Chapter 6

Chapter 6 - Chapter 6: The Integumentary System Structure...

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Chapter 6: The Integumentary System Structure of the Skin and Subcutaneous tissue The skin is the body’s largest organ. 1. Skin consists of two layers: the epidermis and the dermis 2. Skin varies in thickness dues to variations in the stratum corneum. The Epidermis 1. The epidermis is stratified squamous epithelium. 2. The epidermis is cornified with the protein keratin. 3. The stratum basale, a single layer of cuboidal to low columnar cells, rests on the basement membrane and consists of three types of cells. a. Keratinocytes give rise to most new epidermal cells that are pushed outward during cell division. b. Melanocytes produce the pigment melanin, which is passed from them to keratinocytes through phagocytosis. c. Tactile (Merkel) cells are receptors for the sense of touch. 2. The stratum spinosum is made of several layers of flattened keratinocytes in which organelles are degenerating. a. The cells are attached to each other by desmosomes, giving them a spiny appearance as they shrink. b. Macrophages are present in this layer and the stratum ganulosum. 3. The stratum granulosum consists of three to five layers of cells with granules of keratohyalin. 4. The stratum lucidum is a thin, translucent zone seen only in thick skin, such as the soles of the feet. 5. The stratum corneum consists of up to 30 layers of dead, keratinized cells, making a waterproof, protective out layer.
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The Dermis 1. The dermis is primarily composed of fibroconnective tissue, with blood vessels, nerve endings, sweat glands, sebaceous glands, hair follicles and nail roots. 2. The papillary layer of the dermis is a zone of areolar tissue in and near the dermal papillae. a. Blood vessels extend close to the epidermis within the papillae, and the large number of white blood cells within this layer helps prevent infection. 2. The reticular layer contains dense irregular connective tissue. Stretching of the skin causes tears in this area, called striae or stretch marks. The Hypodermis 1. The hypodermis (subcutaneous tissue, or superficial fascia) is composed of areolar and adipose tissue between the skin and underlying muscle. 2. When adipose tissue dominates, the hypodermis is called the
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This note was uploaded on 04/17/2008 for the course BIOL 211 taught by Professor Wilson during the Fall '07 term at Winona.

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Chapter 6 - Chapter 6: The Integumentary System Structure...

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