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.

I am sorry, give me a minute.
…

You see, I easily lose my head. So, I need to use medications to balance my mood. Oh my God! That was supposed to be a secret, and it just slipped from my mouth to an admirer. Look, I suspect that once you learn my most-hidden aspects, my reputation with you will be ruined, and you won’t love me anymore. And it really distresses me to have failed your high expectations of an equation like me.

Nevertheless, it is such a heavy burden to suppress one side of mine while constantly showing the other. Yes, being an equation, I am well balanced and very clear about my views. I am one of those lucky theories that have a sound mathematical foundation, and this is why even the psychologists could not suspect a grain of problem due to my childhood. But I am telling you: I am bipolar….

Well, wait a minute! Who are you, and why would I share my secret with you? Go away with your own business, and leave me alone. I mean, I don’t want to disrespect you, but this is my private life, you know! …

No, no, wait, wait… Give me a second… Let me take my medication!

I know it sounds ridiculous if an equation complains of a disorder. How can you be an equation if you have a disorder, and how can you be in disorder if you are an equation? Well believe it or not, that’s exactly what I have been suffering from for such a long time. I am both orderly and disorderly; just like light is both wave and particle at the same time….

Hey, why are you looking at me like that? I told you to leave me alone. It was you who insisted on waiting and learning my secret. I don’t care if your designs are ruined or whatever. Actually, I’m the one who should be blamed. Why did I trust a person whom I met just a few minutes ago? I am like a fish that is eager to eat the worm on the hook. Such an idiot, I am…

Hello? Are you still there? I think I am losing my head again. Where are my pills?

Look, this is not easy for me to do, because in my routine life, people are obsessed with my equation aspect. And, they are passing this obsession from generation to generation. Every time I meet a young brain, my dream to finally meet an unconditioned mind fails. I am always too late to reach the fresh and eager minds. People always manage to find them before me, and instruct them to treat me as a well-established equation. No matter how much I want to show otherwise, they refuse to see my imperfect side, even if the experiments hit them in the face.

Why do they keep doing it? Much like a missionary, they are converting people into the belief of the Bernoulli Equation. I am telling you guys: I am bipolar, and I have imperfections, too!

What am I doing?! You are not going to believe me anyway. I am telling you my deepest secret, and making myself vulnerable as can be, but I still can’t wake you from a dream. You don’t want to wake up anyway; why would you? Do you have any other theory to believe in? Do you have another equation with which to orient yourself in an ocean of unknowns? Go on with your sleep, have nice dreams…

Unfortunately, I don’t have the same luxury as you. My continual tumbling between the two aspects of my reality never allows me to dream… Sometimes, I feel so energetic, so elated. I feel part of everything in the universe, and fall into an ecstasy by realizing that I contain everything in me. And the flow of time stops; we all become one and at peace with each other. No need to rush anywhere, no need to do anything… Just be…

But then my other side kicks in. I feel depressed under the burden of my duties and deadlines. I find myself in an ever faster pace of life, where there is no time to “just be”. There is always an action being commanded; there is always a motivation behind exchanges with others. The universe appears to be made of distinct individuals, like broken pieces of glass. Each is headed to a target of its own, unaware of any union. When life is filled with such a merciless momentum, what is more meaningful than getting rid of my life altogether?

Then, in that gloom, as my dizziness fades, my energetic side starts shining. By virtue of having been created in the same story, I focus on myself to read the universe. I realize that I carry the traits of anything and everything else around me. Once again, I start breathing the life that is gushing forth from me.

As I lose my conscience by getting high in life, I get stuck with the fact that losing my conscience defeats the purpose of being whole. You cannot hold onto the entities whose existence you fail to recognize. I start criticizing myself for disrespecting those around me. I blame myself for being such an addict and a loser; the shame of creation…

You see, there is no end to my ups and downs. As a remedy to these continuous head losses, I am using medications, but they have side effects. I am constantly growing fat, and losing my beauty. I hope one day, someone is going to be inspired with another equation that can take over my duties. Then I can retire from this bipolar life, and be mentioned in the scientific stories as a respectable grandparent…

The Bernoulli Equation given in its simplest form contains a pressure term (P) and a velocity term (1/2 (pV)^2), the sum of which is constant along a streamline:

P+1/2 pV^2=P_0

Thus, pressure and velocity work inversely with each other. As one increases, the other decreases.

The Bernoulli Equation can be derived in two independent ways. First, one can start with the conservation of energy (1st law of thermodynamics), and then follow some assumptions to end up with the Bernoulli Equation. Energy has a scale but no direction, and can be transformed from one form to another. Therefore, everything in the universe can essentially be converted into each other, just like the pressure and velocity terms in the Bernoulli Equation.

The second way to reach the Bernoulli Equation is based on the momentum equation (Newton’s second law). Again using few assumptions, one can achieve the nice and simple Bernoulli Equation. Unlike energy, momentum has both scale and direction. Any changes to this directionality require a forceful interaction between two objects.

Having its base on two fundamental laws of physics, hence reflecting both energy and momentum, makes the Bernoulli Equation one of the strongest and most beautiful equations of science, but not perfect!

The underlying theory of the Bernoulli Equation requires that the density (p) of the fluid be constant – in other words, incompressible. Therefore, the Bernoulli Equation fails to accurately explain the flow of gases at high speeds, which involves density changes. Similarly, the effects of viscosity are neglected in the foundations of the Bernoulli Equation. This means that the variation of pressure and velocity near a solid object cannot be explained by the Bernoulli Equation.

