A DAY IN THE LIFE OF A BUTTERFLY

 IF YOUR daily routine seems stressful and difficult, spare a thought for the hardworking butterfly. At first you may think that a butterfly’s work schedule looks like a dream vacation. Flitting from flower to flower, supping a little nectar here and there, basking at will in the sunshine, the butterfly appears to be the epitome of the carefree life-style.

But in the insect world, things are not always what they seem. Butterflies are busy creatures who perform a vital service while constantly working against the clock. Let’s join a butterfly on a typical workday.

A Sunshine Breakfast

Do you wake up feeling groggy? Early morning blues are endemic among butterflies. Some mornings they can’t get going at all—literally. Their problem is body temperature, which fluctuates according to their surroundings. After they spend a cold night perched on a leaf, their blood is so cold they can hardly move, much less fly. So they must wait for the sun.

When the sun rises, the butterfly opens his wings and angles them toward its warming rays. The outstretched wings, acting like miniature solar panels, soon capture the necessary heat, and off the butterfly sails. But what if the sky is cloudy? In cool temperate regions, butterflies must stay put—immobilized on a convenient twig or flower—until the sun shines. This is not laziness. It’s sheer necessity.

If the day is not too hot, the butterfly pauses from time to time for further sunshine therapy. Like a car refueling at a gas station, he needs his fill of solar energy. In the tropics the butterfly may need to bask only first thing in the morning or after a shower of rain. Generally speaking, the cooler the weather, the more time he spends basking. Once his energy is restored, he continues with the work at hand.

‘Love at First Scent’

The most urgent task is to find a mate. With a life expectancy that rarely exceeds a few weeks, there is no time to lose. And finding a mate in the butterfly world is no easy job—it requires heroic patience and persistence.

“Love at first sight” is unknown among butterflies. They are notoriously nearsighted, and more often than not they mistake a different species for one of their own. This leads to many a fruitless chase that comes to naught when the butterfly suitor finally realizes his eyes have deceived him.

To make life even more difficult, the female usually isn’t receptive. The ardent male flies persistently around her, in a type of high-speed aerial waltz, hoping that she will eventually relent. But these spectacular butterfly ballets usually come to an abrupt end when the female flies off, leaving the hapless male to continue his search.

Surprisingly enough, the female isn’t that fussy about the fancy colors of her male consort. Although Darwin blithely assumed that butterflies’ brilliant colors provided some ‘evolutionary advantage,’ the evidence has not been forthcoming. In one experiment females of the North American species Anartia amathea mated quite happily with males whose bright crimson and black wings had been painted black all over. What seems to matter most is the male’s flight pattern, his persistence, and, above all, the unique “love-dust.”

The love-dust carries a pheromone that is the male’s trump card. It is a heady perfume, tailor-made to affect the females of his species. During courtship he attempts to dust her with this “superscent.” Although the love-dust is no guarantee of success, it works wonders when a willing female is finally found.

A Taste of Nectar

All the energy expended in this search for a mate must be replenished. Hence the butterflies’ taste for nectar. Flowers advertise this high-energy food by means of attractive shapes and colors. Once he alights on the flower, the butterfly deftly sucks up the nectar with a long tubelike proboscis, which he pokes into the base of the flower.

While feeding on the nectar, the insect gets a dusting of pollen on his hairy body, thus taking the pollen with him to the next flower he visits. During a typical workday, hundreds of flowers are pollinated. In tropical forests, however, flowers do not abound. What do tropical butterflies usually drink?

Tropical butterflies like nothing better than gorging on rotten fruit. The overripe fruit that falls to the ground provides them a plentiful source of sugary energy.

Butterflies also like salt. They may often be found sucking up the salty moisture from a patch of wet ground or occasionally the perspiration on the hand of a human admirer. The intrepid flambeau butterfly has even been spotted drying the tears of the caiman.

While busily looking for a mate, pollinating flowers, and keeping well fed, our winged friend must also keep an eye out for enemies. He may look defenseless, but he has several tactics to avoid capture.

