The skin is the body largest organ because , it measures an impressive (21 1/2 ft square)
Your skin cells are constantly growing , dying and replacing themselves so that this organ can keep doing its main job efficiently -keeping out potentially harmful micro organisms such as bacteria .Kept waterproof and supply by an oily substance called sebum , your skin helps to control body temperature and to shield you from the harmful effects of the sun. Its receptors also give you all kinds of sensory information about the world around you.
Layers of the skin
The skin is composed of two layers the epidermis and the dermis
Epidermis – is the upper layer of the skin which is made of sheets of dead cells. Cells at the base of the epidermis continually grow , divide and migrate to the surface . As they travel , upwards,they fill with a tough fibrous protein called keratin which makes your skin strong and suppleness . (Your hair and nails are also made principally of keratin , and so are considered to be closely allied to the skin.)
By the time they reach the surface the skin cells are dead and are then shed as flakes of skin , making way for new skin . The epidermis also contains cells called melanocytes . These make the pigment melanin , which is responsible for filtering ultraviolet (UV) light from the sun and also give your skin color.
Dermis –The lower level is made of strong elastic tissue . The dermis contains all the blood vessels , nerves , lymph vessels , sweat glands , sebaceous glands , hair follicles , muscle fibre and receptors( sensitive organs that detects touch pressure , heat and cold ) that supply and support the epidermis . The cells that repair any damage are also found here.
Functions of the skin
1. Controlling body temperature
As well as protecting the body temperature internal organs from the the outside world , the skin has another vitally important function – helping to control body temperature . If your body becomes too hot , then the blood vessels in the dermis widen to disperse the heat , and sweat glands release perspiration to cool you down . If the body starts to get cold the blood vessel become narrower to hold the warm blood , and hair all over your skin stand on end to trap a layer of warm air around the body .
2. The protects you from sun UV ray
Most of us love the sunshine and the sun does have beneficial effects , but its ultraviolet radiation can also do great damage to the skin . The skin pigment melanin , reduces the amount of UV that can reach the dermis , but this is often not enough . Even the indigenous populations of very hot climates , whose dark skin means that they have high levels of filtering melanin , can still suffer from sunburn if over -exposed to the sun . As its name suggests , sunburn can be a serious burn and , apart from being very painful , can cause scarring premature aging of the skin .
Regularly exposing your skin to the sun with insufficient protection can quickly lead to damage that may go much deeper into the skin’s pigment -producing cells – called a malignant melanoma . This cancer is responsible for a large number of deaths worldwide each year. However , it can be cured if it caught early enough – prompt detection is the key .
The message is simple : Always cover up properly with sunscreen creams , hats and other clothing in strong or prolonged sun -especially if you are fair .UV protection sunglasses should also be worn since your eyes can be sunburned because it is also covered with skin . Research has shown that several episodes of serious sunburn in childhood can lead to cancer later in life , so keep babies and children well protected
UV light does , however , bring some good news . A certain amount of UV is vital to body processes and and the UV light that does penetrate the skin is crucial to production of Vitamin D , which is in turn essential for strong bones.
3. Tackling skin diseases
The skin’s role as protector of the body from infections and injury means that it is exposed to a wide range of dangers, including viral and bacterial infection and various allergens and irritants . Many skins conditions manifest themselves as rashes or raised red mark and typical symptoms include itchiness and sore or broken skin.
The skin defends your body against diseases by keeping a tight barrier on the top layer to keep out dirt and bacteria.
The inner layer of the skin which is the dermis contains the sebaceous gland which makes a oily substance called sebum , the sebum protects your you from these disease by making the skin acidic which is an environment that bacteria cannot multiply. Your skin also Langerhans cells which act as an immune system it attracts white bloods cells to any area of the skin that is broken to fight disease or infection .