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The Integumentary System Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 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 2 Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 3 Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 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 4 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. 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) 6 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. 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 8 Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 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 9 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 Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 11 Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 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 12 Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. The Skin • Structure – Dermis • • • • • contains nerve endings muscle fibers hair follicles sweat and sebaceous glands many blood vessels 13 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 Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 15 Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 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 16 Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 17 Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 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 18 Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 19 Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 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 20 Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 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 21 Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 22 Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 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 23 Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 24 Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. The Skin • Skin glands—two main types – Sweat, or sudoriferous – Sebaceous 25 Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 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 26 Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 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 27 Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 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 28 Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 29 Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 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 30 Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 31 Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 32 Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 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 33 Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 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 34 Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 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 35 Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 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 36 Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 37 Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.