Did you know that...

Did you know that...
as many as 250,000 new nerve cells can be formed each minute during a baby's development inside its mother? By the time the baby is born, the brain will have almost all the nerve cells, or neurons, it will ever nave. However, a child's brain continúes to increase in size after birth as other brain cells, called glia, grow around the neurons, insulating them and carrying out various "housekeeping" functions in the brain. A baby is also born with trillions of connections, or synapses, be-tween neurons. As the child learns various skills, many of these synapses are stimulated and become permanent connections.

Did you know that . . .

   Some 650 muscles cover the body's skeleton? Muscles do more than shape and define the contours of our bodies. They are responsible for all of the body's movements. Muscles are attached to bones by tough, hard tissue called tendons. In response to instructions from the brain, muscles contract and pull on the bones and movement occurs. Usually skeletal muscles work in groups. Even aseemingly simple task such as taking one step involves about 200 muscles! Some muscles lift and move your leg forward, while others in the back, chest, and abdomen help keep you from losing your balance during the motion.

What is a harelip?

    A Harelip is a cleft (split) through the upper lip. It is called harelip because it looks like the hare's lip, which is split. Doctors do not know what causes harelip. Something prevents this section of the lip from growing together before the baby is born. Harelip may be single; that is, only one side of a lip may be cleft. Or both sides of a lip may be open. Cleft palate, an opening in the roof of the mouth, often occurs with harelip. Sometimes a deformity of the nose also occurs. Doctors can successfully close these openings by means of surgical operations.

What is the pineal gland?

    The pineal gland is located in the lower central part of the brain. It may be all that remains of a third eye that ancestors of vertebrates (animals with backbones) once had. An ancient-type lizard in New Zealand (sphenodon) has a light-sensitive place on its head above the pineal body. Scientists now know that the pineal is a light-sensitive gland that makes a hormone.
    The pineal gland is rich in serotonin, a substance secreted by the nervous system. Recently a new hormone, melatonin, and an enzyme found only in the pineal were isolated. Research showed that the enzyme acted on serotonin to form melatonin, Mela¬tonin acts on the sex glands to inhibit (stop) the sexual cycle.
    Light controls the amount of hormone produced through the sympathetic nervous system. The concentration of melatonin shows a 24-hour rhythm, decreasing during the day and increasing at night.

Pineal gland

What is fibrin?

   Fibrin is a protein that is formed during the clotting of blood. Fibrin, which is a whitish, elastic substance composed of many tiny strands, is not normally found in the blood. In the process of clotting, however, a network of fibrin strands is formed from fibrinogen, another protein, which is normally present in the blood. Blood cells then become entangled in the strands of fibrin. The mixture of fibrin and blood cells is called a blood clot. With time, the fibrin strands contract and shorten, causing the clot to become more dense.

The first human heart transplant

   Christiaan Barnard was the South African surgeon who performed the first human heart transplant. This historic operation took place on December 3, 1967. Barnard removed the healthy heart of a young woman who had been fatally wounded in an automobile accident. He transplanted her heart into the chest of Louis Washkansky, a 55-year-old man whose heart was failing. Washkansky lived for 18 days with the transplanted heart.
   Although Washkansky died of pneumonía soon after the transplant, the operation was considered a success—Washkansky's new heart beat strongly until the end. Barnard performed his second heart transplant opera¬tion a month after the first one. This time, the recipient of the transplanted heart lived for 18 months. Barnard continued doing trans¬plant operations with critically ill patients. His innovative surgical procedures included another first. In 1974, he transplanted a sec¬ond heart in a human being. The hearts were linked together, forming a kind of double pump to circulate blood throughout the body.
   Christiaan Barnard was born on November 8, 1922, in a small town called Beaufort West, South Africa. His father was a minister and the family was quite poor. Barnard's mother had high expectations of her children and urged them to work hard and strive to be the best in their classes. Barnard studied hard and was admitted to medical school in Cape Town, South Africa. He received advanced training in heart surgery at the University of Minnesota in the United States. It was in 1958 that Barnard returned to South Africa and introduced the revolutionary new technique of operating directly on the heart—the procedure called open-heart surgery.
   Barnard retired as a surgeon in 1983. The effects of chronic arthritis eventually made it difficult for him to operate.

What happens in the body during exercise?

When you step on the accelerator of your car, the carburetor feeds more gasoline to the engine. The engine runs faster — that is, the chemical energy of the fuel is changed into heat energy and mechanical energy at an increased rate. But it is not enough to supply the engine with more gasoline; if that were all, your car would soon be on the scrap heap. A great many other factors are involved.

In order to burn the fuel, a greater supply of oxygen is needed; hence, the carburetor must suck in air to the engine in greater quantities than before. A good deal more heat is generated at high speeds. To keep the engine from becoming overheated, more cooling must be provided by the water pump, which circulates water through the engine jacket, and by the fan, which blows air over the radiator. The ignition must produce more sparks per minute to fire the fuel in the cylinders; more oil must flow in order to lubrícate the working parts. Many operations are required, therefore, in order to bring about an increased rate of energy transformation in your automobile.
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Did you know that fingernails grow at different rates?

  Nails grow at very different rates. Those on the fingers advance at about three or four times as rapidly as those on the toes. The fingernails on the longest fingers (the middle fingers) grow most quickly; those on the shortest or little fingers, most slowly. There appears to be no significant difference, with respect to growth, between the nails of the right and left hands. In summer the nails, like the hair, advance faster than in winter; the thumbnail, for instance, grows an average of one-ninth of an inch per month in the winter and one-seventh of an inch in the summer.
  Beyond providing a livelihood for manicurists and nail-polish manufacturers, the function of human nails is not clear. Fin-gernails can be used for scratching; they also provide a mechanical  support for the tips of the fingers and thus, perhaps, in¬crease the latter's efficiency as organs of touch. But human toenails, as far as we can see, serve no useful purpose, though they may have been useful at one time.