What is health?

Being healthy involves far more than simply not being ill. If you feel you're in good health, your organs will be working properly and you will have the energy to live life to the full. This feeling of wellbeing affects your mind and your body.

The environment you live in, your diet and your lifestyles affect your health. Physical fitness is an important part of health, and this means that your heart, lungs, skeleton and muscles all work together smoothly to carry out your daily activities. Fitness involves strength, stamina and suppleness, and you need regular exercise to maintain all these conditions. Careful exercise develops a healthy heart and lungs, and gives you the strength and stamina that allow you to run, cycle and swim. A sensible diet and sufficient sleep also help you to keep healthy.

Air pollution is an environmental factor that can damage health. Exhaust fumes from motor vehicles contain substances that can cause asthma and other breathing problems. In hot climates, smog can also develop, trapping these air pollutants and making the health risk greater.

Many diseases are infections that are caused by bacteria or virus. Other illnesses are caused by failure of some of the body's organs or tissues. Sometimes part of the body wear out or are not replaced properly, but most health problems are caused when the body simply fails to maintain itself. Joints can wear out, causing arthritis, or the digestive system may not work as efficiently, causing various types of stomach upsets. Other diseases may be caused by a person's own lifestyle, for example lack of exercise or poor eating habits. Smoking is now known to be a contributory factor in many diseases.

What are Hormones?

Hormones are chemical messengers that are produced in one part of the body and have an effect on another part.

Hormones switch body processes on and off, and they regulate most of the body's activity. The nervous system also helps in these processes, giving pared instructions along the nerves. The body's endocrine system uses hormones which work much more slowly. The majority of hormones are carried around the body in the bloodstream, reaching all the major organs and tissues.

The body has more than 30 different hormones. They are mostly produced in organs called endocrine glands.

These glands discharge the hormones directly into the bloodstream. Other types of glands pass their secretions through ducts to the point where they are needed. Endocrine glands are found in the head, neck and torso. The amount of hormones in the body is regulated by a feedback system. This means that once hormones are produced, the body measures them and once they have reached the required level, their production is switched off again. Sometimes this mechanism does not work properly and over or underactive glands such as the thyroid can produce illness.

What is the appendix for?

The appendix is probably a leftover from our very ancient ancestors, and in humans it has very little use. In animals that eat a lot of plant material, such as rabbits, the appendix is large and contains bacteria that helps digestion. The human appendix is a tiny finger-like projection from the lower part of the gut. It sometimes become inflamed and has to be remove surgically.

Eating Ice Cream and Other High-fat Dairy Foods Can Help Women get Pregnant?

A study shows that women who ate at least one fatty dairy food a day were 27 % less likely to have a trouble conceiving than women who ate two or more low-fat dairy products a day. Eating ice cream and other high-fat dairy foods may lower the risk of one type of infertility, the study suggests. Eating ice cream may help women get pregnant.

This was the findings of well-known Nurses Health Study at the Harvard School of Public Health.

But some doctors say that this study sounds too good to be true and probably is. Even the researchers said that women should not conclude to this results because this study are only based to the reports of what women said they ate over many years.

The study doesn't apply to most cases of female infertility - not ovulating is to blame only one-third of the time.

The Harvard study, funded by the university and a long-running federal study, involved 18,555 women, ages 24 to 42, who became pregnant or tried to from 1991-99. Among them, 3,430 reported infertility, including 2,165 who saw a doctor for it. Of those, 438 said an ovulation problem was to blame.

If women do eat more high-fat dairy foods to try to boost their odds of conceiving, it would be important to cut calories elsewhere to avoid gaining weight, doctors said. They also should switch back to low-fat dairy foods once the baby is born, to limit saturated fats.

What happens after fertilization?

The fertilized egg begins to divide as it travels down the fallopian tube towards the womb. By the time it enters the womb, it has divided into a ball of about 100 cells. It settles on the wall of the womb and sinks into the surface, becoming firmly fixed. At this point, the female is pregnant.