Keeping Danger at Bay

A gaudy butterfly fluttering over a meadow would presumably be a tempting morsel for any insect-eating bird. But the butterfly’s haphazard, jerky flight makes catching him a very tricky job. Most birds give up after a few tries. Even when a bird does catch a butterfly, the insect may succeed in escaping by leaving behind a portion of his wing in the bird’s beak.

Eyesight is another protection. Although butterflies are nearsighted, their compound eyes are highly efficient at detecting movement. They will dart away at any hint of danger, as anyone who has tried to photograph a butterfly knows only too well.

Some slow-flying butterflies have another safety device—their nasty taste. It is caused by their feeding on poisonous plants when they were caterpillars. Once he has bitten such a butterfly, a bird will usually shy away from a second encounter. Often these foul-tasting butterflies—like the monarch—are brightly colored, a visual warning that apparently reminds the bird to keep clear.

Journey’s End

The World Book Encyclopedia notes that most butterflies do not live longer than a few weeks, but that some species may live up to 18 months. Some are dormant during the cold winter months or during a prolonged dry season in the tropics.

But despite their short lives, butterflies can accomplish amazing feats. Last century the monarch butterfly crossed the Atlantic in sufficient numbers to establish itself in the Canary Islands, off the coast of Africa. Another great traveler, the painted lady, regularly journeys from North Africa to the north of Europe in the summer season.

During their brief life span, the tireless butterflies do a vital job pollinating flowers, shrubs, and fruit trees. And much more than that, their presence adds a touch of beauty and delight to the countryside. Summer would not be summer without them.

For more informative articles please see AWAKE magazine at www.jw.org

THE AMAZING HEMOGLOBIN MOLECULE---A MIRACLE OF DESIGN

“Breathing seems so simple, yet it appears as if this elementary manifestation of life owes its existence to the interplay of many kinds of atoms in a giant molecule of vast complexity.”—Max F. Perutz, a sharer of the Nobel Prize in 1962 for his studies of the hemoglobin molecule.

BREATHING—what could be more natural? Most of us rarely give it a thought. Breathing, however, could not keep us alive if it were not for the human hemoglobin molecule, a complex molecular masterpiece designed by our Creator. The hemoglobin that is inside each of our 30 trillion red blood cells transports the oxygen from the lungs to the tissues throughout the body. Without hemoglobin, we would die almost instantly.

How do hemoglobin molecules manage to pick up tiny oxygen molecules at the right time, hold them safely until the right time, and release them at the right time? Several amazing feats of molecular engineering are required.

Tiny Molecular “Taxis”

You might think of each hemoglobin molecule in a cell as a tiny four-door taxi, with room for exactly four “passengers.” This molecular taxi does not require a driver, since it is riding inside a red blood cell, which could be described as a traveling container full of these hemoglobin molecules.

The journey for a hemoglobin molecule begins when red blood cells arrive at the alveoli of the lungs—the “airport.” As we inhale air into our lungs, the huge crowds of tiny recently arrived oxygen molecules start looking for a ride in a taxi. These molecules quickly diffuse into red blood cells, the “containers.” At this point, the doors of the hemoglobin taxis within each cell are closed. However, it does not take long before a determined oxygen molecule in the bustling crowd squeezes in and takes a seat in a hemoglobin taxi.

Now something very interesting happens. Inside the red cell, the hemoglobin molecule begins to change its shape. All four “doors” of the hemoglobin taxi begin to open automatically as the first passengers get in, which allows the remaining passengers to hop aboard more easily. This process, called cooperativity, is so efficient that in the time it takes to draw a single breath, 95 percent of the “seats” in all the taxis in a red blood cell are taken. Together the more than one quarter of a billion hemoglobin molecules in a single red blood cell can carry about a billion oxygen molecules! Soon the red blood cell containing all these taxis is off to deliver its precious supply of oxygen to body tissues that need it. But, you might wonder, ‘What keeps oxygen atoms inside the cell from getting out prematurely?’

