Facts about obesity

Women are more likely than men to be obese in all age groups.

Babies born to obese mothers have an increased risk of asthma.

Obesity and overweight pose a major risk for chronic diseases, including type 2 diabetes, cardiovascular disease, hypertension, stroke, and certain types of cancer.

According to some facts, obesity increases the chances of developing osteoarthritis. This is because excess weight puts more pressure on the articular cartilage.

Obesity in children and adolescents is also associated with an increased risk of emotional problems. Adolescents with weight problems tend to have low self-esteem.

A normal person has between 25 and 35 billion fat cells, but this number can increase in times of excessive weight gain, with a maximum of 100 to 150 billion cells.

According to some facts, Mexican-American children between the ages of 6 and 11 are more likely to be overweight (22 percent) than black children (20 percent) and Caucasian children (14 percent).

Childhood obesity has reached epidemic proportions in the 21st century with rising rates in developed and developing countries. Obesity rates in Canadian children have increased from 11% in 1980 to more than 30% in the 1990s, while during this same period rates of increase were from 4% to 14% in Brazilian children.

Obesity may be common in the same family, but this is not necessarily genetic and may result from the adoption of similar eating habits and lack of exercise.

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How can an x-ray see inside the human body?

X-rays are like ordinary rays of light, except for one thing, they have a shorter wavelength. Because of this, a beam of this length has more energy and will be more penetrating than a simple beam of light, even through solid substances such as wood, metal and concrete.

An X-ray machine has a high voltage current flowing through X-ray tubes. Inside each tube is an airtight glass container. Inside it are two electrodes, or terminals, one negative and one positive. The negative is called a cathode. It is a tungsten coil that is heated by an electric current causing it to release electrons, or charged particles.

These electrons travel from the cathode to the anode, or positive, at very high speeds, from 96,000 to 282,000 kilometers per second. The anode, also called the target, is usually a tungsten block.

The anode stops the fast electrons. Some of the energy of the electrons is transformed into heat and the rest into X radiation. This X radiation, or X-rays, escapes through a window of the tube and goes to the part of the body that is going to be x-rayed.

Since these X-rays pass through the body, they cast shadows on a piece of photographic film, much like the film used in an ordinary camera.

In the hands of qualified technicians, X-rays can help save lives by killing cancer cells, helping doctors spot broken bones and diseased organs in a person's body, and even sterilizing medical supplies that cannot be boiled.

X-rays are also used in commerce and industry to locate product defects and to examine luggage at airports. But X-rays can also cause harm to humans by destroying healthy tissue, causing cancer and skin burns, and even modifying genes that pass traits from one generation to the next.

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Natural body coats

An effective insulator is needed to maintain body temperature in an icy climate. Mammals have hair or fat that isolates their bodies, but humans lack the necessary fat and their body hair is relatively scarce, so it is necessary to protect themselves with clothing.

Mammals are characterized by two types of hair. The longest, protective, is erectile: erectile when the animal is afraid or angry, as in the neck of dogs. Underneath, the shorter hair is soft and dense, and retains air close to the skin. The air is a bad conductor of heat, so the trapped layer receives heat from the body and keeps the animal warm.

When it rains or if the animal gets into the water, the outer coat becomes tangled and forms a waterproof layer, which prevents the shorter hair and skin from getting wet and losing their insulating properties. When it stops raining or the animal comes out of the water, a simple shake removes the water retained in the body.

By taking advantage of qualities such as wool, man can imitate what mammals do. Clothing close to the skin traps the air, which is kept warm and creates a protective layer. Raincoats prevent clothes from getting wet and losing their insulating properties.

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why does the human brain have wrinkles?

It has a very simple reason: to increase the area of the cortex - where the most important brain processes of our and other species take place - without the need to increase the cranial size.

Many vertebrate animals -among them man- owe their "intelligence" to the circumvolutions of their brain, which provide a very high and better neuronal activity. For example, the brain of the dolphin and that of the shark are similar in size, but that of the marine mammal has a greater number of circumvolutions, that is, it has a greater area for ''thinking''. A cat and a rabbit also have a brain of similar size, but the cat being a carnivore has a more refined way of life, so it needs greater intelligence, ie a cortex with more ridges and wrinkles'.

Animal dimensions are also an important factor. Rats and mice, despite their ''intelligent'' behaviour, do not possess brains with circumvolutions and, on the contrary, the cortexes of elephants and whales are more wrinkled even than that of man.

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What is the most common blood group?