For the first eight weeks of pregnancy, the developing egg is called an embryo. A liquid-filled bag develops around the embryo to protect it. By the fourth week of pregnancy, the embryo is the size of a grain of rice. It has a head and a tail and the beginning of limbs, and its tiny heart begins to beat. The placenta is the embryo's life-support system. It is a red, flattened organ that becomes deeply embedded in the wall of the womb. The placenta extracts food substances from the mother's blood and passes waste material from the embryo back to the mother for disposal. The placenta is connected to the developing baby by a thick umbilical cord, which contains large blood vessels.

After the first eight weeks of pregnancy, the developing baby is called a fetus. by now, all of its major organs have formed and it is growing at a very fast rate. By the 16th week, the fetus starts to move about and by the 20th week it may already have eyebrows and fingernails. It weighs approximately 350 grams.

At the 26th week, the baby is big enough to survive if it is born prematurely. It weighs about 1.5 kg and from now on it increases in weight ready to be born. Soon the bay turns over into a head-down position ready for the birth, which usually takes place at around the 38th week.

What is a human egg cell?

The ovaries of a newborn baby girl contain about 250,000 egg cells. By the time she reaches maturity, there will be about 10,000 remaining, However, only a few of these eggs will be used - one each month throughout the years when she can have a baby. Every 28 days, a swelling appears on an ovary. This releases the egg cell then enters the fallopian tube. The swelling it emerged from produces hormones to prepare the womb to receive the egg.

Each month, an egg cell is released from the ovary. When this happens, the lining of the womb changes so that it is ready to receive the egg if it is fertilized.

If the egg is not fertilized, the womb lining brakes down, and blood and tissue pass out through the vagina. this process is called menstruation and it happens about every 28 days. The time from one period to the next is known as the menstrual cycle.

Hormones from the pituitary gland and the ovaries control the menstrual cycle, which maybe irregular. However, it usually settles into a regular cycle.

Are all drugs dangerous?

People take so-called recreational drugs, such as cannabis and heroin, because of the effect they have on the brain. These drugs are different from medical drugs that people take when they have an illness disease. Recreational drugs can be a danger to health. Some of them make people feel excited and full of energy. Others make them feel sleepy and some drugs can make people experience imaginary situations. All these drugs cause the brain to malfunction, and if taken regularly they can cause permanent damage to health.

Some of these drugs are addictive. This means that they cause changes in the brain that make people crave them, even though the pleasant effects may wear off.

Medical drugs work by correcting the chemical reactions within the body that are responsible for disease. For example, insulin injections replace insulin that is not being produced by the pancreas, so sugar can be used properly by the body. In depression and mental illness, drugs can restore the balance of chemicals in the brain. Aspirin is often given to cure a headache, but it can also neutralize the inflammation that causes the pain in the joints of people suffering from arthritis.

Modern drug research studies the cause of diseases, and then designs molecules that interrupt or reverse the disease process. All drugs cause some unwanted effects, and scientists try to find new drugs that relieve the disease without causing further problems.

How are sperms made?

Sperms, the male sex cells, develop in the testes. They are stored for several days until needed. The testes contain long tubes called seminiferous tubules, which are tightly coiled. sperms are produced continuosly in these tubes and then passed to tyhe epididymis and are stored in a large duct called vas deferens. Here liquid is added to the sperm to make a milky fluid called semen. It is stored in pouches called semenal vesicles. during sexual intercourse, the seminal vesicles contract and force out the sperm. It passes out of the penis and into the female sezual organs.

Up to 100 million sperms are produced everyday by the male. If they are not released, they are soon destroyed and replaced. sperms look like tiny tadpoles, with rounded heads and long lashing tails. They use their tails to swim at a speed of about one cm per minute. The head of the sperm contains the nucleus, which will join with the egg cell during fertilization.

Why does the brain have two sides?

The cerebrum is divided lenghtways into two halves, called cerebral hemispheres. Each side of the brain controls the opposite side of the body.For example, if you move your right leg, the instructions for nthat movement come from the left side of the brain. The nerve cells that carry messages from the brain cross over at the base of the brain. In most people, the left side controls speaking, writing and logical thought, while the right side controls artistic abilities and creative thinking. Most people seem to use one side more trhan the other. This is why some people seem to be more artistic than others, or are better at scientific and mathematical thinking. Usually, the left side of the brain is more dominant as far as movement is concerned, which is why most people are right-handed. About 10 % of people are left-handed.

