Vaccines

 Vaccines

Vaccines are substances that help the body fight off diseases and illnesses. In the past they have helped save millions of lives around the world.

Diseases are often caused by bacteria or viruses that attack the human body.  A vaccine is a dead or very weak form of such a virus. When you get a vaccination from your doctor the body it gets used to these weaker viruses and can produce antibodies which stay active for a long time. When the real virus or bacteria attack, the body becomes immune and can defend itself.

People can get their vaccinations in many forms.  Very often the vaccine is injected into your body, but vaccines are also taken by mouth or are inhaled.

Although many vaccines protect you throughout your life, some provide immunity for only a certain time.  Vaccines against the flu must be administered every year, because the flu virus can change or may appear in a different form.

Most people already have a certain amount of immunity in their bodies. It is passed to them from their mother. However, these antibodies do not protect a baby for a long time, so that many vaccines are given to infants in their first years.

Some illnesses only occur in certain areas. If you travel, for example, to tropical regions, you should get vaccines to protect you from yellow fever, malaria or hepatitis.

Vaccines have saved the lives of millions of people in the past and virtually eradicated many diseases. Smallpox, for example, was once one of the world’s most serious diseases, which killed millions every year. By the end of the 1970s smallpox had disappeared completely because nearly everyone was vaccinated.

The first vaccines were created towards the end of the 18th century.  An English scientist, Edward Jenner, carried out experiments with cowpox, a milder form of smallpox. He found out that people who got cowpox rarely got ill from smallpox. In France, Louis Pasteur developed a weak form of rabies to protect people from dog bites.  In the 20th century polio has been wiped out completely.

Today there are vaccines for many illnesses. The most common are the flu, cholera, the plague , hepatitis.

Although vaccination is widely available and a part of the regular health program in almost all industrial countries, there are still countries, especially in the Third World where people die of serious diseases.  About three million children each year are killed by diseases that could have been prevented. In developing countries almost two thirds of all children are not vaccinated. The World Health Organization is fighting to provide vaccines for these children.

Bacteria

  Bacteria

Bacteria are small living things that can be found almost everywhere. They live on the ground, in oceans, in the food that we eat and even in our bodies. They have been on earth long before there were any other organisms .Bacteria are so small you can only see them with the help of a microscope. They have only one cell and very simple structures.

Bacteria have outer cell walls that protect the inside. A cell membrane is inside the cell wall. It prevents harmful substances from getting in and out. Inside the membrane is a soft, jelly-like substance called the cytoplasm. It has chemicals that help build the parts of a cell and break down food. Within it is the nucleoid, which contains the DNA. It controls a cell’s growth and other activities

Bacteria appear in different shapes. Spherical bacteria are round or ball-like. Rod-shaped bacteria live in your intestine and form chains. Spiral-shaped bacteria have a twisted form.

Bacteria absorb nutrients and remove waste through their cell walls. They reproduce by splitting themselves in the middle. The two new cells can then split into four cells and so on. In a short time a single bacteria can reproduce billions of times.

Some bacteria can get inside the human body, reproduce and cause an infection. These harmful bacteria are called pathogens.  Our immune system is in charge of fighting off these bacteria.  However, sometimes we need a vaccine to help fight off these intruders. Vaccines are weak or dead forms of the bacteria itself. Such a substance helps our body fight off bacteria in the future.  Some examples of illnesses caused by bacterial infections are tuberculosis or pneumonia.

The best way to protect yourself form bacteria is to keep yourself clean and wash your hands. Because bacteria may be transported by air, we should cover our nose and mouth when we sneeze. Vitamins also help strengthen our immune system and fight off bacteria.

Bacteria can be helpful to the human body as well. They live in our stomach and help us digest food. Other bacteria create cheese and yoghurt.  Bacteria are at work in the soil and decompose dead plants and animals.

VITAMINS

 

VITAMINS

The word “vitamin” goes back to the Polish scientist Casimir Funk in 1912.  He was studying a substance in the layer that covers rice.  This substance was believed to cure a disease called beriberi.

Funk believed the substance belonged to a group of chemicals known as amines.  He added the Latin word "vita," meaning life.  So he called the substance a “vitamine” -- an amine necessary for life.

