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Chapter 6.

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Presentation on theme: "Chapter 6."— Presentation transcript:

1 Chapter 6

2 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.

Epithelial Membranes Connective Tissue Membranes THE SKIN Structure of the Skin Appendages of the Skin Functions of the Skin DISORDERS OF THE SKIN Skin Lesions Burns Skin infections Vascular and Inflammatory Skin Disorders Skin Cancer

A. Classification of body membranes (Figure 6-1) 1. Epithelial membranes—composed of epithelial tissue and an underlying layer of connective tissue 2. Connective tissue membranes—composed largely of various types of connective tissue Page(s)

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B. Epithelial membranes 1. Cutaneous membrane—the skin 2. Serous membranes—simple squamous epithelium on a connective tissue basement membrane a. Types (1) Parietal—line walls of body cavities (2) Visceral—cover organs found in body cavities b. Examples (1) Pleura—parietal and visceral layers line walls of thoracic cavity and cover the lungs (2) Peritoneum—parietal and visceral layers line walls of abdominal cavity and cover the organs in that cavity Page(s)

B. Epithelial membranes 2. Serous membranes—simple squamous epithelium on a connective tissue basement membrane c. Diseases (1) Pleurisy—inflammation of the serous membranes that line the chest cavity and cover the lungs (2) Peritonitis—inflammation of the serous membranes in the abdominal cavity that line the walls and cover the abdominal organs 3. Mucous membranes a. Line body surfaces that open directly to the exterior b. Produce mucus, a thick secretion that keeps the membranes soft and moist Page(s)

C. Connective tissue membranes 1. Do not contain epithelial components 2. Produce a lubricant called synovial fluid 3. Examples are the synovial membranes in the spaces between joints and in the lining of the bursal sacs Page(s)

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10 THE SKIN A. Structure (Figure 6-2)-two primary layers called epidermis and dermis 1. Epidermis a. Outermost and thinnest primary layer of skin b. Composed of several layers of stratified squamous epithelium c. Stratum germinativum—innermost layer of cells that continually reproduce; the new cells move toward the surface d. As cells approach the surface, they are filled with a tough, waterproof protein called keratin and eventually flake off Page(s)

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12 THE SKIN A. Structure (Figure 6-2) —two primary layers called epidermis and dermis 1. Epidermis e. Stratum corneum—outermost layer of keratin—filled cells f. Pigment-containing layer—epidermal layer that contains pigment cells called melomocytes, which produce the brown pigment melanin (1) Vitiligo—acquired loss of epidermal melanocytes (Figure 6-4) g. Blisters—caused by breakdown of union between cells or primary layers of skin h. Dermal-epidermal junction—specialized area between two primary skin layers Page(s)

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14 THE SKIN Structure (Figure 6-2) —two primary layers called epidermis and dermis fibers 2. Dermis a. Deeper and thicker of the two primary skin layers; composed largely of connective tissue b. Upper area of dermis characterized by parallel rows of peglike dermal papillae c. Ridges and grooves in dermis form pattern unique to each individual (basis of fingerprinting) d. Deeper areas of dermis filled with network of tough collagenous and stretchable elastic fibers Page(s) 151,

15 THE SKIN A. Structure (Figure 6-2) —two primary layers called epidermis and dermis 2. Dermis e. Number of elastic fibers decreases with age and contributes to wrinkle formation (1) Striae—stretch marks f. Dermis also contains nerve endings, muscle fibers, hair follicles, sweat and sebaceous glands, and many blood vessels (1) Birthmarks—malformation of dermal blood vessels (a) Strawberry hemangioma (b) Port-wine stain (c) Stork bite Page(s) 151,

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17 THE SKIN B. Appendages of the skin 1. Hair (Figure 6-6)
a. Soft hair of a fetus and newborn called lanugo b. Hair growth requires epidermal tubelike structures called hair follicle c. Hair growth begins from hari papilla d. Hair root lies hidden in follicle; visible part of hair called shaft e. Alopecia (Figure 6-7) hair loss f. Arrector pili—specialized smooth muscle that produces “goose pimples” and causes hair to stand up straight Page(s) 151,

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19 THE SKIN B. Appendages of the skin 2. Receptors (Figure 6-2)
a. Specialized nerve endings—make it possible for skin to act as a sense organ b. Meissner’s corpuscle—capable of detecting light touch c. Pacinian corpuscle—capable of detecting pressure Page(s) 151, 161

20 THE SKIN B. Appendages of the skin 3. Nails (Figure 6-8)
a. Produced by epidermal cells over terminal ends of fingers and toes b. Visible part called nail body c. Root lies in a groove and is hidden by cuticle d. Crescent-shaped area nearest root called lunula e. Nail bed may change color with change in blood flow Page(s) 161

21 THE SKIN B. Appendages of the skin 3. Nails (Figure 6-9)
f. Normal variations in nail structure (1) Longitudinal ridges in light-skinned individuals (2) Pigmented bands in dark-skinned individuals Page(s)

