Integumentary System Ch 5 Marieb
Terms
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- Skin Functions
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⬢ Cushions and insulates deeper organs
⬢ Protects body from bumps, scrapes, and cuts
⬢ Protects body from chemicals, heat, and cold - Layers of Epidermis
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Stratum basale (stratum geminativum)
Stratum spinosum
Stratum granulosum
Stratum lucidum (only in thick skin)
Stratum corneum - Layers of Dermis
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•Papillary layer – includes dermal papillae
•Reticular layer – deeper layer – 80% of thickness of dermis - Keratinocytes
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• Keratinocytes – most abundant cell type in epidermis
• Arise from deepest layer of epidermis
• Produce keratin – a tough fibrous protein
• Produce antibodies and enzymes
• Keratinocytes are dead at skin's surface - Pigments
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• Melanin – most important pigment – made from tyrosine
• Carotene – yellowish pigment from carrots and tomatoes
• Hemoglobin – Caucasian skin contains little melanin
• Allows crimson color of blood to show through - Sebaceous Glands
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Sebaceous Glands
•Occur over entire body, except palms and soles
•Secrete sebum – an oily substance
•Simple alveolar glands
•Holocrine secretion – entire cell breaks up to form secretion
•Most are associated with a hair follicle
•Functions of sebum
• Collects dirt; softens and lubricates hair and skin - Two types of sweat gland
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Eccrine gland
•Most numerous – produce true sweat
Apocrine gland
•Confined to axillary, anal, and genital areas
•Produce a special kind of sweat - Thick vs Thin skin
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⬢Stratum lucidum layer
(only in thick skin) - Tissues of Dermis & epidermis develpo from
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⬢Epidermis develops from embryonic ectoderm
⬢Dermis and hypodermis develop from mesoderm - 77
- 77