【课件】ChapterTheIntegumentarySystem.ppt

Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,5-,*,Tortora&Grabowski 9/e,2000 JWS,*,ChapterTheIntegumentarySystem,General Anatomy,A large organ composed of all 4 tissue types,22 square feet,1-2 mm thick,Weight 10 lbs.,2,Overview,3 Major layers of skin,Epidermis is epithelial tissue only,Dermis is layer of connective tissue,nerve&muscle,Hypodermis(subcutaneous)is layer of adipose&areolar tissues,3,Overview of Epidermis,Stratified squamous epithelium,Contains no blood vessels,4 types of cells,5 distinct strata(layers)of cells,4,Cell types of the Epidermis,Keratinocytes-90%,produce keratin,Melanocytes-8%,produces melanin pigment,melanin transferred to other cells with long cell processes,Langerhan cells,from bone marrow,provide immunity,Merkel cells,in deepest layer,form touch receptor with sensory neuron,5,Layers(Strata)of the Epidermis,Stratum corneum,Stratum lucidum,Stratum granulosum,Stratum spinosum,Stratum basale,6,Stratum Basale,Deepest single layer of cells,Combination of merkel cells,melanocytes,keratinocytes&stem cells that divide repeatedly,Cells attached to each other&to basement membrane by desmosomes&hemidesmosomes,7,Stratum Spinosum,8 to 10 cell layers held together by desmosomes,During slide preparation,cells shrink and look spiny,Melanin taken in by phagocytosis from nearby melanocytes,8,Stratum Granulosum,3-5 layers of flat dying cells,Show nuclear degeneration,Contain dark-staining keratohyalin granules,Contain lamellar granules that release lipid that repels water,9,Stratum Lucidum,Seen in thick skin on palms&soles of feet,Three to five layers of clear,flat,dead cells,Contains precursor of keratin,10,Stratum Corneum,25 to 30 layers of flat dead cells filled with keratin and surrounded by lipids,Continuously shed,Barrier to light,heat,water,chemicals&bacteria,Friction stimulates callus formation,11,Keratinization&Epidermal Growth,Stem cells divide to produce keratinocytes,As keratinocytes are pushed up towards the surface,they fill with keratin,4 week journey unless outer layers removed in abrasion,Hormone EGF(epidermal growth factor)can speed up process,Psoriasis=chronic skin disorder,cells shed in 7 to 10 days as flaky silvery scales,abnormal keratin produced,12,Skin Grafts,New skin can not regenerate if stratum basale and its stem cells are destroyed,Skin graft is covering of wound with piece of healthy skin,autograft from self,isograft from twin,autologous skin,transplantation of patients skin grown in culture,13,Dermis,Connective tissue layer composed of collagen&elastic fibers,fibroblasts,macrophages&fat cells,Contains hair follicles,glands,nerves&blood vessels,Major regions of dermis,papillary region,reticular region,14,Papillary Region,Top 20%of dermis,Composed of loose CT&elastic fibers,Finger like projections called dermal papillae,Functions,anchors epidermis to dermis,contains capillaries that feed epidermis,contains Meissners corpuscles(touch)&free nerve endings(pain and temperature),15,Reticular Region,Dense irregular connective tissue,Contains interlacing collagen and elastic fibers,Packed with oil glands,sweat gland ducts,fat&hair follicles,Provides strength,extensibility&elasticity to skin,stretch marks are dermal tears from extreme stretching,Epidermal ridges form in fetus as epidermis conforms to dermal papillae,fingerprints are left by sweat glands open on ridges,increase grip of hand,16,Skin Color Pigments(1),Melanin produced in epidermis by melanocytes,same number of melanocytes in everyone,but differing amounts of pigment produced,results vary from yellow to tan to black color,melanocytes convert tyrosine to melanin,UV in sunlight increases melanin production,Clinical observations,freckles or liver spots=melanocytes in a patch,albinism=inherited lack of tyrosinase;no pigment,vitiligo=autoimmune loss of melanocytes