As a result of these imperfections, the Bernoulli Equation describes a fluid as a pile of metal sheets, and explains a flow as the sliding and bending of these metal sheets around each other. Clearly, this is not what a fluid is and not what happens in a real flow. Therefore, predictions of the Bernoulli Equation are inherently wrong, especially when there are sharp turns or obstructions in the way of the fluid.

In order to compensate for some of these deficiencies, a concept known as head loss (hloss) is introduced. Head loss is experimentally measured and then artificially added to the Bernoulli Equation, which then becomes:

P+1/2 pV^2+pgh_(loss,turns)+pgh_(loss,obstructions)+pgh_(loss,wall shear)=P_0

The final result is an equation that is useful but repulsively oversized, and it is certainly not well-established in theory.

Skin is composed of two main interwoven layers of dermis, on the inside, and epidermis, on the outside. The epidermis, which is composed of five sub units, possesses the most important sign of our identity. Each thin layer is arranged in a way to carry out different tasks. A significant amount of elasticity and flexibility is provided to skin via these five layers. These layers can glide on each other slightly and can also be compressed under pressure. They are compressed when we sit on a hard surface. This situation can be similar to the compression of the spring in a click pen, or the suspension of a vehicle under a load. They regain their previous state upon termination of the pressure, like standing up. This elasticity is crucial for skin’s integrity.

The thin construct of our skin contains sweat glands that are embedded in the fibrous connective tissue. There are sensory receptors, hair roots, and hair muscles connected to them, and also loose nerve endings, and a network of capillary vessels. Free nerve endings are created to specialize in various functions so as to sense hot, cold, pressure, and pain. Likewise, the continuation of blood flow relies on very intricate calculations that are hard to explain. When blood vessels arrive at the skin, they are dispersed like a net in the form of capillaries.

The blood pressure of the arteries located at lower section of the skin is higher than the pressure of pulmonary veins. If pressure is applied to skin for a long duration from outside, the pressure in the pulmonary veins builds up and regional blood flow is disrupted. Therefore oxygen, glucose, and other nutritional substances cannot be delivered to these areas; along with inhibition of waste product removal, it leads to a nutritional abnormality in the tissue.

Sensory cells within our skin detect and report nutritional abnormalities of tissue to our brain via various chemical substances (like acetylcholine, bradykinin, and histamine). Thus we change our position consciously or subconsciously with the intervention of our brain to avoid the danger of a nutritional abnormality, and therefore the area regains normal circulation. In this stage, the process is still reversible; however, should the pressure continue, skin cells will start to die from, from the outside in. These systems do work well in healthy persons but in cases of stroke or coma, the intervention system does not work.

This critical picture can be understood better with an example. Just like roads need to be used in order to carry goods and remove trash, the transportation of minerals, vitamins, and many other life saving substances to the distant parts of the body and removal of waste products requires blood vessels to remain open. This must continue in a perfect balance without any interruption throughout our lives.

If a pressure ulcer occurs, it is like being exposed to external dangers in a house if a door or window breaks. It is like a free entrance visa is granted to germs that were blocked. Our back and pointy areas, like, thighs knees, heels, and shoulders are under more pressure, and therefore at more risk when we lie down. Two to six hours of pressure to one of these areas is enough time to disrupt skin integrity. Our daily sleep requirement is around 6-8 hours, therefore we need to switch positions a couple of times during our sleep. Therefore we face this risk everyday in our sleep; however, thanks to the perfectly functioning protective systems, without noticing during our sleep, our position is changed and this dangerous situation is avoided. Intensive care doctors and staff know better what a great blessing that is are since intensive care patients are mostly unable to move. Despite the use of many preventive efforts, like turning the patients in certain periods or the use of air beds, pressure ulcers still occur and a significant portion of patients die of the microbial infections caused by these wounds.

The story of sleepers

“The Seven Sleepers” story in the Christian tradition is retold in the Qur’an as “the People of the Cave.” The story is about a group of young believers who took refuge in a cave fleeing the oppression of the pagan Roman emperor. Both traditions narrate that they fell asleep in the cave, where they stayed asleep for hundreds of years. The Qur’anic account, however, mentions that they were made to change position during their centuries-long sleep: “You would have thought them awake though they were asleep. We caused them to turn over to the right and the left…” (18:18). It is an interesting nuance that they were made to change position, for it sounds rather irrelevant to the rest of the story. However, with the medical conditions of our skin that were explained above, this nuance makes perfect sense as advice to us on how we should treat patients who are unable to move.

The harmful foodstuff eaten is spat out quickly through vomiting and so damages of such foodstuff is minimized. Occurring upon taking of any poisonous food or alcohol, vomiting directly contributes to treatment by ensuring a quick disgorge of the harmful stuff. Variations in amounts of estrogen and progesterone hormones during pregnancy helps in noticing even the least amount of toxins (poisons) found in the blood by way of increasing sensitivity of the chemoreceptor trigger zone within the brain stem. When this zone of the brain takes notice of toxins in the blood, it immediately activates feeling of nausea and vomiting. Margie Profet, a researcher from the University of California at Berkeley was the first person who drew attention to this issue in 1995. She asserted that food craving is a divinely merciful mechanism aiming at protection of the miraculously developing embryo against probable dangers within the human body. She also asserted that food craving protects the embryo from natural toxins in foods. Vomiting may also happen to travellers and sufferers of migraine. Certain psychological factors such as unpleasant smell and excessive fear may result in vomiting as well.