The answer is that inside each hemoglobin molecule, oxygen molecules attach to waiting atoms of iron. You have probably seen what happens when oxygen and iron get together in the presence of water. The result is usually iron oxide, rust. When iron rusts, the oxygen is locked up permanently in a crystal. So how does the hemoglobin molecule manage to combine and uncombine iron and oxygen in the watery environment of the red blood cell without producing rust?

Taking a Closer Look

To answer that question, let us take a closer look at the hemoglobin molecule. It is made up of some 10,000 atoms of hydrogen, carbon, nitrogen, sulfur, and oxygen that are carefully assembled around just 4 atoms of iron. Why do four iron atoms need so much support?

First, the four iron atoms are electrically charged and must be carefully controlled. Charged atoms, which are called ions, can do a lot of damage inside cells if they get loose. So each of the four iron ions is secured in the middle of a protective rigid plate. Next, the four plates are carefully fitted into the hemoglobin molecule in such a way that oxygen molecules can get to the iron ions but water molecules cannot get to them. Without water, rust crystals are unable to form.

By itself the iron in the hemoglobin molecule cannot bind and unbind oxygen. Yet, without the four charged iron atoms, the rest of the hemoglobin molecule would be useless. Only when these iron ions are perfectly fitted into the hemoglobin molecule can the transport of oxygen through the bloodstream occur.

Releasing the Oxygen

As a red blood cell leaves the arteries and moves into the tiny capillaries deep in the body tissues, the environment around the red blood cell changes. Now the environment is warmer than in the lungs, and there is less oxygen and more acidity from the carbon dioxide surrounding the cell. These signals tell the hemoglobin molecules, or taxis, inside the cell that it is time to release their precious passengers, oxygen.

When the oxygen molecules get out of the hemoglobin molecule, it changes its shape once more. The change is just enough to “close the doors” and leave the oxygen outside, where it is most needed. Having the doors shut also prevents the hemoglobin from transporting any stray oxygen on the way back to the lungs. Instead, it readily picks up carbon dioxide for the return trip.

Soon the deoxygenated red blood cells are back in the lungs, where the hemoglobin molecules will release the carbon dioxide and be recharged with life-sustaining oxygen—a process that is repeated many thousands of times during a red blood cell’s life span of about 120 days.

Clearly, hemoglobin is no ordinary molecule. It is, as stated at the beginning of this article, “a giant molecule of vast complexity.” Surely, we are awed and thankful to our Creator for the brilliant and meticulous microengineering that makes life possible!

[Footnote]

This plate is a separate molecule called heme. It is not made of protein but is incorporated into the protein structure of hemoglobin.

 

TAKE GOOD CARE OF YOUR HEMOGLOBIN!

  “Iron poor blood,” an expression common in some places, is really hemoglobin-poor blood. Without the four essential iron atoms in a hemoglobin molecule, the other 10,000 atoms in the molecule are useless. So, it is important to get enough iron by eating a healthful diet. Some good sources of iron are listed in the accompanying chart.

  Besides consuming foods rich in iron, we should heed the following advice: 1. Get regular and appropriate exercise. 2. Do not smoke. 3. Avoid secondhand smoke. Why are cigarette and other forms of tobacco smoke so dangerous?

  It is because such smoke is loaded with carbon monoxide, the same poison emitted as exhaust by automobiles. Carbon monoxide is the cause of accidental deaths and is also a means by which some people commit suicide. Carbon monoxide binds to iron atoms in hemoglobin over 200 times more readily than oxygen does. So cigarette smoke quickly affects a person adversely by crowding out his intake of oxygen.

