The Skin

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The Skin
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• Skin is the main part of the _integumentary____
  system.
• Skin is the __largest______ organ in the body (on
  average about _9_ pounds)
• General Functions of the Skin
• 1. Protection against infection and dehydration
• 2. Body temperature regulation ? homeostasis
• 3. Vitamin D production ? bone health (calcium)

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• Layers of the Skin
• Epidermis
• The __outer________ layer of the skin
• Structure and Function
• Composed of _stratified squamous____ epithelium
• Cells are called _keratinocytes_ ? produce
  _keratin (protein)_ for protection
• Epithelial cells have a very limited _blood
  supply____
• Deeper epidermis contains _melanocytes__ ?
  produce pigment _melanin__
• The _higher ____ the amount of __melanin_____,
  the __darker___ the skin

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• Dermis
• The _inner_________ layer of the skin
• Structure and Function
• Relatively _thicker___ than the epidermis
• Made up of many components
• Dense irregular connective tissue
• Epithelial cells ? hair follicles
• Nervous tissue ? receptors
• Blood vessels ? diffusion of nutrients
• _Glands__, _fingernails _hair__ follicles
  originate in dermal tissue

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Skin Accessories Hair Where does hair come
from? A depression (hair follicle) in the dermal
tissue extending out through the epidermis Where
is hair found? All body surfaces except palms,
soles, lips and nipples What is hair made
of? Keratinized (dead) epidermal cells What is
hairs function? Provide warmth
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• Nails
• Structure and function
• _Modified epithelial cells__ used for
  __protection____
• Found on the ends of the __fingers ____
  ___toes___

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Glands Description _ Function Sebaceous
gland specialized epithelial cells secretes oil
(keeps hair soft, waterproof) Eccrine
sweat gland sweat gland with odorless temperature
secretion regulation Aporcrine
sweat gland less abundant sweat gland wets
skin during pain (secretions with odor) or
fear Ceruminous gland modified sweat
gland secretes ear wax Mammary gland modified
sweat gland secretes milk