Human Anatomy

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Human Anatomy

• The Integument System

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Function(s)

• Physical protection
• Thermoregulation
• Excretion
• Synthesis of vitamin D3

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Structure of Skin
2 layers epidermis and dermis
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A. Epidermis

• Consists only of epithelial cells
• Avascular no blood supply
• No nerve supply
• 5 distinct layers of epithelial cells

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Epidermis
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2
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1. Stratum Germinativum

• Deepest layer, in contact with dermis
• Single layer of cells
• Only layer of epidermis capable of cell division
• Contain melanocytes

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Melanocytes
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Melanocytes
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Melanocytes

• Capable of producing the brown pigment, melanin
• Melanin can absorb energy from ultraviolet (UV)
  light
• UV light contains high energy photons that can
  damage DNA mutations
• Melanin can prevent damage to DNA, helps to
  prevent skin cancer

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Melanocytes
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2. Stratum Spinosum

• Several layers thick
• Cells of this layer begin to produce keratin
• Keratin is a water-insoluble protein that
  protects the body from water

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2. Stratum Spinosum
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3. Stratum Granulosum

• Multilayer and cells become compressed
• Keratin crystallizes into granuoles within the
  cytoplasm
• Cells are metabolically dead

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3. Stratum Granulosum
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4. Stratum Lucidum

• Clear layer of cells
• Only present in thick skin
• Cells nothing more than a bag of keratin

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4. Stratum Lucidum
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5. Stratum Corneum

• Multiple layers of flattened, dead cells
• Number of layers depends on region of the body
• More friction, more layers of cells

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Accessory Structuresof the Integument

• Hair follicles
• Oil and sweat glands
• Nails

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Skin Color

• Is determined by 3 pigments
• Hemoglobin red pigment within rbc
• Melanin brown pigment in melanocytes
• Carotene orange-yellow pigment found in both
  epidermal cells and dermal fat cells

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B. Dermis

• Consists of other 3 tissue types
• CT
• Muscle
• Nervous
• Has blood supply and nerves

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Dermis
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Dermis

• CT adds collagen and elastic fibers which give
  strength and stretch properties

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Dermis

• 2. Muscle arrector pili m. which is attached
  to shaft of hair follicle

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Dermis

• 3. Nervous detects light touch, stretch, deep
  pressure,vibration and temperature