 There is information that 45 percent of the world's population belongs to blood type O, so it is sometimes referred to as 'universal'. There are countries where some types of blood predominate over others, such as Norway and Finland, where the majority of the population belongs to group A. On the other hand, 100 percent of the natives of the American continent have the O group in their veins. However, the least common is one known as the Bombay blood type (subtype h-h), which was found in a Czechoslovak nurse in 1961 and a pair of American twins in 1968.

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What is Physiology?

Claude Bernard, the father of Physiology

     Physiology is the study of how living structures work. For example, in order to keep alive, all living things get ENERGY from food. They grow and reproduce new living forms just like themselves. They react to the world around them, and try to adjust to changes. As plant and animal life becomes larger and more complicated, the different parts of a body must be coordinated so they work together. Physiology studies these processes.
   Because the scientist must first understand how a thing is made, before he can understand how it works, a physiologist studies the various parts of the living structure—its ANATOMY. He studies the functioning of the structure. He may study how an individual NERVE CELL sends an impulse, how the muscles of the body move together, or why a plant produces flowers at certain times of the year.
But to have an understanding of the building materials of living things and the natural laws governing them, a physiologist must also know the basic PHYSICS and CHEMISTRY of the non-living world, as well as the biophysics and biochemistry of living structures.
   For example a boy or girl eats food and grows bigger. The physiologist checks digestion, circulation, elimination, metabolism, respiration, and excretion to find out what is happening to the food inside the person's body.

What is Menstruation?

   Menstruation is the term applied to the periodic discharge of blood from the womb or uterus of the human female. This normal function of the body usually starts between the ages of 11 and 16 years and continues at regular intervals until the age of about 45 years. The word "menstruation" comes from the Latin word meaning "month." The usual interval between periods is 28 days although variation from 20 to 35 days must be considered within the normal limits. The flow lasts from three to five days.
   The first appearance of the discharge is one of the signs of approaching maturity. Other signs are a change in body contour and particularly in the breast structure. Accompanying behavior and emotional changes awaken in the newly-developing young woman evidence of her responsibility.
   The monthly reappearance of the flow may be accompanied in a few individuals by discomfort. There may be a feeling of fullness in the breasts or abdomen or an irregularity of the bowel function.
   Menstruation occurs after the development and discharge of the EGG or ovum. The inner cellular lining of the uterus is rejuvenated with a fresh supply of blood as part of the preparation for the reception in the Fallopian tubes of an egg properly fertilized by a male SPERM. When such fertilization does not take place, the uterus discharges these engorged cells and is ready for a new cycle. Menstruation, then, depends upon the regular development of the egg—a process called OVULATION—or its discharge.
   Periodic menstruation normally continues throughout the years of life during which conception is possible. It is intimately linked to the operation of glands which supply the internal secretions. The ovaries are both stimulated and inhibited in their activity by the PITUITARY gland which lies at the base of the brain.

What is gangrene?

   Gangrene is the death and decay of body tissue. There are several kinds of gangrene. The most common kind, called dry gangrene, occurs in the extremities of the body when the supply of blood to a tissue is cut off. As a result, cells in the tissue cannot receive adequate nutrients and cannot get rid of their waste products. The affected area turns dark, then blackens, and slowly dries up and becomes shriveled. It is eventually separated from the healthy surrounding tissue by a sharp line of demarcation, after which the dried-up tissue falls or sloughs off. The most frequent causes of dry gangrene are obstruction of a blood vessel, usually by a clot, and hardening of the arteries, especially in old people and diabetics. It may also occur after fingers or toes have been badly frostbitten and frozen.
   Moist gangrene can affect any tissue in the body. It is caused by certain kinds of bacteria that produce toxins, or poisons, destructive to tissue. There is a foul-smelling watery discharge in the affected area. Another kind of gangrene, called gas gangrene, is also caused by bacteria. The bacteria, which usually infect deep wounds, produce gases that collect in the tissue.
   Gangrene is very serious. Moist gangrene and gas gangrene require prompt treatment. The affected tissue must often be surgically removed to prevent the spread of gangrene to healthy tissue. Antibiotic treatment is sometimes helpful. Dry gangrene does not require emergency surgical treatment. Instead, the physician tries to keep the gangrene from spreading by dilating the blood vessels to improve circulation or by removing obstructions from the vessels. After this the process is allowed to run its natural course until demarcation and sloughing off occur.

What are Viruses?