If, however, vomiting recurs and turns out to become a habit, one should be careful, for vomiting causes new problems such as electrolyte losses and dehydration while irritating the alimentary canal, throat, mouth and teeth through which vomited matter passes. In addition to these, regurgitating might be inadvisable and indeed should be avoided in certain cases of poisoning which develop due to ingestion of petroleum products and burning chemicals like hypochlorite and ammonia which are used in house cleaning. The reason for this is because petroleum products may cause pulmonary infection of chemical origin in the lungs and burning chemicals may cause scalds on the tissues they touch during regurgitating.

Just like all the systems that our bodies are equipped with, vomiting also happens in accordance with a plan and program during which a wonderful co-ordination is displayed. The vomiting center in the brain is responsible for such co-ordination.

Rapid increase in salivation and nasal secretion prior to vomiting plays a key role in alleviating damages of the highly acidified vomited matter over the interior surfaces of the mouth and nose. Increased salivation helps with the protection of tooth enamel too. The pushing process of the foods eaten normally occurs from the intestines towards the bowels during the course of digestion. However, it reverses and occurs from the intestines towards the stomach during which the muscles of gastrointestinal tracts relax, open and the contents of the intestines are thus gathered in the stomach. Taking deep breaths prior to vomiting decreases the need for breathing during vomiting and blocking of the air passage by vocal cords’ converging prevents aspiration, that is, the passage of contents of stomach to the lungs. If such mechanisms did not exist, every vomiting attack might have ended catastrophically. Breathing attempts apply negative pressure on the rib cage and convulsion of stomach muscles applies positive pressure within the abdomen in spite of the converging of vocal cords. A pressure decrease is observed in order for contents of the stomach to be regurgitated. Muscles of the gastrointestinal tract tighten while muscles of the gate between alimentary canal and stomach relax just before vomiting. So, regurgitating via alimentary canal occurs without passage of stomach contents to intestines. Upon completion of vomiting, there is the disappearance of abdominal convulsions and the secretion of endorphin in the blood, so a person breathes sigh of relief.

In conclusion, although vomiting is perceived as something which is seemingly unpleasant, it is indeed a fine product of Divine artistry like all other systems and mechanisms of our body. Vomiting, as one of the proofs that God has created nothing useless and unnecessary, is certainly a great blessing bestowed upon us.

References

• “Sickening sounds – research to make your ears cringe.” University of Salford. January 28, 2007.
• Lunsden, K, and Holden WS. 1969. “The act of vomiting in man.” Gut 10: 173-179.
• Margie Profet (1995) Protecting Your Baby-to-Be: Preventing Birth Defects in the First Trimester. Reading, MA: Addison-Wesley. pp. viii, 312.
• Flaxman, S.M. and P.W. Sherman 2000. “Morning sickness: A mechanism for protecting mother and embryo.” Quarterly Review of Biology June 2000. 75:1-36.

By examining the heart of a crocodile, researchers have discovered how it is that an air-breathing land animal can manage to glide through murky waters for several hours without the need to surface.

There is that one scene in documentaries that we often come across on television: Crocodiles gliding gracefully inside the water, waiting for hours for the perfect time to pounce and snatch their prey from their necks and into the water. But how do these animals manage to stay underwater for almost two hours without surfacing for air even though they, just like human beings and other land animals, live on pulmonary respiration and are in need of the free oxygen in the air?

A member of the reptiles class, crocodiles do not have gill nor can they have skin respiration since their skin is covered with a thick and airtight keratin armor. Just as every living organism are provided with a suitable anatomic and physiological character for their survival, crocodiles are also granted with a system that facilitates their long stay in the water.

Crocodiles are bestowed with a special heart anatomy different to other reptiles like lizards, tortoises, and snakes. The hearts of other reptiles are designed to contain three sections including two atriums and one ventricle. The right atrium, which collects the returned oxygen-deprived (deoxygenated) blood and the left atrium which collects the oxygen-rich (oxygenated) blood retrieved from pulmonary arteries of the lung, transports the blood to one common ventricle. Because there is only one ventricle to receive and combine oxygenated and deoxygenated blood, a mixture of less oxygenated blood is pumped to their body. Depending on outside temperature, the body temperature of a reptile increases or decreases. Their metabolism slows down, almost to a halt, while their body temperature decreases when outside temperature drops near or beyond freezing conditions. Hibernation begins as a result. Frogs and reptiles stop hibernating as soon as their body temperature increases depending on the outside temperature when the weather gets warm. These organisms are called cold blooded animals (with variable body temperatures) because of this feature.

The heart of a crocodile is different to other reptiles in that it has four chambers just like birds and mammals. Blood is sent to the lungs for gas exchange from the right, and from the left ventricle it is pumped to the body. Thus the two types of blood do not mix in the heart. However, what is interesting is that blood is mixed as soon as it leaves the heart via a valve (foramen of panizza) placed in between the right and left aorta.

What could be the purpose of blood, which does not normally mix in the heart, mixing through the medium of a hole? Does this opening in between two aortas indicate a flaw? It is understood after some research that this hole in fact is not a flaw or an anomaly; on the contrary, it is a necessity for a metabolism suited perfectly to the lifestyle of the crocodile.

