The thyroid hormones are responsible for the growth, metabolism, development and the organization of the activities in the nervous system.
The Rhythm of Life: The Thyroid Gland
Children especially have a high rate of metabolism. This is because they obtain a higher energy production from the nutrients in their cells. It is the thyroxine hormone that determines and supervises the speed at which the body cells work.
Today in factories and modern industrial plants, the most important thing on the agenda is "productivity." Every department of a factory must work with ideal speed but it is not enough that the individual units work to the ideal speed by themselves. Every unit must work in harmony with the others. If one unit thinks that there is an advantage in working on its own faster than the others, this could cause harm rather than benefit. For this reason, industrial engineers and strategic planners work in factories and plants to put planning into place and ensure productivity.
Imagine a factory that produces millions of different products, operates twenty-four hours a day without a break, and has 100 trillion workers. No doubt, an army of engineers and business planners would be required in this factory to formulate a productivity plan and determine how quickly each group of workers will work must productively.
In real life there exists such a factory, but engineers and business administrators do not work in it. The work is done by a small set of cells and the hormones that they secrete.
This factory is, of course, the human body and what is responsible for the productivity of this factory is the thyroid gland. With the help of the thyroxine hormone secreted by the thyroid gland, 100 trillion cells are individually organized to function according to a certain rhythm and at a certain rate of speed. This hormone determines how quickly nutrients are converted into energy and how efficiently food burns in the body.
For a factory to achieve the highest level of productivity, the speed at which the workers do their jobs must be both organized and controlled.
For example, most young people, especially those still in the process of growth, have a very high rate of metabolism, and the food they consume is quickly turned into energy. In other words, the nutrients they eat are quickly burned so that they do not gain weight easily. Generally, as people grow older, there is no difference in their appetite but, if they eat the same amount of food as when they were younger, they gain weight. The reason for this is that, when they were younger, the body cells produce energy from their food at a higher rate. When a person gets older, the energy produced by the cells from the burning of nutrients is lower and unburned food is stored in the body as fat.
If you were a factory owner, you would work to ensure that your employees worked in the most productive manner and, at the same time, you would make sure that they paid attention to their own health and safety. If the employees in one department of your factory worked more slowly than they should, it would not be good for the factory's general production. If there is no foreman to tell the workers what job they must do and how quickly they must do it, production will suffer.
The same thing happens in our bodies. If there were no foreman to tell your cells how quickly they must work, the result would cause the activity of the cells to slow down, the food you ate would turn to fat, you would not have enough energy to raise your arm, and your whole body would come to the point of exhaustion. When too little thyroxine hormone is secreted, a condition called hypothyroidism occurs which is characterized by these symptoms.11
But even if you are not aware of it, your thyroid gland is working for you, secreting the thyroxine hormone that controls each one of the 100 trillion cells and prevents them from slowing down. As a result, you can live your daily life normally.
Thyroxine not only prevents the cells from moving too slowly, it also prevents them from working too fast. Because this hormone is secreted in a definite amount, the speed at which the cells work is kept in balance. If the cells of the body worked more quickly than they should, "toxic goiter" would develop, caused by the excessive secretion of thyroxine.12Symptoms of this disease include the increase of the metabolic rate, a rise in body temperature and blood pressure, weight loss, excessive sweating and general nervousness. The eyes bulge in their sockets and, in advanced stages of this disease, blindness and even death (due to cardiac insufficiency) can result.
One of the conditions caused by the malfunction of the thyroid gland is Grave's disease. This condition causes the eyes to bulge (near right). Goiter is a condition caused by the enlargement of the thyroid gland (far right)
The tissues that make up the human body are continually being renewed. Every day approximately 200 grams of muscle and tissue cells are renewed.13Every minute 200 million cells in our bodies are produced to replace dead cells,14 and it is the thyroxine hormone that determines the speed at which this renewal takes place.
