Hair follicle receptor contains nerve endings Surrounds each hair bulb Allows

Hair follicle receptor contains nerve endings

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Hair follicle receptor – contains nerve endings Surrounds each hair bulb Allows us to feel when something touches our hair
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Nails Nail = keratinized cells of the epidermis that form a clear protective covering on ends of fingers and toes Nails contain hard keratin Each nail has a free edge, a body, and a root Root is embedded in the skin Nail bed - the deeper layers of the epidermis extend beneath the nail
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Nails Nail matrix – part of nail bed responsible for nail growth Nails appear pink because of capillaries in the underlying dermis Region of nail bed that lies over the thick nail matrix appears as a white crescent called the lunula
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Nail
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Functions of Skin Protection – acts as a chemical, physical and biological barrier Body temperature regulation Cutaneous Sensation Skin is supplied with cutaneous sensory receptors Meissner’s corpuscles - allow us to sense something against our skin Pacinian corpuscles – allows us to feel pressure Hair follicle receptors Nerve endings – alert us of pain
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Functions of Skin Metabolic functions – production of vitamin D from sunlight Blood Reservoir – dermis is highly vascularized Excretion – elimination of nitrogenous wastes (urea, ammonia, uric acid) as sweat
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Skin Cancer 1 in 5 Americans will develop skin cancer at some point in their lives Most skin tumors are benign and do not metastasize (spread to other areas) Crucial risk factor for skin cancer is overexposure to UV radiation in sunlight Damages DNA bases – causes cross-linking of DNA strand called “primer dimers” UV radiation also disables a tumor suppressor gene called p53
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Skin Cancer Cells with severely damaged DNA die after prolonged exposure to the sun Causes skin to peel after a sunburn Cells that DON’T die could have mutated DNA When cells proliferate – DNA damage could lead to uncontrolled growth cancer New skin lotions claim that they can fix damaged DNA in cells before they develop into cancer cells Lotions contain enzymes to repair cross-linked DNA strands
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Basal Cell Carcinoma Basal cell carcinoma - most common type but least malignant and of skin cancer Cancer lesions occur most often on sun-exposed areas of the face Appear as shiny, dome-shaped nodules that later develop a central ulcer Slow-growing, rarely metastasizes Growth is removed by surgical resection
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Squamous Cell Carcinoma Squamous cell carcinoma - arises from the keratinocytes of the stratum spinosum Lesion appears as a scaly reddened papule (small, rounded elevation) Usually found on the head (scalp, ears, and lower lip), and hands Grows rapidly and metastasizes if not removed
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Melanoma Melanoma - cancer of melanocytes Rare, but most dangerous type of skin cancer Can be treated if caught early Highly metastatic and resistant to chemotherapy Accounts for about 5% of skin cancers
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