   Most viruses are very small (submicroscopic) bodies. They can be seen best only with an electron microscope. Viruses will pass through a filter that does not allow bacteria to pass.
   Usually, when viruses enter a living plant or animal cell, they grow, multiply and cause disease. Some can live in a cell without harming the victim (host) cell. But if the same viruses enter another kind of host, they produce disease. In addition to causing plant diseases, some viruses cause animal illness, as distemper in dogs, and colds, mumps and polio in man.
   Viruses have various shapes. They may be spherical, rod-like or bottle-shaped. None of them can move by themselves.
   Chemically, a virus consists of a core of NUCLEIC ACID, either RNA, DNA or both. This core is surrounded by a sheath of non-acid PROTEIN. Some viruses leave the sheath behind when they enter a cell. Others are believed to separate the sheath and acid core right after invading the host cell.
   Once inside a living cell, viruses organize the cytoplasmic activities (enzyme systems) of the host and start to reproduce. Using raw materials supplied by the host cell, virus particles of RNA or DNA make copies of themselves.
   Scientists have been unable to decide whether viruses are living or non-living. Because of their chemical composition, and their behavior within a cell, they appear to be living particles. It has been said that viruses are "cell nuclei in search of some cytoplasm." On the other hand, viruses can be crystallized. In this form, they are inert like non-living substances.

Gastritis

   Gastritis is the acute or chronic inflammation of the mucous membrane that lines the stomach. Gastritis is characterized by nausea, vomiting, and cramp like pain and often by loss of appetite.
   Acute gastritis is a common form of upset stomach. It is usually caused by the consumption of irritating foods or liquids, particularly alcohol. These substances produce a mild temporary inflammation that is cured by avoiding the offending substance and by eating bland foods. If the condition results from prolonged use of alcohol, it may be chronic, as well as acute, and abstinence from alcohol is necessary to effect a cure.
   Severe cases of acute gastritis may be caused by the swallowing of acids, lyes, or other poisons. If the condition is not promptly treated, death may result.
   Chronic irritation, which may develop from acute gastritis or other disturbances in the intestinal tract, can cause thickening of the stomach lining or partial destruction of the lining. Chronic gastritis may lead to ulceration and other disorders of the stomach.

What is Cancer?

   The tiny "bricks" our bodies are built of are called cells. A single one of these cells is too small to be seen without a microscope. Once in a while some cells somewhere in a person's body go on a rampage. They begin to grow and multiply very fast. In time they begin crowding other cells and stealing food the other cells need. They cause the disease which is called cancer.
   Cancer used to be incurable. But now many people who have cancer get well. If it is discovered in time, the chances of curing it are very good. One reason why everyone should go to a doctor for a yearly checkup is to make sure no cancer cells are starting to grow.
   Many doctors are at work in hospitals, universities, and laboratories trying to learn what causes cancer. When the cause is known, doctors will be better able to prevent and cure cancer.

Nerve cells

   Nerve cells or neurons are found in the nervous system and help parts of the body work together. They also make an animal or man aware of what is happening in the outside world. For example, if one touches a hot stove, he jerks his hand back quickly. The hot stove is the stimulus, and the neurons, or nerve cells, in the nervous system are responsible for the quick action or response of the body muscles.

   The cell body or cyton of the neuron is composed of a nucleus surrounded by cytoplasm. The neuron differs from other cells because cytoplasmic processes, or threadlike pieces, extend out from the cyton. On one side of the cyton are a number of short, rough, branched processes called dendrites. On the other side is a smooth process called an axon which is usually long.

What is digestion?

   Digestion is the breakdown of complex food materials into simple compounds by chemical and physical means. The digestion of food supplies body cells with materials needed to carry on various activities, such as the release of energy, repair, and growth. In man, digestion starts in the mouth and is completed in the small intestine, where the simple end products are absorbed and carried by the bloodstream to all cells of the body.
   The three major kinds of food are carbohydrates, which are broken down into simple six-carbon sugars; proteins, which are digested to amino acids; and fats, which are split into fatty acids and glycerol. The digestion of these complex compounds involves many separate chemical reactions. Each of these reactions requires a special enzyme, a chemical substance that speeds up a chemical reaction. Other substances, such as water, hormones, and hydrochloric acid, are also essential for the process of digestion.

WHAT IS DERMATITIS?

   Dermatitis is an inflammation of the skin. Dermatitis may be caused by infectious microorganisms; allergies; chronic irritation; exposure to heat, cold, X rays, or ultraviolet light; hypersensitive reactions to medications; or emotional stress. The treatment of dermatitis depends on its cause.

