Term
| What are the General Functions of Skin? |
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Definition
1. Protective 2. Sensory 3. Thermoregulation 4. Metabolic Functions |
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Term
| What are the 3 layers of skin? |
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Definition
Epidermis Dermis Hypodermis |
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Term
| What are some characteristics of the Epidermis? |
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Definition
1. The outer epithelial layer 2. Keratinized stratified squamous epithelium 3. Major cell type of the keratinocyte 4. Minor cells types are Merkel cells, Langerhans cells, and melanocytes |
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Term
| What are the 5 layers of the Epidermis? |
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Definition
Stratum Basale Stratim Spinosum Stratum Granulosum Stratum Lucidum Stratum Corneum |
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Term
| What are the characterstics of the Stratum Basale? |
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Definition
- Basal most layer
- Basement membrane containing single layer of low columnar cells
- Desmosomes bind the cells at the upper and lateral surfaces of hemidesmosomes bind the cells to the basal lamina
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Term
| What are the characteristics of the Stratum Spinosum? |
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Definition
- Contains 2 to 4 layers of cells connected by desmosomes
- Cells have a spiny appearance
- These cells contain keratin filaments organized into bundles called tonofibrils
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Term
| What are the characteristics of the Stratum Granulosum? |
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Definition
| Contains 2-3 layers of flattened squamous epithelial cells with cytoplasm filled with coarse basophilic granules. |
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Term
| What are the characteristics of the Stratum Lucidum? |
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Definition
| An extremely think translucent layer more apparent in thick skin. |
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Term
| What are the characteristics of the Stratum Corneum? |
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Definition
| The apical more layer, contains many layers of flat-cornified cells with cytoplasm filled with 8-10 ηm keratin filaments. |
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Term
| What are the 2 major zones of the Dermis? |
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Definition
1. Papillary Dermis - layer adjecent to epidermis, loose areolar connective tissue, plexus of blood vessels 2. Reticular Dermis - Deepest Layer, Dense irregular connective tissue. |
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Term
| What are the cells that are found in the epidermis? |
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Definition
| Keratinocytes, Melanocytes, Langerhans cells, Merkel cells |
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Term
| What are characteristics of the Keratinocytes? |
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Definition
- Primary cell type in the basal epidermis
- Originate in the basal epidermis
- Differentiation involves production of keratin and epidermal water barrier
- Melanosome complexes are characteristic features of these cells
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Term
| Describe the process of Keratinization |
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Definition
1. Keratinocytes in Stratum Basale synthesize keratin that will assemble into keratin intermediate filaments (tonofilaments) 2. In Stratum Spinosum, keratin filament assembly continues and they become grouped in bundles 3. Tonofilaments become large enough to be visualized in light microscope and are called tonofibrils 4. Keratohyaline granules begin to be formed in the upper stratum spinosum and become distinctive features of the stratum granulosum 5. Keratohyalin granules increase and release contents into cytoplasm including filaggrin and trichohyalin that promote tonofilament assembly and initiate the process of cornification. |
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