Y khoa - Dược - Chapter 23: The integumentary system

23The Integumentary SystemLearning Outcomes (cont.)23.1 Describe the functions of skin. 23.2 Describe the layers of skin and the characteristics of each layer. 23.3 Explain the factors that affect skin color. 23.4 Summarize types of common skin lesions.Learning Outcomes (cont.)23.5 Describe the accessory organs of skin along with their structures and functions. 23.6 Explain the process of skin healing, including scar production. 23.7 Describe the common diseases and disorders of the skin.Introduction Integumentary system SkinBody’s outer coveringLargest organAccessory organs:Hair folliclesNailsSkin glandsFunctions of the Integumentary SystemProtectionFirst line of defenseBacteriaVirusesProtects underlying structures UV radiation DehydrationFunctions of the Integumentary System (cont.)Body temperature regulationIf too hotDermal blood vessels dilateMore blood to surface so heat escapesIf too coldDermal blood vessels constrictPrevents heat from escapingFunctions of the Integumentary System (cont.)Vitamin D productionSkin must have sunlightNeeded for calcium absorptionSensation – receptorsExcretion – perspirationApply Your KnowledgeWhat are the functions of the integumentary system?ANSWER: The functions of the integumentary system are protection, regulation of body temperature, vitamin D production, sensation, and excretion.Skin StructureEpidermisDermisHypodermis or subcutaneous layerEpidermisSuperficial layer of the skinMajor layers Stratum corneum Outermost layerMostly dead cells form an impermeable layerStratum basaleDeepest layerCells constantly dividing and pushing older cells outwardTo Figure of SkinEpidermis (cont.)Cell typesKeratinocyte Most commonMakes and accumulates the protein keratin Melanocyte ~ makes the pigment melaninDermisDeeper, more complexContains all major tissues, plusSudoriferous glandsSebaceous glandsHair follicles and arrector pili musclesCollagen, elastin, and nerve fibersBlood vesselsTo Figure of SkinSubcutaneous LayerHypodermisComposed ofAdipose (fat) and loose connective tissueBlood vessels and nervesTo Figure of SkinSkin StructureBackStratum corneumSebaceous glandStratum basaleArrector pili muscleHair follicleSudoriferous (Eccrine) glandAdipose tissueApply Your KnowledgeWhat are the layers of skin and what is their function?ANSWER: Epidermis – superficial outer layer; cells produce keratin which makes it waterproof and resistant to bacteria and viruses; and melanin which absorbs UV radiation.Dermis – most complex layer; contains all major tissue types; binds epidermis to subcutaneous tissueSubcutaneous layer – inner most layer of adipose and loose connective tissue; the adipose cushions and insulates underlying structures and organs.Skin ColorDetermined by amount of melanin and activity of melanocytesGenetic trait Skin Color (cont.)Oxygenated bloodOxygen dissolved in the hemoglobin of the red blood cellsWell-oxygenated blood ~ pink skinPoorly oxygenated blood ~ pale or bluish skinApply Your KnowledgeWhat affects skin color?ANSWER: The amount of melanin produced by the melanocytes and the oxygenation of the blood.Skin LesionsAny variation in the skinAs simple as a freckleAs serious as a tumorSkin Lesions (cont.)Primary – originate from disease or body changesSecondary – reaction to external traumaVascular – anomalies of blood vesselsSkin Lesions (cont.)Lesion NameDescriptionBullaA large blister or cluster of blistersCicatrixA scar, usually inside a wound or tissueCrustDried blood or pus on the skinEcchymosisA black-and-blue mark or bruiseErosionA shallow area of skin worn away by friction or pressureSkin Lesions (cont.)Lesion NameDescriptionExcoriationA scratch; may be covered with dried bloodFissure A crack in the skin’s surfaceKeloidAn overgrowth of scar tissueMaculeA flat skin discoloration, such as a freckle or a flat moleNodule A large pimple or small nodeSkin Lesions (cont.)Lesion NameDescriptionPapuleAn elevated mass similar to but smaller than a nodulePetechiaePinpoint skin hemorrhages that result from bleeding disorders PlaqueA small, flat, scaly