The foot is a limb that is not given much importance when compared to other vital organs such as the brain or heart. However, the foot is a very complex mechanical structure that is made of 26 bones, 33 joints, and more than 100 muscles and ligaments. About a quarter of the bones in the human body and about a fifth of the joints are found in our two feet. That is why Leonardo da Vinci described the human foot as an engineering and artistic masterpiece.

A healthy person takes about 5,000 steps a day. Given a life of eighty years, a person takes about 150 million steps throughout their life. Assuming that each step is 75 cm, a person walks about 110,000 kilometers throughout his life. This corresponds to walking around the equator about 3 times. Apart from that, a typical person stands for around 2-4 hours a day. During all these activities, the human foot carries the entire body’s weight. In standing position, body weight is supported by two feet while activities such as walking and running are done by only one foot for a certain period of time. While standing, the feet carry 100% of their body weight, while walking, this rate rises up to 150%. While walking, the foot that needs to be lifted from the ground approaches the ground again with an acceleration in the same direction as gravity. Therefore, the impact force at the moment the foot touches the ground corresponds to 150% of a person’s body weight. In cases of severe effects such as running and jumping, this force easily increases up to 5 times the body weight and up to 10 times in some people. For a person weighing 70 kilograms, this force can be 105 kg (or about 1050 Newton) in walking, and easily 350 kg (or about 3500 Newton) in running or jumping. Assuming that a person walking for an hour takes 5,000 steps, the foot pulls a total of about 500 tons of load (5,000 steps x 105 kg). In running, this figure will increase approximately three times.

The foot has been created with a wonderful mechanical and construction design that is able to consistently sustain such high loads. The bones and muscles of the foot add two different belt designs to it. One of them, the structure called the longitudinal belt starts from the heel bone (calcaneus) and ends with its metatarsal bones (Figure 1). Some researchers claim that the long arch is divided into two parts as the inner (medial arch) and the outer arch (lateral arch). However, both structures resemble bridges built in arches. The second arch on the foot is called the transverse arch. This belt is perpendicular to the long belt from the right side of the foot to the left side and is shorter in length (Figure 2).

Therefore, the foot is a marvelous structure consisting of roughly two arches. This structure of the foot can be compared to arch bridges or a dam. The arch structure is known as the strongest structure against steep loads in construction areas due to the robustness of the designs against compression forces in cases of vertical loading. Therefore, hydroelectric dams are constructed in the form of arches or arcs in order to make the most resistant model against hydrostatic pressure.

The arch structure of the foot is very flexible and can also move up and down like a car suspension and acts as a shock absorption. If there was no such structure on the foot, the impact forces during walking and running activities would be higher and cause chronic foot pain. The flatfoot complication is a result of a damage in the arch structure in the foot which comes from birth or develops afterwards. Flatfoot patients are often unable to perform long-term activities and experience foot pain as well as complications in other organs of the body.

Our feet’s arch structure is not the only factor involved in shock absorption that is designed against mechanical forces. The layer of fat on the bottom of the foot also contributes to this process. In a healthy person, this fat layer, which has a height of 2.5 cm under the heel, drops to 5-7 mm in the front part of the foot. It also helps to distribute the vertical and horizontal forces caused by standing or walking evenly on the sole of the foot. At the same time, it serves as a source of heat insulation and helps protect our feet from hot or cold surfaces. In some diseases such as diabetes, in which this fat layer melts or decreases, wounds called foot ulcers can develop because the shock absorption and load distribution get damaged. Mechanical pressure is calculated by dividing the amount of mechanical force by the surface area on which it is applied, meaning that smaller surfaces areas are subjected to more pressure. This is why very tiny needles, despite weighing almost nothing, can pierce our skin and cause pain. Similarly, damage to the fat layer under the foot causes the forces applied under the foot to act on a limited surface area. For example, the reduction of fat in the area just below the heads of the metatarsal bones reduces the “cushioning” effect in this area and causes a pressure in high values. This extra pressure can cause tissue damage along with the aforementioned foot ulcers.

Such a situation that will cause pain in a normal person cannot be felt by many diabetics. If diabetes is not well controlled, neuropathy or a “lack of feeling” may occur as a complication. Dead nerve cells become unable to feel pain which can result in people not knowing about harm that is being done to their body. Diabetic patients who develop neuropathy would not feel fatty layer damage and accompanying high pressure values whereas a typical person normally would. Untreated foot ulcers can become infected and can turn into gangrene. Since the gangrenous foot has to be cut, diabetes unfortunately causes a large number of amputations. Such amputations are sadly quite frequent throughout the world due to diabetic neuropathy. Dr. Paul Brand, who studied diabetic foot ulcers, defined pain as a gift from God that no one wanted. Sometimes, what we do not like might be better for us (Qur’an 2:216); likewise, pain can cause a lot of trouble to people but it can also alert us of dangers and harm to our bodies.

Thus, foot care is very important in diabetics. The following three actions are recommended to patients; daily inspection of the foot; daily washing; and control of the inside of the shoes. The pest, pebble, or similar hard object in the shoe that can be very harmful for diabetics with loss of sensation would be removed this way. On the other hand, when such a hard object remains in the shoes, patients may step on them repeatedly without feeling it which will likely lead to an ulcer case.

With its pain that works like a health alarm, extraordinary mechanical loads it carries, heat insulation and shock absorbing features, the human foot is a wonder of art that calls for contemplation.

Jakus AE et al. Hyperelastic “bone”: A highly versatile, growth factor-free, osteoregenerative, scalable, and surgically friendly biomaterial. Science Translational Medicine. September 2016.

Bone implantation surgery is both challenging for doctors and a painful process for patients, especially children. It usually requires either harvesting existing bone tissue from elsewhere in the body, or using metallic implants. While these approaches may work for adults, they are not a permanent solution when used for growing children. In a recent study, scientists reported a 3D printable ink that forms a synthetic bone implant and induces bone generation and growth. This biomaterial is composed of a mix of 90% hydroxyapatite, a calcium mineral found in human bone, and 10% biodegradable polymer, which is commonly used in medical applications, including sutures. The key feature of this new hyper-elastic biomaterial is its ability to create porous structures where blood vessels and other cells can infiltrate to create a scaffold. Animal studies showed that when stem cells are placed on these scaffolds, they turn into bone cells and initiate the regeneration process. Additional factors can also be easily integrated into the biomaterial, such as antibiotics to prevent post-surgery infections or growth factors to further enhance the regeneration process. The advantage of 3D printing technology will enable doctors to create personalized bone structures with custom shapes and properties for each patient.  In the near future, hospitals with biomaterial and 3D printing facilities may revolutionize the field of craniofacial and orthopedic surgery.

Gene behind “sixth sense” discovered

Chesler AT et al. The Role of PIEZO2 in Human Mechanosensation. The New England Journal of Medicine. September 2016

Close your eyes and bring your finger to your nose. It’s an easy task for almost all of us, isn’t it? Awareness of the position of one’s body in space is called proprioception, also commonly known as the “sixth sense.” A recent study describes the cases of two patients who lack proprioception. These patients could not walk, keep their balance, or even touch their noses when blindfolded. Genetic analyses revealed that both patients had mutations on a gene called PIEZO2, suggesting that this gene is responsible for the sense of touch and proprioception in humans. Further investigation of the PIEZO2 gene showed that it controls mechanosensation by generating nerve signals in response to any force touching the skin, thus allowing us to sense the touch. The patients seem to compensate for a lack of proprioception by relying primarily on vision. While these patients have non-functional PIEZ02 genes, there is an intriguing possibility that there could be other variations of this gene in the human population, which may generate a spectrum of symptoms from superior athletic performance to clumsiness, depending on the P

The findings in mice imply that humans might also possess similar characteristics. This increases the possibility and brings hopes of having a baby even at older ages along with treatments in the future, just like in the miraculous story of Prophet Abraham and Sarah as narrated both in the Qur’an (ad-Dhariyat 51:24-30) and the Bible (Genesis 21:7), showing us one aspect of the possibility and ultimate limits of knowledge and technology that humans can attain one day so that these miracles can become true, though to some extent, with the advancement of medicine.

Bone borne eggs

An interesting study showed an unexpected source of oocytes in the bone. Study by Tilly’s group at the Harvard Medical School in 2004 showed that cells in the bone marrow of mice could be a source of oocytes that are developing in the ovaries [1, 2]. Their first observation was the expression of genes related to egg cells in the bone marrow samples of mice. To test the possibility of bone marrow cells as a source of new oocytes, they chemically generated infertile mice. Treating mice with two chemotherapy drugs called cyclophosphamide and busulfan causes infertility. Once they treated the mice with these drugs, the mice had extensive damage in their ovaries along with an end in new oocyte production in their follicles. Ovarian follicles are spherical aggregations in the ovaries which periodically produce oocytes. Remarkably, when they transplanted bone marrow from female donors, they found a number of oocyte containing follicles (about several hundred). Interestingly, the appearance of those oocytes were rapid and thought to be due to circulating oocytes originating from the bone marrow and developing as they travel through the blood stream. Although they don’t have the evidence that those cells could be fertilized, findings could lead to fundamental changes in the current understanding of the female reproductive system.

