What is it that helps a newborn baby weighing 3 kilograms (6 pounds) and only 50 centimeters (19 inches) tall to turn into an adult weighing around 80 kilograms (176 pounds) and some 1.80 meters (6 feet) tall over 20 to 25 years?
The answer to that question lies hidden in growth hormone, a miraculous molecule secreted by the pituitary gland.
Growth in the body takes place in two different ways. Some cells simply increase their volume, while others divide and multiply, creating more of themselves. But growth hormone directs and brings about both of these processes.
Growth hormone affects all the body's cells. Every cell knows the meaning of the message secreted by the pituitary gland. If it needs to grow, it does so, and if commanded to divide and multiply, it does so.
For example, the heart of a newborn baby is about 1/16 the size of an adult's. Yet it contains the same number of cells as an adult heart. Growth hormone affects the heart cells one by one during their developmental stage. Every cell develops to the extent commanded by the growth hormone. Thus it is that the heart grows and eventually reaches an adult size (Figure 48).
Figures 48 and 49.
While the baby is still in the mother's womb, at the end of the sixth month of gestation, the multiplication of nerve cells in the heart comes to an end. From this stage on, from birth and until adulthood, the number of cardiac nerve cells remains fixed. Growth hormone commands the nerve cells to grow in volume, not in number, and the nervous system thus achieves its final state with the end of the growth phase (Figure 49).
Other cells in the body—those of muscle and bone cells, for instance—divide and multiply throughout the developmental stage. Once again, it is growth hormone that informs these cells how much they need to grow (Figures 50 and 51).
That being the case, we have to ask the following question:
How does the pituitary gland knows the requisite formula for cells to divide or grow? This is a very miraculous phenomenon, because a parcel of tissue no larger than a chickpea governs all the cells in the body and provides for the growth of these cells, either by expanding their volume or by dividing and multiplying.
Another question we need to ask ourselves is this: why does this piece of tissue perform this task? Why do these cells spend their entire existence sending messages telling other cells to divide?
At this point, the perfection of God's creation once again reveals itself. Cells in one tiny region ensure that trillions of other far-flung cells divide and grow within a regular order. Yet these cells have no way of perceiving, seeing the human body's symmetry from the outside, nor of knowing how much the bones and muscles still need to grow, nor what stage of the developmental process has been reached. These unconscious cells produce growth hormone inside the darkness of the body, without even knowing what they are doing—and yet, also halt the process when the appropriate time comes. The system has been created so flawlessly that every phase of growth and the secretion of this hormone is kept under control at all times.
The way that growth hormone commands some cells to increase their volume and others to multiply through division is an entirely separate miracle—because the hormone that reaches both types of cell is exactly the same. However, the way that the cell receiving the hormone is to behave is encoded in its genes. Growth hormone issues the command to grow, but the way in which this process is to take place is written inside that cell. This once again demonstrates the might and majesty of creation in every point in the human body.
Another very important detail here is yet another great miracle: the way that growth hormone affects all the body's cells. If some cells obeyed the growth hormone while others ignored or rebelled against it, then undesirable, even catastrophic consequences would result. For example, if cardiac cells were to increase in size, in the manner that growth hormone commands while bone cells in the ribs refused to multiply and increase their number and mass, then the expanding heart would be trapped in the narrow ribcage and slowly be crushed to death.
Or if the nasal bone continued growing while the skin stopped, the nasal bone would break through the skin and come to the surface. The harmonious growth of muscles, bones, skin and other organs is ensured by the obedience of each individual cell to the growth hormone.
The growth hormone also gives the command for the development of cartilage at the ends of the bones. This cartilage is like a template for the newborn baby's body. So long as it does not grow, neither can the baby.9The cells in a bone lengthen it, but how can the cells know that this is necessary? If this bone thickens and only grows in diameter, then the legs will not grow longer, and the femur bone may even stretch the skin and erupt at the surface. However, our Almighty God has installed the information and all details regarding the human body inside the nucleus of every cell. Thus the bones lengthen and grow.
The hypothalamus, which directs on the secretion of vitally important hormones, occupies a very small space in the brain.
Another miracle manifested by growth hormone concerns the time and the quantities in which it is released. Growth hormone is secreted in just the appropriate amounts and at those times when growth is most intense. This is vitally important, because if slightly more or slightly less hormone than necessary were released, it would give rise to most unwelcome consequences. Too little growth hormone being secreted leads to dwarfism, and too much being released leads to gigantism.10
Therefore, a very special system has been created to regulate the amount of growth hormone released in the body. The hypothalamus, regarded as the decision-making part of the pituitary gland, decides how much of the hormone should be secreted. When the time comes for growth hormone to be secreted, it sends a growth- hormone-releasing hormone (known as GHRH) to the pituitary gland. When too much growth hormone accumulates in the bloodstream, the hypothalamus sends another message (via the hormone somatostatin) to the pituitary gland, slowing its release of growth hormone11(Figure 52).
Figures 53 and 54.
How do the cells composing the hypothalamus know how much growth hormone there should be in the blood? How do they measure the levels of growth hormone there and take the appropriate decisions accordingly?
In order to appreciate what a great miracle this actually is, consider the following analogy:
Assume that using special technology yet to be invented, we have shrunk an entire human being down to the size of a cell. This tiny person has been placed inside a special capsule and inserted next to one of the cells in the region of the hypothalamus.
This individual's job is to count the number of growth-hormone molecules inside the capillary vessels before him. He must also determine whether their number has risen or fallen. It is well known that, there are thousands of different substances flowing past in the blood. Bearing in mind the structure of molecules, (unless this lone individual has received special, expert biochemical training). it will be impossible for him to determine whether or not the compounds flowing past him belong to growth hormone. Yet it is essential that the person installed in the hypothalamus recognize every growth hormone molecule from among all the other thousands of molecules, because he must monitor the levels of growth hormone at all times (Figures 53 and 54).
How do hypothalamus cells perform a task which would be extremely difficult even for a human being of any size? How can they measure the amount of growth hormone, which is always present in the blood, even after skeletal growth stops, to maintain the division of cells? How do they distinguish between growth hormone and the countless other molecules? These cells have no eyes with which to recognize molecules, nor brains with which to analyze the results. Yet they carry out the task given them within the system established by God in a flawless manner. Thanks to this immaculate system, human beings have perfectly proportioned and aesthetically pleasing organs and bodies. God has created all things with perfect features:
He is God—the Creator, the Maker, the Giver of Form. To Him belong the Most Beautiful Names. Everything in the heavens and earth glorifies Him. He is the Almighty, the All-Wise. (Surat al-Hashr, 24)