Integumentary System
It’s Skin-tastic!!
Fun Facts
•  Considered the body’s largest organ
–  15-20 square feet.
•  Also considered an organ system
General Functions
1.  Protection
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Mechanical
Chemical
Bacterial
UV
Desiccation
2.  Temperature Homeostasis
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Too hot: sweat glands, flushing
Too cold: arrector pilli, pale
3.  Excretion
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Sweat glands release water, salts,
ammonia
Oil glands release lipids, acids
5.  Sensation
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Touch
Pressure
Heat
Cold
Pain
5.  Synthesis
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Light passes through skin to convert
vitamin D into usable form
7.  Non-Verbal Communication
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Facial expressions
Anatomy
•  Epidermis
Skin
•  Dermis
•  Subcutaneous layer or hypodermis
Layer #1
•  Epidermis - Top Layer
–  Five layers
–  Top layer is keratinized (waxy) for protection
and water proofing
–  Replaced every 35-45 days
–  Holds melanocytes, which are responsible for
turning your skin colors
Layer #2
•  Dermis - Middle Layer
–  Mostly connective tissue for strength
–  Lots of blood vessels
–  Dermal papilla: makes finger prints
–  Sebaceous gland: produces oil
–  Arrector Pili: muscle makes hair stand up
–  Sweat gland: helps regulate temperature
Layer #3
•  Hypodermis - Bottom layer
–  Mostly fat
–  Good for insulation (not as much in babies/
elderly)
–  Attaches the dermis to the underlying
organs
–  Contains LOTS of blood vessels
Accessory organs or epidermal
derivatives
•  Hairs
–  Epidermal growths that function in
protection
–  Shaft, root, and folllicle
–  Sebaceous glands, arrector pili muscle,
and hair root plexus (touch)
–  Hair growth and replacement have a
cyclical pattern
–  ‘male-pattern’ baldness
Nails
•  Plates of highly packed, keratinized
cells
•  Protection, scratching, & manipulation
•  Formed by cells in nail bed called the
matrix ( in area of lunula)
•  Grow 1 mm / week
•  Eponychium - cuticle
•  Hyponychium - little skin under nail
Skin Glands
•  Sebaceous (oil) glands
–  Usually connected to hair follicles
–  Moistens hair and waterproofs skin
•  Sweat glands
•  Water, salt, wastes
•  Function is to cool the body (also nervous)
•  Odor occurs when broken down by bacteria
•  Ceruminous glands
–  Modified sweat glands
–  Secrete cerumen (ear wax)
•  Mammary glands
–  Secrete milk
Skin color
•  Genetic factors
–  All races have the same number of
melanocytes, but the types of pigments
they have are different
–  Albinism
•  Environmental factors
–  Uv light or x-rays
Skin Pigments
Three pigments contribute to skin color:
1.  Melanin:
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Yellow to red to dark brown
Responsible for darker skin colors
Freckles and moles come from large
accumulations of melanin
Skin Pigments
2.  Carotene:
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Yellow to orange
Most obvious in the palms and soles of
feet
Found in carrots
Skin Pigments
3.  Hemoglobin:
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Reddish pigment
Responsible for the pinkish hue of the
skin
Carried in blood