Warm blooded vertebrates like birds and mammals with a four chamber heart have faster metabolic speeds and higher blood pressures. For these organisms can only supply the energy they consume during their daily activities via such a fast metabolism and a high level of oxygen provided with oxygenated blood.

If the metabolism of a crocodile was fast like mammals all throughout the year, it would have to continuously be nourished and use oxygen. Furthermore, because crocodiles do not have much predators, they could have also lead to the extinctions of some species by overpopulating if they featured a faster metabolism. The low ratio of heart-body mass in crocodiles (0.15%) compared to mammals and birds (0.40%-0.50%) cause the movements of crocodiles to be relatively slower. The Almighty, who creates everything with his wisdom, lowers the blood oxygen ratio and the metabolic speed of crocodiles by creating a valve that combines the two aortas. Thus eliminating the possibility of crocodile overpopulation.

Crocodiles have two aortic arches whereas mammals only have a left, and birds have one right aortic arch. The left aortic arch, despite some contact with the returned blood via foramen of panizza, delivers the oxygenated blood towards intestines, stomach, spleen and the liver after receiving it from the left ventricle of the heart. This is because the digestive system of a crocodile requires oxygen-rich blood. Deoxygenated blood while exiting the right ventricle goes towards the pulmonary arteries of the lung for exchange and mixes with oxygenated blood coming from the right aorta, feeding other organs that are instrumental for its slow metabolism.

Under the water, separated oxygen-rich and oxygen-poor blood mixes when exiting the heart and switches route, thus making oxygenated blood vessels start to carry oxygen poor blood. So what is the reason behind this switch in the direction of the bloodstream under the water? See at this point, the extraordinary features of the crocodile blood circulation system kick in. The two anatomical features belonging only to only crocodile hearts is what enables them to stay under water without breathing. Because of little or no lung use under the water, a big portion of the blood stream is diverted away from lungs; therefore oxygen poor blood is pumped back to the body. As one feature of the two, foramen of panizza restricts (does not close) upon signals coming from nostril sensors under the water but expands and remains open on land. The two aortic arches connects with each other via foramen of panizza as soon as they leave the heart but merge completely in the lower parts of the body away from the heart (anastomosis).

The second feature stems from a serrated valve. Refilling of pumped blood is stopped via a passive, thin leaf-shaped valve which is located at the tip of the pulmonary artery exiting the right ventricle. Thus, one-way direction of blood flow in the heart is maintained. These valves, which carry nodules made of connective tissue, constrict during the dive and blood flow to the lungs is reduced greatly. Therefore blood rejoins the systemic circulation from the right aortic arch.

The blood circulation of crocodiles is similar to birds, mammals, and humans while they are active on land. Oxygen-deprived blood is sent to lungs for gas exchange. The only difference is the turning of the right aorta to the left and the left aorta to the right. Oxygen rich blood not only flows through the left aorta but also through the right aorta via foramen of the panizza as well causing distribution via two channels into the body. However, the foramen of the panizza being open is not sufficient for these two channels to be used. At the same time, the pressure of the blood within the left ventricle needs to be higher as well. This way, high pressure oxygenated blood flows into the right aorta through the opening of the panizza, applying pressure to the valve at the tip of the right aorta to close it in order to prevent the mixing of the oxygen-poor blood into this route. As a result, oxygenated blood gets distributed quickly by each aortic arch without mixing with the used blood. Thus, oxygen-poor and oxygen-rich blood follows the following route on land

* Deoxygenated blood: Body – superior and inferior pulmonary veins – right atrium – right ventricle – lung pulmonary artery – lungs.

* Oxygenated blood: Lung pulmonary vein – left atrium – left ventricle – right aorta and left aorta via panizza valve (both aortas are active) and body.

The opening of the panizza narrows with the help of signals coming from the nostrils when crocodiles submerge. At the same time serrated valves at the tip of pulmonary artery that transports the blood to the lungs also constrict. While this serrated valve is at work, a majority of the blood returning from the body is not sent to the lungs because they are not functioning at the time. This serrated valve also increases the pressure of the right ventricle. This pressure, along with elevated resistance in pulmonary circulation and lowered pressure of systemic circulation, leads to the opening of normal valves at the tip of the left aorta. In the end, the left aorta which normally carries oxygenated blood on land starts carrying oxygen deprived blood, and there is a route switch.

The most beneficial part of this switch is to re-route the deprived blood back to the body via a different route, that is, the left aorta. This by-passes the lungs and prevents time loss. Despite the fact that blood of the left aorta mixes with the oxygenated blood of the right aorta to some degree via the panizza valve, the main function of this opening while submerged is to supply blood flow to the arteries feeding the heart and brain through the transfer of some poor blood from the left aorta into the right aorta; this way vital organs are not left without blood.

Blood returning from the body is not sent to the lungs for gas exchange when crocodiles are under the water. However, existing oxygen in the blood can be delivered to the tissues quickly by a route switch. The amount of bicarbonate ions that is important in the transport of CO2 in the blood increases when oxygen pressure in the tissues drop. Anaerobic respiration of tissues increases. This leads to an increase in lactic acid levels and reduces pH. Eventually, it facilitates the release of oxygen carried by hemoglobin. In the end, oxygen that is bonded with hemoglobin is used more efficiently. In the meantime, the body temperature of a crocodile submerged under water decreases and slows down its metabolism, reducing the need for oxygen. Oxygen stored in the blood can be sufficient up to two hours under the water. However when these reserves are consumed, crocodiles have to resurface to breathe even though it may cost a prey to escape.

