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The Integumentary Syste3

The Integumentary Syste3 - keratinocytes Merkel cells...

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The Integumentary System The Skin (Integument): composed of 2 regions: - Epidermis: outermost layer composed of epithelial cells - Dermis: underlying layer composed of fibrous connective tissue; vascularized Hypodermis: subcutaneous layer just deep to the dermis - mostly adipose with some areolar connective tissue Epidermis: keratinized stratified squamous epithelium - 4 distinct cell types: keratinocytes: produce the fibrous protein keratin tightly connected by desmosomes outermost cells dead & keratinized ; lifespan of 25-45 days melanocytes: spider-shaped cells that produce the pigment melanin located in deepest layer of epidermis; melanosomes in melanocyte processes transfer melanin to keratinocytes melanin granules protect the cell nucleus from UV radiation - Langerhans' cells (epidermal dendritic cells): macrophages ; part of immune system
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Unformatted text preview: keratinocytes- Merkel cells: associate with disclike sensory nerve endings to form Merkel disc - a sensory receptor for touch Layers of Epidermis:- Thick skin has 5 layers (strata) Stratum basale, stratum spinosum, stratum granulosum, stratum lucidum & stratum corneum- Thin skin has only 4 layers. .. missing stratum lucidum; stratum corneum thinner Stratum Basale (Stratum Germinativum): basal layer; deepest epidermal layer firmly attached to dermis- single layer of cells; cell division produces new keratinocytes for all layers Stratum Spinosum: several layers thick; intermediate filaments form network & attach cells at desmosomes- keratinocytes are flat & spiny (prickle cells)- some melanin granules; Langerhans' cells Stratum Granulosum: 3-5 cell layers thick- keratohyaline granules: help in keratin formation- lamellated granules: contain waterproofing glycolipid - released into extracellular space to prevent water loss...
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The Integumentary Syste3 - keratinocytes Merkel cells...

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