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Cards In This Set
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2 regions of skin (integument)
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- Epidermis - superficial region
- epithelial tissue - Dermis - underlies epidermis - mostly fibrous connective tissue |
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Hypodermis (superficial fascia)
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- subcutaneous layer deep to skin
- not part of skin but shares some functions - mostly adipose tissue that absorbs shock and insulates - anchors skin to underlying structures - mostly muscles |
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Epidermis
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- keratinized stratified squamous epithelim
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4 or 5 layers of Epidermis
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- stratum basale
- stratum spinosum - stratum granulosum - stratum lucidum (only in thick skin) - stratum corneum |
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4 cell types of epidermis
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- Keratinocytes
- melanocytes - dendritic (langerhans) cells - tactile (merkel) cells |
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Stratum corneum
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Most superficial layer - 20-30 layers of dead cells; essentially flat membranous sacs filled with keratin. Glycolipis in extracellular space.
Protect from abrasion and penetration Barrier against biologics, chemical and physical assaults |
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Stratum granulosum
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Typically five layers of flattened cells, organelles deteriorating; cytoplasm full of lamellar granules (release lipids) and keratohyaline granules.
cells above this layer die - too far from dermal capillaries |
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Stratum spinosum
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Several layers of keratinocytes unified by desmosomes. cells contain thick bundles of intermediate filaments made of pre-keratin.
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Stratum basale
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Deepest epidermal layer; one row of actively mitotic stem cells; some newly formed cells become part of the more superficial layers. see occasional melanocytes and dendritic cells.
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Cells of Epidermis
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- Keratinocytes
- Produce fibrous protein keratin - tightly connected by desmosomes - Melanocytes - produce pigment melanin - packaged into melanosomes - Dendritic (Langerhans) cells - macrophages - key activators of immune system - Tactile (Merkel) cells - sensory touch receptors |
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Stratum Basale
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Also called stratum germinativum
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Stratum Lucidum (Clear Layer)
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- Only in thick skin
- thin, translucent band superficial to the stratum granulosum |
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Apoptosis
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Allows cells to change from stratum basale to stratum corneum
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Dermis
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- strong, flexible connective tissue
- Cells - fibroblasts, macrophages, and occasionally mast cells and white blood cells - Fibers in matrix bind body together - "hide" used to make leather - Contains nerve fibers; blood and lymphatic vessels - Contains epidermal hair follicles; oil and sweat glands |
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2 layers of Dermis
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- Papillary
- Reticular |