Crocodiles can live on land and in the water and adapt to their environments with ease and efficiency thanks to the ponderous working of their mechanisms under water, the change in blood circulation, slow blood flow, reduced body temperature and metabolic speed bestowed upon them. Just like humans in sleep, crocodiles can remain submerged for long periods (4-6 minutes in usual dives; up to 2 hours when pressed) with this perfect system granted to them. Crocodiles use these mechanisms not only when under water, but also while resting or for periods after heavy feeding.

Carbon atom, which composes nearly 0.2% of the earth’s crust, has a very special place among elements. All living beings are formed from carbon-based compounds. In addition, 94% percent of compounds—that is, more than 4 million—contain carbon atoms. Certain carbon compounds form nearly 18% of the matter in living beings. The rest is mostly water. These compounds are used as building blocks in cell formation. Only carbon has the ability of compounding with other elements in sufficient variety and complexities in order to carry out the main functions that life is based on. As carbon atoms easily form chains by making chemical bonds, no other element is given such a quality. These chains formed in a line can separate into branches and can connect to form rings. These rings are actually polygons formed by three, four, five, six, or more carbon atoms. Due to this quality, carbon is the element that forms the basis of many things from the foods we eat, to the clothes we wear, from the fuels we use, to the furniture we have.

The heat level that makes carbon compounds possible is between -20 and +120 0C. Carbon compounds begin freezing at -20 0C and they begin breaking at 120 0C. In space, where extreme heat and freezing cold exists, the only heat range that makes carbon compounds possible is found on earth and this is a very sensitive heat range. Temperatures in our neighboring planets give a better idea: as hot as 450 0C in Venus, and as cold as -53 0C in Mars. Under these temperatures, it is impossible for carbon element to form compounds and thus living beings. Therefore, the earth is the only planet created with the suitable conditions that make life possible.

Crystal structures of carbon atom

Particular repeating arrangement of atoms in three dimensional space to form a certain geometric shape is known as a crystal structure.

Different crystal structures of the same substance are named “allotrope.” Carbon has three different allotropes found in nature: amorphous carbon (coal), graphite, diamond. In addition to these, an artificially produced allotrope is fullerene.

Amorphous carbon (coal)

Amorphous structure is one without a definite crystal structure; that is, one where atoms take their places in free order. A mass of carbon atoms of amorphous structure is known as coal. After plants die, they undergo chemical transformation with the activities of microorganisms. If dead plants collect in a suitable wetland and are buried into the ground with a geological process, the carbon amount in their body increases and they begin transforming into coal. Types of coal are categorized according to the carbon percentage they contain. Geologically, this transformation process takes a period of 15 to 345 million years. Coal is one of the most commonly used forms of energy.

Graphite

In graphite, carbon atoms are found in a hexagonal crystal structure. These sheets, resembling the surface of a honeycomb, pile up and form graphite. As the sheets are not connected with firm bonds, they easily shift when some force is applied. This is why graphite is used for eliminating friction at machine industry. The black substance in pencils is graphite hardened by adding some clay. Graphite can resist very high temperatures. Therefore it is used within the steel industry and melting metals. In addition, it is a very good conductor of electricity. For this reason, the brushes of the electric engines in household machines such as a washing machine and a vacuum cleaner are made of graphite. In recent years, graphite has been used as heat shields of space shuttles.

Diamond

Diamond is the hardest natural substance we know. In spite of being a transparent substance and having no color of its own, it can be found in pastel colors such as yellow, brown, or even dim black, owing to being mixed with other minerals. Diamond is a perfect electric isolator and is the substance with highest heat conductivity. For this reason, it can be cut without being deformed. In diamond, carbon atoms are found in a pattern to form a cubical crystal structure. Extraordinary resistance of carbon-carbon bond and its hard and integrated structure prevents its reacting with other things around. It burns at a heat of 850 0C. In a piece of diamond, there can be other atoms that cause impurity and decrease the value. In good quality natural diamonds, there is only 1 alien atom versus 100,000 carbon atoms. In addition to jewelry, diamonds are widely used at industrial products such as drills, glass cutters and the like. 75-80 % of diamond production is used in this industry.

Formation of coal, graphite, or diamond from carbon

Carbon based organic compounds were buried underground as a result of movements by the earth’s crust millions of years ago. Physical and chemical changes occurred with those organic masses through heat and pressure. Gradually, water, carbon dioxide, oxygen, and—in the highest phases—hydrogen leaves these masses. This organic matter called “turba” (first transforms into lignite, then to sub bituminous coal, then to bituminous coal, and then to anthracite). If the conditions allow, it transforms into graphite. Coal is the first type of substance formed by carbon atoms on their journey to become diamond. As lower values of heat, pressure, and time suffice for coal formation, graphite requires much higher values. Diamond is formed in the mantle layer of the earth at about 150-200 depth. This valuable substance is later carried to the surface of the earth by volcanic rocks such as lamproite and kimberlite. In order for diamond to form, an atmospheric pressure of 50,000 atm, 2,400 0C of heat, and a period of 3 billion years are required. Without this immense pressure and long time, the substance to be formed by carbon will simply be graphite. It is possible to transform graphite into diamond artificially; however, according to calculations, a minimum pressure of 10,000 atm is required. In 1955, for the first time artificial diamond was obtained under 100,000 atm, 2,500 0C heat, and by using chrome as catalyzer. However, the pieces of diamond obtained were small and black, most of them did not classify as jewels. In another attempt made in 1962, graphite turned into diamond under 200,000 atm, 5,000 0C heat, without using any catalyzer.