Tilly and colleagues also report that bone marrow and blood transplants could also induce the development of oocytes in a genetically infertile mice model (which has a mutation in ATM gene) [3]. This mutant mice lack follicles and developing oocytes and are unable to produce mature germ cells (egg producing cells). Their study shows that bone marrow or blood transplant from healthy donors induces production of oocytes in this mice model. They conclude from those studies that bone marrow could be a source of germ cells to the ovaries throughout adult life. Their findings are somewhat supported by the clinical studies on cancer patients who were expected to be infertile but they could have babies after bone marrow transplant.

Another study on the circulating cells for female fertility used parabiotic (the union of two mice through an exchange of blood) mice model. This study by Eggan and colleagues tested the capacity of circulating bone marrow cells to generate ovulated oocytes and could not show any contribution of bone marrow cells to ovulated oocytes [4]. Blood or bone borne oocytes are highly debatable but bone marrow cells, at least, might have a role in enhancing women’s fertility. This might lead to the treatment of infertility. In addition, it might bring new opportunities for those dreaming of having a baby even at a late stage, but requires much additional research to be realized.

Lab & bone borne sperms

Sperm formation is known to continue throughout adulthood. It involves various steps of cellular differentiations. Maturation of sperms in the body takes more than a month in most mammals. Trials to mimic this complex process in petri dishes failed to demonstrate the production of normal, fertile sperms.

Scientists had dreamed of growing sperms in petri dishes for years. Recently, researchers in Japan developed a technique that allowed production of fertile mammalian sperms in a petri dish [5]. Attempts to make such mature sperms usually failed due to meiosis, a specific type of cell division that halves the number of chromosomes. Meiosis is very essential step for sperm cells to get ready to fuse with an egg. Ogawa and colleagues demonstrated that meiosis of sperm cells lay in a simple change to standard petri conditions. They tried various petri conditions but they ended up with a special serum free medium that is commonly used for growth of embryonic stem cells. Several weeks later, they observed formation of mature sperm cells and even half of them had flagella, a tail-like structure that sperm cells use to swim. Injection of those sperms into egg was also able to produce offspring. In addition, when they used frozen testis tissues of newborn mice, they could grow sperms as well. This discovery in reproductive biology is likely to be beneficial not only for people having infertility problems associated with sperm maturation but also children that undergo cancer therapy which destroys fertility. It is known that chemotherapy impairs fertility. Adults could freeze their sperm before such treatment, but young boys can’t. This new discovery offers such patients hope. In addition, this finding opens new avenues for protection of endangered animals that might die before reaching sexual maturity. It is a matter of time for the same technique to be applied to humans and other species.

There are also reports suggesting the generation of male germ stem cells (sperm producing cells) from bone marrow [6, 7]. Mesenchymal stem cells, which are derived from the bone marrow, have shown to differentiate into male germ cells. Studies testing the effect of retinoic acid and testicular extracts showed to induce human bone marrow stem cells to differentiate into male germ cells as shown by male germ-cell specific marker expressions. Another approach tested the possibility that bone marrow-derived stem cells would differentiate into germ cells when transplanted into the mouse testis. Using GFP positive bone marrow cells transplantations, it has been demonstrated that bone marrow-derived stem cells can also be induced to differentiate into germ cells. Interestingly, there seems to be a connection between bones and fertility.

Bones and fertility

The Qur’an tells the story of Prophet Zachariah, peace be upon him, when he secretly prayed to God to ask for a successor. He said “My Lord! My bones have grown feeble and my head glistens with gray hair from old age…” (Maryam 19:4). His prayer was accepted and the angels came with the glad tidings of his son, John. He was surprised as to how he could have a son while his wife was barren and that he had already reached infirmity in old age. It has been said by scholars that weakness of bones here refers to weakness in engaging in sex due to old age and gray hairs as a sign of infertility. It is also worthy to mention another verse where the creation of human is described as happening from a lowly fluid that gushes forth the vertebra and rib bones: Let human, then, consider from what he has been created. He has been created from some of a lowly fluid gushing forth. It proceeds (as a result of incitement) between the (lumbar zone in the) vertebra and the ribs (At-Tariq 86:5−7). As commentator Ali Unal explains, these verses refer to both the mechanism of the ejection of the seminal fluid and where it is emitted [8], which is a relatively recent discovery in biology. Remarkably, the Qur’an mentions two major bones where this fluid is emerging. Our current knowledge in medicine do not say anything about the role of ribs in reproduction or fertility but both the Islamic and Judeo-Christian traditions mention the creation of Eve from Adam’s ribs, peace be upon him. Could this refer to the relation between bones and fertility? God knows best. Lastly, it is of importance to note that one of the symptoms of menopause is the loss of bone mass. Isn’t it amazing how mysterious events regarding bones and fertility are taking place beyond our control and knowledge?

Ali Fethi Toprak is a PhD candidate at University of Texas Southwestern Medical Center.

References

1. Johnson, J., et al., Germline stem cells and follicular renewal in the postnatal mammalian ovary. Nature, 2004. 428(6979): p. 145-50.
2. Vogel, G., Reproductive biology. Controversial study finds an unexpected source of oocytes. Science, 2005. 309(5735): p. 678-9.
3. Johnson, J., et al., Oocyte generation in adult mammalian ovaries by putative germ cells in bone marrow and peripheral blood. Cell, 2005. 122(2): p. 303-15.
4. Eggan, K., et al., Ovulated oocytes in adult mice derive from non-circulating germ cells. Nature, 2006. 441(7097): p. 1109-14.
5. Sato, T., et al., In vitro production of functional sperm in cultured neonatal mouse testes. Nature, 2011. 471(7339): p. 504-7.
6. Hua, J., et al., Derivation of male germ cell-like lineage from human fetal bone marrow stem cells. Reprod Biomed Online, 2009. 19(1): p. 99-105.
7. Lue, Y., et al., Fate of bone marrow stem cells transplanted into the testis: potential implication for men with testicular failure. Am J Pathol, 2007. 170(3): p. 899-908.
8. Unal, A., The Qur’an with Annotated Interpretation in Modern English. Vol. Qur’an 86:5−7, 51;24−30 and 19:4. 2009.

The miracle of life appears in the form of a baby which develops from a fertilized ovule (zygote) following millions of other events. This series of events, which is almost always the same for every fetus, can be grouped as reproduction, differentiation, and development. The zygote completes its development in the womb; postnatal growth can continue until 20 years of age. Even though every event during the baby’s development seems to take place with chaotic reactions, harmony and order are there for us to discover. One of these astonishing events is the perfectly symmetric growth of the fetus/baby. Most organs in the human body appear in pairs and are symmetric. Babies are born with 300 bones; however, some bones later fuse with other bones, leaving only 208 bones in the adult human. It is still a mystery how long bones such as the humerus, radius, ulna, femur, and tibia are able to grow on both sides of the human body in a symmetrical manner.

Mechanisms that control growth in organs

In vertebrates, both internal developmental programs and the external factors which stimulate or inhibit growth play a role in the ultimate size of an organ. But the relative effects of these two mechanisms can vary significantly in different organs. When pieces of spleen from an embryo that is at a later stage of growth are transplanted to a newly developing embryo, each new piece grows, but not to the size of the original spleen. The total weight of all the transplanted spleen pieces is equal to a normal spleen’s weight. When the spleen reaches a certain weight, growth inhibiting factors are secreted, which stimulate negative feedback mechanisms that limit growth. When a spleen reaches a certain size, the density of the inhibiting factors increases simultaneously, halting growth. Growth in the liver is controlled by extracellular factors (various substances in the blood, hormones, vitamins, minerals, etc.). When a section is cut off of the liver, the section continues growing and developing until it reaches the size of the original liver. The thymus has a growth process that is executed by a cellular genetic program. When sections of a thymus taken from the embryonic period are injected into developing mouse embryos, every section grows until it reaches the ultimate size.

More evidence of cellular growth programs was acquired via an experiment that was carried out with the salamander genus Ambystoma. When the leg bud of the larger species was injected into the smaller species, it would at first grow slowly, but then it would reach the normal size of its own species (the larger species).

Distinguishing growth and symmetry from one another

Both the arms and legs have long bones. A long bone consists of two parts (diaphysis and epiphysis). The diaphysis is the middle (core) part of the long bone. It consists of hard bone tissue, and is like a tube. The hyaline cartilage-covered joint forms the epiphysis of the long bone. In a growing bone, there is a growth plate (epiphysis plaque) made of hyaline cartilage; this is located between the diaphysis and the epiphysis. The epiphysis plaque causes the bone to grow longer; when growth is complete, the epiphysis plaque ossifies (becomes bone). In other words, growth stops. There are some clues that show the existence of positive feedback mechanisms which control the symmetric and balanced development of the arms and legs while the fetus is still growing. The arms and legs grow due to the development and growth of the plaques located at opposite ends of the long bone. The ultimate size of the arms and legs are proportional to the size of the finger bones (phalanx) and the metacarpus. According to current knowledge, growth in our arms and legs is only controlled by internal growth programs and the active growth of the plaques. We do not yet know the mechanism through which how much the bone must grow and symmetrically with the organ (the other arm or leg) on the other side of the body. But even if this is discovered in the future, we will continue to appreciate the perfect and miraculous aspect of this phenomenon.

