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The Integumentary System
The Skin and its Appendages
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The Skin Two main components Epidermis Dermis (Hypodermis)
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Epidermis Keratinocytes Melanocytes Dendritic Cells (Langerhans cells)
Cells of the Epidermis Keratinocytes Melanocytes Dendritic Cells (Langerhans cells)
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Epidermis Thick Skin Thin Skin Stratum Basale Stratum Spinosum
Layers of the Epidermis Thick Skin Stratum Basale Stratum Spinosum Stratum Granulosum Stratum Lucidum Stratum Corneum Thin Skin Absence of Stratum Lucidum
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Epidermis Stratum Basale (germinatum) Single row of stem cells
Layers of Epidermis Stratum Basale (germinatum) Single row of stem cells 10-25% melanocytes very small amount of tactile cells
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Epidermis Stratum Spinosum Layers of the Epidermis several cells thick
weblike intermediate filament network melanin granules and dendritic cells present
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Epidermis Stratum Granulosum Layers of the Epidermis
Keratinization Begins Keratohyaline granules Lamellar granules
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Epidermis Stratum Lucidum Layers of the Epidermis
Only present in thick skin 2-3 rows of clear, flat, dead keratinocytes
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Epidermis Stratum Corneum Layers of the Epidermis anucleate
20-30 cells thick ¾ of epidermis high keratin content thickened, glycoprotein covered plasma membranes loses 50k cells/min
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Dermis Composition Connective Tissue proper
Rich nerve and vascular supply contains hair follicles, glands, and sensory receptors Layers Papillary Layer Reticular Layer
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Dermis Thin areolar highly vascularized
Papillary Layer Thin areolar highly vascularized low density (great for phagocytes) Dermal papillae (form friction ridges in thin skin)
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Dermis 80% of Dermis dense irregular connective tissue
Reticular layer 80% of Dermis dense irregular connective tissue blood vessel network (cutaneous plexus) cleaveage and flexure lines
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Appendages of the Skin Hair and Hair Follicles Nails Sweat Glands
Eccrine Glands Apocrine Glands Sebaceous (oil) Glands
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Appendages of the Skin Structure of hair Structure of a hair follicle
Hair and Hair Follicles Structure of hair Structure of a hair follicle Types and growth of hair Hair thinning and baldness
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Appendages of the skin Produced by hair follicles
Structure of a hair (fig 5.5) Produced by hair follicles Conists primarily of dead keratinized cells cells contain hard keratin Regions Shaft Root Concentric Layers Medulla Cortex Cuticle
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Appendages of the skin Epithelium based Hair bulb
Structure of a Hair Follicle (fig 5.5) Epithelium based Hair bulb Hair follicle receptor Hair papillae Peripheral connective tissue sheath Epithelial root sheath
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Appendages of the Skin Types and Growth of Hair Vellus Hair
Terminal Hair
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Appendages of the Skin Hair Thinning and Baldness Alopecia
True Baldness (Male Pattern)
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Appendages of the Skin Nails (fig 5.6)
Scale-like modification of epidermis hard keratin free edge, nail plate, root nail bed nail matrix nail folds and cuticle
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Appendages of the Skin Eccrine (Merocrine) Sweat Glands
Sweat (Sudoriferous) Glands Eccrine (Merocrine) Sweat Glands Apocrine Sweat Glands
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Appendages of the Skin Sebaceous (Oil) Glands
Simple branched alvolar glands secrete sebum holocrine type glands secrete into hair follicles and occasionally pores
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Skin Functions Chemical Barriers Physical Barriers Biological Barriers
Protection Chemical Barriers acid mantle Physical Barriers Biological Barriers dendritic cells, macrophages, DNA
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Skin Functions Body Temperature Regulation Heat Loss Vaodilation
heat loss through sweat evaporation Heat conservation Vasoconstriction
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Skin Functions Cutaneous Sensation
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Skin Functions Metabolic Functions Produces vitamin D precursor
disarm cancer causing chemicals activate some steroid hormones
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Skin Functions Blood Resevoir 5% of total blood volume
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Skin Functions Excretion ammonia, uric acid, urea, salt, water.
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Homeostatic Imbalances of Skin
Skin Cancer Basal Cell Carcinoma Squamous Cell Carcinoma Melanoma Asymmetry Border Irregularity Color Diameter Elevation
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Study Guide Will Post Wednesday
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