Scientists have discovered fourteen kinds of vitamins.  They are known as vitamins A, the B group, C, D, E and K.  Scientists say vitamins help to carry out chemical changes in cells.  If we do not get enough of the vitamins we need in our food, we may develop a number of diseases. 

This brings us back to Casmir Funk.  His studies of rice were part of a long search for foods that could cure disease.

One of the first people involved in that search was James Lind of Scotland.  In the 1740s, Lind was a doctor for the British navy.  He investigated a problem that had existed in the navy for many years. 

The problem was the disease scurvy.  So many sailors had scurvy that the navy’s lost some of its strength.  The sailors were weak from bleeding inside their bodies.  Even the smallest wound would not heal.  Doctor Lind thought the sailors were getting sick because they failed to eat some kinds of foods when they were at sea for many months.

Doctor Lind separated twelve sailors who had scurvy into two groups.  He gave each group different foods to eat.  One group got oranges and lemons.  The other did not.  The men who ate the fruit began to improve within seven days.  The other men got weaker.  Doctor Lind was correct.  Eating citrus fruits prevents scurvy.

Types of Vitamins

Vitamin A helps prevent skin and other tissues from becoming dry.  It is also needed to make a light-sensitive substance in the eyes.  People who do not get enough vitamin A cannot see well in darkness.  Their eys may get dry.  This can result in infections and lead to blindness.

Vitamin A is found in fish liver oil.  It also is in the yellow part of eggs.  Sweet potatoes, carrots and other darkly colored fruits and vegetables contain substances that the body can change into vitamin A. 

Vitamin B-one is also called thiamine.  Thiamine changes starchy foods into energy.  It also helps the heart and nervous system work well.  Without it, we would be weak and would not grow.  We also might develop beriberi. Apart from rice thiamine is found in beans , peas, nuts, meat and fish.

Another B-vitamin is niacin.  It helps cells use food energy.  It also prevents pellagra -a disease that causes weakness, reddish skin and stomach problems.  Niacin is found in meat, fish and green vegetables.

Vitamin B-12 helps produce red blood cells.  It is found naturally in foods such as eggs, meat, fish and milk products.  It also helps babies of pregnant mothers before they are born .  Vitamin B-12 is found in green leafy vegetables and other foods and citrus fruits.  In some countries, it is added to products like bread.

Vitamin C is needed for strong bones and teeth, and for healthy blood.  It also helps wounds heal quickly.  Because our body stores little vitamin C we must get it every day in foods such as citrus fruits, tomatoes and cabbage.

Vitamin D helps make calcium in the blood.  Calcium is needed for nerve and muscle cells to work normally.  It also is needed to build strong bones.  Ultraviolet light from the sun changes a substance in the skin into vitamin D.  Fish liver oil also contains vitamin D.  In some countries, milk producers add vitamin D to milk so children will get enough.

Vitamin K is needed for healthy blood.  It thickens the blood around a cut to stop bleeding.  Bacteria in the intestines normally produce vitamin K.  It can also be found in pork products, liver and in vegetables like cabbage, and spinach.

Some people fear they do not get enough vitamins from the foods they eat.  So they take products with large amounts of vitamins.  They think these products or vitamin supplements will improve their health and protect them from disease.

Experts note that taking too much of some vitamins can be harmful.  People should be sure to discuss what vitamins they take with their doctors.  This is because some vitamins can cause harmful effects when mixed with medicines.

Coffee - a Popular Hot Drink

   Coffee - a Popular Hot Drink

Coffee is one of the most popular hot drinks in the world. Almost a third of the world’s population drinks coffee.  People often meet at cafes or coffee shops for a coffee break during the middle of the morning or stop work in the afternoon to drink coffee.

About 7 million tons of coffee are produced every year. Brazil is, by far, the world’s largest coffee producer. About a third of the world’s production comes from this South American country. Other coffee producing countries include Vietnam, Indonesia and Columbia.

The United States is the biggest coffee consumer in the world. About 1.2 billion kilograms of coffee are consumed there every year. Drinking coffee is extremely popular in European countries, like Italy, France and Germany, as well as in Brazil.

The coffee plant

Coffee grows as a green-leaved tree or bush with blossoming white flowers. The coffee shrub originally comes from Ethiopia but, in the course of time spread to Southeast Asia and South America.

