Ch 5 Book notes.docx - 1 Chapter 5 The Integumentary System 5-1 Describe the main structural features of the epidermis and explain the functional

Ch 5 Book notes.docx - 1 Chapter 5 The Integumentary System...

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1 Chapter 5 : The Integumentary System 5-1 Describe the main structural features of the epidermis and explain the functional significance of each. Avascular and NO blood vessels Rely on the diffusion of nutrients and oxygen from capillaries within the underlying dermis Keratinocytes are the body’s most abundant epithelial cells o Form several layers or cells and contain keratin Thick skin found on palms of hands, soles of feet, contains 5 layers of cells Only four layers make up thin skin which covers rest of the body Stratum Basale – deepest epidermal layer o Hemidesmosomes attach the cells of this layer firmly to the basement membrane o Form epidermal ridges which extend into the dermis Between ridges, dermal projections called dermal papillae extend upward into the epidermis Increases the surface area for diffusion of nutrients between the dermis and epidermis o Superficial ridges on palms and soles increase surface area of skin and increase friction ensuring a secure grip o Basal cells or germinative cells dominate the stratum Basale Continuous division replaces cells that are lost or shed at epithelial surface Intermediate Strata o Stratum spinosum – continue to divide and add to the thickness of the epithelium Consists of keratinocytes held together by desmosomes
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2 Chapter 5 : The Integumentary System Contains branched dendritic cells that take part in the immune response o Stratum granulosum – consists of cells displaced from the stratum spinosum Stopped dividing and have begun making large amounts of the protein keratin o In thick skin, palms and soles have a glassy stratum lucidum covers that covers stratum granulosum The cells are flattened, densely packed, and filled with keratin Stratum Corneum o Contains 15-30 layers of flattened and dead epithelial cells packed with filaments of keratin o Dead cells in each layer remain tightly connected by desmosomes It takes 7-10 days for cells to move from stratum Basale to the stratum corneum 5-2 Explain what accounts for individual differences in skin color and discuss the response of melanocytes to sunlight exposure. The Role of Pigmentation o Carotene is an orange-yellow pigment that normally accumulates in epidermal cells found in carrots, squashes, and orange-colored vegetables eating lots of carrots skin of light skinned individuals to turn orange carrots can be converted to vitamin A which is required for maintenance of epithelial tissues and synthesis of photoreceptor pigments in the eye o Melanin is pigment made by pigment-producing cells called melanocytes
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3 Chapter 5 : The Integumentary System Two types: red-yellow and brown-black form
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