area of skinPurpuraPurple-red bruises usually due to clotting abnormalitiesPustuleAn elevated (infected) lesion containing pusSkin Lesions (cont.)Lesion NameDescriptionScaleThin plaques of epithelial tissue on skin’s surfaceTumorA swelling of abnormal tissue growth UlcerA wound that results from tissue lossVesicleA blisterWhealAnother term for hiveApply Your KnowledgeMatch the following:___ Keloid A. A blister___ Vesicle B. A crack in the skin’s surface___ Crust C. An overgrowth of scar tissue___ Fissure D. A small, flat scaly area of skin___ Ulcer E. Dried blood or pus on the skin___ Plaque F. A wound that results from tissue lossAEBFDCANSWER:BRAVO!Accessory Organs Hair folliclesTube-like depressions in the dermis of skinGenerate hairsAlopecia – follicles dieArrector pili ~ muscles that pull on folliclesDiagramAccessory Organs (cont.)Sudoriferous glandsEccrine glandsWatery sweatActivated by heatApocrine glandsThicker sweat Armpit and groin areasActivated by nervousness or stressSebaceous glandsProduce sebum to keep hair softPrevent bacteria from growing on skinDiagramAccessory Organs Nails Protect the ends of fingers and toesEpithelial cells with hard keratinNail bodyNail rootLunulaNail bed Apply Your KnowledgeMatching:Sudoriferous glands Sebum Apocrine glandsHair folliclesNailsEccrine glandsAlopeciaSebaceous glandsArrector pili tube-like depressions in the skin’s dermis; generate hairs baldness produce watery type of sweat muscles attached to hair follicles; cause “goose bumps” produce sweat produce sebum keeps hair soft and pliable protect the ends of fingers and toes become active during pubertyANSWER:ABCDEFGHIPerfect!Skin HealingInjury  inflammationRedness due to dilation of nearby blood vesselsSwelling because vessels leak fluid into spaces between cellsPain because excess fluid activates pain receptorsSkin Healing (cont.)Inflammation promotes healing Extra blood to areaExtra nutrientsDefensive cells Injury occursBlood clot formsClotted blood and other dried tissueScab replaces blood clotBinds the edges of wound; scar may formCollagen fibers replace scabApply Your KnowledgeHow does inflammation promote healing of the skin?ANSWER: Inflammation promotes healing by bringing extra blood, nutrients for skin repair, and defensive cells to the area of injury. Common Diseases and Disorders of the SkinBurns Extent of body surface area and degree of a burn Rule of nines is used to determine extent of burnEstimate body surface area11 body areasBurns 4½%4½%Head and neck9%Arms, hands, and shoulders18%4½%4½%Perineum 1%Anterior legs and feet 18%Posterior legs and feet 18%Anterior trunk18%Posterior trunk and buttocks18%BackBurns (cont.)Superficial Epidermis onlyPain, redness, swellingPartial-thicknessEpidermis and dermisPain, redness, swelling, blistersFull-thicknessAll layers of skin and often underlying structuresSkin appears charredAlways requires medical attentionBurns 1st Degree 2nd Degree 3rd DegreeBackPartial thicknessFull thicknessBurns (cont.)General guidelines for treatmentDo not remove anything sticking to the burnDo not apply butter, lotions, or ointmentsCool with large amounts of waterBurns (cont.)General guidelines for treatmentCover with sterile sheet or plastic bagContact emergency servicesCheck airways for swellingSkin Cancer and Common Skin DisordersSkin – vulnerable due to exposureSkin cancerEpidermis Excessive exposure to sunlightTypes Basal cell and squamous cell carcinomaMalignant melanomaSkin Cancer and Common Skin Disorders (cont.)Basal Cell Signs / symptomsGrowth or sore that will not healWaxy, smooth, red, pale, flat, or lumpyTreatmentCurettage and electrodessicationMohs surgeryCryosurgeryLaser therapySkin Cancer and Common Skin Disorders (cont.)Squamous Cell Less common than basal cellFlat cells of the epidermisFound on face, lips, ears, and backs of handsSigns and symptoms and treatments are the same as for basal cell carcinoma Skin Cancer and Common Skin Disorders (cont.)Malignant MelanomaSigns / symptomsMole that itches or bleedsABCDE ruleTreatmentSurgery Determination if cancer has spreadChemotherapy and radiation