skin-outline - Integumentary System page 1 of 8 ANAT 11110...

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Integumentary System page 1 of 8 ANAT 11110 Lectures 14, 15, 16, & 17 Fall 2011 The Integumentary System I. Introduction A. Skin: aka, integument, an organ within the integumentary system B. Integumentary system: composed of skin + accessory organs (nails, hair, glands, nerve endings, etc.) II. Function A. Protective covering B. Regulation of body temperature 1. Retains internal body heat via subcutaneous layer 2. When necessary, eliminates excessive body heat a. Radiation of heat through subcutaneous dilated blood vessels b. Evaporation of perspiration on surface of skin c. Convection and conduction of heat directly through skin C. Housing of sensory receptors D. Synthesis of various chemicals (e.g., keratin, melanin, vitamin D) E. Excretion of waste materials (by means of perspiration) III. Structure of skin A. Epidermis: keratinized stratified squamous epithelium 1. Stratum basale: deepest layer, actively mitotic 2. Stratum spinosum: slightly mitotic, in conjunction with the stratum basale, referred to as the stratum germinativum; synthesis of keratin (a structural protein)
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Integumentary System page 2 of 8 3. Stratum granulosum 4. Stratum lucidum: present only in the thickest skin 5. Stratum corneum: 20-30 layers of flattened, keratinized dead cells B. Dermis 1. Composed of connective tissue, and housing muscle fibers, blood vessels, hair follicles, exocrine glands, and sensory nerve fibers 2. Two layers a. Papillary layer: loose connective tissue directly underlying the epidermis i. Dermal ridges (such as fingerprints) due to the pulling of elastic fibers in the papillary layer b. Reticular layer: dense irregular connective tissue underlying the papillary layer i. Quite distensible and resilient; when over-stretched, it tears, producing 'stretch marks' C. Subcutaneous layer (aka, hypodermis): loose connective tissue and adipose tissue interlaced with blood vessels 1. Adipose tissue serves as heat insulator and energy reservoir a. Conserves internal body heat or impedes entrance of external heat b. Distribution of subcutaneous adipose varies throughout the body and between the sexes (generally 8% thicker in women than in men) c. Thickness of subcutaneous layer can be indicative of nutritional status 2. Binds skin to underlying organs (as ‘superficial fascia’)
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Integumentary System page 3 of 8 IV. Skin color A. Causes of skin coloration 1. Pink: Blood flow in dermis and subcutaneous layers imparts a pinkish coloration to the skin 2. Yellow a. Carotene: Yellowish pigment acquired through the diet b. Having a thicker stratum corneum with an associated increase in the
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skin-outline - Integumentary System page 1 of 8 ANAT 11110...

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