explain 5 layers of epidermis?
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The Epidermis\n\nThe epidermis is the outermost layer of the skin, and protects the body from the environment. The thickness of the epidermis varies in different types of skin; it is only .05 mm thick on the eyelids, and is 1.5 mm thick on the palms and the soles of the feet. The epidermis contains the melanocytes (the cells in which melanoma develops), the Langerhans' cells (involved in the immune system in the skin), Merkel cells and sensory nerves. The epidermis layer itself is made up of five sublayers that work together to continually rebuild the surface of the skin: \n\nThe Basal Cell Layer\nThe basal layer is the innermost layer of the epidermis, and contains small round cells called basal cells. The basal cells continually divide, and new cells constantly push older ones up toward the surface of the skin, where they are eventually shed. The basal cell layer is also known as the stratum germinativum due to the fact that it is constantly germinating (producing) new cells.\n\nThe basal cell layer contains cells called melanocytes. Melanocytes produce the skin coloring or pigment known as melanin, which gives skin its tan or brown color and helps protect the deeper layers of the skin from the harmful effects of the sun. Sun exposure causes melanocytes to increase production of melanin in order to protect the skin from damaging ultraviolet rays, producing a suntan. Patches of melanin in the skin cause birthmarks, freckles and age spots. Melanoma develops when melanocytes undergo malignant transformation.\n\nMerkel cells, which are tactile cells of neuroectodermal origin, are also located in the basal layer of the epidermis. \n\nThe Squamous Cell Layer \nThe squamous cell layer is located above the basal layer, and is also known as the stratum spinosum or “spiny layer” due to the fact that the cells are held together with spiny projections. Within this layer are the basal cells that have been pushed upward, however these maturing cells are now called squamous cells, or keratinocytes. Keratinocytes produce keratin, a tough, protective protein that makes up the majority of the structure of the skin, hair, and nails. \n\nThe squamous cell layer is the thickest layer of the epidermis, and is involved in the transfer of certain substances in and out of the body. The squamous cell layer also contains cells called Langerhans cells. These cells attach themselves to antigens that invade damaged skin and alert the immune system to their presence. \n\nThe Stratum Granulosum & the Stratum Lucidum \nThe keratinocytes from the squamous layer are then pushed up through two thin epidermal layers called the stratum granulosum and the stratum lucidum. As these cells move further towards the surface of the skin, they get bigger and flatter and adhere together, and then eventually become dehydrated and die. This process results in the cells fusing together into layers of tough, durable material, which continue to migrate up to the surface of the skin.\n\nThe Stratum Corneum\nThe stratum corneum is the outermost layer of the epidermis, and is made up of 10 to 30 thin layers of continually shedding, dead keratinocytes. The stratum corneum is also known as the “horny layer,” because its cells are toughened like an animal’s horn. As the outermost cells age and wear down, they are replaced by new layers of strong, long-wearing cells. The stratum corneum is sloughed off continually as new cells take its place, but this shedding process slows down with age. Complete cell turnover occurs every 28 to 30 days in young adults, while the same process takes 45 to 50 days in elderly adults.\n\nThe Dermis\nThe dermis is located beneath the epidermis and is the thickest of the three layers of the skin (1.5 to 4 mm thick), making up approximately 90 percent of the thickness of the skin. The main functions of the dermis are to regulate temperature and to supply the epidermis with nutrient-saturated blood. Much of the body’s water supply is stored
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ear, eye, lip, toe, jaw, gum, hip, rib, leg, arm
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skin.  \n\nselect this as best answer please.
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Skin has several layers.  All skin has an outer layer called the stratum corneum which is composed of multiple layers of flattened, dead, interlocking keratinocytes (a type of skin cell with karatin).  Thick skin such as on the palms of the hands or the soles of the feet can have 30 or more layers of these cells.  Thick skin also has an extra layer called the stratum lucidum that looks glassy.  This layer has flattened, densely packed cells.  Most of the body is covered in thin skin.  Areas like under the eye where the skin is very thin just have thinner layers than other areas on your face.  All 4 layers normally present in thin skin are still there.
