Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. Chapter 6 The Integumentary System and Body Membranes

Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 2 Objectives Classify, compare the structure of, and give examples of each type of body membrane Describe the structure and function of the epidermis and dermis List and briefly describe each accessory organ of the skin List and discuss the three primary functions of the integumentary system List and describe major skin disorders and infections Classify burns and describe how to estimate the extent of a burn injury

Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 3 Classification of Body Membranes Classification of body membranes –Epithelial membranes—composed of epithelial tissue and an underlying layer of connective tissue –Connective tissue membranes—composed exclusively of various types of connective tissue

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5 Classification of Body Membranes Epithelial membranes –Cutaneous membrane—the skin –Serous membranes—simple squamous epithelium on a connective tissue basement membrane Parietal—line walls of body cavities Visceral—cover organs found in body cavities

Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 6 Classification of Body Membranes Examples –Pleura—parietal and visceral layers line walls of thoracic cavity and cover the lungs –Peritoneum—parietal and visceral layers line walls of abdominal cavity and cover the organs in that cavity

Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 7 Classification of Body Membranes Diseases –Pleurisy—inflammation of the serous membranes that line the chest cavity and cover the lungs –Peritonitis—inflammation of the serous membranes in the abdominal cavity that line the walls and cover the abdominal organs

Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 8 Classification of Body Membranes Mucous membranes –Line body surfaces that open directly to the exterior –Produce mucus, a thick secretion that keeps the membranes soft and moist

Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 9 Classification of Body Membranes Connective tissue membranes –Do not contain epithelial components –Produce a lubricant called synovial fluid –Examples The synovial membranes in the spaces between joints and in the lining of the bursal sacs

Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 10 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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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 12 The Skin Structure –Epidermis Stratum germinativum—innermost (deepest) layer of cells that continually reproduce; new cells move toward the surface –Sometimes called the pigment layer –Pigment cells called melanocytes, which produce the brown pigment melanin As cells approach the surface, they are filled with a tough, waterproof protein called keratin and eventually flake off Stratum corneum—outermost layer of keratin-filled cells

Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 13 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) –Increased skin pigmentation caused by hormonal changes in pregnant women –Freckles—small, flat macules—common normal skin pigment variation

Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 14 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. 15 The Skin Structure –Dermis Deeper and thicker of the two primary skin layers and composed largely of connective tissue Upper area of dermis characterized by parallel rows of peglike dermal papillae Thick skin has parallel friction ridges and no hairs Thin skin has irregular, shallow grooves and hair Deeper area of dermis is filled with network of tough collagenous and stretchable elastic fibers

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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 17 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. 18 The Skin Structure –Dermis Dermis also contains nerve endings, muscle fibers, hair follicles, sweat and sebaceous glands, and many blood vessels –Birthmarks—malformation of dermal blood vessels »Strawberry hemangioma »Port-wine stain »Stork bite

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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 –Hair Soft hair of fetus and newborn called lanugo Hair growth requires epidermal tubelike structure called hair follicle Hair growth begins from hair papilla

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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 22 The Skin Appendages of the skin –Hair Hair root lies hidden in follicle; visible part of hair called shaft Alopecia (Figure 6-8)—hair loss Arrector pili—specialized smooth muscle that produces “goose pimples” and 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. 24 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. 25 The Skin Nails –Produced by epidermal cells over terminal ends of fingers and toes –Visible part called nail body –Root lies in a groove and is hidden by cuticle –Crescent-shaped area nearest root called lunula –Nail bed may change color with change in blood flow

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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 27 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. 29 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. 30 The Skin Skin glands –Sweat, or sudoriferous, glands Eccrine sweat gland –Most numerous, important, and widespread of the sweat glands –Produce perspiration or sweat, which flows out through pores on skin surface –Function throughout life and assist in body heat regulation

Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 31 The Skin Skin glands –Sweat or sudoriferous glands Apocrine sweat glands –Found primarily in axilla and around genitalia –Secrete a thicker, milky secretion quite 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. 32 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. 34 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. 37 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. 38 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 color

Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 39 Disorders of the Skin (Dermatoses) Skin lesions—any measurable variation from the normal structure –Elevated lesions—cast a shadow outside their edges Papule—small, firm raised lesion Plaque—large raised lesion Vesicle—blister Pustule—pus-filled lesion Crust—scab Wheal (hive)—raised, firm lesion with a light center

Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 40 Disorders of the Skin (Dermatoses) –Flat lesions—do not cast a shadow Macule—flat, discolored region –Depressed lesions cast a shadow within their edges Excoriation—missing epidermis, as in a scratch Ulcer—craterlike lesion Fissure—deep crack or break –Some lesions are produced by scrapes and cuts—the skin can repair itself

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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 42 Burns Treatment and recovery or survival depend on total area involved and severity or depth of the burn Classification of burns –First-degree (partial-thickness) burns—only surface layers of epidermis involved –Second-degree (partial-thickness) burns— involve deep epidermal layers; always cause injury to upper layers of the dermis

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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 44 Burns Classification of burns –Third-degree (full-thickness) burns— characterized by complete destruction of the epidermis and dermis May involve underlying muscle and bone (fourth degree) Lesion is insensitive to pain because of destruction of nerve endings immediately after injury—intense pain is experienced soon thereafter

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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 46 Burns Estimating body surface area using the “rule of nines” in adults –Body divided into 11 areas of 9% each –Additional 1% of body surface area around genitals

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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 48 Skin Infections Impetigo—highly contagious staphylococcal or streptococcal infection Tinea—fungal infection (mycosis) of the skin; several forms occur Warts—benign neoplasm caused by papillomavirus Boils—furuncles; staphylococcal infection in hair follicles Scabies—parasitic infection

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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 50 Vascular and Inflammatory Skin Disorders Decubitus ulcers (bedsores) develop when pressure slows down blood flow to local areas of the skin Urticaria or hives—red lesions caused by fluid loss from blood vessels Scleroderma—disorder of vessels and connective tissue characterized by hardening of the skin; two types: localized and systemic

Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 51 Vascular and Inflammatory Skin Disorders Psoriasis—chronic inflammatory condition accompanied by scaly plaques Eczema—common inflammatory condition characterized by papules, vesicles, and crusts; not a disease itself but a symptom of an underlying condition

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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc. 53 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. 54 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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