Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. The Integumentary System

Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 2 The Skin Structure—two primary layers called epidermis and dermis –Epidermis Outermost and thinnest primary layer of skin Composed of several layers of stratified squamous epithelium

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4 The Skin Structure –Epidermis Stratum germinativum—innermost (deepest) layer of cells continually reproduce new cells move toward the surface –Sometimes called the pigment layer –Pigment cells called melanocytes –Produce the brown pigment melanin

Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. The Skin Keratin- tough, waterproof protein –Fill cells as they move toward surface –Flake off at surface Stratum corneum—outermost layer of keratin-filled cells 5

Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 6 The Skin Structure –Epidermis Skin color changes –Pink flush indicates increased blood volume or increased blood oxygen –Cyanosis—bluish gray color indicates decreased blood oxygen level –Vitiligo—patchy light skin areas resulting from acquired loss of epidermal melanocytes (Figure 6-4)

Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. The Skin –“mask of pregnancy”- Increased skin pigmentation caused by hormonal changes in pregnant women –Freckles—small, flat macules—common normal skin pigment variation 7

Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 8 The Skin Dermal-epidermal junction specialized area of contact between the epidermis and dermis sometimes described as “spot welds” provide support for epidermis weakened or destroyed junctions can cause blisters

Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 9 The Skin Structure –Dermis Deeper and thicker of the two primary skin layers Composed largely of connective tissue Upper area of dermis characterized by –parallel rows of peglike dermal papillae

Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. Thick skin has parallel friction ridges and no hairs Thin skin has irregular, shallow grooves and hair Deeper area of dermis –filled with network of tough collagenous and stretchable elastic fibers 10

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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 12 The Skin Structure –Dermis Number of elastic fibers decreases with age and contributes to wrinkle formation –Striae—“stretch marks”; elongated marks caused by overstretching of skin

Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 13 The Skin Structure –Dermis contains nerve endings muscle fibers hair follicles sweat and sebaceous glands many blood vessels

Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. –Birthmarks—malformation of dermal blood vessels »Strawberry hemangioma »Port-wine stain »Stork bite 14

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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 16 The Skin Appendages of the skin –Hair Hair follicle - epidermal tubelike structure from which hair grows Hair papilla- cap-shaped cluster of cells from which hair growth begins

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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 18 The Skin Appendages of the skin –Hair Hair root-hidden in follicle Hair shaft- visible part of hair Alopecia (Figure 6-8)—hair loss Arrector pili—specialized smooth muscle –produces “goose pimples” –causes hair to stand up straight

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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 20 The Skin Appendages of the skin –Receptors Specialized nerve endings Make it possible for skin to act as a sense organ –Meissner (tactile) corpuscle—capable of detecting light touch –Lamellar (Pacini) corpuscle—capable of detecting pressure

Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 21 The Skin Nails –Produced by epidermal cells –Cover terminal ends of fingers and toes –Nail bed may change color with change in blood flow –Nail body- visible part –Root -lies in a groove, hidden by cuticle –Lunula -crescent-shaped area nearest root

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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 23 The Skin Nails –Normal variations in nail structure Longitudinal ridges in light-skinned individuals Pigmented bands in dark-skinned individuals –Abnormal variations in nail structure Onycholysis—separation of nail from nail bed Pitting—common in psoriasis

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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 25 The Skin Skin glands—two main types –Sweat, or sudoriferous –Sebaceous

Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 26 The Skin Skin glands –Sweat, or sudoriferous, glands Eccrine sweat gland –Most numerous and widespread of the sweat glands –Produce perspiration or sweat, flows out through pores (openings) on skin surface –Function throughout life –Assist in body heat regulation

Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 27 The Skin Skin glands –Sweat or sudoriferous glands Apocrine sweat glands –Found primarily in axilla and around genitalia –Secrete a thicker, milky secretion, different from eccrine perspiration –Breakdown of secretion by skin bacteria produces odor

Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 28 The Skin Skin glands –Sebaceous glands –Secrete oil or sebum for hair and skin –Secretion increases during adolescence –Amount of secretion regulated by sex hormones –Sebum in sebaceous gland ducts may darken to form a blackhead –Acne vulgaris—inflammation of sebaceous gland ducts

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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 30 Functions of the Skin Protection—first line of defense –Against infection by microbes –Against ultraviolet rays from sun –Against harmful chemicals –Against cuts and tears –Bruising can cause discoloration as blood released from damaged vessels breaks down –Skin grafts may be needed to replace skin destroyed by disease or trauma

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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 33 Functions of the Skin Temperature regulation –Skin can release almost 3000 calories of body heat per day –Mechanisms of temperature regulation Regulation of sweat secretion Regulation of flow of blood close to the body surface

Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 34 Functions of the Skin Sense organ activity –Receptors serve as receivers for the body, keeping it informed of changes in its environment –Skin can detect sensations of light touch, pressure, pain, heat, and cold

Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 35 Skin Cancer Three common types –Squamous cell carcinoma—the most common type, characterized by hard, raised tumors –Basal cell carcinoma—characterized by papules with a central crater; rarely spreads –Melanoma—malignancy in a nevus (mole); the most serious type

Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 36 Skin Cancer The most important causative factor in common skin cancers is exposure to sunlight Kaposi sarcoma, characterized by purple lesions, is associated with AIDS and other immune deficiencies

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