How does this hormone-producing thyroid gland know the speed at which the cells in our bodies must function? How does it determine the speed of the replacement of body cells? The person himself does not even know the speed at which his body's cells have to function, and most people are not even aware that their body cells have a particular speed at which they must function. If someone wanted to interfere with the speed at which his body cells work, he could certainly not affect the cells with his own will. In order to do this, he would have to obtain medical help or take some medication. Human beings do not determine the speed at which their own cells work; this is under the control of that small piece of flesh called the thyroid gland.
How has the thyroid gland determined the ideal working speed for the cells? How does it know the working speed of the hundreds of different systems contained in the cells—systems that scientists are still investigating? Let scientists continue to try to understand these systems; the thyroid hormone knows all the details of these systems, including what kind of intervention is needed to increase their working speed. To do this, it produces a specific molecule type and sends them to each of the cells one by one. In light of this, we must accept that the cells, which make up the thyroid gland and produce thyroxine, have a much higher intelligence about this process than human beings.
The structure of the thyroid hormone that determines the speed at which the body cells work.
Remember, like all the cells in the body, cells that compose the thyroid gland do not have any conscious intelligence.
As can be seen in the picture on the left, a thyroid molecule is composed of lifeless, unconscious atoms. The cells perform their function according to humanly inconceivable genetic program written in their nuclei. This fact brings to light even more the enormity of the miracle of creation.
It is God, the possessor of eternal intelligence and knowledge, Who wonderfully created the cells of the body, the genetic program that determines the functioning of this system, and the inner systems of the cells that translate and interpret this genetic program.
Moreover, in the genetic programs of the cells that compose the thyroid gland, He wrote the molecular formula of the hormone that accelerates the activity of other cells. So it is evident that a remarkably harmonious system has been put in place which proves once more the perfection of God's creation. In the Qur'an, God reveals harmony and perfection that is seen everywhere in the world:
He Who created the seven heavens in layers. You will not find any flaw in the creation of the All-Merciful. Look again – do you see any gaps? Then look again and again. Your sight will return to you dazzled and exhausted! (Qur'an, 67: 3-4)
The Proportion in Our Bodies
Thyroxine has another wonderful characteristic in that it works in cooperation with the growth hormone. These two molecules act together in harmony toward a common goal. There is only one explanation for this: these two molecules were created for this common task.
You will recall from earlier pages that the growth hormone is the molecule that orders the cells of a developing child to grow and multiply. This hormone stimulates the cells to grow in both size and number. But there is another very important detail that must be planned—the speed of cell division. Thyroxine influences the speed of cell division during the period of growth, ensuring complete development of the body.
To understand the importance of thyroxine, we just have to look in a mirror. So long as there is no birth defect, every individual's mouth, nose, eyes, the face—in short, everyone's whole body—has a proportion that resembles that of almost everyone else. The body has this proportion due to the perfect functioning of the thyroxine hormone that God created. If you were reading these sentences years ago as a young person in your developing years, and the thyroxine molecules did not go to each one of your individual cells and inform them of the speed at which they must divide, your body's organs would have developed without proportion. You could even have become mentally impaired, as is the case when cretinism occurs as the result of insufficient secretion of thyroxine immediately after birth. The bodies of people afflicted with this condition lack proper proportions when grown; generally they have very short legs and a large skull. In addition, a lack of thyroxine also causes dwarfism.15
The three-dimensional structure of the thyroxine hormone.
Most of the people you see in your daily life (your schoolmates, fellow workers, people in the street, and your family) have bodies perfectly shaped by God's creation by means of the activity of two small molecules—growth hormone and thyroxine. These hormones are secreted at the right time and in the right amount, commanding trillions of individual cells with orders as to how much and how fast they have to multiply. As a result, a perfectly formed human body comes into being.
In the majority of human beings, the amount of this molecule is adjusted in a very special way so that neither too much nor too little is produced. If the amount of these hormones produced varied too much from one individual to another, there would be major physical differences between people; millions of people would be between 2.5 and 3 meters tall; millions would be one meter or less in height, everyone would have a body and facial structure lacking proportion, and almost everyone would be mentally retarded. Millions of people would die while still in adolescence.