22 THE SKIN B. Appendages of the skin 3. Nails
g. Abnormal variations in nail structure (Figure 6-10) (1) Onych0lysis—separation of nail from nail bed (2) Pitting—common in psoriasis Page(s)

23 THE SKIN B. Appendages of the skin 4. Skin glands a. Types
(1) Sweat or sudoriferous (2) Sebaceous b. Sweat or sudoriferous glands (1) Types (a) Eccrine sweat glands (1) Most numerous, important, and wide-spread of the sweat glands (2) Produce perspiration or sweat, which flows out through pores on skin surface (3) Function throughout life and assist in body heat regulation Page(s) 162

24 THE SKIN B. Appendages of the skin 4. Skin glands
b. Sweat or sudoriferous glands (1) Types (b) Apocrine sweat glands (1) Found primarily in axilla and around genitalia (2) Secrete a thicker, milky secretion quite different from eccrine perspiration (3) Breakdown of secretion by skin bacteria produces odor (c) Sebaceous glands (1) Secrete oil or sebum for hair and skin (2) Level of secretion increases during adolescence (3) Amount of secretion regulated by sex hormones (4) Sebum in sebaceous gland ducts may darken to form a blackhead (5) Acne vulgaris (Figure 6-11) inflammation of sebaceous gland ducts Page(s)

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26 THE SKIN C. Functions of the skin 1. Protection—first line of defense
a. Against infection by microbes A b. Against ultraviolet rays from sun c. Against harmful chemicals d. Against cuts and tears e. Skin grafts (Figure 6-12) Page(s)

27 THE SKIN C. Functions of the skin 2. Temperature regulation
a. Skin can release almost 3000 calories of body heat per day (1) Mechanisms of temperature regulation (a) Regulation of sweat secretion (b) Regulation of flow of blood close to the body surface 3. Sense organ activity a. Skin functions as an enormous sense organ b. Receptors serve as receivers for the body keeping it informed of changes in its environment Page(s) 164

A. Skin lesions (Table 6-1) 1. Elevated lesions—cast a shadow outside their edges a. Papule—small, firm raised lesion b. Plaque—large raised lesion c. Vesicle—blister d. Pustule—pus-filled lesion e. Crust—scab f. Wheal (hive)—raised, firm lesion with a light center 2. Flat lesions—do not cast a shadow a. Macule—flat, discolored region 3. Depressed lesions cast a shadow within their edges a. Excoriation—missing epidermis, as in a scratch wound b. Ulcer—crater-like lesion c. Fissure—deep crack or break Page(s) 164

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B. Burns 1. Treatment and recovery or survival depend on total area involved and severity or depth of the burn 2. Classification of burns (Figure 6-13) a. First—degree (partial-thickness) burns—only surface layers of epidermis involved b. Second-degree (partial-thickness) burns—involve the deep epidermal layers and always cause injury to the upper layers of the dermis c. Third-degree (full-thickness) burns (Figure 6-14) characterized by complete destruction of the epidermis and dermis (1) May involve underlying muscle and bone (fourth degree) (2) Lesion is insensitive to pain because of destruction of nerve endings immediately after injury—intense pain is soon experienced Page(s) 165

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B. Burns 3. Estimating body surface area using the "rule of nines" (Figure 6-15) in adults a. Body divided into 11 areas of 9% each b. Additional 1% of body surface area around genitals Page(s) 165, 167

C. Skin infections (Figure 6-16) 1. Impetigo—highly contagious staphylococcal infection 2. Tinea—fungal infection (mycosis) of the skin; several forms occur 3. Boils—furuncles; staphylococcal infection in hair follicles 4. Scabies—parasitic infection Page(s)

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D. Vascular and inflammatory skin disorders 1. Decubitus ulcers (bedsores) develop when pressure slows down blood flow to local areas of the skin 2. Urticaria or hives—red lesions caused by fluid loss from blood vessels 3. Scleroderma—disorder of vessels and connective tissue characterized by hardening of the skin; two types: localized and systemic 4. Psoriasis—chronic inflammatory condition accompanied by scaly plaques 5. Eczema—common inflammatory condition characterized by papules, vesicles, and crusts; not a disease itself but a symptom of an underlying condition Page(s)

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E. Skin cancer 1. Three common types a. Squamous cell carcinoma—the most common type, characterized by hard, raised tumors b. Basal cell carcinoma—characterized by papules with a central crater; rarely spreads c. Melanoma—malignancy in a nevus (mole); the most serious type of skin cancer 2. The most important causative factor in common skin cancers is exposure to sunlight 3. Kaposi sarcoma, characterized by purple lesions, is associated with AIDS and other immune deficiencies

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44 Credits All photos and references are taken from:
Thibodeau, Gary, & Patton, Kevin. (2005). The Human body in health & disease. Mosby. ISBN:

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