5. The Vital Functions of Your Skin
Skin is the largest organ of the human body. It covers the body entirely and is composed of primarily two layers. The outermost, or upper layer of the skin is called the epidermis, the part we see, feel and touch. The epidermis, which consists of several layers, is mostly made of dead epithelial cells.
Directly beneath the epidermis is the other primary skin layer, the dermis. This layer has small blood vessels, nerve endings, oil and sweat glands and hair follicles. The dermis also contains collagen and elastic tissue, which function to keep the skin firm and strong. There is an extra layer underlying the dermis called the subcutaneous layer, made up of fatty tissue that acts as a foundation for the dermis.
1. Protection As the first line of defense against the external environment, the epidermis is continuously replenishing and shedding tens of thousands of dead cells every minute to protect the body from:
▶ Mechanical Impact Skin is the first physical barrier to withstand any pressure, stress or trauma. When this mechanical impact is stronger than the skin, a wound will occur, as a breakage through skin with loss of one or more of the skin functions.
▶ Fluids Due to the tight packing of cells in the outermost layer of the epidermis (the stratum corneum layer,) our skin helps us retain necessary body fluids and moisture and protects us from the
absorption of external fluids or liquids. We can bathe, swim and walk in the rain without concern. Our skin prevents the absorption of any harmful substance or excessive water loss through skin.
▶ Radiation If it weren’t for skin, the ultraviolet light (UV light) radiating from sun would damage the underlying tissue in our bodies. This protection is provided by the melanin pigmentation
in the epidermis. The skin and its pigmentation helps protect us from many medical illnesses like skin cancers, but because it doesn’t offer complete protection, we should avoid excessive exposure to sunlight by using sunblock and adequate clothing.
▶ Infection The top layer of skin is covered with a thin, oily coat of moisture that prevents most foreign substances or organisms, such as fungi, viruses and bacteria from entering the skin. The epidermis also has Langerhans cells, which help to regulate immune responses to pathogens that come into contact with the skin.
2. Thermal Regulation Temperature regulation is aided by the skin through the sweat glands and blood vessels in the dermis. Increased evaporation of the secreted sweat decreases the body temperature. Vasodilation (relaxing of small blood vessels) in the dermis makes it easier for the body to release some heat and lower the body temperature through skin. Vasoconstriction (contracting small blood vessels,) causes the dermis to retain some of the internal body temperature. The fatty subcutaneous layer of the skin also acts as an insulation barrier, helping to prevent the loss of heat from the body and decreasing the effect of cold temperatures.
3. Sensation An important function of the skin dermis is to detect the different sensations of heat, cold, pressure, contact and pain. Sensation is detected through the nerve endings in the dermis which are easily affected by wounds. Sensation in the skin plays a role in helping to protect us from burn wounds. The skin’s sensation can protect us from first and second degree burns, but in cases of third degree burns, it is less effective, as we don’t feel any pain due to the fact that the nerve endings in the skin are destroyed, indicating a more severe injury.
4. Endocrine Function Skin is one of our main sources of vitamin D, through the production of Cholecalciferol (D3) in the two lowermost layers of the epidermis, the stratum basale and stratum spinosum.
Stay tuned – more useful skin care information coming!
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