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anatomy8
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Cutaneous Membrane Accessory Structures
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Integumentary System
Made up of all 4 tissue types . . . .??
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Two Major SubdivisionsTwo Major Subdivisions
• Cutaneous Membrane– Epidermis– Dermis– Hypodermis
• Accessory Structures – Excretory glands (?)– ?– ?
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EpidermisEpidermis• Type of Epithelium?
• _vascular
• Different layers (=strata)– 4 layers in
thin skin
– 5 layers in thick skin
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Stratum germinativum
= stratumbasale
Innermost, single layer
Stratum GerminativumCell types:• Stem cells (basal cells)• Melanocytes• Merkel cells (touch receptors in hairless skin only)
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Stratum spinosumSeveral cells
thick
Stratum Spinosum• Stem cell daughter cells (some can still divide)• Melanocytes & Langerhans cells• Establishment of Desmosomes
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Stratum granulosum
Stratum Granulosum• Cells displaced from stratum spinosum Keratinocytes• Production of keratohyalin and keratin fibers• Cells start to die. Dehydration leaves interlocked layers of
keratin, keratohyalin & PL membranes
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Stratum lucidum
Stratum Lucidum• In palms of hands and soles of feet • Cells do not stain well clear (lucid) looking
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Stratum Corneum
• Many layers of flattened, dead cells, filled with keratin• Continually shed in sheaths• Water-resistant but not water proof ( insensible
perspiration)• Relatively dry - advantage?• Keratinization occurs everywhere except for anterior
surface of eye
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15-30 layers (much thicker in thick skin)
Thin vs. Thick Skin
• Up to 6 x thicker• Where??
• Average 0.08 mm• Rest of body
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Refers to epidermis
Contour of skin surface follows pattern of epidermal ridges. Advantage ??
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Unique fingerprints
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Skin Color depends on 3 pigmentsHemoglobin (dermal blood supply)
– Reddish tones– Pale, due to?– Bluish (=?), due to?
Melanin – Produced by melanocytes of stratum basale
Carotene Obtained from plant foods
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Number of melanocytes same in all people, production levels differ !
Melanocytes
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Function ?
DermisDermis
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Papillary layer loose c.t.
Reticular layer dense irregular c.t.
Papillary LayerPapillary Layer
• Dermal papillae project between epidermal ridges.
Consist of
• Loose c.t. = _____
• Capillaries
• Tactile receptorswww.freelivedoctor.com
M
Reticular LayerReticular LayerConsist of
• ______________ c.t.
• + ??
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Pacinian corpuscule(deep pressure)
HypodermisHypodermis
• 2 other names ?2 other names ?
• Indistinct boundary (c.t. fibers interwoven)
Made up of– Loose c.t. + lots of . . .
Function– Stabilization of skin while
allowing for independent movement
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Accessory Structures: Hair Follicles & Hair
• 5 mio hair/hu body. (98% not on top of head)
• Three hair types (vellus – intermediate – terminal)
• Function ?
• Hair color
• Growth cycle
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Skin Glands: 1) Sebaceous GlandsSkin Glands: 1) Sebaceous GlandsHolocrineSebum discharged into hair follicles
(lubrication & bactericidal)excessive shampooing leads to dry & brittle hair
Sebaceous follicles, = Large sebaceous glands, discharge directly to epidermis
Where ?Folliculitis; furuncle (boil); acne
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2) 2) Apocrine Sweat GlandsSweat Glands• Have merocrine secretion!!
• Empty into hair follicle
• Location: armpits, groin, nipples
• Viscous, cloudy secretion good nutrient source for bacteria (odor !!)
• Secretion may contain Pheromones
• Secretion begins at puberty and is stimulated during emotional distress (cold sweat)
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3) Merocrine Sweat Glands3) Merocrine Sweat Glands
• Empty directly onto skin surface
• Location: most all over body (esp. abundant on palms & soles: ~ 500/cm2)
• Clear, watery secretion (99% H2O; rest NaCl + some waste products)
• Sensible perspiration; Function: ?
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For purpose of completion:
Other integumentary Glands:
• Mammary glands: Modified apocrine sweat glands
• Ceruminous glands: modified sweat glands in __________
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Nails not covered.Skin and Aging Process
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