In addition, in growth-plaque transplant experiments, the development of the transplanted growth plaque is dependent only on the age and size of the donor. Growth plaques cause the bone to grow, but the plaques themselves remain the same size for years. The cartilage cells they produce (chondrocytes) exchange places with the bone cells (osteocytes) in harmony and without destroying the length of the bone. Cells from different areas of the growth plaque act differently. Stem cells are found on the upper section, near the epiphysis. Immediately above them is an area where cells reproduce very quickly. At the bottom of the epiphysis, the cartilage cells grow up to 4 to 10 times larger than their normal size (hypertrophy). Cell reproduction here is mostly due to hypertrophic chondrocytes. The chondrocytes die and break up, then change places with the bone tissue. The dynamic process of these events in the growth plaque repels it from the bone area, and as a result, the bone grows longer.

Sustained symmetry despite cell sequence and speed of reproduction

The rapid growth rate in the legs and arms during the embryonic period continues to increase until the child is three years of age. This growth rate slows down until the individual reaches adolescence. During the fastest growth period, which is from adolescence to the early 20s, the growth rate rapidly increases. For example, most people who grow between 30 and 37.5 cm during the first two years of life can grow between another 7.5 and 10 cm every year during adolescence. At the onset of adolescence, rapid growth due to a sudden change in the volume of cells is observed. After adolescence a sudden falling off in the speed of growth can be observed due to the effect of hormones on the growth plaques in the spine and other long bones. The growth plaque now fuses with the neighboring cells and growth stops. However, the fusing of the growth plaque is the result of the cessation of growth, not the cause. After growth stops, the growth plaques begin to disappear. When the reproduction potential of the cartilage cells in the growth plaque has been exhausted, the growth plaque begins to disappear.

Growth plaques in different bones can trigger growth at various rates; these rates can differ as much as seven times. In fact, growth plaques on different ends of a bone can have different growth rates, provided that this rate is consistent with the genetic program. The number of cells on the growth line is 40 times more than in other areas. The number of cells produced here can exceed 10,000 cells per day. For symmetric growth between the arms and legs to be sustained, the number of cells in the growth plaque must be the same or very close. Experiments carried out on rats show that eight cartilage cells leave the growth plaque to exchange places with cells above them every day. It can be said that the growth of the bone is caused by the increase of cells in the growth plaque (which sustains its size). The growth rate caused by the growth plaque can be calculated by multiplying the growth plaque’s cell production rate by the average length of all of its cells. Different growth plaques provide different growth rates. This difference can be caused by the difference in the size of the growth plaques, the difference in cell production rates, and/or the difference in the hypertrophy (growth) rate of every cell. The upper growth plaque in the tibia of mice generates 16,400 cells every day; the average life span of these cells is around 30 hours. Can such harmonious, symmetric, and equivalent growth in the arms and legs-despite the large number and variety of cells-be the work of pure coincidence, mindless nature, or unconscious molecules?

Do hormones play a role?

The main molecular players that organize longitudinal growth in bones during childhood are the growth hormone, the thyroid hormone, and corticoids. The sex hormones (androgens and estrogens) are programmed to influence growth during adolescence. Estrogen is the main determiner of characteristics related to increased height and an increase in bone quality, as well as adolescent-related physiology. These hormones are in charge of coordinating growth throughout the body. It is for this reason for women, after the menopause, the production in estrogen decreases and osteoporosis and brittle bones can occur. According to the current view, cartilage cells have a certain genetic reproduction potential, and when this potential finishes, growth stops. The growth rate during the embryonic period is 20 times higher than that of mid-childhood. The growth rate drops greatly during mid-childhood. If we exclude the noticeable increase during adolescence, the cells responsible for growth have begun to age. The bones on opposite sides of the body stay about the same size, despite all of these changes in growth rates. Circulating hormones and neuroendocrinal factors are believed to play important roles in maintaining symmetric growth. But there is no conclusive evidence to support this belief. Even though one can think of factors such as pressure, tension, and sports as helping control harmonious and symmetric growth of bones, no proof has been attained from controlled experiments. As a person ages, a gradual decrease in growth can be observed. Even if a growth plaque is placed into another organism, be it young or old, the growth rate of the bone does not change. This shows that symmetric growth in long bones is controlled by a program that is operated by internal factors, which is also compatible with the genetic program. When chemical-based medication is given to postpone growth, after the medication has been eliminated, the growth plaques grow faster for a short period to compensate for the lost time. These findings show that timing and the location and circumstances of the cell are critical parameters for reproduction. If the cartilage stem cells in the growth plaque have a certain reproduction potential, then it is clear that cartilage cell reproduction stops when growth comes to an end. If growth inhibiting factors slowly accumulate in the growth plaque, this might cause a deceleration of growth over time. Another possibility is some sort of “meter” in the unconscious and mindless stem cells, which keeps track of the number of cell divisions and thus controls aging. The estrogen in our body has a duty of closing down the growth plaques and speeding up the aging of cells. However, we should not forget that estrogen plays the special role of closing down all of the growth plaques at the same time. Estrogen is one of the visible causes of fertility, growth and development, and resilience. Estrogen also represents femininity and fertility at all levels.

When the signals from unconscious cells in the growth plaques and the quite sophisticated interactions among all the factors that influence growth, all of which require an all-encompassing knowledge to be executed, are taken into account, the impeccable genetic programs of different growth plaques on the two sides of the body that leads to the formation of the arms and legs, as if they have been molded in a factory, is absolutely amazing for anyone who reflects upon it.

References

• Wolpert L. (2010).”Unsolved Mystery: Arms and the Man: The Problem of Symmetric Growth.” PLoS Biology. 2010 Vol. 8(9). pp 1-3
• Extremity Development during the Embryonic Period (www.visembryo.com)

Dear Peter! I, your muscular system, would like to talk to you today; I allow you to walk and do all kinds of movements very easily. In the most recent essay of this department, the skeletal system, which works together with me, discussed how it protected your body and enabled you to stand straight and firm. Sure, this is true. However, as you know, huge rocks and trees can stand straight, too; but they do not have what you do-the ability to move. They are rigid and inflexible because they do not have a system that allows them to move.

You on the other hand, as the most splendid creation in the entire universe, have mobility. All animals have mobility at different levels, thanks to the muscular tissues, which work dynamically behind all the moving organs. However, you, human beings are like neither the animals nor the plants. You have not been created to live like a tree that is pegged down in earth or like an animal that unconsciously tries to meet only its biological needs. Our Designer, God, has made you and your descendants the most important of all creation. He has given you qualities that help you to discover the world, learn, invent and establish new civilizations. To realize such potential and to carry out such duties, you need to first have the freedom to make changes in your small immediate world, which can only be done through motion. In order to enable you with this ability to move, my Creator has put me at your service. I am a system that comprises hundreds of muscles and millions of packed cells.

My most important feature is the cells that move by burning sugar, like a motor consuming fuel in order to work. My cells can shorten and lengthen thanks to the intracellular fibrils (myofilaments) that contract and expand. As a result of each contraction, I pull the bone or the organ that I am attached to and cause it to move or change shape. With the exception of your heart, your bones and organs cannot move on their own. Their ability to move depends on the nature of the muscle they are attached to.

Indeed, I can be called both an organ and a form of tissue. I can use my contraction ability not only as muscle tissue, but also as an organ and a system which runs throughout your body. That is the reason why I appear in so many different types and shapes of muscle bundles. Let me give you an example to help you better understand what a muscle consists of: Let us imagine that a thin thread is like a basic muscular cell. Let us now bring together a great number of threads and make string out of them. Then, let us bring together those strings and make a clothes line. Next, let us bring together a great number of clothes lines and make a very thick rope. Now, imagine this thick rope as a muscle and an organ. Yet, this example is too basic compared to the sophisticated muscle.

Very thin cotton fibrils make up the thin threads. In the muscle fiber, like those cotton fibrils, there are two filaments formed by the two types of protein molecules called actin and myosin, which help in the contraction function. Those little filaments are placed facing one another and they slide past each other during the contraction, which causes the muscle fibers to shorten. That is how the contraction and relaxation of a muscle occurs.

Peter, do you think that coincidence plays a role in this complex and wonderful mechanism and the incredible structure which I have attempted to simplify with an example? Not even a simple thread can be produced without a thread-maker or a machine. Each of your muscles comprises billions of fibers, wrapped all around your bones and giving shape to your body. Can such a complex and delicately intricate structure exist on its own and be positioned in the best place it could possibly be?