What job do the kidneys do?

Kidneys are very effective at removing most of the waste from our blood.

Blood is pumped through groups of tiny tubes inside the kidneys and harmful waste material passes out through the walls of these vessels and down a long tube called the ureter, into the bladder. Here it is stored until ready to be discharged from the body as urine. The kidneys have a very important function in controlling the amount of water in the body. water balance needs to be kept at exactly the right level if the body cells are to remain healthy.

If the kidneys become diseased and stop working, it is necessary to use a kidney machine to remove waste from the blood. This machine process is called dialysis. It involves pumping blood from a tube in a person's arm into thin tubing that runs through a tank of sterile liquid. Waste passes from the blood through the walls of the tubing and the cleaned blood is returned to the body. This has to be done throughout the person's life, unless the new kidney can be provided in a transplant operation. Dialysis needs to be carried out frequently-several times a week- to stop waste from building up to dangerous levels.

Why is the body complicated?

If we were simple single-celled animal, we would not need a complicated body system to stay alive. Single-celled animals absorb oxygen directly from the water around them, and they get rid of waste in the same way. Many feed by simply crawling over food material and absorbing it, or by letting food pass through the flexible membrane around it.

Human cells operate in a similar way. Our organ systems simply provide the basic conditions that the billions of individual cells in our bodies need to survive. In general, the bigger an animal is, the more complicated its body needs to be in order to survive and reproduce.

What causes muscle cramps?

Cramp is caused by a build-up of a waste substance called lactic acid. When a muscle works harder than usual, it starts to break down stored food without using oxygen. This process is called anaerobic respiration. it produces lactic acid as a waste product. As the lactic acid builds upit interferes with muscle action, making the muscle feel tired, until the acid is flushed away by the blood. If too much lactic acid builds up, it makes the muscle contract very sharply and painfully, causing a cramp.

Why can a body reject a transplant organ?

All your body cells carry a "label" or marker substance on the outside of the cell. This marker is recognized by the immune system, which will not attack it. In some very serious illnesses, when a person's organ has failed completely, an organ from another individual may be transplanted. The donated organ carry different marker substances, so the immune system treats them as invaders and will mount an attack on them called rejection. These attacks from the immune sysyem can be reduced or prevented by the use of powerful drugs.

Why can too much cholesterol be bad for you?

Cholesterol is a natural fatty subtance that is found in many foods such as dairy produce, eggs and meat. it is also produced naturally in the body. High levels of cholesterol in the blood can sometimes collect on the inside the arteries, like the fur inside a kettle. This gradually reduces the blood flow and can lead to the formation of a clot that may break off and block smaller arteries. Sometimes an artery becomes almost completely blocked by these cholesterol deposits. It becomes so narrow and rigid that it can not expand to let enough blood to pass through. This kind of blockage usually happens in the legs, and is a common result of cigarette smoking.

Can our bodies attack themselves?

Sometimes the immune system mistakes some harmless material for an invader and this can cause illness.

Grass pollen and dust are harmless materials are often ihaled. In some people the body mounts a fierce attack on them. The immune system releases the substances normally designed to fight infection, and their effects can cause illnesses such as hay fever and asthma. Sometimes the immune system attacks normal tissue or organs, causing a condition called auto-immune disease. This can produce serious illness, but fortunately it is quite rare.

How does smoking harm the lungs?

Smoking damages the natural cleaning mechanism of the lungs and also poisons the cells that line the lungs. Tobacco smoke paralyzes the tiny beating hairs inside the air passages of the lungs. These hairs normally clean out any material that is inhaled. Tar from the smoke accumulates inside the lungs, together with small grains of soot and chemicals that can somtimes cuse cancer. These substances are absorbed into the blood and can cause damage to the heart and circulation.

Regular smoker often suffer from lung diseases such as bronchitis, which are caused by tobacco smoke.