skin-outline - Integumentary System page 1 of 9 ANAT 51210...

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Integumentary System page 1 of 9 ANAT 51210 Lectures 22, 23, 24, & 25 Fall 2011 Skin and 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, cutaneous sensory receptors) 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 cutaneous sensory receptors D. Excretion of waste materials (by means of perspiration) III. Structure of skin A. Epidermis 1. Composed of keratinized stratified squamous epithelium 2. Histologically, divisible into four or five distinct layers, depending upon skin thickness
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Integumentary System page 2 of 9 a. Layers deepest to most superficial: stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum b. Stratum basale + stratum spinosum = stratum germinativum, the only mitotic layers i. Keratin: a structural protein which toughens and waterproofs the surface of the epidermis; manufacture begins in the stratum spinosum c. 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: thin layer of loose connective tissue directly underlying the epidermis i. Dermal ridges (such as fingerprints and toe prints) due to the pulling of elastic fibers in papillary layer b. Reticular layer: dense irregular connective tissue underlying the papillary layer i. Quite distensible and elastic; when over-stretched, it tears, producing ‘stretch marks’ C. Subcutaneous layer (aka, hypodermis or superficial fascia): loose connective tissue and adipose tissue interlaced with blood vessels; no sharp boundary between dermis and subcutaneous layers 1. Functions of adipose tissue a. Insulation: conserves internal body heat or impedes entrance of external heat
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Integumentary System page 3 of 9 b. Distribution of subcutaneous fat varies throughout the body and between the sexes (generally 8% thicker in women than in men) c. Thickness of subcutaneous layer indicative of nutritional status 2. Binds skin to underlying organs 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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This note was uploaded on 01/03/2012 for the course ANAT 51210 taught by Professor Manley-buser during the Fall '11 term at Palmer Chiropractic.

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skin-outline - Integumentary System page 1 of 9 ANAT 51210...

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