresh water, so they gradually become weaker and weaker.


They often wear themselves out trying to reach the exact place where they want to deposits their eggs. The young salmon remain in the river for a few months, then make the journey to the sea. They stay there for up to four years, then the cycle begins all over again.

Fact:

Adult frog very often return to the pond in which they hatched to lay their spawn. Frog spawn hatches into larvae called tadpoles after about a week.



A Sockeye Salmon Spawns in the Shallow Water of the Adams River Photographic Poster Print by Paul Nicklen, 48x64
Journey Home of the Chinook Salmon
Atlantic Salmon Swimming Upriver to Spawn Photographic Poster Print by Paul Nicklen, 36x48
Pink Salmon Head Upstream to Spawn Photographic Poster Print, 30x40

Why are the Terracotta warriors famous?

In China the powerful Qin dynasty came to power in the 3rd century BC. They swiftly conquered their neighbors to make a large empire covering most of modern China. The Qin emperor Shi Huangdi standardized weights and measures and introduced a single form of currency. He is best remembered for his construction of the Great Wall of China which stretches for 2,250 km across the north if China.

When the emperor died a huge tomb was built to hold his body. It was filled with a guardian army of thousands of life-sized terracotta ( or pottery ) warriors. Each figure was individually modeled. The figures were placed in three pits inside the large complex surroundings the emperor's tomb.



The figures vary in height (184–197cm - 6ft–6ft 5in), according to their role, the tallest being the Generals. The figures include warriors, chariots, horses, officials, acrobats, strongmen, and musicians. Current estimates are that in the three pits containing the Terracotta Army there were over 8,000 soldiers, 130 chariots with 520 horses and 150 cavalry horses, the majority of which are still buried in the pits.

Why did the Egyptians make Mummies?

The Egyptians believed in an afterlife to which human souls journeyed after death. They thought it important that the bodies of the dead should be preserved for life in the next world, and so they developed techniques for making "mummies".

The dead person's organs were removed and the body was embalmed and dried, using salts and chemicals, and then wrapped in linen bandages. It was then placed inside a coffin. Even animals such as cats and monkeys were sometimes mummified. Many thousands of mummies must have been made, but only about 1,000 survive today.

Tutankhamun(pictured above ) means "Living Image of Amun". became king of Egypt at the age of nine and died when he was about 18. His tomb is one of more than 60 royal tombs around the Valley of the Kings. Its four rooms contained more than 5,000 objects which included ostrich feathers, model ships, a throne and a gold death mask.

Fact File:

Osiris, god of the dead, was often shown as a mummy on a throne, wearing the crown of Upper Egypt.



Mummies: Secrets of the Pharaohs [Blu-ray 3D]
The Everything Kids' Mummies, Pharaohs, and Pyramids Puzzle and Activity Book: Discover the mysterious secrets of Ancient Egypt (Everything Kids Series)National Geographic's Egypt - Secrets of the Pharaohs [VHS]

Why is Snow White?

Snow is actually frozen water, and as we know ice has no color, why then is the snow white?
The reason is that each snowflake is made up of large number of ice crystals. These crystals have many surfaces. It is the reflection of light from all of these surfaces that makes snow look white.

Snow forms when water vapor in the atmosphere freezes. As the vapor freezes, clear transparent crystals are formed. The currents that are in the air makes these crystals go up and down in the atmosphere.

Fact File:

The Inuit people live in the icy lands of the Arctic North. They were self- sufficient and lived a life on the move, hunting and fishing to survive. They built homes,called igloos, out of solid snow.