There are two basic types of coffee. Arabica accounts for about 70% of the world’s coffee production. It is grown in the higher regions of central and South America and is popular for its flavor and fragrance. Robusta has spread throughout central and eastern Africa. Although it makes up only thirty per cent of the total coffee production it has become more important because it can resist diseases better. It also has smaller beans and can grow at lower altitudes than Arabica.

Coffee plants grow in the warm and moist climate of the tropics and subtropics. Most coffee trees grow best between 1000 and 2500 meters above sea level.

Coffee trees produce fruits called berries. At first they are yellow, and then become red as they mature. An average coffee tree can produce enough berries to make about a pound (half a kilo) of roasted coffee.

Coffee seeds are grown in nursery beds. After a year they are planted in specially prepared fields. It takes a coffee tree about six years to produce a full harvest of coffee berries.  The largest ones can get up to six meters tall, but they are normally trimmed to a height of 1.5 to 4 meters.

Harvesting and processing coffee

Most coffee berries are picked by hand, which makes sure that only the good berries are used. After separating berries from leaves and other waste materials, the beans are then taken out, cleaned and dried. Only the best beans make it to the market. Then they are put into bags and shipped to countries where they are roasted.

At their destination the beans are combined to make different blends of coffee. Roasting for about 15 minutes brings out the true flavor of the coffee. The roasted coffee beans are packaged; some of them are crushed to ground coffee.

Effects of coffee

Coffee contains caffeine, a substance that stimulates parts of the body, especially heart and muscles. People often drink coffee to help them stay awake or keep them alert. Although coffee has some negative effects it is not thought to be a harmful drink. Children and people who have heart problems should not drink coffee it in great quantities. In decaffeinated coffee the caffeine is extracted in a chemical process.

How coffee is brewed.

Coffee must be ground before it is brewed. Grounding usually takes place inside a coffee machine, but you can also buy ground coffee in shops. The simplest brewing process is pouring boiling water over a filter of ground coffee and letting it flow into a pot. Coffee is often made by using simple machines that force hot water through a pad of pressed coffee. Espresso machines press hot water through ground coffee.

Instant coffee is made by pouring hot water over powdery coffee. It dissolves at once and you do not need a special machine.

History of coffee

Coffee originated in the east African highlands in the 6th century. It was then brought to Arabia where people used it as food and medicine. During the 11th century the first coffee drinks came up. In the 16th and 17th centuries coffee became widely popular in Europe when the Turks brought it to Central Europe. In the 17th and 18th century coffee conquered North and South Amercia.

Coffee houses soon became popular all over the world. In the 1900s chains of coffee shops developed in Europe and America. Today, Starbucks is the largest coffeehouse chain in the world, with over 20,000 stores in 60 countries.

Types of Coffee drinks

Espresso is probably the most popular coffee drink in the world. It is made by forcing hot water through a pad filled with dark ground coffee. Although there is not much coffee in the cup an espresso is very strong. It is usually drunk black, with no milk added.

Americano is an espresso with hot water added to make it weaker.

Café Latte is an espresso with a lot of hot milk and foam added on the top.

Cappuccino is a cup of espresso, together with warm milk and a lot of milk foam at the top. In some coffee shops it is decorated with flaked chocolate or cocoa.

Cafe Mocha is a cappuccino with chocolate or cocoa added.

Frappe is a cold espresso  that you can get at some coffee shops during the hot summer months.

Turkish coffee is usually thicker than normal coffee. It is made by combining  ground coffee and water to a muddy mixture.

Chocolate - History and Production

 Chocolate - History and Production

Chocolate is a food that is popular all over the world. It is made from the seeds of the cacao tree. It can be eaten and also used as a flavour in ice cream, candy and other foods. Many people like the taste of chocolate and those who work hard eat it to give them energy.

History of chocolate

Chocolate originally came from Mexico and Central America. Historians think that the Maya took the wild cacao trees from the rainforest and planted them in their own gardens. They crushed the seeds and mixed them with water and spices to make a hot drink.

Chocolate and cacao were very important for the Mayan culture. Families drank a hot chocolate drink at special occasions and at parties.

The Aztecs, a people who lived centuries later, used cacao beans as a form of money. They traded other valuable goods to get them because they didn’t grow there. Only the rich people had the money to buy cacao and drink hot chocolate.

