1. Chapter 6 The Integumentary System and Body Membranes

2. Objectives O Classify, compare the structure of, and give examples of each type of body membrane O Describe the structure and function of the epidermis and dermis O List and briefly describe each accessory organ of the skin O List and discuss the three primary functions of the integumentary system O List and describe major skin disorders and infections O Classify burns and describe how to estimate the extent of a burn injury 2

3. Classification of Body Membranes O Classification of body membranes O Epithelial membranes—composed of epithelial tissue and an underlying layer of connective tissue O Connective tissue membranes—composed exclusively of various types of connective tissue 3

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

6. Classification of Body Membranes O Examples O Pleura—parietal and visceral layers line walls of thoracic cavity and cover the lungs O Peritoneum—parietal and visceral layers line walls of abdominal cavity and cover the organs in that cavity 6

7. Classification of Body Membranes O Diseases O Pleurisy—inflammation of the serous membranes that line the chest cavity and cover the lungs O Peritonitis—inflammation of the serous membranes in the abdominal cavity that line the walls and cover the abdominal organs 7

8. Classification of Body Membranes O Mucous membranes O Line body surfaces that open directly to the exterior O Produce mucus, a thick secretion that keeps the membranes soft and moist 8

9. Classification of Body Membranes O Connective tissue membranes O Do not contain epithelial components O Produce a lubricant called synovial fluid O Examples O The synovial membranes in the spaces between joints and in the lining of the bursal sacs 9

10. The Skin O Structure—two primary layers called epidermis and dermis O Epidermis O Outermost and thinnest primary layer of skin O Composed of several layers of stratified squamous epithelium 10

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12. The Skin O Structure O Epidermis O Stratum germinativum—innermost (deepest) layer of cells that continually reproduce; new cells move toward the surface O Sometimes called the pigment layer O Pigment cells called melanocytes, which produce the brown pigment melanin O As cells approach the surface, they are filled with a tough, waterproof protein called keratin and eventually flake off O Stratum corneum—outermost layer of keratin-filled cells 12

13. The Skin O Structure O Epidermis O Skin color changes O Pink flush indicates increased blood volume or increased blood oxygen O Cyanosis—bluish gray color indicates decreased blood oxygen level O Vitiligo—patchy light skin areas resulting from acquired loss of epidermal melanocytes (Figure 6-4) O Increased skin pigmentation caused by hormonal changes in pregnant women O Freckles—small, flat macules—common normal skin pigment variation 13

14. The Skin O Dermal-epidermal junction—specialized area of contact between the epidermis and dermis; sometimes described as “spot welds” O Provide support for epidermis O Weakened or destroyed junctions can cause blisters 14

15. The Skin O Structure O Dermis O Deeper and thicker of the two primary skin layers and composed largely of connective tissue O Upper area of dermis characterized by parallel rows of peglike dermal papillae O Thick skin has parallel friction ridges and no hairs O Thin skin has irregular, shallow grooves and hair O Deeper area of dermis is filled with network of tough collagenous and stretchable elastic fibers 15

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17. The Skin O Structure O Dermis O Number of elastic fibers decreases with age and contributes to wrinkle formation O Striae—“stretch marks”; elongated marks caused by overstretching of skin 17

18. The Skin O Structure O Dermis O Dermis also contains nerve endings, muscle fibers, hair follicles, sweat and sebaceous glands, and many blood vessels O Birthmarks—malformation of dermal blood vessels O Strawberry hemangioma O Port-wine stain O Stork bite 18

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20. The Skin O Appendages of the skin O Hair O Soft hair of fetus and newborn called lanugo O Hair growth requires epidermal tubelike structure called hair follicle O Hair growth begins from hair papilla 20

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22. The Skin O Appendages of the skin O Hair O Hair root lies hidden in follicle; visible part of hair called shaft O Alopecia (Figure 6-8)—hair loss O Arrector pili—specialized smooth muscle that produces “goose pimples” and causes hair to stand up straight 22

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24. The Skin O Appendages of the skin O Receptors O Specialized nerve endings—make it possible for skin to act as a sense organ O Meissner (tactile) corpuscle—capable of detecting light touch O Lamellar (Pacini) corpuscle—capable of detecting pressure 24

25. The Skin O Nails O Produced by epidermal cells over terminal ends of fingers and toes O Visible part called nail body O Root lies in a groove and is hidden by cuticle O Crescent-shaped area nearest root called lunula O Nail bed may change color with change in blood flow 25