To repeat: the external appearance and physical characteristics of human beings is due to two small molecules that God has wonderfully created—the growth hormone and thyroxine. This is another proof of how God has constructed human beings on a foundation of delicate balances:
He created the heavens and the Earth with truth and formed you, giving you the best of forms. And He is your final destination. (Qur'an, 64: 3)
One Hundred Trillion Micro-Heaters
Cells, which act as micro-heaters, supply the heat needed by our bodies.
In order for you to be able to read this page, your body temperature must be at a certain level. If this temperature falls or rises too much, you will die. For this reason, some systems that keep the body temperature at a definite level have been created and placed within the human body. One of these remarkable systems is the thyroxine hormone. The body reaches a certain temperature as the result of the activities of its 100 trillion cells. We can compare these cells to micro-heaters, and the wonderful molecule that controls how much heat each micro-heater must produce is the thyroxine hormone.
It is in itself a wonder that cells produce a certain amount of heat as they do their work and that the total amount of heat produced by the 100 trillion cells is exactly the amount that is required for human beings to survive. Moreover, the thyroxine molecules know how much heat the cells must produce. Together with all of this, the fact that the cells know how they can act on the metabolism and raise the body's temperature is one more wonder of creation.
A Delicate Control Mechanism
A highly advanced and organized system has been created to regulate the amount of thyroxine secreted. The secretion of thyroxine occurs again as a result of a chain of command of a set of unconscious cells organized in a highly disciplined hierarchy.
When thyroxine is needed, the brain of the hormonal system—the hypothalamus—sends a command (the TRH—Thyroid-releasing Hormone) to the conductor of the hormonal system orchestra (the pituitary gland). When it receives the command, the pituitary gland understands that the thyroid gland must be activated and immediately sends a command (the TSH—Thyroid Stimulating Hormone) to the thyroid gland. The thyroid gland, as the last point in this chain of command, immediately secretes thyroxine in compliance and distributes it throughout the whole body by way of the blood.
How is the amount of this hormone that needs to be secreted determined? How is it that, except in cases of illness, neither more nor less of this hormone than is needed is secreted?
The amount of thyroxine secreted is determined by a special system created by the great artistry of God. This system is based on two separate, negative feedback mechanisms and is an example of an incomparable wonder of engineering design.
When the amount of thyroxine in the blood rises above normal, the thyroxine hormone produces a very interesting effect on the pituitary gland and sometimes directly on the hypothalamus: it reduces the sensitivity of the pituitary gland to the TRH hormone.
When there is need for thyroxine, the hypothalamus sends a command to the pituitary gland (TRH). The pituitary gland that receives the command understands that the thyroid gland must be activated. The pituitary gland immediately sends a command to the thyroid gland (TSH). In compliance with the order it receives, the thyroid gland immediately produces thyroxine, and the thyroxine is distributed throughout the body by the blood stream.
The function of the TRH hormone is to activate the pituitary gland to send a command (the TSH hormone) to the thyroid gland. This command is the second point on the chain of command in the production of the thyroxine hormone.
The system is so intricately designed that the excess thyroxine takes highly intelligent measures so that the sources in which it is itself produced do not make too much, and it interferes with and severes the chain of command established for its own production. By this means, when the thyroxine in the blood rises above normal, the production of thyroxine is automatically curtained.
We can understand this more easily with some examples: imagine that small intelligent machines were made in a factory. These machines were made in three stages:
1. First stage: computer A sends a production command to computer B.
2. Second stage: computer B translates this command into another language and sends it to computer C.
3. Third stage: computer C begins to produce the desired machines with the help of a robot.
Suddenly, production exceeds what is required and there are more machines in stock than are needed. At this stage, one section of the machines in stock goes to computer B and removes the cable connecting computer B with computer A. Now, computer B cannot receive a command from computer A. Since the production command cannot reach computer C, production ceases and the computers in stock last until the supply runs out. When the stock runs low, the cable connecting computer A with computer B is again attached by the machines and production resumes.