The Nails

   Nails, claws and hoofs are found at the end of the digits (fingers and toes). These are all produced by the skin. A hoof surrounds the toe. A claw is sharp and grows out from the end of a toe. Nails are the flattened claws of the highest order of mammals— primates. Animals in this order include monkeys, apes, lemurs and man.
   Nails are composed of a substance called keratin, a horny material which protects and wears. They are modified reptilian scales consisting of a hard top plate, the unguis, and a softer under plate, the subunguis. The subunguis corresponds to the bottom (ventral) side of a claw. In nails, this region is much reduced.
   The crescent or whitish half-moon on the nail base, lies over an area called the matrix. Nails grow Trom the matrix, which is formed by the deepest layer of the outer epidermis, the germinative layer. Growth from the matrix is continuous unless it becomes seriously injured. The average nail grows about one-eighth of an inch a month. A fold of thin skin called cuticle surrounds the nail base.

What is a hernia?

   Hernia, or rupture, results from a break in cavity walls within the body. Many organs of the body, like the lungs, heart, or intestines, are inside hollow places called body cavities. Sometimes the wall of a cavity breaks, or ruptures, and part of the organ pushes through. Then the person has a hernia. When used alone, the word generally means an abdominal hernia. In this type, a loop of the bowel sticks out through the muscular wall of the abdomen. The hernia often occurs at a weak point of the muscular wall. It usually pushes out a part of the inner lining of the abdomen, the peritoneum, and forms a hernial sac. This sac may be felt or seen underneath the skin of the abdomen.
   The danger of abdominal hernia is that the abdominal muscles may contract, strangulating (choking off) the part of the bowel that protrudes. Doctors usually operate immediately on persons with this condition. Supports such as trusses may relieve abdominal hernia; by keeping die bowel inside the abdominal wall. Bu: the only cure for a hernia is an operation.
   In hernia cerebri, a portion of the brain protrudes through an opening in the skull. Hernia may also occur in various other internal organs, such as the bladder.
Hernia results from many causes. An abdominal hernia sometimes results from lifting a heavy object, or from a strain or other injury.

The nose

   The nose is an area on the front end of the head. It usually has two openings. Some animal noses stick out as man's does. The trunk of an elephant is its nose. Most animals, however, have flat noses which are part of the upper jaw area. The nose is used to smell things that are in air or water. Animals with lungs use the nose in breathing.
   The external nose is made of skin, bone, and CARTILAGE. The internal nose consists of two airways separated by a septum. The minute hairs in the nose function as air filters. The cells lining the tubes secrete mucus which moistens the surface. The olfactory nerves are stimulated when certain odors reach the nose. These chemo-receptors send the message to the brain.

What are Geriatrics?

   Everywhere people are living longer. Consequently it is estimated that before long one-third of the entire population of the United States will be 50 years old or older. In a few years more there will probably be twice as many people over 65 years of age as there are now. Because of the already great increase in the number of older people and the still greater increase coming in the future, the medical problems peculiar to the aged have become more important. This has resulted in the development of a new medical specialty called geriatrics, which deals with the medical problems of old age and which is comparable to pediatrics, the specialty dealing with children. Geriatric medicine as now defined includes all fields of medical practice as applied to people who are past the prime of life. Geriatrics may be divided into two main subjects: the medical problems associated with the process of normal aging; and the effects of disease in older people, in so far as these are different from those in younger people.

Dandruff

   Dandruff is a white or grayish scales shed from the scalp. Dandruff is a symptom of a skin disorder, known as seborrheic dermatitis, which is the most common scalp disorder. Its cause is unknown. The disorder appears as irregular reddish patches, which may be sore and itchy, and is usually accompanied by excessive secretion of oil from the sebaceous glands attached to the roots of the hair. The extreme oiliness of the scalp may make the dead skin, or dandruff, that flakes off the irritated patches very greasy. It may also promote an increase in the bacteria and fungi normally present in the hair. When the itchy patches are scratched, these germs may enter the scalp and produce secondary infections. If the condition is severe and persists long enough, gradual permanent loss of the hair may result.
   The best treatment for mild cases of seborrheic dermatitis is frequent washing and brushing of the hair and scalp. Severe seborrheic dermatitis may be treated with sulfur compounds, and germicidal substances are sometimes necessary to stop infections. Chronic cases can be difficult to treat, and a physician should be consulted.

Corns and calluses

   Corns and calluses are thickenings of the outer layer of skin caused by friction, chronic irritation, or pressure. Corns are cone-shaped and have hard, shiny surfaces. The point of the cone extends deep into the skin and, upon pressure, pushes against the tender lower layers of the skin, causing pain. Corns can be cut away, although there is a danger of infection if the removal is not properly done. Before removal, corns are usually softened by ointments or medicated plasters. A common cause of corns is wearing shoes that do not fit properly.
   Calluses involve only the upper layer of skin and are generally not painful. They disappear without treatment when the cause of their formation is removed.