We tend to overlook our skin, but it performs many vital functions for our bodies – including coming to our rescue in emergencies.

Since it is designed to function within very precise limits, our body is very susceptible to small temperature changes. Since abnormalities in these changes occur, the body has various mechanisms to keep its temperature constant. One of these mechanisms works by changing the amount of blood in the veins underneath the skin. When talking about body temperature, it is important to distinguish between the internal and external body temperature. The internal temperature is the temperature of the brain and internal organs, while the external body temperature is the temperature of the skin.

Normally, arteries that transport clean blood, and veins that carry dirty blood, are not connected; therefore clean and dirty blood never mix. However, as a consequence of some illnesses or birth defects, an abnormal bridge between arteries and veins may be present. This kind of condition is usually called arteriovenous shunts, or arteriovenous fistula. In these kinds of situations, blood is pumped directly from arteries to veins. In other words, clean blood flows towards dirty blood. Normally, the clean blood has to travel the body, providing oxygen and other supplements to cells, while collecting carbon dioxide and returning to the heart to be cleaned again.

An incredible network for the transportation of substances from the blood in arteries and veins has been created. If this system, known as the “capillary network,” did not exist, none of our organs could be fed, and the circulatory system would not be able to provide its vital function.

The system is necessary for two reasons. The speed of the blood in the arteries and veins is too fast for anything to be transported to the organs, and their walls are too thick to allow transportation of substances. Therefore, the blood travels from the arteries to the capillaries, and after the trading of oxygen and other substances with carbon dioxide is completed, it flows to the veins. If any kind of abnormalities exist, the blood flows directly from the arteries to the veins, therefore skipping the capillaries. As a consequence, the organs aren’t fed and the blood gathers in the veins without fulfilling its purpose. Naturally, the oxygen and nutrition balance of the organs gets messed up. The blood is pumped out of the heart with no purpose and heart failure becomes inevitable.

The capillary network has been assigned the task of communication between arteries and veins. The skins is our only organ where the blood flows directly from arteries to veins; AV shunts accomplish a very important duty in this function.

There is a network of veins underneath the skin. The number of veins in this network is so many that if they were completely filled up, they could hold up to two liters of blood in the skin. Blood is pumped to the skin for two purposes: to provide oxygen and nutrients to the cells, and to collect carbon dioxide and waste products in the cells, as is done with every organ; and to monitor the internal temperature of the body by sending blood to the skin if the temperature gets too high, similar to what radiators in cars do when the engine gets too hot.

There is also the subcutaneous fat tissue underneath the skin which acts as an insulator. The vein network mentioned above is inside this fat tissue. There is a continuous flow of blood from the capillaries that feed the skin towards this network of veins. Moreover, especially in areas where the skin is exposed – such as the hands, feet, face and ears – there is a blood flow from the small arteries towards this network of veins. Contrary to other organs in the body, blood flows directly from the arteries to the veins. If this direct blood flow did not exist, the amount of blood in the skin’s veins would be close to zero, because the amount of blood necessary for skin nutrition is very little. However when the internal temperature rises too much, the amount of blood, which is normally close to zero, can suddenly increase to as much as 30% of the blood pumped by the heart. In this case, the body’s internal temperature is being transported to the skin. This is an incredibly efficient cooling system. However, if the weather is cold, the AV shunt veins are switched off and the skin’s blood flow is decreased until close to zero, therefore maintaining internal temperature. The fat tissue underneath the skin also has a very important function, as it acts as insulation, helping maintain temperature.

Body temperature and the body’s systems work in perfect coordination with each other. We can observe a very simplified version of this system in computer based air conditioners. However, when we reflect upon the incredibly sophisticated cooling system of the human body, we come to the conclusion that no other system is as perfect as that.

The hypothalamus, which has various vital duties for the brain, was also given the very important mission of controlling the body’s temperature. There are hot and cold heat receptors in various parts of the hypothalamus. When body temperature increases, these receptors are activated. As a consequence of this warning, skin veins all over the body expand. Simultaneous with the expansion of the veins, sweat is excreted.

The hypothalamus also has the duty of suppressing the mechanisms that produce heat throughout the body. For example, trembling is stopped and general metabolism is slowed down to decrease body temperature. As metabolism slows down, the production of heat becomes minimal, and cooling takes place. In conditions where the body temperature is too cold, some hormones secreted in the hypothalamus trigger the pituitary, and then the thyroid, hormones. Since thyroid hormones are responsible for increasing metabolism, body temperature increases. However if body temperature increases above normal, the control of the hypothalamus on the thyroid is reversed, and thyroid hormones are decreased, therefore decreasing body temperature.

