Ch.5- Integumentary Sys.docx - Ch 5 Integumentary System The Skin and the Hypodermis o Skin our largest organ Accounts for 7 of our body weight Varies

Ch.5- Integumentary Sys.docx - Ch 5 Integumentary System...

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Ch. 5- Integumentary System - The Skin and the Hypodermis o Skin- our largest organ Accounts for 7% of our body weight Varies in thickness from 1.5 to 4.4cm Divided into 2 distinct layers Epidermis Dermis Hypodermis- lies deep to the dermis Composed of areolar and adipose tissues Not part of the integumentary system, but shares some of skin’s properties o 5 important functions 1. Protection a. Cushions organs and protects from bumps, chemicals, water, loss, UV radiation 2. Body temperature regulation a. Capillary network and sweat glands heat loss 3. Excretion a. Urea, salts, and water lost through sweat 4. Production of vitamin D a. Epidermal cells use UV radiating to synthesize vitamin D 5. Sensory reception a. Contains sense organs associated with nerve endings - Epidermis o Is composed of keratinized stratified squamous epithelium o Contains 4 main cell types Keratinocytes Location- stratum spinosum; produce keratin, a fibrous protein Melanocytes Location- basal layer; manufacture and secrete pigment Tactile epithelial cells (Merkel cells) Location- basal layer; attached to sensory nerve endings Dendritic cells (Langerhan’s cells) Location- stratum spinosum; part of immune system; macrophage-like o Keratinocytes- most abundant cell type in epidermis Arise from deepest later of epidermis Produce keratin, a tough fibrous protein Produce antibiotics and enzymes Keratinocytes are dead at skin’s surface - Layers of the Epidermis o Stratum corneum o Stratum lucidum (only in thick skin) o Stratum granulosum o Stratum spinosum o Stratum basale (stratum geminativum) 1
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- Stratum Basale o Deepest layer of epidermis o Attached to underlying dermis
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