In the 16th century Spanish explorers brought cacao back to Europe, where the drink became popular quickly, especially among kings, queens and noblemen. Other European powers began to plant cacao trees in their own colonies.

During the Industrial Revolution new technologies were able to make the production of cacao cheaper, so that poorer people could also afford it. In the 19th century the beans were pressed together with butter and mixed with sugar into a new form, chocolate.

Today the biggest chocolate producing countries are the United States, Great Britain, Germany, Switzerland, the Netherlands and France.

How cacao grows

Cacao trees grow in the tropical regions of South America, Africa and Asia. The biggest cacao bean producers are the Ivory Coast, Ghana, Indonesia and Brazil. The cacao tree can grow to a height of 7 metres. After about 5 years the cacao trees produce large fruits. When the fruit is ripe it can contain 20 to 40 seeds.

How chocolate is made

After the cacao seeds are harvested they are transported to factories, where they are cleaned and dried. The outer parts of the seeds are removed.

Workers then roast the beans to give them a certain flavour. The seeds of the cacao beans have a lot of fat in them. They are grinded and mixed together with butter to form cocoa butter.

A dry powder can be made by pressing fat and water out of the cocoa butter. This powder is used for baking and also mixed with hot milk to drink.

Chocolate bars are made by putting sugar and milk into the cocoa butter. This paste is then put into different kinds of moulds.

Chocolate making is a big business. More than five billion dollars worth of cacao beans are sold every year. Americans, for example, eat five kilograms of chocolate every year.

Value of Chocolate

Chocolate has a lot of calories but it also has carbohydrates, fats, and other vitamins and minerals. It can give you a lot of energy that you need to do sports or hard work.

Scientists have found out that eating chocolate reduces blood pressure and the risk of heart disease and cancer.

There are also negative effects of chocolate. It can make you addicted and lead to obesity. Chocolate in large amounts lead to tooth decay.

Carbon dioxide

 Carbon dioxide

Carbon dioxide is a compound in which two oxygen atoms are connected to a carbon atom. At normal temperatures it is a colourless gas that exists naturally in the Earth’s atmosphere. The air that we breathe has about 0.03% of carbon dioxide in it.

Carbon dioxide is an important part of the carbon cycle and essential for life on Earth.  Without it temperatures on our planet would be very low.

Plants use the sunlight and take up the CO2 in the atmosphere to produce energy and oxygen. This process is called photosynthesis.

The gas is also produced when fossil fuels are burned. Carbon dioxide that has been stored for millions of years in coal, oil and natural gas is set free. Living creatures produce carbon dioxide when they breathe out. It is emitted from volcanoes and hot springs. Deforestation sets carbon that is stored in trees free.

Carbon dioxide is an important greenhouse gas. Light that enters the atmosphere it is converted to heat. Higher amounts of CO2 make the atmosphere denser and keep it from getting out. CO2 is a gas that is highly responsible for global warming. Since the Industrial Revolution of the 1800s the amount of CO2 in our atmosphere has risen by 40%.

Throughout the centuries carbon dioxide has been in balance. Now more carbon dioxide is being produced than can be absorbed by nature.

Uses of Carbon Dioxide

Carbon dioxide is used in various industries to produce food, chemicals and oil products. It is especially common as a food additive and is added to beverages to give fizz to sparkling wine and water. It is also responsible for a beer’s foam.

As a pressurized gas carbon dioxide is used in fire extinguishers because it does not burn. Put in cartridges it can be used to inflate bike tires. In its solid form CO2 is called dry ice. It is used for cooling fresh food or ice cream. Liquid carbon dioxide is needed to remove caffeine from coffee.

Carbon dioxide in oceans

Oceans are carbon sinks. They absorb more than 25% of all the carbon dioxide that people emit into the atmosphere. As a result, the ocean’s water is becoming more acidic. This change affects the food chain and all sea organisms.

Carbon dioxide poisoning

Although carbon dioxide is not poisonous in normal amounts it can kill you if there is more than 10% in the air. High concentrations can lead to dizziness, bad sight, breathing problems as well as a high blood pressure and an increased heart beat. High levels of CO2 occur when there is not enough fresh air in a room.

 

What is ACID RAIN?

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