My muscles consist of bundles that are made of thousands of muscle fibrils; the size and shape of each muscle depends on which bone it is attached to and what function it does. For example, the muscles that move the bones in your arms and legs are long and spindle-shaped; whereas the ones that are attached to your body can be circular, or triangular, or spread over a broad area. Whatever shape they have, the red skeletal muscles, which are attached to your bones, are very strong and they are voluntary muscles, which mean you can control their movement. When you walk, run, do something with your hands, lie down or stand up, you always use my red striated muscles. The strias (stripes) can only be seen under a microscope because of the histological structure of these skeletal muscles that make up a great part of your body.

My smooth muscles are involuntary muscles that work without your control. Their movements are slow and their contractions last longer, which is the reason why they do not tire easily. The smooth muscles lie in the walls of digestive system, blood vessels, and urinary tract, but I will not talk much about them since each system has referred to the smooth muscles within itself and in detail in previous talks. Because they are not attached to your skeleton to work, the smooth muscles do not play a role in your movements, such as walking around; they only work for the movements of your inner organs.

The third type of muscle belongs to your heart (cardiac muscle) and although the heart has a little striated muscle tissue, it, too works involuntarily. Therefore, you should be aware of the fact that it is the striated muscles which work for the movement of the skeleton and do the major job, and that it is this that we refer to when we say “muscle.”

A great number of bones have been created in order to support your body, and joints have been placed between those bones for them to take the proper shape according to every movement. However, none of those joints have the ability to move by itself. A door or a window, no matter how good it is, cannot be opened or closed without an outside force to pull or push it. In the same way, a joint needs a force to move it and that force is produced by your muscular system. There are around 340 muscles included in your muscular system. It has been estimated that all the muscles in your body perform 510 different functions! While some of those functions are bone movements in your joints, other muscles can perform movements without moving a bone at all. Muscles that are placed in your forehead, face, eye lids and abdomen are those kinds of muscles. They can help you look worried by wrinkling your forehead or grimacing when you are disgusted by something.

Keeping with tradition, the muscles that are included in my system have been named based on the function they perform. For example, the muscle which moves an organ part towards another part is called an abductor, while the muscle that straightens a joint is an extensor, and the muscle that bends a joint is a flexor; the muscle that raises a part of the skeleton is a levator, that which the muscle makes a part of an organ prone is a pronator, the muscle that rotates a part of an organ is a rotator and that which brings an organ into a supine position is called a supinator.

In order for you to make all the movements that your body needs, my muscle components have to be both very strong and flexible. The most important feature of my muscle components is that they can be trained and strengthened with a systematic workout. The main goal of all sportsmen who compete is to increase the strength and the endurance of their muscles. As a result of intense exercises with weight and speed, the number, the diameter and the length of my muscle fibers will increase. Thus, I can gain more power to be able to do more work and also gain the ability to contract faster.

However, in addition to all this training and exercise, genetic factors also play a role in my health. For this reason, not everybody who works out can become a good sportsman; but if the person has innate muscular and skeletal capacity, with good exercise this capacity can certainly be enhanced and developed. However, if a person does not have the proper muscular structure for a particular sport, it would be unfair to expect them to be a champion! Although my muscles always seem to be of the same type at first sight, I might show different behavior depending on the distribution of the special fibers inside them. Some of my fibers twitch fast and tire easily, some of them twitch slowly and tire later. Depending on the distribution of these different fibers, the movements and sport that every person can do differ from person to person. In this case, an athlete who can run only 100m and an athlete who can run 10,000m do not have the same development of muscles; they have different amounts and distributions of special muscle fibers.

The contraction of any of my muscles can occur in two different ways: If the pressure put on my muscle is stronger than the resistance of the tissue, the tension remains constant and the muscle shortens. This is called an isotonic contraction. If the pressure put on my muscle is equal to the resistance, the tension of my muscle increases and its length does not change. That is called an isometric contraction. The amount of force that occurs during the contraction of my muscle depends on its length and the amount of the stimulus.

In order to produce muscle contraction, an electrical signal is sent through a motor neuron to the synaptic gap, which is positioned between the muscle cell membrane and the nerve cell. As a result, a chemical reaction occurs, which, in a very short time, causes the actin and myosin proteins in the muscle fibril to slide past each other and thus shorten the fibril, contracting the muscular cells. During this reaction, the temperature also rises a little and the total heat generated by all the muscles determines your body temperature. For this reason, in cold weather, my muscles vibrate, increasing your body temperature and trying to maintain it. You may now understand why moving the parts of the body in cold weather helps people avoid from getting sick or freezing. As you can see, every act of my Creator is quite purposeful. He can create two or even more functions within one task: Through your muscles, He not only provides you with the ability to move freely, but heat is also produced and you are protected from getting cold.

When a muscle fiber contracts frequently as a result of successive electrical impulses from a nerve fiber, it becomes tired after a while and needs rest. In this case, other muscle fibers which have not contracted for a while will take over and continue the job. However, if the electrical impulses from the nerve come too frequently and my muscle fibers do not have an opportunity to rest, a condition of constant contraction, which is known as physiologic tetanus, occurs.

The tension receptors that are placed on my muscles help maintain the harmony and coordination of all your movements including walking and running, bouncing and sitting down. They do this by constantly signaling the nerve system and providing feedback about the condition of my muscles, and about the speed and the intensity of contraction. Thus, through these receptors which control and coordinate my muscle activities, the well-being of my system is ensured. It is this that prevents you from wobbling when you walk, or helps you to take a spoonful of soup to your mouth without spilling it.

Like any other tissue or system, I, too, have some special disorders. The most common disorders are: weakness, malformation, muscles that develop and move involuntarily and habitually, especially in your face (tic), infected muscles (myosite), muscle dystrophy, muscle rigidity (the Stiffman Syndrome), benign or malignant muscle tumors (leiomyom, rhabdomyoma, or Rhabdomyosarcoma). These disorders differ in their degree of severity and risk.

Dear Peter! You have now seen that each muscle helps your organs to move, holding your bones and giving shape and function to your body, making you a beautiful model and an inspiration for sculptors. You may have understood that this is a work of knowledge and might; there is no way that the myofibril in my one cell could form by itself as a result of a coincidence.

Irfan Yilmaz is a professor of biology at Dokuz Eylul University, Izmir, Turkey.

I consist of 217 bones in your body (however, since the bones in the thigh and sacrum areas fuse together in order to form a stronger bone, their number decreases, and the anatomists accept the number of bones as 206). I have 22 skull bones, 33 spinal bones, 24 rib bones, 64 bones in the hands, the forearms, the arms and the shoulder girdle and 66 bones in the feet, the legs, the thighs and the hip area. In addition, I have 6 small ear bones, 1 breastbone and 1 hyoid bone (at the root of your tongue), which make up the total of my 217 bones. It is quite amazing that so many different bones have cooperated with each other and contributed to such a perfect system.

Each piece of my skeleton has been created with special shape and quality that is proper to its place and duty. The bones that protect your brain are flat, whereas the bones in your arms and legs are long and cylindrical; while the bones in your wrists and ankles are short and rounded, your hips and girdles have been made of wide and big bones. The craggy surface of my bones makes it easy for the muscles to attach to them firmly. Each bone has certain durability that protects me from undue weight, flexure, twisting, and pressure. Bioengineers carefully examine my bones that have been created in a perfect form for where they are positioned and for what they do. They take my wonderful structure as a model, and they use it for producing new technology such as buildings or bridges. As you know, constructional engineers have to be very careful in their estimates of material and durability. They have to use different materials for different places, and these points will be exposed to forces like pressure, compression, tensile, or flexure (bending). If the estimates of the materials are not made accurately, the building or the bridge can easily collapse. When you humans build a strong building, it might be too heavy and bulky, resulting in a waste of material and money. Even if you use good quality material, if you do not use it in the right place, all your work might be unusable. Unlike human beings, the Creator has made me such a delicate and well-balanced system, in which you cannot find any material missing or unnecessary or any wrong line in a particular bone. That can only be explained with the boundless knowledge of God the Almighty. He knows exactly how you will be able to do hundreds of different movements in all your life-including running, lying down, jumping, lifting a heavy item, playing sports, writing, and eating. In order to allow you to perform those actions, He has created a perfect design for each piece of my bones and the joints that connect them.

In building my structure, He has used materials in different hardness and durability to make your movements easy. The first material is the bones. Not all bones are the same. Compact bone (dense bone) is found in my hardest parts. For example, the long bodies of the femur, the tibia, and the fibula (bones between knee and ankle) are made of compact bone, and they are very rigid and strong. Softer bones, which look like a sponge, are found at the edges of those long bones and within my flat bones. The second material, my cartilage, is placed at the bone edges and on the joints where, by absorbing excessive pressure, the cartilages are able to prevent damage to the surface of joints and to the nerves that go through the vertebra. My cartilages achieve this thanks to their soft and flexible substance, which also provides a perfect aesthetical quality. In addition, because of this flexibility given by God, cartilages protect the bones from breaking easily (depending on the rigidity of the bones), and they balance your strong and abrupt movements. If it were not for the cartilages on the joints, not only the bony surface would be damaged but also my movements would be mechanical and harsh just like those of a robot. My third material is the ligament, and its main substance, the fibers, that are made of collagen protein. The fibers of this ligament are very strong straps, which hold my bones and cartilages together.