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27. The Skin O Nails O Normal variations in nail structure O Longitudinal ridges in light-skinned individuals O Pigmented bands in dark-skinned individuals O Abnormal variations in nail structure O Onycholysis—separation of nail from nail bed O Pitting—common in psoriasis 27

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29. The Skin O Skin glands—two main types O Sweat, or sudoriferous O Sebaceous 29

30. The Skin O Skin glands O Sweat, or sudoriferous, glands O Eccrine sweat gland O Most numerous, important, and widespread of the sweat glands O Produce perspiration or sweat, which flows out through pores on skin surface O Function throughout life and assist in body heat regulation 30

31. The Skin O Skin glands O Sweat or sudoriferous glands O Apocrine sweat glands O Found primarily in axilla and around genitalia O Secrete a thicker, milky secretion quite different from eccrine perspiration O Breakdown of secretion by skin bacteria produces odor 31

32. The Skin O Skin glands O Sebaceous glands O Secrete oil or sebum for hair and skin O Secretion increases during adolescence O Amount of secretion regulated by sex hormones O Sebum in sebaceous gland ducts may darken to form a blackhead O Acne vulgaris—inflammation of sebaceous gland ducts 32

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34. Functions of the Skin O Protection—first line of defense O Against infection by microbes O Against ultraviolet rays from sun O Against harmful chemicals O Against cuts and tears O Bruising can cause discoloration as blood released from damaged vessels breaks down O Skin grafts may be needed to replace skin destroyed by disease or trauma 34

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37. Functions of the Skin O Temperature regulation O Skin can release almost 3000 calories of body heat per day O Mechanisms of temperature regulation O Regulation of sweat secretion O Regulation of flow of blood close to the body surface 37

38. Functions of the Skin O Sense organ activity O Receptors serve as receivers for the body, keeping it informed of changes in its environment O Skin can detect sensations of light touch, pressure, pain, heat, and color 38

39. Disorders of the Skin (Dermatoses) O Skin lesions—any measurable variation from the normal structure O Elevated lesions—cast a shadow outside their edges O Papule—small, firm raised lesion O Plaque—large raised lesion O Vesicle—blister O Pustule—pus-filled lesion O Crust—scab O Wheal (hive)—raised, firm lesion with a light center 39

40. Disorders of the Skin (Dermatoses) O Flat lesions—do not cast a shadow O Macule—flat, discolored region O Depressed lesions cast a shadow within their edges O Excoriation—missing epidermis, as in a scratch O Ulcer—craterlike lesion O Fissure—deep crack or break O Some lesions are produced by scrapes and cuts—the skin can repair itself 40

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42. Burns O Treatment and recovery or survival depend on total area involved and severity or depth of the burn O Classification of burns O First-degree (partial-thickness) burns—only surface layers of epidermis involved O Second-degree (partial-thickness) burns—involve deep epidermal layers; always cause injury to upper layers of the dermis 42

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44. Burns O Classification of burns O Third-degree (full-thickness) burns—characterized by complete destruction of the epidermis and dermis O May involve underlying muscle and bone (fourth degree) O Lesion is insensitive to pain because of destruction of nerve endings immediately after injury—intense pain is experienced soon thereafter 44

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46. Burns O Estimating body surface area using the “rule of nines” in adults O Body divided into 11 areas of 9% each O Additional 1% of body surface area around genitals 46

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48. Skin Infections O Impetigo—highly contagious staphylococcal or streptococcal infection O Tinea—fungal infection (mycosis) of the skin; several forms occur O Warts—benign neoplasm caused by papillomavirus O Boils—furuncles; staphylococcal infection in hair follicles O Scabies—parasitic infection 48

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50. Vascular and Inflammatory Skin Disorders O Decubitus ulcers (bedsores) develop when pressure slows down blood flow to local areas of the skin O Urticaria or hives—red lesions caused by fluid loss from blood vessels O Scleroderma—disorder of vessels and connective tissue characterized by hardening of the skin; two types: localized and systemic 50

51. Vascular and Inflammatory Skin Disorders O Psoriasis—chronic inflammatory condition accompanied by scaly plaques O Eczema—common inflammatory condition characterized by papules, vesicles, and crusts; not a disease itself but a symptom of an underlying condition 51

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53. Skin Cancer O Three common types O Squamous cell carcinoma—the most common type, characterized by hard, raised tumors O Basal cell carcinoma—characterized by papules with a central crater; rarely spreads O Melanoma—malignancy in a nevus (mole); the most serious type 53

54. Skin Cancer O The most important causative factor in common skin cancers is exposure to sunlight O Kaposi sarcoma, characterized by purple lesions, is associated with AIDS and other immune deficiencies 54

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