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CH 6 The Integumentary System
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Integumentary System

• Skin
• Accessory Structures
• hair
• nails
• glands

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Functions

• Protection
• Maintenance of normal body temp.
• Storage, Excretions, Synthesis
• Sensory reception

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Skin (Cutaneous Membrane)

• Epidermis
• Dermis
• Hypodermis

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Epidermis

• Stratified squamous epithelium
• Stratum corneum
• Intermediate layer
• Stratum germinativum

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Stratum Corneum

• Flattened dead epithelial cells
• Tightly joined
• Filled with keratin

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Stratum Germinativum

• Bottom layer
• Produces ridges
• Contains stem cells

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Melanocytes

• Specialized cells which produce pigment (melanin)
• Pigment injected into epithelial cells

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Skin Color

• Due to amount of pigment produced
• Number of melanocytes same in all races
• Freckles are due to uneven distribution of pigment

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Ultraviolet radiation

• Melanin absorbs UV radiation
• UV damages cells (DNA)
• Limited exposure good since some cell produce
  Vitamin D in response

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Dermis

• Lies below epidermis
• Contains
• glands
• muscles
• hair follicles
• nerves
• BVs

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Dermis

• Loose CT on top
• Dense CT on bottom

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Hypodermis

• Also called subcutaneous layer
• Loose CT, especially adipose
• Blood vessels at D/Hd junction

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Accessory Structures

• Hair
• Glands
• Nails

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Hair

• Originates in hair follicle
• Originates in dermis, may extend into hypodermis
• Attached to Arrector pili muscles (produce goose
  bumps)
• Formed from epithelial cells coated with keratin

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Hair Texture and Color

• Hair texture derived from differences in shape of
  hair shaft/hair follicle
• Hair color comes from melanocytes at base of
  follicle

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Function of Hair

• Protection from UV radiation
• Cushioning
• Heat retention
• Prevent entry of foreign substances (nose, ears,
  eyelashes)

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Exocrine Glands

• Sebaceous glands
• Sweat glands

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Sebaceous Glands

• Duct of gland may empty into hair follicle or
  surface of skin
• Secretion sensitive to hormones (acne)
• Produce sebum
• waxy, oily secretion
• lubricates hair shaft
• inhibits bacterial growth

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Sweat Glands

• Two types of Sudoriferous glands
• Apocrine
• Merocrin (eccrine)

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Apocrine Sweat Glands

• Found in axillary regions, and around nipples
• Empty into hair follicles
• Produces thick cloudy secretion
• produces odor when broken down by bacteria

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Merocrine Sweat Glands

• More numerous than apocrine
• Open directly onto surface of skin
• Functions to cool body
• Produce clear secretion (sweat)
• 99 water
• salts, urea (nitrogenous waste)

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Nails

• Form over tips of phalanges (finger and toes)

• Nail body grows from nail root
• Cuticle is stratum corneum