STRUCTURE AND FUNCTION
 Called
three things:
 1.
Membrane—
 because it covers the body
 2.
Organ—
 because it contains several kinds of tissues
 3.
System—
 because it contains organs that work
together to perform specific functions
 Protection:
 Body
Chemical, Physical, Biological
Temperature Regulation
 Storage
 Absorption
 Excretion
 Production
or Metabolic Functions
 Outer
layer/no blood vessels
 95% of the cells are keratinocytes—keratin
 Five different sub-layers
 New skin cells-basal layer
 Change from square to flat as move to the
surface
 Very tough; withstand scuffs and scrapes
 Melanocytes and Langerhans cells
 25-45 days
 Function-continuous supply of new skin cells,
resists friction, waterproof, and prevents
water loss
 Stratum
corneum (Horny layer) 15-25 layers
of dead, flat, squamous, epithelial cells.
Thicker over soles and palms
 Stratum lucidum (clear layer) only located in
the thicker areas
 Stratum granulosum (Granular layer)
waterproofing with keratin and lipids
 Stratum spinosum (Prickly layer) usually the
thickest layer, Langerhans cells—part of the
immune response
 Stratum basale (Basal cell layer) stem cells,
keratinocytes, Merkel cells, and melanocytes
 Thicker
than the epidermis
 Provides epidermis with nutrients
 Strong and flexible
 Fibroblast cells—collagen and elastin
 “body stocking”
 Two layers: Papillary and Reticular
 Hair follicles, sebaceous glands, blood
vessels, and sense receptors
 Papillary
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Phagocytes
Friction Ridges and fingerprints
 Reticular
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80% of the thickness of the dermis
Tension or cleavage lines
Flexure lines
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1,s:0
 Not
considered a skin layer
 Subcutaneous tissue
 Fat, blood vessels, and sensory receptors
 Cushions and insulates
 MELANOCYTES
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Everyone has the same #
Difference comes from the kind and amount of
melanin made and retained
Protection from the sun
Freckles and moles
 CAROTENE
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Yellow to orange pigment, converted to Vitamin
A
Asian
Palms, heels, and soles of feet
 HEMOGLOBIN

Rosy complexion in fair skin
 Cyanosis

Poor oxygenation
 Albino

Absence of color pigment
 Erythema

Redness
 Pallor,

blanching
Loss of color
 Jaundice

Yellow cast
 Bronzing

Copper color
 Hematomas

Black and blue marks/bruising
 Sweat
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Glands or sudoriferous glands
Up to 3 million per person
Two types: eccrine and apocrine
Eccrine—99% water
Primary purpose is to prevent overheating
Heat induced sweating begins on the forehead
Emotionally induced begins on the palms, soles,
and axillae
 Sebaceous

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
Glands
Oil glands
Everywhere except palms and soles
Sebum
Blemishes

Hair Follicles and Hair

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Millions cover our bodies except…..
Protection
Pigment/Color—melanocytes
Red hair—pigment containing iron
Gray or white hair—decreased melanin
Arrector pili—”raiser of hair” muscle and secretes
sebum out of the hair follicle
Normal hair loss
Fastest hair growth
Nutrition and hormones
Hirsutism
Alopecia
Baldness
Hair thinning
 Our
“hooves” or “claws”
 Protect fingers and toes
 Useful as “tools”
 Dead keratinized epidermal epithelial cells
 Pink from rich bed of capillaries in the
underlying dermis
 Nail matrix
 Changes in nail appearance:




Yellow-tinged
Thickened
Outward, concavity (spoon nail)
Horizontal lines (Beau’s lines)