[Chart]

THE FOOD               PORTION SIZE               IRON(mg)

Blackstrap molasses    1 tablespoon               5.0

Raw tofu                         1/2 cup                    4.0

Lentils                             1/2 cup                    3.3

Beef chuck                    3 ounces                   3.2

Dried peaches                5 halves                   2.6

Kidney beans                  1/2 cup                    2.6

Wheat germ              1 ounce (1/4 cup)          2.6

Chickpeas                       1/2 cup                    2.4

Broccoli                      1 medium stalk             2.1

Dark meat turkey           3 ounces                   2.0

Spinach                         1 cup raw                  0.8

 

Heme

In the oxygen-rich environment of the lungs, an oxygen molecule will bind to the hemoglobin

After the first oxygen molecule binds, a slight change in the shape of hemoglobin allows three more oxygen molecules to bind rapidly

Hemoglobin transports the oxygen molecules away from the lungs and then releases them where they are needed in the body

For more informative articles please see AWAKE magazine at www.jw.org

MEET THE ALPINE MARMOT

A loud whistle pierced the air. It sounded like a boy whistling to a friend—but was much louder. The whistle echoed across the mountainside, giving little indication of its source. Then I noticed a small furry rodent dart into a nearby burrow. A quick look at my guidebook confirmed that I had just seen and heard an alpine marmot.

DURING the next few days, I became familiar with these furry rodents. I learned which rocks they preferred for sunning themselves, where their principal burrows were located, and how they survive in the harsh environment above the tree line.

Family Cooperation and Vigilance

Life on the alpine pastures is not easy for the marmot. Winters are cold, and its habitat may be snowbound for months. Also, predators on land and in the sky pose a threat. So the marmot’s survival depends on cooperation, planning, and vigilance.

Marmots are family-oriented, usually living in groups that consist of a breeding pair and their offspring. Each family has several burrows—one serves as the family home and the others provide shelter in times of danger. Sometimes marmots excavate their burrows in crevices underneath large boulders. These castlelike dwellings offer the marmots vantage points that serve both as turrets for observation and as sun terraces for relaxing.

The marmot takes hygiene seriously. A separate burrow is used as a toilet so that the home burrow is kept clean. At the end of their main burrow, marmots prepare an enlarged den, which they line with grass. This den provides a safe haven where the female gives birth. It also offers a warm sanctuary where the whole family can huddle during the long winter hibernation.

Perhaps the most important family responsibility is that of guard duty. An adult marmot acts as a sentinel while other family members forage nearby. To check for danger, the marmot sometimes stands on its hind feet to survey its surroundings better. Eagles, foxes, and humans are the main threats to the alpine marmot. Their presence or the sight of any large bird of prey will elicit an alarm call. Interestingly, the alarm call for eagles—the marmot’s principal winged predator—is noticeably distinct. At the sound of a warning call, the marmots scamper for safety. In an instant, it seems, no marmot can be seen above ground!

Obedience may well be a matter of life and death, especially in the case of young marmots, which are a favorite food of golden eagles. If the threat seems immediate, the guard retreats into a nearby burrow along with the others. Then, after a few minutes, he cautiously pokes his head out to see if the danger has passed.

Keeping Cool and Sleeping Well

In the high meadows where alpine marmots live, there is abundant grass to eat, and the summer climate is temperate. If the weather is cool, marmots will sunbathe on a suitable rock. High temperatures create more problems for them, since they cannot remove their furry coat. For this reason marmots are usually more active in the early morning and late afternoon.

Insomnia is certainly not a problem for alpine marmots; they hibernate for about six months. A related species, the hoary marmot, may hibernate for as long as nine months. During hibernation, the alpine marmot’s heart slows down to one or two beats per minute, and its body temperature drops to about 41 degrees Fahrenheit [5 degrees Celsius]. Understandably, fasting for such a long period requires preparation. During summer and early autumn, the marmots eat voraciously to acquire fat reserves that will last them through the long winter hibernation.

Young marmots are playful and often run around in circles chasing each other. I watched one group of three youngsters tumble down a grassy slope as all three of them engaged in a mock fight. Marmots of all ages greet each other by touching noses; family members also groom each other and snuggle during cold spells to keep warm.

Marmots prepare for the future and are alert to danger. (Job 12:7) Perhaps human families can learn from these rodents.

 Taken from AWAKE magazine 2010  For more please go to www.jw.org

BONE--A MARVEL OF STRENGTH

Was It Designed?