therapyImmunotherapySkin Cancer and Common Skin Disorders (cont.)Asymmetry – a mole should not become asymmetrical. Border – a mole should not have irregular borders and edges should not blur into normal tissue.Color – a mole should not change or become mixture of colors. Skin Cancer and Common Skin Disorders (cont.)Diameter – a mole should not grow larger than the diameter of a pencil eraser (6 mm.)Evolving – a mole that has been changing in size, color and appearance, or growing in an area of previously normal skinSkin Cancer and Common Skin Disorders (cont.)Stage 0Only found in epidermisStage ISpread to epidermis and dermis (1 to 2 mm thick)Stage II2 to 4 mm thick and may be ulceratedStage IIISpread to one or more nearby lymph nodesStage IVSpread to other body organs or lymph nodes far from original melanomaStages of MelanomaCommon Skin and Hair DisordersAlopecia Hair lossHeredity CellulitisInflammation of connective tissue in skinRed, tight, painful skinDermatitis Inflammation of skin or a rashEczema ~ chronic dermatitisFolliculitis Swimmer’s rashInflammation of hair folliclesCommon Skin Disorders (cont.)Herpes simplex Type 1 Cold soresSpread through salivaType 2 – genitalGenital Sexually transmittedNo cureHerpes zosterShinglesChicken pox virus lies dormantSymptomatic treatmentVaccine Common Skin Disorders (cont.)Impetigo Oozing skin lesions that eventually crust overHighly contagiousPediculosisCapitus ~ head liceCorporis ~ body licePubis ~ pubic licePsoriasis – chronic, inflammatory skin condition Common Skin Disorders (cont.)RingwormThree typesTinea corporisTinea capitisTinea pedisDermatophytesAntifungal agents RosaceaDilation of small facial blood vesselsNot curable Common Skin Disorders (cont.)Scabies Contagious skin condition caused by mitesRedness and itchingTreat entire familyWarts Harmless growths caused by a virusVary in appearanceOTC medicationsApply Your Knowledge1. True or False:___ Basal cell carcinoma is the most aggressive form of skin  cancer and can form anywhere.___ Squamous cell carcinoma is more likely to spread to  surrounding tissues.___ Lesions of melanoma appear on trunk, head, neck of  men and on arms and legs of women.___ The borders of skin cancers are usually regular.___ Basal cell carcinoma progresses slowly and rarely  spreads to other body parts.ANSWER:FTTFTGood Job!Melanomas are more aggressive.Borders are irregular.Apply Your KnowledgeUsing Figure for Rule of Nines, determine burn extent for a patient who has burns to his anterior face and both arms.Click for Rule of NinesANSWER: Face = 4.5%Both arms, hands, and shoulders = 18%4.5% + 18% = 22.5%It all adds up to a right answer!In Summary23.1 The functions of skin include: protection, body temperature regulation, vitamin D production, sensation, and excretion. 23.2 The topmost layer of the skin is the epidermis. The dermis is the complex middle layer. The innermost layer attaching the skin to muscle is the subcutaneous layer. 23.3 The amount of melanin affects and determines skin color. The amount of oxygen-carrying hemoglobin in the blood also affects skin color. In Summary (cont.)23.4 Skin lesions are split among three main types: primary lesions such as macules and vesicles; secondary lesions, which include ulcers and keloids; and vascular lesions, which involve blood vessels and include telangiectasias and ecchymoses. 23.5 The accessory organs of skin include: hair follicles, arrector pili muscles, sebaceous glands, sudoriferous glands, and keratin-filled nails.In Summary (cont.)23.6 Injured skin becomes inflamed from dilating blood vessels that leak and cause swelling. A blood clot is formed, which is replaced by a scab, which is then replaced by collagen fibers that produce scar tissue. 23.7 Common diseases and disorders of the skin include alopecia, cellulitis, dermatitis, eczema, folliculitis, herpes simplex, herpes zoster, impetigo, pedicuosis, psoriasis, ringworm, rosacea, scabies, and warts.We may have different religions, different languages, different colored skin, but we all belong to one human race. ~ Kofi AnnanEnd of Chapter 23