All my joints and tendons that fasten the muscles to my bones are tied up and strengthened by those ligament fibers, which vary in shape, length, and quality. The collagen fibers are also used as the basic substance of my bones and cartilages. Those fibers, which are placed among the cells of the tissues of my bones and cartilages, provide the tissues with strength and durability. The distribution of the fibers in my bones is determined according to the direction and intensity of the pressure coming upon me. To see an example, you can look at the head of my femur (between my knee and thigh) where it makes a joint with the thigh bone. The spread and design of the fibers placed right at this joint requires a flawless calculation, which you can better understand by examining a diagram of it.

Not all my joints are flexible in the same degree. For example, the joints in your skull, which protects your brain and sensorium, resemble the toothed blade of a saw. They are strong joints, which are firmly locked with each other, and they allow no mobility. Of course, it can be no one but God who is able to give my skull such strength and hardness, since He knows exactly how much protection my delicate brain, eyes, and ears need. Moreover, my skull is not shaped simply as a bony capsule; at certain places, God has put little channels for the blood vessels to go through, little cavities for the sensory organs, and a big hole for the spinal cord to connect to the brain. Can any of these be formed by coincidence? The joints between the vertebrae (little bones of your spine) are more movable than the skull and less movable than your fingers. They help to allow you stand upright and sit, twist, and bend or lie down. The joints in my shoulders and legs are freely movable, which enables you to do movements in all directions. Perhaps the most wonderful of all are the joints in your hands! It would not be a distortion to say that-behind all your work to make a discovery or an invention or a new technology-is the skillful creation of my hand joints. Everything that you use with your hands-including all kinds of tools, furniture or appliances, art works, and books-can be produced or utilized only through the perfect ability of my joints to move. If my fingers lacked that great ability to move freely, many of my thoughts or intentions would not be able to be translated into actions.

Your muscles that help in the movement of all my movable parts have to attach to my bones to be supported. While one end of your muscle holds my bone firmly, the other end pulls another bone with the help of the joints. That is how movement in your body occurs and how you can take a step, do exercise, or wave your hand.

Although not as much as the skin, I have a very good ability to renew myself. When one of my bones is broken, if you line up the two pieces exactly in relationship to each other, the bone cells, called osteoblast, quickly divide to produce new cells, fill the gap, and repair the break. Then, I take calcium salts, which harden and strengthen the area, and gain back my health. Calcium is a vital mineral in the growth of bones. When you are a little but growing fetus in your mother’s womb, you need plenty of calcium for your bones to develop. If your mother gets sufficient amounts of dairy products, fish, and green vegetables, there will not be a calcium deficiency. But the good news is that, even if an expectant mother does not get enough calcium, the unborn baby is unlikely to have calcium deficiency. That is because Our Lord God, whose Mercy is infinite, provides baby with calcium by making it be absorbed from the mother’s bones and teeth and ensures the healthy development of the baby’s tiny skeleton. The mother has the willpower to feed herself, but since the baby is helpless, its need is met by the calcium taken from the mother’s body. After birth, the baby has to be nourished well with calcium and vitamin D by means of healthy foods, and it has to have enough exposure to sunlight. In order to maintain my health, my biggest need is calcium salts and vitamin D, a vitamin that needs the body’s exposure to the sun in order to contribute to healthy bone growth. For this reason, you have to take care of me especially at your young age. If you do not get those salts and vitamins, your bones will not develop well, and this could result in skeleton disorders.

The cavities within my bones are called marrow cavities (or medullar space) and they have important duties too. If your bones were filled merely with bony substance, my weight would be too much, and you would not even be able to stand up. Moreover, my bones would not be as strong as they are now. According to calculations with static forces, a rounded iron stick, which is filled, is less durable than the one with a hole in it, and the stick with a hole in it can be bent easily. My long, rounded bones have been designed according to that principle, and they are more resistant to twisting and bending. Another important function of my marrow cavities is to house the production of little red blood corpuscles, which have important duties within the blood. When you are young, all my bone marrows are red, and they produce red blood cells. Then, slowly after the puberty, the bone marrows in my long rounded bones start to turn yellow, get fatty, and produce white blood cells. The spongy bone marrows in my flat bones, however, stay red in color during your entire life, and they keep producing red blood cells.

The shape and size of my bones and their proportions to each other all determine the shape and quality of your body. Although I develop according to my genetically inherited qualities, the loads that you made me carry and outside impacts all affect my development significantly. When you are a baby, my bones start out as cartilages. At young ages when I am just starting to become bony, if I have to carry too heavy things, I start to harden and become bony too fast. This leads to the incomplete growth of the length of your neck bones, and your arms and legs which will remain too short. Playing basketball or volleyball stimulates the growth and elongation of your bones. Mineral salts, vitamin D, and the hormones secreted by the parathyroid gland play role in the ossification of my bones. The elongation of my long bones is achieved by the cell division and formation of new cells in the areas called epiphysis, which are the rounded ends of the long bones. This bone-lengthening process ends after puberty. While the lengthening of bones stops earlier in girls around ages eighteen or nineteen, it continues in boys until the ages twenty-one or twenty-two, which is the reason why men are generally taller than women.

When you were born, all of my components were cartilages, which are very soft and flexible. That is the measure that the all-knowing and all-caring God has taken, to ensure that neither you nor your dear mother gets any harm during your birth. If I became bony before the birth, your mother could die, and many of your bones could break during the birth. However, thanks to the cartilaginous components, which are like plastic, the risk of death and becoming disabled decreases greatly. As you become older, the cartilages are replaced with bone cells, and the accumulation of calcium salts make me hard and bony. The cartilages remained only on the joint surfaces and at the ends of ribs.

Dear Peter! Now it is time to ask a question that might bother you a little: have you ever been at a reopening of a grave? Sometimes in graveyards, when they do not have extra space for new burial, the dead person’s body is buried next to a body that belonged to a family member. When the grave is reopened, you can clearly see that, except for the newly buried body, all parts of the other dead body have been mingled with the earth. You can see that only my skull and other bone components have remained without decaying. After a very long time, those bones will decay too but much later than my other tissues. In the past, when the Holy Qur’an was just being revealed, some people refused to believe in God and the Day of Judgment, and asked: “Who is going to resurrect those decayed bones?”(Qur’an 36:78). The following verse is an answer: “Say, ‘He who created them in the first place will give them life again: He has full knowledge of every act of creation’” (Qur’an 36:79). In many other verses of the Qur’an, which deal with both the first creation and the Judgment Day, also mention decayed or dried bones, which still exist after many years. This means that God wants to draw your attention to the bones of your body! Perhaps, He is saying: “O, Peter! I created your bones, your joints, and your whole skeleton flawlessly. I took all measures for you to be able to live your life perfectly; to the littlest details, I created a delicate body, mind, and soul free of defects or faults. When I created you that perfectly, do you think I took something else as a model, or applied someone else’s plans? Not at all! Therefore, I, who created you out of nothing with my infinite knowledge and might, will of course be able to recreate you!”

Well, Peter! That is how I understand my Creator and the message of His Holy Book, which appeals to all of humanity. Your ability of comprehension and appreciation is more perfect than mine. Therefore, each time you move your body or body parts, just think of the wonderful pieces of bone accompanying and supporting your organs. Reflecting on them for some time will gain you a fresh view of life. That is what I wish as your skeleton!

Irfan Yilmaz is a professor of biology at Dokuz Eylul University, Izmir, Turkey.

Birds, class Aves, are the only animals that have feathers. Aves is a large, highly diverse class with 8,600 species of water birds, songbirds, and birds of prey, including huge flightless runners, deep divers, and migratory species that travel thousands of miles each year. Although most birds have similar body structures, taxonomists, those who classify and name things such as animals and plants in groups, use variations in bone structure, muscles, and internal organs to distinguish one order from another. Variations in the shape and structure of the bills, wings, tails, and feet are also useful for classification and identification. Birds inhabit a wide variety of habitats and can be found on all the continents, most islands, and even on the open sea. They also have a wide range of size. The largest birds are the ostriches of Africa, up to 2m tall and weighing 136kg, and the great condors of the Americas, with wingspreads of up to 3m. The smallest known bird is Helena’s humming bird of Cuba, less than 6cm long and weighing less than 4g.