● Bone has been described as “an engineering masterpiece of tensile, compressive and elastic strength.” Why?

Consider: The human skeleton consists of approximately 206 bones and 68 joints. The longest bone is the femur, or thighbone; the smallest is the stapes, a bone inside your ear. As skilled gymnasts clearly demonstrate, bones, muscles, cartilage, and joints can give a healthy body an astonishing degree of flexibility and range of movement. “The thumb alone would convince anyone that the architect of our body (whoever that may be to each one of us) had to be a genius!” says the National Space Biomedical Research Institute.

Bones can also take an incredible pounding. “[They] are constructed in exactly the same way that reinforced concrete is constructed,” states the institute. “The steel of reinforced concrete provides the tensile strength, while the cement, sand, and rock provide the compressional strength. However, the compressional strength of bone is greater than that of even the best reinforced concrete.” “We only wish we could mimic it,” said Robert O. Ritchie, a professor of materials science at the University of California, Berkeley, U.S.A.

Unlike concrete, bone is an essential part of countless living organisms. And it is dynamic. It is able to repair itself, respond to hormones that affect its growth and development, and even play a key role in the manufacture of blood cells. Also, like muscle, it slowly grows stronger as the load on it increases. Hence, athletes have heavier bones than do so-called couch potatoes.

What do you think? Is bone a product of chance? Or was it designed?

For more please go to www.jw.org

A VERSATILE VEGETABLE

By “Awake!” correspondent in Australia

HOW would you like to plant a vegetable that would supply you and your family with some food for up to 20 years? What if it did this without any replanting or much cultivation? Would it not also be appealing if the plant had the habit of yielding when other vegetables are in short supply? Well, that versatile vegetable is asparagus! And for that lengthy supply, a family of five would need only about 12 crowns of it.

Do you wonder about nutritional value? Well, asparagus contains varying amounts of calcium, phosphorus, sodium, potassium and iron, as well as vitamins A, B₁, B₂, C and niacin—all necessary for a healthful diet. That in itself is good reason to include asparagus in the home garden bed!

This tasty relative of the regal lily has been lending interest to menus ever since it was cultivated by the ancient Egyptians. By 200 B.C.E. information on its cultivation was being recorded by the Romans.

While many consider asparagus a common vegetable, others classify it as a delicious luxury. Although usually retailed in canned form, the fresh spears also are of delectable flavor. Both white and green asparagus is cultivated, green possibly being best for the home gardener because it combines higher food value with better flavor.

In growing white asparagus, the crowns are planted in a trench and mounds are built up above them to blanch the spears before they emerge from the soil. For green asparagus, no earthing up is done. The spears are cut when they are seven to nine inches (18 to 23 centimeters) above the ground.

Asparagus Culture

Asparagus can be grown from seeds, or crowns can be purchased from a nursery. It is noteworthy that male plants yield a much higher crop than do female plants. The difference between the two can be seen during the second season, when female plants produce seed. Asparagus is not restricted to one type of soil. However, the soil must be well drained (especially if it is heavy) and well watered if sandy.

Preparation should include the digging in of animal manure or compost. The crowns should be set 30 inches (76 centimeters) apart on a small heap of soil in a trench eight inches (20 centimeters) deep and 12 inches (30 centimeters) wide. (A complete fertilizer should have been applied previously to the bed.) The crowns should then be covered with two inches (5 centimeters) of soil, and the bed should be kept well cultivated until the appearance of the first shoots. As the plants develop, the trench should be gradually filled up with soil. In the case of white asparagus, the mounds should be raised nine to 12 inches (23 to 30 centimeters).

When well fertilized, the plants produce a fernlike growth above the ground and sturdy, vigorous crowns beneath the surface. Very important factors are the elimination of perennial weeds from the bed during preparation, as well as good weed control throughout the growing season. However, the use of herbicides may lead to damage, if they are used more than once each season.