in areas of the skin produces white patches,17,Skin Color Pigments(2),Carotene in dermis,yellow-orange pigment(precursor of vitamin A),found in stratum corneum&dermis,Hemoglobin,red,oxygen-carrying pigment in blood cells,if other pigments are not present,epidermis is translucent so pinkness will be evident,18,Accessory Structures of Skin,Epidermal derivatives,Cells sink inward during development to form:,hair,oil glands,sweat glands,nails,19,Structure of Hair,Shaft-visible,medulla,cortex&cuticle,Root-below the surface,Follicle surrounds root,20,Hair Related Structures,A,rrector pili,smooth muscle in dermis contracts with cold or fear.,forms goosebumps as hair is pulled vertically,Hair root plexus,detect hair movement,21,Hair Color,Result of melanin produced in melanocytes in hair bulb,Dark hair contains true melanin,Blond and red hair contain melanin with iron and sulfur added,Graying hair is result of decline in melanin production,White hair has air bubbles in the medullary shaft,22,Functions of,Hair,P,revents heat loss,Decreases sunburn,Eyelashes help protect eyes,Touch receptors(hair root plexus)senses light touch,23,Glands of the Skin,Specialized exocrine glands found in dermis,Sebaceous(oil)glands,Sudiferous(sweat)glands,Ceruminous(wax)glands,Mammary(milk)glands,24,Sebaceous(oil)glands,Secretory portion in the dermis,Most open onto hair shafts,Sebum,combination of cholesterol,proteins,fats&salts,keeps hair and skin from soft&pliable,inhibits growth of bacteria&fungi(ringworm),Acne,bacterial inflammation of glands,secretions stimulated by hormones at puberty,25,Sudoriferous(sweat)glands,Eccrine(sweat)glands,most areas of skin,secretory portion in dermis with duct to surface,regulate body temperature with perspiration,Apocrine(sweat)glands,armpit and pubic region,secretory portion in dermis with duct that opens onto hair follicle,secretions more viscous,function after puberty,“cold sweat”,26,Ceruminous glands,Modified sweat glands produce waxy secretion in ear canal,Cerumin contains secretions of oil and wax glands,Helps form barrier for entrance of foreign bodies,Impacted cerumen may reduce hearing,27,Structure of Nails,Tightly packed keratinized cells,Nail body,visible portion pink due to underlying capillaries,free edge appears white,Nail root,buried under skin layers,lunula is white due to thickened stratum basale,Eponychium(cuticle),stratum corneum layer,28,Nail Growth,Nail matrix below nail root produces growth,Cells transformed into tightly packed keratinized cells,1 mm per week,29,Types of Skin,Thin skin,covers most of body,thin epidermis(.1 to.15 mm.)that lacks stratum lucidum,lacks epidermal ridges,has fewer sweat glands and sensory receptors,Thick skin,only on palms and soles,thick epidermis(.6 to 4.5 mm.)with distinct stratum lucidum&thick stratum corneum,lacks hair follicles and sebaceous glands,30,General Functions of the Skin,Regulation of body temperature,Protection as physical barrier,Sensory receptors,Excretion and absorption,Synthesis of vitamin,31,Skin Cancer,1 million cases diagnosed per year,3 common forms of skin cancer,basal cell carcinoma (rarely metastasize),squamous cell carcinoma (may metastasize),malignant melanomas (metastasize rapidly),most common cancer in young women,arise from melanocytes-life threatening,key to treatment is early detection watch for changes in symmetry,border,color and size,risks factors include-skin color,sun exposure,family history,age and immunological status,32,Types of Burns,First-degree,only epidermis(sunburn),Second-degree burn,destroys entire epidermis&part of dermis,fluid-filled blisters separate epidermis&dermis,epidermal derivatives are not damaged,heals without grafting in 3 to 4 weeks&may scar,Third-degree or full-thickness,destroy epidermis,dermis&epidermal derivatives,damaged area is numb due to loss of sensory nerves,33,