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Chapter 5 Integument Functions Protection Barrier to microorganisms, abrasions, and water loss Thermoregulation Vasoconstriction or –dilation of blood vessels, Goose bumps or sweat Fat and hair Sensation Nerve endings to detect external stimuli throughout Meissner’s corpuscles, Merkel discs, Pacinian corpuscles, hair follicle receptors, and free nerve endings Metabolic roles Vitamin D from cholesterol Proteins to deter wrinkles Excretion Removes wastes from body (sweat) Functional Organization of Integument Integument System Cutaneous Membrane Epidermis Accesory Structures Hair Follicles Dermis Papillary Layer Reticular Layer Exocrine Glands Nails The Skin as an Organ Largest of the body All 4 epithelial tissue types represented Ranges in thickness Thick (palms, fingertips, soles of feet) Thin (rest of body) 2 layers Epidermis is stratified squamous 4/5 layers and 4 cell types Dermis is dense irregular CT Multiple cell types and accessory structures; 2 layers Hypodermis not true integument Connective tissue and fat cells Epidermal Cells Keratinocytes Produce keratin Joined by desmosomes Formed deep Dead at surface Accelerated on feet/hands Calluses from constant friction Melanocyte Produce melanin Formed deep Keratinocytes take up Skin color due to activity not number Tans signal DNA damage, fades as keratinocytes destroy Epidermal Cells (cont.) Merkel cells Touch sensitive cells Epidermal/dermal border Langerhans cells Phagocytic cells Assist immune system response Formed in bone marrow Epidermal Layers Stratum basale Single row, many nuclei Attached to basal lamina Some melanocytes and langerhans cells Stratum spinosum Thick layers of ‘spiny’ keratinocytes Langerhans cells most abundant Stratum granulosum Thin, 3-5 layers Keraticoytes fill w/ keratin Cell ‘toughen’ and die Stratum lucidum Thin, translucent layer Only in thick skin Few, dead, densely packed keratinocytes Stratum corneum 20-30 cells thick 14 days for cells to reach and remain 14 more Dermis Flexible and strong CT Elastic, reticular, and collagen fibers Fibroblasts, macrophages (WBC), and mast cells (histamine) Tearing causes stretch marks (striae) Blisters when epi- and dermis separate by fluid-filled pocket 2 layers Papillary layer Reticular layer Dermal Layers Papillary layer (20%) Reticular layer (80%) Areolar CT Dense irregular CT Ridged surface projections = Accessory structures dermal papilla Epidermal ridges feet/palms Increase friction, enhance grip, and fingerprints (sweat gland) Contain pain and touch receptors (Meissner’s corpuscle) Collagen fibers and adipose Holds water = hydration Cleavage lines Orientation related to skin stresses Parallel cuts remain closed = faster healing Right angles pulled open with recoil Skin Coloration Melanin is black, yellow-brown, or brown Made by skin and stimulated by sun Freckles and moles are accumulations Carotene is yellow to orange pigments Accumulates in st. corneum and fatty tissue in skin Most obvious where st. corneum thickest Hemoglobin is crimson colored respiratory pigment Reduced blood supply turns skin white Poorly oxygenated blood appears blue = cyanosis Response to extreme cold or from respiratory disorders Skin Color Disruptions Leathery skin – clumping of elastin fibers from excessive sun (cancer too) Redness – embarrassment, fever, inflammation or allergy Pallor/blanching – emotional distress, anemia, low BP Jaundice – liver disease, bile pigment deposition Bronzing – hypofunctioning of adrenal cortex, Addison’s Black and blue – escaped blood clots in tissue, hematomas Sudoriferous (Sweat) Glands Almost everywhere Innervation contracts secretion Eccrine sweat glands Palms, soles, forehead Hypotonic blood filtrate released by exocytosis Body cooling Emotional Gland in dermis, duct into surface pore Apocrine sweat glands* Axillary and anogenital regions Secretions into hair follicle ducts Similar to sweat Starts at puberty = body odor Ceruminous Cerumen (earwax) Mammary glands Sebaceous (Oil) Gland Almost everywhere, but palms and soles Holocrine: collect and then burst, releasing sebum Secreted onto hair follicle or into a pore Softens hair and prevents water loss = brittle Sodium laureth sulfate Lubricates skin Antibacterial function Disorders Whitehead, blackhead, acne ‘Cradle cap’ Dandruff , seborrheic dermatitis http://z.about.com/d/dermatology/1/0/p/6/Comedone_papule.jpg Hair Other mammals = warmth Humans = protection, sensation, filters Few areas lack (palms, soles, lips) ‘Hair’ (shaft and root) are dead, keratinized cells Ribbonlike = kinky, oval = wavy, round = course Matrix with 3 layers: medulla, cortex, cuticle Follicle into dermis expands to bulb Receptors surround Papilla w/ capillaries = nutrients Arrector pili muscle Hair pigment from melanocytes Nails Modified hard keratinized epidermis Protect, grasp, and itch Richly vascularized Free edge, nail body (st. corneum), nail bed (st. spinosum), and root (lunula) Nail folds (lateral and proximal) extend = eponychium (cuticle) Hyponychium (quick) Burns Loss of fluids renal shut down, denatured proteins IV of fluids immediately Extra caloric intake Sepis Protective role decreased after 24 hours Immune system done 1 -2 days after Rule of nines 11 areas at 9% body (genitals 1%) Estimate Classifying 1st degree: epidermal damage; redness and swelling (sunburn) 2nd degree: epidermis and upper dermis; blisters form (cooking) 3rd degree: epidermis and dermis; gray-white/blackened, nerve destruction Skin grafting