Harvesting the Crop

Having established your asparagus bed, patience is essential. The spears should not be harvested during the first season. Instead, allow the crowns to build up. They should be harvested only lightly—for no more than two weeks—during the second season. But when the bed has been established for three years, you can go right ahead and enjoy the fruits of your labors.

Check the bed every day during the harvest season. Growth then is rapid and, if the spears are left too long, they will become tough at the butt. White asparagus is cut by inserting a knife into the mound eight or nine inches (20 or 23 centimeters) below the tip of the spear as soon as it breaks through the ground. Green asparagus is cut just below the surface when the tip is seven to nine inches (18 to 23 centimeters) above the ground and before the scales on the tip begin to open.

In a mature bed, the harvesting period lasts for three months, and at the end of that time a change will be seen in the growth of the spears. At this stage they will appear to be stunted, and this is the signal to stop harvesting the crop and allow the bed to complete the growing cycle. The resultant fernlike growth, which has no nutritional value, should be cut in the late autumn or early winter, just prior to the full ripening of the seed. This can then be burned or composted. The period of top growth allows time for the root system to build up strength for the growth of the next season.

Preparation for the Table

“What shall we eat?” This versatile vegetable may be just the thing needed to answer that familiar question. Whether the occasion calls for a quick snack or a bowl of hot soup, asparagus may suit your taste. Simply steam some of it slowly in a small amount of salted water to which a little vinegar has been added. This produces a delicious asparagus to be eaten alone, served either on hot, buttered toast, or with a salad. For the vegetable to be more pleasing to the eye when served, the tips of the spears should not be broken. Careful cooking will prevent this. You may prefer to cook the spears in a vessel that allows them to stand upright, with the tips pointing upward, since the butts require more cooking.

Is it a cold day? If so, perhaps a bowl of hot soup will be more appetizing than a cold meal. To enhance your menu, a very nourishing soup can be prepared by using about 8 ounces (227 grams) of asparagus boiled in 1-1/2 pints (.71 liter) of water with finely chopped onion, celery and turnip, if desired. When the vegetables are tender (in about 30 minutes), they should be pressed through a sieve or liquefied in a blender. Then they should be thickened with 1-1/2 ounces (43 grams) of flour and 2 ounces (58 grams) of butter, blended with 1 pint (.47 liter) of milk and boiled for five minutes. Salt and pepper should be added according to taste. Then serve the soup hot, garnished with finely chopped parsley.

So, you might consider asparagus the next time you hear the question, “What shall we eat?” Maybe this versatile vegetable will then become a nourishing and palate-pleasing addition to your menu.

For more informative articles please go to www.jw.org

MADE TO BEAT FOREVER!

WITHIN your chest beats a truly astonishing organ about the size of your fist—your heart. Without pause, it pumps the blood that carries life-sustaining nourishment to your billions of body cells. Of this pump, doctors in the book Your Heart observe: “It is more efficient than any machine of any kind yet devised by man.”

The forces involved in the design and construction of the heart are beyond human understanding. At conception, for example, the blueprints for the heart, as well as all other body parts, are drawn up. Amazingly, in a matter of minutes all the instructions are determined within the fertilized cell to make a new person! No scientist knows how this is done.

Without observable direction, the original fertilized egg cell soon begins to divide, forming cells that are different from their predecessors. Shortly, there are many different kinds of cells that start to form into various organs. At three weeks the partly developed heart begins to beat, probably even before the mother-to-be knows that she is pregnant.

What causes these heart cells, which at first form only a straight tube, to begin to contract rhythmically? “We are still a long way from finding the final answer,” admits Dr. Robert L. DeHaan who has been studying the subject for years.

What is known, however, is fascinating. It inspires awe. Consider, for example, this beat, or contraction, of the heart that forces blood out to the rest of the body. Do you know what causes the heartbeat?

The Remarkable Control System

Responsible is the amazing ability of the heart to generate electrical impulses. Thus, if provided with oxygen and kept from drying out, the heart will continue to beat for a while even after it is removed from the body. Within the heart there is a complex system for generating and regulating electrical impulses. This remarkable control system is made up of special cells concentrated in groups in different parts of the heart.

