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Integumentary System
Skin & its appendages
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Cutaneous Membrane
Thin skin, relatively flat organ.
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Epidermis
-Superficial, thinner layer
-Epithelial Layer derived from the ectodermal germ layer of the embryo
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Dermis
Dense, vascular connective tissue layer that may avg more than 4 mm in thickness.
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Dermoepidermaljunction (DEJ)
The area where the cells of the epidermis meet the the tissue cells of the dermis
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Hypodermis
Located beneath the dermis , and is rich in fat and loose connective tissues.
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Thin skin
Most of what the body surface is covered with.
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Thick skin
Hairless skin covering the palms of the hands, fingertips, soles of the feet, and other body areas subject to friction.
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Friction Ridges
In thick skin the underlying dermal papillae are raised in curving parallel to form fingerprints and footprints, that are visible on the overlying epidermis.
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Keratinocytes
Epidermal cell reponsible fro synthesizing keratin.
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Keratin
Tough fibrous protein substance in hair, nails, outer skin cells, and horny tissues.
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Melanocytes
Cell type in the stratum basale of the skin that produces melanin pigment granules, releasing them to other nearby skin cells.
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Dendritic Cells
Also called Langerhan cells, phagocytic cells in the skin. Play a role in immunity.
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Stratum Basale
'Base layer', Single layer of columnar cells. Deepest layer of the epidermis; cells in this layer are able to reproduce themselves.
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Stratum Spinosa
'Spiny layer'; layer of the epidermis that is rich in RNA to aid in protein synthesis req'd for keratin production
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Stratum Granulosom
'Granular layer', layer of which keratinization begins.
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Keratohyalin
Staining granules located within the stratum lucidum; required for surface keratin formation.
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Stratum Lucidum
'Clear' layer of the epidermis, in thick skin between the stratum granulosum and the stratum corneum.
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Eleidin
Substance found in the dying cells of the stratum lucidum; transforms to keratin.
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Stratum Corneum
Tough outer layer of the of the epidermis; cells are filled with keratin.
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Keratinization
Process by which cells of the stratum corneum become fitted with keratin and move to the surface.
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Sebaceous Glands
Found everywhere except palms and soles. They secret sebum (oil) and are usuallly associated with hair follicles.
-Function of sebum is to lubricate hair & skin, their secretion is stimulated by hormones, especially adrogens.
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Sudoriferious Glands
Eccrine sweat glands are simple tubular glands important in temp regulation.
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Ceruminous Glands
Found in ear canals. Secretes cerumen which prevents dryness of the skin of the ear canal, and repels insects.
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Hair Follicles
Composed of dead, keratinized cells and is produced by hair follicles. Arrector pilli muscles are assoc. with ea. hair follicle and is responsible for goose bumps.
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Dermis
Responsible for most of structural strength of the skin.
Cells found in the dermis are, fibroblasts, macrophages, and mast cells.
Dermis contains blood vessels, nerves, hair follicles, arrector pili muscles, and glands.
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Dermal Layers
Reticular Layer
Papillary layer
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Reticular Layer
Comprises abt 80% of the dermis, blends into the hypodermis.
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Papillary Layer
Has more cells, and fewer fibers, and looser. Contains many blood vessels in this layer to support the epidermis.
The papillae of the dermis of thick skin ( on soles and palms ) are in parallel, curving ridges, that shape the epidermis into fingerprints and footprints which inprove grip.
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Hypodermis
Also known as the subcutaneous (subQ) layer.
Not a part of skin, attaches skin to underlying muscles and is composed of loose connective tissue and fat.
Half of the body's fat is in the subQ layer, variations depend on age, sex, and weight.
Fat in the hypodermis serves as an effective shock asborber
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