Were the skin human, she would always be seen at the shrink’s office, complaining of how much she is undervalued, uncared for, and unappreciated, despite her doing so much. The skin is not only the largest organ of the body but also one of the most important. It serves as a mediator between our internal environment and the outside world; protecting our internal organs from trauma, variations in temperature and infections from pathogens. The skin does so much and despite being plain on the surface, it is composed of various important structural machineries that susceptible to the harmful effect of the sun.
Integument, which is what the skin is popularly called in the anatomical world, consists of three major components, which are the hypodermis, the dermis and the epidermis. The hypodermis is what reduces the pain of sitting for too long. Thickest in the buttocks, palms, and soles of the feet, it is the deepest section of the skin that acts as a padded shock absorber and as an insulator. The dermis which comes between the hypodermis and the epidermis is a layer of the skin that comprises of a fibrous network of tissues, which encompass structural proteins (collagen and elastin), blood vessels, specialized cells (mast cells and fibroblasts), nerves, hair follicles, sweat glands and sebaceous glands. This fibrous network of tissue provides support and nutrition for the epidermis, which ultimately gives the skin its strong structural integrity and flexibility. The epidermis is the tough outermost layer that acts as a protective shield and protects the body from infections, dehydration and external abrasions.
Truly, the skin is undervalued and one cannot but marvel at the several vital functions of the skin. The skin protects the body from external mechanical damage and abrasions, infectious biological components of the environment, and also chemical damage. With aid of the blood vessels, it helps regulate body temperature, and provide nutrition for the upper layers of the skin. The skin also contains many nerve endings that confer to us the ability of feeling. The feeling of heat, cold, pressure and even pleasure are as a result of the nerve endings present in the skin. You’ll think I’m done, but guess what? That’s only a meager amount of what the skin does. The skin acts as food storage in the form of fats which serves as a backup. Its structural integrity also helps in retaining fluids, thus preventing us from dehydration even in harsh conditions. The skin also protects the body from harmful ultraviolet rays, by stimulating the production of melanin which absorbs light and prevents damage of skin. The skin with the aid of a cholesterol compound (7-dehydrocholecalciferol) in the dermis, makes the harmful effect of UV radiation beneficial by synthesizing vitamin D which is essential for bone formation and bone health. The skin truly amazing and versatile in function, just as it provides nutrition; it is also a means by which waste products such as urea and sodium chloride are excreted out of the body. And as the first line of immune defense, it fights bacterial, fungal and viral pathogens, even if they invade it. Lastly the skin is a tell sign of the physiological state and well being of the body. It helps communicate to us and the physician whether there’s a problem. Instances are feeling hot when you have a fever, sweating profusely, having rashes or blisters or boils when you have an infection, and looking pale when you’re ill and yellow when you have jaundice. It also influences our social interaction, like blushing when you’re embarrassed, having goose bumps when you’re irritated, smelling when you need a bath and that which I’m not sure of is turning green when you’re jealous. All the same, the skin is truly special and all-rounded in function.
With the skin offering so much protection one can only wonder why we don’t do our best to protect it. While the effect of UV radiation can be beneficial in terms of aiding the synthesis of vitamin D and increasing the levels of serotonin that lifts our mood, it is very harmful to the skin and our health. Components of the skin such as collagen that provides strength to the skin, elastin which confers elasticity to skin, and keratin which is the strongest protein in the skin are the major important structural components that are affected by ultraviolet rays. The collagen is the most abundant structural protein that makes the skin look youthful, thus preventing wrinkles and accelerated fine lines. The mesh-like framework houses the elastin and when attacked by UV radiation leads to tangling of elastin. UVR irradiation of human skin also causes the appearance of dyskeratotic keratinocytes, which is commonly known as sunburn cells. Sun damage to the various structural components of the skin is what eventually leads to premature aging, wrinkling and sagging of the skin.
It is completely natural for the skin to age over time; with the skin thinning, wrinkling and becoming more fragile as one gets into the late years. But while it is natural for the skin to age, it is made worse and accelerated by external factors such as smoking and prolonged sun exposure. Prolonged exposure to UV radiation from the sun, increases production of free oxygen radicals (reactive oxygen species) which damage the skin cells in a process called oxidative stress. Oxidative stress is the leading cause of photoaging with the harmful UV radiation breaking down the skin collagen and elastin that gives the skin a youthful appearance. Harmful radiations from the sun causes severe sun damage that induces abnormal structural makeup and alterations in keratinocytes, melanocytes and functional changes in Langerhans cells, which help with immune response when faced with infection. The sun emits two types of ultraviolet rays, the UVA and UVB rays. The UVB rays which has a shorter wavelength is the sun burn ray which is scientifically described as an induced erythema of the skin caused by vasodilatation of dermal vessels. UVB rays not only cause sun damage but penetrate and mutate skin cells to cause direct DNA damage that leads to skin diseases such as keratosis and skin cancer. The UV-A ray which is more penetrative is the leading cause of premature aging and can cause skin cancer through indirect mutation of skin cell DNA.
Melanocytes are specialized epidermal cells that produce the pigment melanin that gives color to the skin and protects the body from UV radiation. On prolong exposure to the sun, and instances when sun burn occurs, the skin produces more melanin which darkens the skin and prevent cellular DNA damage. Even though melanin offers some protection to the skin from UV radiation, excessive sun exposure alters this process and leads to hyperpigmentation and other skin disorders. It is also important to know that melanoma skin cancer develops in the melanocytes and it is the most dangerous form of skin cancer, causing 75% of all skin cancer deaths and if untreated quickly can spread to other parts of the body to cause more havoc. Be it non-melanoma skin cancer (basal and squamous skin cell cancer), or malignant melanoma, there’s a positive correlation between prolonged sun exposure and the development of these cancers, and this is made evident in the sun exposed areas which are mainly affected, such as the head and neck. The level of protection provided by melanin is unclear which is why, while melanin offers protection from UV radiation, it still important to protect the skin as melanin cannot offer 24 hour protection, doesn’t protect the skin from UV-A rays and most importantly doesn’t make you immune to skin cancer.
For healthy skin, it then becomes important to not only take care of the skin but also protect the skin from sun damage, since it causes severe skin damage that alters the structural identity, matrix composition, vascular structure, function, and cellular activities of the skin. From sun allergies to severe skin diseases like skin cancer, the sun causes a plethora of skin disorders and infection. Some of which include different forms of hyperpigmentation such as solar lentigos, melasma, rosacea and other photosentivity disorders. All the layers of the skin work in perfect synergy when they’re healthy and since the sun is major threat to skin health, we should avoid prolonged sun exposure, wear appropriate clothing that protects us, wear sun shades, and apply sunscreen that protects the skin from harmful UV radiation.