A principal part of this system is a tiny comma-shaped structure called the sinoatrial node, or S-A node, a special tissue that is a cross between heart muscle and nerve cells. This is the heart’s primary pacemaker, and so has been called the “spark plug” for the heart. Here a regular series of electrical pulses are generated that travel through the heart and trigger its beat. The basic rate of contraction generated by these sinoatrial node cells is about 70 beats per minute, the normal heart rate of most adults.

Another part of the heart’s control system is the atrioventricular node, or A-V node. The electrical pulses from the sinoatrial node reach this part, where they are properly timed and regulated to assure good coordination of the heart’s pumping action. Then from here these pulses move swiftly through other specialized conduction tissues, including one called the bundle of His, to the rest of the heart.

The atrioventricular node also has an inherent rhythm—about 50 beats per minute—somewhat slower than the sinoatrial node. The impulse-generating function of this structure, however, is not utilized under normal conditions. But in an emergency, if the sinoatrial node fails, the atrioventricular node can serve as a reserve pacemaker. In addition, the bundle of His, along with yet other specialized conduction tissues, can serve as a last line of defense. They, too, can initiate slow contractions of the heart, about 30 to 40 beats per minute, a rate that may sustain life.

How the System Meets Body Needs

If you run to catch a bus, climb stairs, or exercise in a similarly strenuous way, the heart rate must increase to meet the body’s need for more nourishment. What tells the heart to speed up? How does it know the rate at which to beat to meet various body needs?

Signals coming through nerve connections from other parts of the body are particularly responsible. During exercise, for example, your muscles need more oxygen; so they take an increased supply from the blood. The decreased oxygen level of the blood triggers receptors in the arteries to send nerve signals to the brain. Through nerve impulses, the brain, in turn, signals the heart to beat faster, thus providing more oxygen-carrying blood for your muscles.

However, the heart is not dependent solely on such nerve connections, as illustrated in the case of heart transplants. In such operations the vagal and sympathetic nerve systems are severed, yet the transplanted heart continues to some extent to regulate its beat in response to the changing needs of the body. The heart is able to respond directly to chemicals, such as adrenaline, received through the blood stream, and thereby “knows” when to speed up or slow down.

Truly, it is wondrous how the heart is designed to keep just the right amount of blood flowing through the body to meet its changing needs! Amazing, too, are the many “backup” systems that can take over and compensate in emergencies. No wonder doctors say the heart “is more efficient than any machine of any kind yet devised by man.” A look at the heart’s tremendous capacity for work will no doubt astonish you further.

The Heart’s Capability

An adult body contains some six quarts of blood, and about 60,000 miles (96,500 kilometers) of blood vessels, including tiny capillaries. At its normal rate of about 70 beats per minute, the heart will pump some six quarts (6 liters) of blood every minute. Think of it! Your heart pushes your entire blood supply through your body in less than 60 seconds! Under ordinary conditions, it pumps up to 10 tons of blood through your vessels daily. Yet, at this rate, it is not even working very hard.

If yours is a physically fit heart, one trained by regular exercise, it may be capable of pumping as many as 30 quarts of blood or more a minute. At that rate it is pushing your entire blood supply through your body about every 10 seconds! Yes, your heart pumps so steadily and powerfully that every day it can push your blood through several thousand complete circuits of your body!

Such a marvelously designed organ may make you wonder: Were humans originally meant to live for only 70 to 80 years or so and then die? Could the heart beat indefinitely?

Meant to Beat Forever

The heart, as well as the rest of the body, is designed quite differently from any machine made by men. Machines of human design are made with permanent parts, which, of course, eventually wear out. The human body, however, differs considerably in its makeup. Years ago Dr. Paul C. Aebersold, then director of the Isotopes Division of the Atomic energy Commission, explained:

“Medical men used to think of the human body as an engine that takes in food, air, and water mainly as fuel to keep running on. Only a small part was thought to go for replacement of engine wear. Investigations with isotopes have demonstrated that the body instead is much more like a very fluid military regiment which may retain its size, form, and composition even though the individuals in it are continually changing, joining up, being transferred from post to post, promoted or demoted, acting as reserves, and finally departing after varying lengths of service.

