Chapter 5 Integumentary System

Chapter 5 - Chapter 5 Integumentary System Angela Peterson-Ford PhD BIOL 2401 A&P I [email protected] Skin(Integument Consists of three

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Chapter 5 Integumentary System Angela Peterson-Ford, PhD [email protected]
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Skin (Integument) Consists of three major regions Epidermis – outermost superficial region Dermis – middle region Hypodermis (superficial fascia) – deepest region
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Skin (Integument) Figure 5.1
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Epidermis Composed of keratinized stratified squamous epithelium, consisting of four distinct cell types and four or five layers Cell types include keratinocytes, melanocytes, Merkel cells, and Langerhans’ cells Outer portion of the skin is exposed to the external environment and functions in protection
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Cells of the Epidermis Keratinocytes – produce the fibrous protein keratin Melanocytes – produce the brown pigment melanin Langerhans’ cells – epidermal macrophages that help activate the immune system Merkel cells – function as touch receptors in association with sensory nerve endings
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Deepest epidermal layer firmly attached to the dermis Consists of a single row of the youngest keratinocytes Cells undergo rapid division, hence its alternate name, stratum germinativum Layers of the Epidermis: Stratum Basale (Basal Layer)
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Layers of the Epidermis: Stratum Basale (Basal Layer) Figure 5.2b
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Cells contain a weblike system of intermediate filaments attached to desmosomes Melanin granules and Langerhans’ cells are abundant in this layer Layers of the Epidermis: Stratum Spinosum (Prickly Layer)
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Thin; three to five cell layers in which drastic changes in keratinocyte appearance occurs Keratohyaline and lamellated granules accumulate in the cells of this layer Layers of the Epidermis: Stratum Granulosum (Granular Layer)
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Thin, transparent band superficial to the stratum granulosum Consists of a few rows of flat, dead keratinocytes Present only in thick skin Layers of the Epidermis: Stratum Lucidum (Clear Layer)
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Outermost layer of keratinized cells Accounts for three quarters of the epidermal thickness Functions include: Waterproofing Protection from abrasion and penetration Rendering the body relatively insensitive to biological, chemical, and physical assaults Layers of the Epidermis: Stratum Corneum (Horny Layer)
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Dermis Second major skin region containing strong, flexible connective tissue Cell types include fibroblasts, macrophages, and occasionally mast cells and white blood cells Composed of two layers – papillary and reticular
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Layers of the Dermis: Papillary Layer Papillary layer Areolar connective tissue with collagen and elastic fibers Its superior surface contains peglike projections called dermal papillae Dermal papillae contain capillary loops, Meissner’s corpuscles, and free nerve endings
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Layers of the Dermis: Reticular Layer Reticular layer Accounts for approximately 80% of the thickness of the skin Collagen fibers in this layer add strength and resiliency to the skin Elastin fibers provide stretch-recoil properties
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Hypodermis Subcutaneous layer deep to the skin Composed of adipose and areolar connective tissue
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This note was uploaded on 01/06/2012 for the course BIOL 2401 taught by Professor Elainefanin during the Spring '11 term at Collins.

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Chapter 5 - Chapter 5 Integumentary System Angela Peterson-Ford PhD BIOL 2401 A&P I [email protected] Skin(Integument Consists of three

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