BIOL 2130 Lecture Notes - Lecture 16: Metabolic Waste, Sebaceous Gland, Lubricant
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Melanin
Pigment (melanin) produced by melanocytes
Color is yellow to brown to black
Melanocytes are mostly in the stratum basale
Melanin accumulates in membrane-bound granules called melanosomes
Amount of melanin produced depends upon genetics and exposure to sunlight
Epidermal Dendritic Cells & Merkel Cells
Epidermal dendritic cells
oAlert and activate immune cells to a threat (bacterial or viral invasion)
Merkel cells
oAssociated with sensory nerve endings
oServe as touch receptors called Merkel discs
Dermis
Two layers
oPapillary layer (upper dermal region)
Projections called dermal papillae
Some contain capillary loops
Others house pain receptors (free nerve endings) and touch
receptors
Fingerprints are identifying films of sweat
oReticular layer (deepest skin layer)
Blood vessels
Sweat and oil glands
Deep pressure receptors (lamella corpuscles)
Overall dermis structure
oCollagen and elastic fibers located throughout the dermis
Collagen fibers give skin its toughness
Elastic fibers give skin elasticity
oBlood vessels play a role in body temperature regulation
oNerve supply sends messages to the central nervous system
Skin Color
Three pigments contribute to skin color:
oMelanin
Yellow, reddish brown, or black pigments
oCarotene
Orange-yellow pigment from some vegetables
oHemoglobin
Red coloring from blood cells in dermal capillaries
Oxygen content determines the extent of red coloring
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