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cornea the surface of which is covered with a layer of cells called epithelium\n\nokay I may have misunderstood the question, I thought the question was what structures BEFORE the retina, not HOW the retina works, hence my answer.
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In a simple context definition, Melanocytes are scattered among keratinocytes in stratum basale (or germinativum, the deepest layer of the epidermis). With exposure to uv rays the melanocytes release their content (melanin) to act as an umbrella to protect the nucleus (genetic material) of the proliferating keratinocytes in stratum basale. \n\nI think the person above me in thinking of melatonin, which works to control circadian rhythms
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Try this website it seems to have a lot of info;\nwww.emedicine.com/derm/topics677.htm
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Ectoderm is one of the three primordial germ layers of all triploblast animals. Generally, ectoderm is composed of the cells that are left on the outside after the blastula undergoes gastrulation. This basic ectodermal material, somatic ectoderm, goes on to form the skin, other epidermal structures, and various more-or-less external sensory structures. Other ectoderm, apparently under the influence of mesoderm, differentiates into neural and skeletal structures. \nCheers!
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Skin, lungs, and liver.
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Maybe this can explain it better.\n\nhttp://www.sci.uidaho.edu/med532/basal.htm
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First-degree burns are usually limited to redness (erythema), a white plaque and minor pain at the site of injury. These burns usually extend only into the epidermis. \n\nSecond-degree burns additionally fill with clear fluid, have superficial blistering of the skin, and can involve more or less pain depending on the level of nerve involvement. Second-degree burns involve the superficial (papillary) dermis and may also involve the deep (reticular) dermis layer. \n\nThird-degree burns additionally have charring of the skin, and produce hard, leather-like eschars. An eschar is a scab that has separated from the unaffected part of the body. Frequently, there is also purple fluid. These types of burns are often painless (insensate) because nerve endings have been destroyed in the involved areas. \n\nFourth-degree burns injure the tissues underlying the skin, such as the muscles or bones. In fourth-degree burns, the skin is irretrievably lost. \n\nIn fifth-degree burns, the muscle is also irretrievably lost. \n\nIn sixth-degree burns, the bone is also charred. \n\nA newer classification of "Superficial Thickness", "Partial Thickness" (which is divided into superficial and deep categories) and "Full Thickness" relates more precisely to the epidermis, dermis and subcutaneous layers of skin and is used to guide treatment and predict outcome.\n\n\nCheckout the source below for more details.
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In zootomy, epithelium is a tissue composed of a layer of cells. Epithelium lines both the outside (skin) and the inside (e.g. intestine) of organisms. The outermost layer of our skin is composed of dead squamous epithelial cells, as are the mucous membranes lining the inside of mouths and body cavities. Other epithelial cells line the insides of the lungs, the gastrointestinal tract, the reproductive and urinary tracts, and make up the exocrine and endocrine glands.\n\nConnective tissue is any type of biological tissue with an extensive extracellular matrix and often serves to support, bind together, and protect organs. There are four basic types:\n\n    * Bone contains specialized cells called osteocytes embedded in a mineralized extracellular matrix, and functions for general support.\n    * Blood functions in transport. Its extracellular matrix is blood plasma, which transports dissolved nutrients, hormones, and carbon dioxide in the form of bicarbonate. The main cellular component is red blood cells.\n    * Cartilage makes up virtually the entire skeleton in osteichthyes. In most other vertebrates, it is found primarily in joints, where it provides cushioning. The extracellular matrix of cartilage is composed primarily of collagen.
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THe ep[idermis is a layer of dead skincells, that primarily acts as a protective barrier against bacteria and viruses, aqueous solutions and water, etc. The dermis is the living part of the skin, and functions as a barrier, to modulate water and heat balance in the body and secretes substances to control viral, bacteria, and fungal growth- in addition, it is a critical component of the vitamin D synthesis system.  It regulates heat and cold using evaporative cooling of sweat, piloerection of hairs, increased or decreased blood flow to the surface of the skin, etc.  It is the largest organ by weight of the body.