There is one more reason for placing so many veins in the perfect and miraculous body’s skin: except for extremely cold weather conditions, quite a large amount of blood exists in these veins that are not used for nutritional purposes. Some of our organs act as storage for blood; two of the most important ones are the spleen and liver. Another one is the skin. In the course of losing blood, or an illness that increases the need for blood, the spleen and liver shrink. As a consequence of this shrinkage, the blood inside them is sent to the heart, through veins, and distributed to the areas in need of blood. This increases the heart rate.

A similar scenario occurs in the skin. The veins responsible for cooling shrink, and the blood they contain is sent to the heart with the help of the main veins, therefore helping the heart pump. During heavy loss of blood, the blood in the skin comes to the rescue. Patients who are losing blood have incredibly cold and pale skin. This is because the blood in the skin has reduced to a minimum.

The obverse of this happens in an illness called erythromelalgia, where more blood than normal flows from the arteries to the veins in the skin. This is mostly seen in the hands, feet, nose, and ears, since AV shunts are more prevalent in these areas of the skin. The symptom of this illness is burning pain, which is triggered by heat and soothed by cool temperatures. The nutrition of the skin decreases and some substances produced because of the absence of oxygen increases redness, heat, and pain, since some of the capillaries feeding the skin shut down and all of the blood flows from arteries to veins with the AV shunts.

Our skin protects our muscles and bones, and contributes to the beautiful aesthetic of our body. It provides our sense of touch, and is therefore a means for us to experience the material world, as well as providing temperature control for our bodies. It can clearly be seen that the relationship between the skin and the veins could not have evolved by the consequence of coincidence.

The skin, which covers a total surface area of approximately 1.65 m2 and which weighs in total about 9.5 kg, is surely the largest and the heaviest organ of the human body; yet its miraculous functions are still a puzzle to us.

A layered structure

The human skin is composed of three layers: the epidermis (outermost layer), the dermis (vascular connective tissue below the epidermis) and the hypodermis (the deepest portion of the skin), each of which has a very complex metabolism of its own. Each of the structures of which the skin is comprised has a wide variety of functions; all of these functions must be in order if we are to maintain our good health. In particular the epidermis and the dermis each have their own distinct functions, but also share some duties, and all of these are essential for the survival of the human. The thickness of the skin varies from 8 mm on the palms and soles of the feet to nearly less than 1 mm on the eyelids. Within the epidermis are found four dif¬ferent types of cells that undertake different tasks; the appearance of our skin, in terms of texture, evenness of color, hydration, and overall youthfulness and constitutional health, is greatly dependent on the interaction of these cellular functions.

A single organ with several functions

It is very interesting that the majority of people are not aware of the fact that the skin is one organ.

Not only does it cover the body, our skin performs many amazing tasks such as,

-helping with water conservation,

-helping with the maintenance of body temperature,

-perception of touch

-providing a barrier to harmful germs,

-storing fat,

-storing vitamin D,

-acting as a mechanical barrier against knocks or bumps,

-helping in the removal of the waste products of metabolism

-providing protection against environmental influences, such as cold or high temperatures, and destructive ultraviolet rays, as well.

It is common knowledge that the major task of our skin is to protect the human body from harmful environmental factors. It is, indisputable that the fundamental purpose of the skin is to provide a flexible, protective shield between us and the outside world. This is made possible by the layers of flattened epithelial cells which hinder micro-organisms and chemicals from entering the body.

Constant replacement

The benefits we have mentioned would not last long, however, if skin cells were not renewed. This amazing regeneration process happens through a replacement operation that is dependent on a continuous cell division in the basal layer. As the cells move towards the outer surface they lose their softness. Consequently, they gradually die off and stiffen. Dead cells are constantly sloughed off from the upper surface of the epidermis and are continuously shed; they are replaced by new cells that are generated in the deeper layers. This process is often referred to as “cellular renewal.” As cells progress through the various stages, they finally stiffen and die or keratinize. This dead cell layer, or keratinocytes, makes up the outermost layer of the epidermis, the stratum corneum. These hardened and cornified cells are designed by our Creator to act as a protective barrier; otherwise, living cells would not be able to provide the protective qualities necessary to isolate the living tissue from exposure to possible detrimental substances and organisms. The living epidermal cells die by an extremely sophisticated process, displaying a voluntary self-sacrifice that enables humans survive, an evident blessing from our Most Gracious Lord.

Regulation of body temperature

The regulation of temperature is considered to be one of the major duties given to the skin. We naturally lose water through constant evaporation throughout our lives. It is of utmost importance that the loss of too much body fluid is prevented. By narrowing or widening the capillary blood vessels and also by means of numerous sweat glands, evaporation on the surface enables our skin to become cooler or warmer, in a strictly limited range of temperatures. The fat cells of the skin prevent losing too much heat, and when the body overheats, the skin’s extensive small blood vessels carry warm blood to the surface where it is cooled. So, as we can deduce from this, the main task of the skin is to prevent the loss of body fluids through evaporation.