The skeleton system of birds is highly adapted for flight. In spite of its low weight, a bird’s skeleton is extremely strong. Hollow and fused bones are the two main bone types. Most bones` being hollow lessens overall body weight making flight more efficient. The skeleton of a bird is much lighter than any other kind of warm-blooded animal. However, this is achieved at a cost, and the skull of a bird is thin and susceptible to fracturing. Further lightening of the bird`s head has also been made possible by the absence of teeth. The other noticeable feature of a bird’s skull is the size of the eye sockets, to house the large eyes. This is probably because vision is a bird’s most crucial sense. The skeletal structure of the wing is relatively constant among the different species, but the actual shape of the feathers can be quite variable, depending on the flying capabilities of the species concerned. To provide effective thrust, the bones in the wing move together. As the bird’s wing beats downwards, special bones prevent its chest from being crushed. The thrust of the wing articulates with the scapula on each side of the body. The corocaid and the wishbone also provide reinforcement. The chest cavity is reinforced by the unusual structure of the ribs. The ribs have projections, known as incinerate process, which are directed backwards, overlapping each other. These help to provide support, especially in diving birds. In cross section, the wings are honeycombed. During flight, this lightens the load on the pectoral muscles which, attached to the keel of the sternum, may account for half of the birds body weight.

Flight is one of the most outstanding characteristics of birds. A bird’s body is adapted to meet the two major requirements for flight, which are low weight and high power. Unlike other vertebrates a bird has a skeleton that is very light in relation to body size, e.g. a pigeon’s skeleton accounts for only 4.4 per cent of its body weight. Birds have a compact, streamlined body, and the fusion of many of the bones gives the body the rigidity needed for flying. A birds wing bone is thin and hollow, with criss-cross reinforcements on the inside which provide support while adding little weight. Besides the unusual structure of bones, it is the presence of feathers that distinguishes birds from all other creatures that have conquered flight. Feathers are made of dead cells, and become dehydrated and are exceedingly light. Thus, they can be large and form the flight surface of the wings and tail without weighing much and without being susceptible to water or heat loss. Along with keeping a birds body warm, feathers function for flight. The long overlapping contour feathers streamline the body. These feathers form the wings and much of the tail. Wings made of contour feathers have much surface area and little weight. They are well adapted for fanning the air and for gliding on air currents.

The flight of birds is one of the most beautiful and wonderful things in nature. The make and arrangement of their feathers and bones, and their stream-lined shapes, from beak to tail, are instances of purposive adaptation. They soar with outstretched wings; they dart with folded wings. Their upward and downward mobility, as well as their stability in the air, and when they rest on their feet, have given many ideas to man in the science and art of aeronautics, But who taught or gave to birds this wonderful adaptation? None but God, Whose infinite Mercy provides for every creature just those conditions which are best adapted for its life. This is stated in a verse in the Qur’an (Mulk, 67.19):

Do they not observe the birds above them, spreading their wings and folding them in? None can uphold them except (God) Most Gracious: truly it is He that watches over all things. 

Flying techniques depend on the principles of aerodynamics. Reducing air pressure and friction against the body requires perfect aerodynamic structure. Up to recent times, a rain drop was accepted as the most perfect aerodynamic shape. However, the shape of a bird’s body is now accepted as the most perfect, and aircraft are designed according to the aerodynamic structure of birds. Compared with birds, the latest aircraft are still clumsier and have less agility than birds. Moreover, hypoxia, which is a deficiency of oxygen and results in drowsiness, mental fugitive, headache, and sometimes euphoria, affects pilots severely and can cause them to lose their consciousness on flying upward. But this is not a hindrance for birds because the air between their feathers, their bodies and wings is absorbing and reducing air pressure, Along with this ability, there are some movements which birds can do easily, such as turning sharply, doing somersaults, steep ascents and descents, whereas manmade flying machines face some serious risks in attempting the same movements. Birds can also glide for long periods without beating their wings while aeroplanes cannot sustain flight with stopped engines. Vertical take off and landing is something many flying animals such as bees and birds have been able to do for millions of years. The structure of birds has inspired engineers to design specific modifications in recent models of aircraft, such as the F-14, F-18, and M1G-25, It is true that producing an aircraft requires complex skills and knowledge, improved steadily over a long time. But is it not marvellous that birds have been demonstrating perfect flight for millions of years?

Birds have become adapted to a variety of environments, and various species have very different types of beaks, feet, wings, tails, and behavioural patterns. Although all birds must eat frequently (because they do not store much and yet must maintain a very high metabolic rate), their choice of food varies widely among species-seeds, fruits, worms, molluscs, rodents, rabbits, fish, snakes, lizards, even dead animals. The shape of the bills reflects the birds feeding habits. For example, nectar-feeders have narrow, pointed bills; finches, which consume large quantities of seed, have short, stout bills; and birds that eat insects and berries have a non-specific bill shape and so on.

Birds also lack teeth and this probably reduces body weight for flight. Instead of teeth, their mouths are modified into bills. In addition to this modification, birds have another adaptation for digesting food. A bird swallows small bits of gravel, which act as teeth in the gizzard, mechanically breaking down food. An interesting feature of the bird’s digestive system is the crop, an expanded, sack-like portion of the digestive tract below the oesophagus, in which food is temporarily stored, and where food such as hard seeds is softened with mucus. As a storage organ, the crop allows the bird to feed rapidly and to store large amounts of food. The bird also produces a white secretion, sometimes called crop milk’, which is rich in proteins and fats, and birds use this secretion to feed their young. Birds (except for the ostrich) do not possess a bladder, and so the uric acid passes directly, through the uretors, to the cloaca. After reabsorbing water back into the bird’s body, uric acid is excreted in the form of a semi-solid, whitish concentrate.

Birds often build up high concentrations in their bodies because they consume salty foods or sea water and lose water through evaporation in the urine and feces. To rid themselves of this excess salt, these animals have salt glands, special secretary organs near the eye or in the tongue that remove excess salt from the blood and secrete it in a solution of tear-like drops. Sensors in the wall of a bird’s heart apparently monitor the osmotic pressure of the blood and send nerve signals to the brain that trigger activation of the salt glands. Thus, the animal can drink sea water and yet, by excreting some of the water and all the salts, achieve a net water gain. This is an adaptive mechanism that helps to maintain a light body weight.

Birds have a well-developed nervous system with a brain. They rely heavily on vision; their eyes are proportionately larger than those of other vertebrates. Hearing is also well developed, in striking contrast to most animals, birds have developed the voice. The spoken word in human speech is different from the means of communication which birds have between each other. But no man can doubt that they have means of communication with each other, if he only observes the orderly flight of migratory birds which live in communities. This is also stated in the sacred book, Qur’an (al-Naml. 27.16):

And Solomon was David’s heir. He said: ‘O ye people! We have been taught the speech of Birds, and on us has been bestowed (a little) of all things.’ this is indeed Grace manifest (from God.)

Most birds have short simple calls that signal danger, or that influence feeding, flocking, or interaction between parent and young. Songs are usually more complex than calls and are performed mainly by males; they are related to reproduction, attracting and keeping a mate, claiming and defending territory.

Birds have a special system of air sacs that make fresh air almost continuously available to the sites of gas exchange. This provides the animal with the large quantities of oxygen needed for long distance, high- altitude flights — even a flight over Mt. Everest. A bird’s many air sacs also lower the body weight relative to its size. Air sacs lying between certain flight muscles are squeezed and relaxed on each stroke of the wing and this helps increase the amount of air during inhalation and exhalation. The faster the bird flies, the more rapid is the circulation of air through the lungs.

The paired lungs are relatively small and nine or more hollow air sacs are attached to the lungs and fill much of the body cavity. They are like balloons that lighten the body and serve as reservoirs for air that will later be needed. Experiments show that air flows continuously during both inhalation and exhalation, in one direction through the lungs, and the air is renewed during each inspiration. Therefore, oxygen and carbon dioxide exchange occurs in the lungs’ air capillaries during both inhalation and exhalation. The direction of blood flow in the lungs is opposite to the that of air flow through the parabrocni, tiny, thin-walled ducts in the lungs. This counter current flow increases the amount of oxygen that enters the blood.

This system enables birds to do the intense work of flying, even at high altitudes, and still maintain a high body temperature. Interestingly enough, rapid breathing also contributes to such a high performance; a Venezuela hummingbird, the sparkling violet ear, breathes 330 times per minute at sea level and 380 times per minute at high altitudes. This is a very high heart beat such as no other warm-blooded animal can accomplish.

The very effective respiratory and circulatory systems provide enough oxygen to the cells to permit a high metabolic rate. This is another important adaptation of birds: the maintenance of a high and constant body temperature in spite of changes in the external environment. High metabolic rate is necessary for the tremendous muscular activity required for flying. Some of the heat generated by metabolic activities is used to maintain a constant body temperature (between 35 and 42 degrees C) which permits birds to remain active in cold climates. Birds are among very few animals able to maintain a constant body temperature. Though birds are sometimes called warm-blooded, the preferred term is homeothermic.

One of the most interesting types of behaviour in birds is migration. Migration is the instinctive movement of animals, usually between their wintering grounds and their breeding grounds. Migration provides birds a better chance of surviving. By instinct, migrating birds make their long journeys each year to reach more favourable habitats. Some birds, such as the golden plover and arctic tern, fly from Alaska to Patagonia, South America, and back each year, flying 25,000km en route.