The similarity between carbon and human beings

As carbon atoms’ properties change according to the crystal structure, people’s lifestyle and view of life depends on the community they live in and their position in that community. In order to become diamond, the highest level of its kind, a person needs to undergo hard conditions. If carbon atoms were to say, “this is more than we can bear, we prefer easier conditions,” then they can be nothing more than graphite. If the conditions for graphite are avoided as well, then one cannot go beyond the level of coal. Diamonds are kept in safes and worn in most important occasions and graphite has different kinds of practical use as an industrial material. As for coal, it ends up in fire. The situation of human beings in a way resembles carbon atoms. Every person is made of the same elements biologically. Their value will naturally be different, according to the processes they underwent and the behaviors they presented. Some show patience in the face of misfortune, put their sincere trust in God, and become the diamonds of humanity. Some others, whom we can compare to graphite, attain a desirable level even if they cannot become diamonds. Those who choose to assume the lowliest form are likely to face a similar fate with the coal.

References

• H. W. Kroto, J. R. Heath, S. C. O’Brien, R. F. Curl ve R. E. Smalley. 1985. “C60: Buckminsterfullerene.” Nature 318. DOI:10.1038/318162a0.
• L. Vlasov, D. Trifonov. 2005. 107 Stories about Chemistry, TUBÝTAK., Ankara.

Octopuses are equipped with a very powerful sensing system in addition to their sharp vision. For example, an octopus whose vision is obstructed can sense the size of objects and the distance between them. Regulation and synchronization of vision is realized with internal and external movement of the lens contrary to human beings. When it faces a threat, the octopus releases dark blue-black ink and tries to repel its enemy. Immediately after the spray, its color changes and it carefully leaves that spot. The secretion glands found in the inner face of the bladder have been programmed to secrete ink the moment the animal becomes frightened. Another function of the ink is to blunt the attacking animal’s sense of smell. Even if the animal touches the octopus at this time, it cannot recognize it.

Another striking and important ability given to the octopus is its ability to camouflage. In some situations it tries to protect itself from danger by hiding itself with this capability. If it has not been able to find a suitable place to hide, the octopus swims among the corals and, taking on the color and shape of its surroundings with the help of color cells comprised of richly colored matter (chromatophores) found under the skin, it camouflages itself perfectly.

At first glance the suckers of an octopus are no different from suction cups vacuum pressed onto smooth surfaces. However, in reality this organ is more complex than it appears to be. This organ was not created just for the purpose of sticking on objects. By means of muscles unique to it, the octopus is able to make various maneuvers.

There are approximately 200-250 suckers in two lines on each arm of the octopus. This means there are approximately 2 thousand suckers on its eight arms. There are two small chambers on each sucker. The external chamber is called a cone and the internal one is called a pot. When it sights its prey, the muscles of the external cone take the shape of the surface of the prey and completely cover it. The muscles of the internal pot structure are full of water and, disconnected from the outside world, decrease the inner pressure. This difference from the outside pressure has the effect of a vacuum. The external muscle structure enables the octopus to turn from an erect or parallel angle by decreasing the pressure difference around the object and without destroying the functional structure of the sucker.

In addition to possessing the complex muscle structures explained above, the suckers have an amazing nerve system. The chemical receptors found on the edge of the suckers (chemo-receptors) give feedback regarding the taste of the object, and the pressure and position receptors give information regarding pressure and touch. The nerves of these receptors, gathered in a node, act as a tiny brain. The chain structure extending the length of the octopus’ arm connects the suckers and nodes and synchronizes them. This structure enables the animal to lift and raise its arms without need of a command from the main brain. How this amazing task is accomplished by the brain, arm and suckers is a subject that needs investigation.

Only considering its suckers, the octopus appears before us as a creature adorned with perfect artistry and special capabilities. The characteristics of these animals being in a wise and most appropriate form is one of the clearest proofs of the blessings and benefaction of a compassionate and merciful Creator.

Canoglu is a freelance writer from Turkey with a degree on zoology.

How is uterus to be placed in the frontier abdomen?

In order for a baby to survive, a suitable space in which it will be fed and protected is necessary. Therefore, the uterus is in the best location as it is, and its equivalent cannot be maintained in the belly. Let us consider that births would really happen through the belly. If the uterus, where a baby develops in 40 weeks, were placed in the belly, then a set of problems would appear. The opening of the uterus would be turned toward the abdomen wall, and thus there would be no strong bonds to tie it up with the surrounding area. In this case we cannot place the intestines, mesenteric blood vessels, aorta, and the net of nerves in connection to them in any way. If the uterus were in the belly, it would unavoidably pressurize the stomach, liver, spleen, and other internal organs, as the mass inside a pregnant woman grew. This could obviously pose a lethal threat for both the mother and the baby.

How would the birth process begin?