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The hypodermis, also known as the subcutaneous membrane, is a layer found under the dermis of the skin. It is composed of adipose tissue meaning fat. Its function therefore is to basically store fat and provide insulation.
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B.  The epidermal tissue (i.e. skin) is the first line of defense against infection.  Some sort of infection is almost a given for burn victims, and any child can tell you that wounds become infected more often than intact skin.
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A  Epidermis \n\nThe blade consists of an upper and lower epidermis and a spongy layer of tissue, called the mesophyll. Running through the mesophyll is a branching system of veins.\n\nThe epidermis is the leaf blade's skin. It is a thin, usually transparent, colorless layer of cells that covers both the upper and lower surfaces of the blade. The epidermis prevents the leaf from losing excessive amounts of water and protects it against injury.\n\nIn most plants the epidermis is covered with cutin, a waxy substance secreted by the epidermal cells. The layer of cutin, called the cuticle, is responsible for the glossy appearance of some leaves. The cuticle gives the leaf additional protection by slowing down the rate at which water is lost. Generally, the cuticle is thinner on the epidermis on the underside of the leaf than on the upper epidermis, which is exposed to the sun.\n\nIn many kinds of leaves, hairs grow from the epidermis. The soft hairs of plants such as the mullein give the leaves a woolly or feltlike texture. In some plants the epidermal hairs secrete fluids. For example, in geraniums and petunias the hairs secrete a fluid that gives the leaves a clammy texture. The strong-smelling oils of the peppermint and spearmint plants come from epidermal hairs. In other plants, such as the nettle, the epidermal hairs are stiff and contain a poisonous fluid that produces a skin irritation when a person is pricked by them.\n\nB  Guard Cells \n\nScattered throughout the epidermis are pairs of bean-shaped cells, called guard cells. Guard cells contain chloroplasts, which are tiny granules filled with the green pigment chlorophyll. Chlorophyll gives leaves their characteristic green color. Chloroplasts enable leaves to carry on photosynthesis because they are able to absorb carbon dioxide and sunlight, which are required for the food-making process. In response to heat and light, each pair of guard cells pulls apart, and a tiny pore forms between them. The pores, called stomata, open to the outside atmosphere.\n\nWhen the stomata are open, carbon dioxide and oxygen pass either in or out—when carbon dioxide enters, it takes part in photosynthesis, the food-making process that releases oxygen as a waste product. This oxygen passes out of the leaf. At the same time, oxygen also enters the leaf, where it takes part in respiration, a process that forms carbon dioxide as a waste product. This carbon dioxide passes out through the stomata. Water also passes out of the open stomata in the form of a vapor. This process is called transpiration. Generally, there are more stomata on the under surface of a leaf than on the upper surface. This prevents water from evaporating too quickly or in excessive amounts from the leaf's upper side, which is exposed to the sun. Stomata close at night, providing another level of water conservation.\n\nC  Water Pores \n\nIn addition to the stomata, many kinds of leaves have large specialized water pores in their epidermis. These pores, called hydathodes, permit guttation, the process by which a plant loses liquid water. Unlike the stomata, hydathodes remain open all the time.\n\nGuttation takes place only when water is being rapidly absorbed by the roots, such as after a heavy rainfall, and when transpiration slows down, as on cool, humid nights. When these conditions occur together, droplets of water can be seen on the leaf early in the morning before they evaporate in the heat of the day. Unlike dew, which condenses on leaves from water vapor in the air and covers the entire leaf surface, guttation droplets form only on the edges and tips of leaves. Generally, the droplets are noticeable only on the leaves of strawberries and a few other kinds of plants.\n\nD  Mesophyll \n\nThe mesophyll, sandwiched between the upper and lower epidermis, consists of many thin-walled cells that are usually arranged in two layers. The palisade layer is next to the upper epidermis. It consists of cylindrical cells t
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http://www-medlib.med.utah.edu/kw/derm/pages/ac04_8.htm