Migration is probably set in by several external stimuli, such as temperature and length of daylight. It is also triggered by the secretion of hormones. For many species the direction of migration is probably based on such factors as the bird’s observation of the sun and stars and even by the earth’s magnetic field. Few modern biological discoveries have been more surprising than the finding, in the 1970s, that bird’s, bacteria, and perhaps many other types of organisms orient their bodies to the earth’s magnetic field, How such animals can have acquired this magnificent ability is a question yet to be answered. How can living things perceive a force as elusive as magnetism?

Many birds and at least one mammal-the porpoise-have a small number of tiny crystals of magnetite (a form of iron oxide) in tissues near the brain. Likewise, magnetobacteria, have magnetite crystals in their cytoplasm and swim toward or away from the poles of an applied magnetic field. How some higher organisms use magnetic particles to sense the direction of the lines of magnetic force generated by the earth’s core remains a subject of research. One hypothesis suggests that the crystals in, for example, a pigeons head, function like tiny compass needless, and mechanoreceptors might detect their relative movement. Other work indicates that in the rat, changes in magnetic yield can alter enzyme activity and levels of melatonin in the pineal gland. Still other work suggests that regularly arrayed layers (also present in pineal glands) undergo certain changes as the head and eyes move relative to the earth’s magnetic field. They could allow the animal to sense magnetic fields, but not by a mechanoreceptor mechanism. Whatever the mechanisms, homing, migration and many other directional animal behaviours depend on detecting magnetic fields.

Birds with their perfect features are wonders in nature to be marvelled at as such. All creation, both animate and inanimate, celebrates Gods praise and bears witness to His power, wisdom and goodness. We can aspire to true knowledge of God through observing the wonders in nature. However, this is possible only if people do not insist on their positivistic viewpoint and see the direct manifestations of God’s Names in His creation:

The seven heavens and the earth, and all beings therein, declare His glory: There is not a thing but celebrates His praise. And yet you understand not how they declare His glory! Truly, He is Off-Forbearing,’ Most Forgiving! (Bani Israll. 17.44)

He was born in Cordova in 52OAH (1126) and named after his grandfather Abu al-Walid Muhammad ibn Ahmad ibn Rushd, who died in the same year. His grandfather was the Chief Judge in Cordova and the foremost authority in Maliki jurisprudence. To distinguish him from his illustrious ancestor, Ibn Rushd was later known as Ibn Rushd al-Hafid (the grandson).

Cordova, where Ibn Rushd grew up, was a thriving centre of all the diverse arts of civilization and culture attracting many great scholars from around the then known world to its wonderful libraries. Ibn Rushd studied and memorized the Qur’an and the Muwatta of Imam Malik. He was an excellent student of jurisprudence and quickly qualified to give legal opinions and sit as judge.

Following his work in the sciences of law, language and Hadith, he went on to study mathematics, astronomy and astrology and then medicine. He was a friend to the most prominent thinkers and writers of his age: Ibn al-Tufayl (d. 1186/6), author of the famous allegory Hayy ibn Yaqzan (said to have influenced Robinson Crusoe ); the philosopher, Ibn Bajja (Avempace in the West, d. 1139); the great jurist and judge Abu Bakr ibn al ‘Arabi (d. l148); the famous physician Abu Marwan ‘Abd al-Malik ibn Zuhr (Avenzoar in the West, d. 1161) and his son Abu Bakr (d. 1198).

Ibn Rushd served as a judge in Ishbiliya (Seville) in 1171 and then in Cordova two years later. His reputation for wide knowledge, correctness and fairness in giving verdicts, led to his appointment as Chief Judge. His book Bidayat al-mujtahid wa nihayat al-muqtasid (The reference for the searcher and the resort for the fair) remains an important reference for students of jurisprudence and is still taught in universities to this day. Although he was a Maliki he used the ideas of other schools of thought. Because he had so many activities and interests besides his public duties, Ibn Rushd had to organize his time very fully: he spent his days working as a judge, teaching, and in academic discussion with other scholars; he reserved his nights for reading and writing.

His friend Ibn al-Tufayl wrote to invite him to visit Marrakech, the capital of the Muwahhidun (Almohades) who had established a powerful and stable state in North Africa after they took over from the Murabitun (Almoravides), and were famous for their patronage of scientists, physicians, theologians and philosophers. Ibn Rushd’s intelligence, learning and ideas so impressed the ruler, Abu Yusuf ‘Abd al-Mu’min, that he was appointed to reform the educational system. This he did successfully before returning to Cordova.

When Abu Ya‘qub ibn ‘Abd al-Mu’min came to power, he appointed Ibn Rushd as his personal physician after Ibn Tufayl. Ibn Rushd held this post for a year (1183) when he was appointed as Chief judge. His success provoked court envy and he was falsely accused of heresy, in particular that he adhered too closely to the doctrines of Aristotle. He was indeed a supporter of Aristotle’s doctrines after these were properly reformed and adapted to Islam. Ibn Rushd fell out of favour at the court and was ill-treated. His books on philosophy were burnt, though his works on medicine and theology were not censored. When Abu Ya‘qub discovered he had been misinformed, he tried to invite Ibn Rushd back to apologise to him, but he was too late. Ibn Rushd died on 9th Safar 595AH (December 1198).

His writings

Ibn Rushd was broadly cultured indeed and wrote on many different subjects. Here we can mention only the most famous of his great works. In jurisprudence, as noted above, he wrote Bidayat al-mujtahid wa nihayat al-muqtasid (The reference for the searcher and the resort for the fair). In philosophy, he wrote Tahafut al-tahafut (refutation of the refutation), his response to Imam al-Ghazali’s famous Tahafut al-falsafa (refutation of philosophy). Ibn Rushd combined both philosophy and religion in mainly two books: Fasl al-maqal wa taqrib ma bayna l-shari‘a wa l-hikma min al-ittisal (an authoritative treatise on the convergence between the religious law and philosophy), and Kitab al-kashf ‘an manahij al-adilla fi ‘aqa’id al-milla wa ta‘rif ma waqa‘a fiha bi hasb al-ta‘wil min al-subah al-muzayyifa wa 1-bida‘ al-mudilla (an exposition of the methodology of demonstrating the creeds and description of the confusions and innovations in interpretation which confound truth and lead to error). In medicine, Ibn Rushd wrote the Kitab al-kulliyyat fi al-tibb (a general reference on medicine) which was translated into Latin and Hebrew and European vernaculars. It was a major reference in medicine though it never reached the standard of al-Qanun fi al-Tibb of Ibn Sina (Avicenna, d. 1037) which was used everywhere as simply T he Canon of Medicine.

Ibn Rushd had prepared this book especially for practising physicians and students of medicine. He apologised for the work’s brevity, a limitation he attributed to his preoccupation with commitments to judging, political affairs and philosophy. He advised those who sought greater detail to consult al-Taysir (The simplification) of Abu Marwan ‘Abd Al-Malik ibn Zuhr. Al-Kulliyyat is organized under seven broad headings or chapters:

1. Anatomy
2. The function of the organs
3. Diseases (pathology)
4. Syndromes: a brief clinical review
5. Health care, especially sports, massage and sleep
6. Medication and diet
7. Healing (particularly of different types of fevers).

The chapter on anatomy in al-Kulliyat

Ibn Rushd criticized the physicians and students of medicine of his time for neglecting anatomy. His own presentation of the subject is both concise and precise. He divides it into two major areas:

a. Anatomy of ‘simple’ organs such as bones, flesh, and veins.

b. Anatomy of ‘compound’ organs-for example, the arm which comprises bones, flesh, veins, tendons, nerves etc.

His description starts with the bones of the head and the teeth. 

Bones

There are six bones in the cranium and 14 in the upper jaw (the maxilla) and the ear, and two in the lower jaw (the mandible). All these bones are attached by seams except the two bones of the mandible that are articulately joined. This was later established as untrue-the mandible in fact has a single bone not two. The first to discover this was the physician and linguist ‘Abd al-Latif al-Baghdadi (Ibn al-Labbad). He examined 10,000 cadavers removed from the hills of al-Muqattam, east of Cairo, during the construction of a road. He realized this fact after observing thousands of examples. This was revealed in his wonderful book al-Ifada wa l-i’tibar fi l-umur al-mushahada wa l-ahwal al-mu‘ayana fi ardi Misr, (review and lessons from examinations and experiences in Egypt).

Ibn Rushd wrote of the teeth that there are 16 in each jaw-two central incisors, two lateral incisors and two canines, and five molars and premolars on both right and left sides. There are three or four roots in the maxilla but only two in the mandible, the remaining teeth have only one root.

He also described the large aperture in the back part of the skull, the foramen magnum, and its relation with the seven vertebra of the neck (cervical vertebrae), which have apertures on the sides. The vertebrae of the chest region are twelve; in the lumbar there are five, linked to the sacrum in which he counted three bones (in fact there are five) attached to the bone of the coccyx which is also composed of three attached vertebrae.