If the uterus were anywhere else than its present position, it would contradict the physiology of birth. The fetus assumes three different positions along the developmental process: as it begins to be formed the head is up and the feet are down. At the sixth month, the baby assumes a horizontal position. When the birth draws near, feet and the hips are positioned on top and the head is turned downward, closer to the opening of the uterus. As the head gets closer to the opening, mechanical pressure increases. Thus, signals for the birth are sent to the brain so that the relevant hormone aid is sent in response. With the effect of the hormones, the uterus begins to contract in order to dispose of the being inside. As the opening of the uterus enlarges, the contractions increase. With its mechanical help, the sacro-coccigeal joint makes a 2-cm stretch to give way and with the support of the pubis bone in front, the birth is realized. If human birth was to occur through the belly, then how would the process—including the brain, pituitary gland, and adrenal glands—be triggered with mechanical pressure without the help of gravitation? If the uterus is placed inside the belly vertically, then a tube or similar opening is needed for a way out from between the legs. Even if there is mechanical pressure and the hormones to facilitate birth are secreted, then what way will the baby move? How can birth be realized through the soft-walled belly without any mechanical support at all? If human birth were possible through the belly without any support from the bones, the duration of birth would be much greater. In addition, as the size of the baby increased, a high positive pressure would be needed in order to balance the effect of gravity. However, the more a belly grows, the weaker its muscles become. If birth would ever be possible through the belly, then the mother would have to deliver her baby by lying prone in order to prevent the soft tissue to be torn. In addition certain flora (beneficial microorganisms) need to be placed to the birth channel in order to prevent relevant complications. Should the genital organ be transferred to the navel? For the best protection against complications, the baby’s head need to be in horizontal position as if it were swimming. The effect of gravitation applies different pressures on the baby’s head while the mother stands, sits, and lies in a supine position. In this case, by which force would the head be directed toward the opening in the frontal abdomen wall to start the birth process? The three different positions of a fetus along its development will never be possible in a uterus located in the belly. Then the fetus would dangle like a tree leaf under the effect of gravitation.

The easiness of normal physiological birth

A form of birth through the belly, a cesarean delivery is only realized in the face of certain anomalies. Although some women assume cesarean as a painless form of birth, findings adds to the cons of cesarean. Accordingly, rate of allergic asthma in cesarean-born children is found six times higher in comparison to others. It is thought that during normal birth, the baby receives some of the microorganisms on the mother’s genital organ and the immune system forms antidote against them, which provides protection against asthma.

Strapping up the uterus?

As the baby develops in a period which lasts more than nine months, the uterus gradually grows. In the mean time, it is necessary to fix the uterus with sound bonds so that it becomes resistible to shakes. Counting in both sides, 14 pieces of bonds fixes the uterus to the bones (ilium, ischium, pubis, sacrum) around the hips. Were the uterus to be in the belly, how could we find such sound structure to support the bonds?

To conclude, God Almighty could have created our body in a different form, and He would have shaped our anatomy accordingly, which would then provide the best means for an ideal birth. Thus, it is nonsensical to seek errors in our present biological makeup in order to dishearten the faithful in their belief. Leaving aside such speculations, one cannot help but admire the perfect arrangement in human anatomy when considered from the perspective of wisdom.

Arslan Mayda is a medical doctor at Sifa Hospital, Izmir, Turkey.

We vessels can be divided into three main groups in terms of structure and function. The ones with thicker walls, which bring every organ the blood they need from the heart, are the arteries. The pressure inside us is higher and we easily carry blood to the organs. The ones with thinner walls, lower pressure, and larger inner space are called veins. As a matter of fact, both arteries and veins have a three-layered structure that is very suitable for holding a fluid like blood. Since our walls are strengthened with both connective tissue and smooth muscle layers, we bear the pressure coming from the heart and help blood proceed by contracting and relaxing. Since arteries are directly subjected to the strong pressure from the heart, our walls were created in a thicker and stronger form. Since the veins return blood to the heart and thus have lower pressure, we have valves that close after blood passes, so it does not flow backward due to gravity. This is a serious challenge for the blood passing through your legs. Varicose veins might develop due to weight gain from pregnancy or obesity, which increases pressure on the legs, or to hours of standing, walking, or running on hard surfaces.

Capillaries are the most delicate blood vessels, with walls made of a single layer of epithelium, which enables us to exchange substances between blood and tissues. As blood vessels, our total length is about 120,000 kilometers. Try to imagine if a fisherman’s net were made from a rope of this length and how wide it would be! And yet, such a vast network of blood vessels is located in your body, and capillaries take blood to every part, without neglecting an area as tiny as the head of a pin.

The well-being of your organs is directly related to us. If our interiors begin to narrow, because of fatty cholesterol plaque for instance, then we begin to lose our flexibility. This means malnutrition for that organ, since a lesser amount of blood than expected can come. If a blood clot sticks to our wall and blocks the blood flow, the relevant organ may be in terrible trouble. If other arteries supply blood to that organ, then it can handle this, but if a main artery is blocked and if secondary channels do not exist or are insufficient, you experience infarction. Taking this into consideration, you need to be careful what you eat and lead a physically active life. When you get old, if sufficient blood does not pass through us in your brain, failures with brain activities appear and you go senile. As the walls of veins and arteries have a rich network of nerves, we let the suitable amount of blood flow according to the need of the organ we’re serving, under the control of the autonomous nervous system. While blood vessels that are connected to an organ not currently requiring much blood contract to reduce the amount supplied, those that are connected to currently more active organs expand. And dear Peter, the greatest blessing here is that none of these activities require any conscious effort from you; everything works smoothly without your even being aware.