If such machines were made which could supervise their own production and that of the machines that produce them so intelligently, a revolution in industry and technology would be the result. In every human being, there exists such a fantastic system of production occurring every minute.
A second system also determines the amount of thyroxine produced. An increase in the amount of thyroxine affects the cells in the hypothalamus. These cells reduce the production of TRH and, therefore, the amount of TSH secreted in the pituitary gland is reduced. By this way, the production of thyroxine is slowed down.
Using the above factory example, it is useful to examine this second system. The effect of the thyroxine on the hypothalamus and its curtailment of the production of TSH can be compared to the machines produced in our imaginary factory that slow down the information flow from that computer. Not only the communication between computer A and computer B is cut, but computer A is also slowed down, thus being prevented from sending a command to computer B.
When the amount of thyroxine in the blood is reduced, the system works in the reverse direction. More commands are sent from computer A and the capacity of computer B to receive these commands is increased. As a result, the hypothalamus secretes more TRH hormone, the pituitary gland becomes more sensitive to TRH, and raises the production of the TSH hormone. In this way, more thyroxine is produced and secreted.16
How does the thyroxine hormone know that the chain of command must be broken in order to stop its production? How do the cells in the hypothalamus know that, when the level of thyroxine is high, its secretion must be stopped and, when it is low, its secretion must be increased? How did this flawless system come into being?
To think that this intricately planned system came to be by time, chance, and natural law is more outside the realm of sound thinking than to think that a computer or a television could come into being by a similar process. In order for this system to be able to function, hundreds of specially designed molecular sized structures (which we have not described in detail) are required. It is a clear fact that this system was created by a supreme intelligence, that is, by God.
1. Computer A sends a production order to computer B.
2.Computer B understands the order, translates it, and sends it to computer C.
3. Computer C begins to produce the desired machines with the aid of a robot mounted on it
When too much stock has been accumulated, one of these machines goes to computer B and cuts its connection with computer A. As a result, computer A cannot give a production command. This situation continues until the stock is depleted.
Four Out of Ten Thousand Molecules
The amount of thyroxine secreted is determined by the amazing system we have described above. But together with all this, there is another remarkable system that keeps the level of thyroxine in the blood stable in times of crisis.
Thyroxine molecules are secreted by the thyroid gland into the blood and must soon become attached to molecules specially designed to transport them in the blood. While they are attached to this molecule, they cannot perform their function. Of the thousands of thyroxine molecules, only a few freely circulate in the blood. It is only about four out of ten thousand thyroxine molecules that affect the metabolic speed of the cells.17
After the free thyroxine molecules enter the target cells, other thyroxine molecules that detach from their carrier molecules take their place. The carrier molecules serve as a storage reservoir to ensure that enough thyroxine is ready when needed.
We have already seen how delicately the balance of the amount of thyroxine required to affect the cells is adjusted and the medical problems that can result if the amount of thyroxine rises or falls. This delicate balance involves a proportion of four free to ten thousand bound thyroxine molecules. In the light of this, these questions must be asked:
Who counted these trillions of molecules and decided that only close to four out of ten thousand are needed for the health of human beings? Who calculated that nine thousand nine hundred ninety-six molecules out of every ten thousand molecules must stand by idly? Who foresees that there will be a reduction of the number of these four molecules out of every ten thousand molecules roaming in the veins, and releases more molecules? Who made this incredible mathematical calculation and created this system that has existed in every human ever born?
Certainly this example is a proof that God is sovereign over everything both visible and invisible, that He encompasses and determines most exactly the number of all things on the face of the Earth.
So that He may know that they have indeed transmitted the Messages of their Lord. He encompasses what is in their hands and has counted the exact number of everything. (Qur'an, 72: 28)