Ibn Rushd said that all vertebrae are articulate except the first two from the neck, because the first vertebra is attached to two appendices ramified from the skull.

He also said the bone of the sacrum is attached from the sides of the hips, in each of which is the acetabulum (socket) which contains the ‘head’ of the thigh bone (femur), often referred to as the ‘pomegranate’.

Ibn Rushd described in detail the bones of the front side starting from the clavicles up to the pubic bone, passing by the ribs and the bones of the shoulders. He also described the upper and lower limbs very precisely. What he wrote is not different from what we know today except that, for the bones of the arm, he uses ‘lower’ and ‘upper’ zanad (forearm) to mean the radius and the ulna. He indicated the bones of the leg, nowadays known as the fibula and tibia, in the same terms.

Veins and arteries

In the old days, the arteries were called the ‘beating veins’ (dhawarib ), and jugular veins were the ‘non-beating’ veins (ghayr al-dhawarib ). Ibn Rushd made a precise distinction between the two types of veins which remains accurate and valid. He wrote:‘Arteries come out of the heart whereas the jugular veins come back to it.’ He also described the difference precisely, the arteries are more solid and have two similar layers: the fibres of the inner layer are crosswise while the outer layer fibres are length-ways-even by modern standards a very professional anatomical description.

Two arteries of different size come out of the heart, the smaller one goes to the lungs and ramifies into them (pulmonary artery). The other (aorta) is larger, divided into many sections and ramifies into the whole body, one section going up to the head and upper limbs, another going alongside the vertebral column with branches leading to the chest and abdomen; it ends in the lower body and feeds the two lower limbs.

Ibn Rushd’s fascinating description is confirmed as correct and accurate. However, he failed to observe the circulation of the blood accurately. This was not properly described until nearly a hundred years later by Ibn al-Nafis (d. 1288) a Damascus-born physician who worked in hospitals in Cairo, and many centuries before William Harvey (1578-1657). 

The nervous system

The nervous system is the most complicated organ in the human body and its anatomy has only gradually become known over recent centuries. Nevertheless, Ibn Rushd was able to describe the brain, its membranes and the cranial nerves. He describes the smelling nerve perfectly, pointing out that it ends with a nipple like that of the breast. He does not consider this nerve as the primary one, giving that distinction to the optical nerve. The first pair of nerves issue from the brain and form the sclera inside the cranium, then come out to the eyes each from its side. This is a wonderfully precise description.

Ibn Rushd then describes the nerves that feed the muscles of the eye. According to modern anatomy, these nerves are the third, fourth and sixth, but Ibn Rushd considers them all as the second pair that ramifies in the muscles of the eyes. He considers the third pair as related to the next (the fourth), and these feed areas of the face, the ear, the palate and the nose-in fact, he was writing about the fifth and seventh pair of nerves according to modern anatomy. As for the fifth, Ibn Rushd says that a part of it leads to the ears and the muscles of the cheeks, whereas this is identified as part of the seventh pair.

Ibn Rushd writes that the sixth nerve feeds the pharynx and the tongue and part of it leads to the muscles near and around the shoulder and another part deviates to the neck and a branch of that goes to the larynx. This is actually the eleventh nerve (the accessory nerve) and there is some confusion in Ibn Rushd’s account with the description of the tenth nerve (vagus; the wandering or confused nerve). Although he attributes many characteristics of the vagus nerve to the accessory one, Ibn Rushd is very accurate in the description of the characteristics themselves. He observes that some of the branches of this nerve lead to the chest and feed the heart, lungs, and esophagus; that it runs through the diaphragm and makes the link with the cardiac and liver membranes, the spleen and the rest of the intestines/bowels.

Ibn Rushd describes the seventh nerve as starting from the back of the brain and ramified in the tongue: he is describing accurately the twelfth nerve (hypo-glossal).

He describes as accurately as modern anatomy does, the nerves that go along the vertebrae. He mentions the eight pairs of cervical nerves, sixteen pairs of dorsal nerves, and five pairs of lumbar nerves.

He misses the correct number of the sacral nerves, they seemed only three to him because they are very closely attached-in fact they are five. Three nerves come from the bone of the coccyx and a single nerve comes out on the sides from the middle. This is absolutely accurate.

Ibn Rushd wrote;

‘The brain has two nipple-shaped appendices that grow from its two advanced abdomens (olfactory bulb). They reach the bone that resembles the cribrium (cribriform plate), which is perforated with many holes [i.e. like a sieve], not smooth but rough with its position in the cranium, where it reaches the end of the nose.’

It would be very hard to improve on the concision or accuracy of this account even today.

About the membranes of the brain, he wrote, again with wonderful, inspiring accuracy:

The brain has two membranes, one is hard and thick (dura mater), and the other is thin (pia mater), they cover the brain very closely and in some locations are completely joined. The thick one is adherent to the cranium. This membrane has many perforations in two places, the first at the canal at the end of the nose (cribriform plate), and the second at the bone of the palate. Under the brain on the thick cover, there is the mysterious net composed of veins that go up to the head.’

The structure of eye

Ibn Rushd’s ability and competence as an anatomist is most clearly demonstrated in his description of the eye and its layers, which compares most favorably with what is known today except some minor differences in terminology. Ibn Rushd had even established the original development of the layers of the eye in the fetus, and discovered that they appear to imitate the layers of the brain and its membranes. Ibn Rushd combined accurate observation with brilliant exposition, sight with insight, presenting the structures of the eye as well as any twentieth-century expert could, and did so many centuries ahead of any physician in Europe.

He wrote:

The eye is composed of seven layers and three liquid areas. The first, from the side of the cranium, is a membranous layer that develops from the thick layer (sclera). The next layer from outside develops from the thinner membrane of the brain; it is called al-mashima (choroid). The next is a layer similar to the net (retina). It grows from the same nerve that comes out of the brain. In the middle of this layer, there is a soft and liquid area called al-rutuba al-zujajiyya (vitreous humour). Inside it, there is another spherical body but with some minor flatness. It is as clear as the ice and called al-rutuba al-jalidiyya , and we call it nowadays al- ‘adasa (lens).’

Ibn Rushd continues this wonderful description, by mentioning al-rutuba al-ma’iyya al-amamiyya (aqueous humour), he also called it al-rutuba al-baydhiyya because its liquid is similar to the soft liquid egg-white:

‘On the outside of this liquid appears a soft body whose inner texture is velvet-like, that follows the al-rutuba of baydhiyya (aqueous humour); smooth from the outside its colour is different from the body of the other, it can be very black or less dark or even blue.’ This is an extremely precise description of the iris (quzahiyyatu al-‘ayn) and the ciliary body (al-jism al-hudhabi).

He adds:

‘Inside the ciliary body, next to the lens, a hole that widens and narrows depending on the extent of darkness that it needs, the hole is called hadaqa (pupil) and the membrane itself is called the inabiyya (grape- like) layer.

‘Next to this layer, a cover that has a hard and clear white and thin plate which is called al-qarniyya (cornea). It takes the colour of the layer below it. On the top of this rises a white body called al-multahim (conjunctiva).’

Ibn Rushd also wrote about the physiology of sight:

‘The sight is not a thing that comes out of the eye as Galinius used to think. The eye receives the colours through the reflecting objects in which they are held, in the same way as a mirror does. Once the colours are reflected in the eye, the object is then conceived by the visioning power.

‘This could well be proved in natural science (physics). That is why any of those parts of the eye is able to reflect the colours because of its very glossy surface. So that body is the special tool to the lens and the advantage of the qarniyya (cornea) is . . . [that] it is made clear and thin so that it does not prevent the ice-like liquid (lens) from receiving the images.’

This is an accurate description of the eye and the physiology of sight that does not differ much from what we know today.

From this brief dip into a chapter of al-Kulliyyat fi al-Tibb , we realize the importance of the work of Ibn Rushd-jurist, philosopher, physician. He was an expert in each of these fields and the most distinguished scholar in Spain and North Africa. He neither experienced nor discovered any contradiction between his religion and his science; rather, his quest for knowledge and excellence, his wonderful curiosity, enlightened and improved his faith. His famous observation- who practises autopsy, his faith in God increases -should silence the false allegation that Muslims never practised anatomy and that they are against applied sciences. What has been written by so many Muslims in all fields of knowledge refutes this allegations. Medicine and the other applied sciences are a necessary and essential contribution to the well-being of humankind. Therefore, to work in them is fard kifaya , a collective obligation upon the community of Muslims as a whole, an obligation which some members of the community must undertake on behalf of the others who cannot.

Islam is the guide for those who seek true and sound knowledge in every subject. All sciences, so long as they are directed to God and not to merely worldly ends or personal glory, bring their students closer to God and make easier the way to approach and please Him: Those who fear God, amongst his servants, are those who have knowledge. And God is the Guide to the straight path.