This wonderful network of ours finds its value in the vital fluid we carry. If it weren’t for blood, we would have no value at all, and such a perfect means of distribution would be unnecessary. Even the duty of the heart is to make this fluid circulate throughout the body. Now, let us step aside and allow blood to have the floor.

When we have been sitting or lying for a long time we can suffer from orthostatic hypotension due to an insufficient operation of the sympathetic nerves.

When we are lying down, the blood pressure in our arteries is pretty much equal throughout the body. When we stand up, the blood pressure is affected by the gravity and increases in the vessels under the heart, while decreasing in the brain. If we lie down again, the blood pressure in the arteries balances once again. If these changes cannot be naturally controlled, then we may suffer an increase or decrease in blood pressure, which could result in a fatal injury.

There are baroreceptors in the walls of main arteries whose tasks are to measure constantly the blood pressure and to send data (electrical signals) to the brain, informing it about the blood pressure in the body. These baroreceptors are located in the aorta as it leaves the heart and in the carotid artery as it enters the brain. With the onset of hypertension, the frequency of the signals that are sent to the brain increases and this drops in case of hypotension. The center of vessel movement in the brain, with regard to the frequency of electrical signals it receives, perceives a low or high blood pressure.

In the brain is a vasomotor center; this continuously controls the blood pressure and regulates it. This center constantly receives data about blood pressure. If the pressure decreases, the signals of the sympathetic nerve increase. If the pressure increases, the signals to the parasympathetic nerves are suppressed. As a result of sympathetic irritability, the heart begins to beat faster and stronger. It pumps much more blood in a unit of time, and thus the blood pressure increases. The arteries and veins also constrict and owing to this constriction in the arteries, the blood pressure increases further. As a consequence of constriction in the veins, the extra blood that is stored inside the veins is pumped into the heart. Now, as the heart is receiving greater volumes of blood, it works faster and contributes to the increase in the pressure. In the meantime, as a result of the suppression of parasympathetic nerve signals, the heart contracts faster and stronger, thus pumping much more blood.

As the blood pressure rises, the mechanism which is in charge of reducing the pressure via vasomotor center is triggered. While pressure is applied to the sympathetic nerves, the signals that are being sent to the heart and vessels decrease. Thus, the rate of systole and the amount of blood which is being pumped decreases. As the arteries receive less blood the volume of blood in the system falls off and as the arteries and veins expand, the blood pressure falls. Due to the dilatation in the veins, the volume of blood which is sent to the heart also decreases and as a result the heart pumps less blood and the blood pressure drops.

However, by triggering the parasympathetic nerves, the signals that are sent to the heart increase. This helps to slow the heart down and ensures that there is less blood pumping through the system. As a result, the blood pressure which has been reduced via the sympathetic system is reduced even further with the parasympathetic system. At this point, it is necessary for there to be a rapid drop in blood pressure, which is provided by the simultaneous functioning of different mechanisms.

We cannot control this system and it acts extremely rapidly and with great elegance. Even in the systole period, when the heart is pumping the blood and there is a short and sudden increase in pressure and in the diastole period, when the heart relaxes and there is a short and sudden decrease in pressure, the system is in charge and functioning at every second, operating to increase the hypotension and to decrease the hypertension. The average healthy human heart beats 70 times per minute. Consequently, there are 70 systole and 70 diastole stages every minute; thus a normal balance can be maintained by decreasing the pressure, which increases 70 times every minute, and by increasing the pressure, which decreases 70 times every minute; this is how the body maintains a normal balance. In other words, this system functions 140 times every minute. Is it possible that this system, which operates throughout our life, a system that we are not aware of, a system that is so sensitive and vital to our lives, a system the details of which have only recently been understood after centuries of observation could be nothing more than a coincidence?

The pressure regulating system mentioned above carries out other important tasks while we are sitting and standing as well. The amount of blood going to the brain is related to the maintenance of a difference in blood pressure between the arteries and veins and to the recirculation of blood. In connection with hypotension, the pressure in the veins to the brain decreases, in order to partially compensate for the decrease in the arteries. By preventing a decrease in the difference of pressure (perfusion pressure) between the two systems, the continuity of blood going to the brain can be maintained.

In addition, a small decrease in the blood going to the brain can lead to an increase in acidity and carbondioxide in the brain tissues and to a decrease in oxygen; this results in the dilatation of the blood vessels in the brain. When these systems go into action anyone who is not suffering from orthostatic hypotension will have a stable amount of oxygen consumption in the brain when they stand up, and thus not experience dizziness.

In fact, scenes from karate movies are wonderful displays of the perfect functioning of this system. In such scenes, the fighter will jump up, and then suddenly fall to the ground; he will then suddenly spring up and performs different moves. Certainly with every movement, the blood pressure changes suddenly, but as a sign of the Creator’s mercy and grace, the body is able to maintain a balance. Should not the person watching these scenes stand in amazement, thinking: “Oh my God, what an incredible order! How great is Your knowledge, power, wisdom and art!”

As mentioned at the beginning of the article with reference to an actual sad incident, when a person whose sympathetic system is not functioning normally suddenly stands up, they can suffer from dizziness and perhaps even faint due to irregular blood pressure.

For patients suffering from orthostatic hypotension patients, it is important that they do not stand up rapidly. In addition, exercises that encourage the use of leg muscles before standing up will help pump blood towards the brain.

Pause for a minute… What would happen if this miraculous system did not exist? Consider how much time it would take you to merely get out of bed every day!