Another task of the skin is the storing of fat and the production of vitamin D [25-dihydroxycholecalciferol]. Vitamin D is a fat-soluble vitamin that is found in food and can also be processed in our body after exposure to ultraviolet (UV) rays from the sun. Sunshine is a significant source of vitamin D because the UV rays from the sun stimulate the synthesis of vitamin D in the skin. This fundamental feature of our skin is, clearly, indispensable to our skeletal development.

The witness

The human skin has also a function in sense communication with the environment. It gathers sensory information from the environment; this is performed by means of a great number of receptors (for example, those for warmth and cold) and intraepithelial nerve endings. Nerve cells in the skin form the body’s first contact with the outer world. At the moment of birth, an infant’s first experiences of the physical world are perceived through the sense of touch. Nerve cells allow the skin to receive and transmit signals from touch, pain, tickling, etc. As the skin is the boundary between a living creature and the world around it, it is also the physical interface between the creature and other creatures and the world. Hence it is the location of all contact, good or bad in kind. The Qur’an declares that the skin will also testify when we are called to account on the Day of Judgment:

Until when they reach it, their ears, and their eyes, and their skins will bear witness against them as to all that they did habitually. They will ask their skins, “Why have you borne witness against us?” They will answer: “God Who makes everything speak has made us speak.” It is He Who has created you in the first instance, and to Him you are being brought back. You did not seek to veil yourselves (when sinning) without ever considering that your ears or your eyes or your skins would one day bear witness against you. (Fussilat 41:21-22)

As pointed out in the verse …the abode of the Hereafter is truly alive (29:64), everything in the Abode of Hereafter will be alive. So, like every part of a human being, the skin will bear witness for or against them. The verse implies that it is the medium where all our contact is recorded and it will be an ideal witness.

Wounds and healing

Another astounding mission of our skin is its role in healing wounds. The human skin has remarkable selfhealing properties, which obviously point to an intelligent design. A skin wound heals from the bottom up and from the edges inward. In the first stages of healing, the basic connective tissue of the skin moves into the injured area. The depth of the wound determines how well it will heal; the regeneration process begins immediately, but we still do not know what the trigger is. As a wound heals, the edges are drawn together by a process called contracture. The most amazing part of this phenomenon are the later stages of healing. It is as if all the cells are fully aware when and where to end the repair. Nobody knows why they abruptly stop working and how they finalize restoration.

A shield against germs

Our skin also serves us by organizing and activating the immune system. Some specific cells, which form a network in the epidermis or in the outer layer of skin, play an important part in this activity, by regulating the immune response to germs. As a major contributor to the body’s immune system, constituting the first line of de fense in keeping out bacteria, viruses, and other organisms that invade the body, the skin is home to enormous quantities of T-lymphocytes, or T-cells. Those domestic defense soldiers attack and destroy bacteria, fungi, viruses, parasites, toxins, and cancerous cells that can cause disease. Thus, the skin is both a watertight barrier surrounding and protecting our body from a number of external assaults, never letting the undesired pathogenic germs penetrate.

Our Almighty and Everlasting Creator has granted us this gift of skin. He knows what those who are in need are in need of, and it is obvious that He is aware of the need of our cells, our organs, and our living metabolism, thus He has given the most favorable structural design to the human body. Just before we pray to Him, we should remember that the more consistent our demands, the more bountiful He will ordain. Frankly, there seems to be no way to explain the miracle of skin other than attributing it to the All- Beneficent God.

References

1. Cognis Deutschland GmbH & Co. KG Skin Care Forum 2006.

2. ABPI – The Association of the British Pharmaceutical Industry.

3. Dr. K.K. LO, Social Hygiene Handbook – 2nd Edition.

4. Helmut Leonhardt, His, Zyt und Mikroanatomie des Menschen, Vol. 3, Thieme, Stuttgart 1990.

5. H. Brannon M.D., The skin anatomy ed. 2002.

6. Beauty Clinics Hashmi.com. Skin Analysis 2005.

7. Goldsmith LA, Biochem and Physiology of the Skin 2nd ed NY Oxford University Press, 1991. 8. Breathnach AS. Atlas of the Ultrastructure of Human Skin. London: J. & A. Churchill, 1971.

9. Elias PM. Epidermal lipids, membranes, and keratinization. Int J Dermatol 1981; 20: 1-19.

10. National Skin Care Institute 2005-2006 website.

11. Ali Ünal, The Qur’an with Annotated Interpretation in Modern English, The Light, Inc., NJ:2006.