“Tracer studies show that the atomic turnover in our bodies is quite rapid and quite complete. In a week or two half the sodium atoms will be replaced by other sodium atoms. The case is similar for hydrogen and phosphorus. Even half of the carbon atoms will be replaced in a month or two. And so the story goes for nearly all the elements. . . . In a year approximately 98 per cent of the atoms in us now will be replaced by other atoms that we take in in our air, food, and drink.”

Thus, regardless of whether a person lives to 20 years of age, 80 years, 800 years, or forever, most of the materials in his body would be less than a year old. Cell duplication theoretically should keep the body alive forever. Medical researchers have, at times, drawn attention to this potential, noting that it is easier to explain why humans should live forever than why they should die.

Nevertheless, as time passes, the heart, along with the rest of the body, fails to maintain its ability systematically to replace its cells before they become defective and die. Why? Cell biologists have many theories. But they do not really know for sure. Obviously, something eventually goes wrong in the inner workings of cells, and those wearing out and dying are not always replaced by new ones through cell division. So humans grow old and die.

If a correction could be made, and the right balance in cell replacement and renewal was maintained, humans could live forever. However, man cannot repair the malfunction. He did not design the body, including its marvelous heart. Only the Creator, Jehovah God, can make the adjustments so that humans will live forever. And in time God will do this, as his Word the Bible promises. For example, Romans 6:23 says: “The gift God gives is everlasting life.” Psalm 37:29 foretells: “The righteous themselves will possess the earth, and they will reside forever upon it.”

For more informative articles please go to www.jw.org

BONE--A MARVEL OF STRENGTH

 Bone has been described as “an engineering masterpiece of tensile, compressive and elastic strength.” Why?

Consider: The human skeleton consists of approximately 206 bones and 68 joints. The longest bone is the femur, or thighbone; the smallest is the stapes, a bone inside your ear. As skilled gymnasts clearly demonstrate, bones, muscles, cartilage, and joints can give a healthy body an astonishing degree of flexibility and range of movement. “The thumb alone would convince anyone that the architect of our body (whoever that may be to each one of us) had to be a genius!” says the National Space Biomedical Research Institute.

Bones can also take an incredible pounding. “[They] are constructed in exactly the same way that reinforced concrete is constructed,” states the institute. “The steel of reinforced concrete provides the tensile strength, while the cement, sand, and rock provide the compressional strength. However, the compressional strength of bone is greater than that of even the best reinforced concrete.” “We only wish we could mimic it,” said Robert O. Ritchie, a professor of materials science at the University of California, Berkeley, U.S.A.

Unlike concrete, bone is an essential part of countless living organisms. And it is dynamic. It is able to repair itself, respond to hormones that affect its growth and development, and even play a key role in the manufacture of blood cells. Also, like muscle, it slowly grows stronger as the load on it increases. Hence, athletes have heavier bones than do so-called couch potatoes.

What do you think? Is bone a product of chance? Or was it designed?

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THE BIRD'S EGG

● The bird’s egg has been called “a miracle of packaging.” Why?

Consider: While it appears solid, the calcium-rich shell of a chicken egg can have up to 8,000 microscopic pores. These allow oxygen to enter and carbon dioxide to escape—an important exchange if the embryo is to breathe. Yet, the shell and several membranes prevent bacteria from infecting the embryo. Albumen—a gelatinlike substance with a high water content—gives the egg its ability to absorb shock.

Researchers would like to imitate the structure of the egg to create products with better shock protection and a film coating that could protect fruit from bacteria and parasites. However, “copying nature is not so easy,” writes Marianne Botta Diener in Vivai magazine. Attempts thus far, she notes, have not been environmentally friendly.

What do you think? Did this “miracle of packaging,” the bird’s egg, come about by chance? Or was it designed?

 

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