2Overview of the Integumentary System Guiding Question: What are the components of the integumentary system?Cells and tissues associated with the skin.
3Overview of the Integumentary System Not just a covering for the bodyLargest organBlood vessels, connective tissue structures, glands, hair, nails, nerves, skinPlays a large role in homeostasisHas inherent and adaptive characteristicsCallusesDarken in sunElasticitySensitive to moistureInherent = characteristics determined by genes BUT adaptive = flexibility designed into the genetics of the cells.
4The Integumentary System Guiding Questions: 1.) What embryonic layers form the integumentary system? 2.) Describe the development of the integumentary system. 3.) What are some various causes of hair loss?
5Development of the Integumentary System Ectoderm & mesoderm in originSkin is a complex structureMany things can go wrong in its developmentLet’s make a timeline!
64 weeks: Simple ectoderm epithelium over mesenchyme outermost layer of skin form a simple squamous tissue that becomes stratified as the embryo develops from the ectoderm
74-5 weeksDeeper parts of skin begin to form from mesoderm (dermis, hypodermis)
88-9 wks: mesenchyme begins to mature and fibroblasts form, and dents occur in the upper squamous layerform lanugo.
910 weeks: ridges form between the outer and inner layers of skin—so don’t separate when rubbed 11 weeks: small nails at the tips of fingers & toes, followed by development of special blood vessels in the layers of skinAngiogenic factors stimulate the production of these vessels
1020 weeks: Glandular structures form Inward growths of the outermost squamous cell layerWill eventually produce oils and sweat25 weeks: Pigmentation
11About 26 weeks: melanoblasts mature into melanocytes (build pigments) nervous tissue structures developMesenchyme: embryonic connective tissue composed of star-shaped cells in the gel-like matrix or extracellular material.Fibroblasts: secretes collagen fibers that strengthen the delicate tissue***Have students create a timeline of skin development. One color card has the # of weeks and a second color card has the development that occurs. They match & put in order. May not need to show this slide…Or have them do a human timeline…
13Skin Structure Guiding ?’s: What are the three major layers of the skin?Describe the basic characteristics of the three major layers of the skin (recommend a chart)
14Skin: Structure – 3 layers 1. Epidermis: EpithelialSuperficial & thinnestcells are very tightly packedNew cells produced here2. Dermis: ConnectiveDeep to epidermis & thickPrimarily connective tissueloosely packed cells3. Subcutaneous/Hypodermis (adipose tissue)Deep to the skin/dermisLayer of insulation
19Stratum corneum:Dead squamous cellsStratum lucidum: (only in thick skin); oils from lysosome disintegrationStratum granulosum:Granules with lipids and keratin – forms waterproof layerStratum Spinosum:cuboidal cells, desmosomeshold together >> spinyStratum Germinativum/ Basale: dividing columnar cells
20Epidermis Specialized cells within epidermis: Melanocytes Melanin: pigment, inc. w/sun (protection)KeratinocytesKeratin: tough, waterproof materialAbrasion resistance for cellsLangerhans cellsImmune response against microbes invading the skin
21Second layer of the skin DermisSecond layer of the skin
26Subcutaneous layer Third, innermost layer of the skin Thickness, composition vary throughout bodyComposed of loosely-arranged elastic fibers that anchor the skin to the fasciaSheet of fibrous connective tissueCovers muscles, skull bones, some organsLarge amount of adipose (fat) cellsLarge network of blood vessels, capillaries, lymphatic vessels
30Sebaceous Holocrine glands (secrete whole dead cells) Produce, store abundance of fat, which burst and die, releasing sebum
31Specialized Structures of the Dermis Sebaceous GlandsSecrete oil (sebum) for hair/skinDucts open into hair folliclesAccumulated sebum enlarges ducts>>white headsDarkened sebum>>black head
32Specialized Structures of Dermis Sudoriferous/Sweat GlandsEccrine GlandsWidespreadWatery FluidSeparate poreApocrine GlandsArmpits/GenitalsThick/milky fluidSecrete into hair follicle
33Sweat Aprocrine Eccrine Odorous, sweat-like material in armpits, navel, groin region, areolaeInactive until pubertyContain pheromonesBroken down by bacteria, creating odorEccrineSkin of armpits, foreheads, palms, solesMostly secrete water, w/ salts, organic compounds, and wastes (like urea)Microbes feed on these as well, producing odors
35Dermis Specialized structures: Hair follicle: cells of the epidermis extend into the dermis forming a small tubeHair bulb: base of the follicleHair papilla: cluster of cells (live); nourished by BV’sRoot: part of hair hidden in follicleShaft: visible part of hair
36Nerves Sensory receptors Free nerve endings/Nociceptor Communicate information from environment to the bodyFound in all skin layersMostly in innermost regions, fasciaFree nerve endings/NociceptorPain-sensing structuresFound throughout inner part of epidermisDetect chemicals associated with tissue damage and bleeding
51Guiding QuestionsWhat are the major roles of the integumentary system?What are “commensals”?How does heat regulation in the skin work?How does sensation in the skin work?Briefly describe the three classifications of burns
52Roles of the Integumentary System ProtectionHeat regulationSensationWaste excretion
53Protection The skin protects from: Chemical Damage Can break down connections between cellsCan disintegrate cellsSweat dilutes & neutralizesCerumen and sebum are oily barriersRepels waterRepels dangerous chemicals that are dissolved in waterPrevents water from escaping the body through the skin.
54Protection The skin protects from: Mechanical Damage Any type of force that can compress, erode, stretch or tear the skin.Loose connective tissue = flexibilityShedding stratum corneum = reduce erosionCalluses, adipose tissue and reticular fibers = shock absorption to minimize compression damage
55Protection The skin protects from Microorganism damage Produce destructive secretions in sebum / sweatKept in check by chemicals that benefit commensals— ”good” bacteria and yeast that reduce the chance that harmful bacteria will survive on the skin.Shedding of stratum corneum removes microorganisms
56Heat RegulationThe body’s ability to maintain a constant internal temperature (98.6F)Blood vessels contract / expandEvaporation of the sweat from the surfaceAdipose tissue is a natural “blanket”
57SensationSensation: received stimuli from the environment which is interpreted in a way that the brain can comprehendDone by sensory nerves in the skinCold, heat, injury, pressure, stretching, touchTransducers: nerve cells that convert various environmental messages into body signals.
58Waste Excretion & More Eccrine sweat glands Other functions Removes urea, organic chemicals, and excess saltsNot as efficient as the Excretory SystemOther functionsVitamin D production when exposed to sunlightPredictor of a person’s health
59BurnsSkin loses ability to maintain homeostasis locally and for the whole bodySun, cooking, acids, bases, corrosive chemicals, electricity, fires, and steam roomsDamage the skin differentlySeverity of burn is based on the extent of the skin damage.
60First Degree BurnsReddening, swellingSuperficial damageSteam, sun
64Third Degree BurnsEntire epidermis affected, could be missing so stratum basale not availableDamage to dermis: nerve cell lossPain registers b/c histamine from immune system is released in response to the damage.Susceptible to dehydration, loss of body heat, and infection
664th degree?Skin entirely damaged; bone, muscle underlying skin damaged as well.(Too graphic to show)
67Pathology of the Integumentary System Guiding Questions:What are the three major categories of disease in the integumentary system?What are the various types of degenerative skin disorders? Genetic skin disorders? Infectious skin disorders?
68Disorders Degenerative Genetic Infectious Progressive deterioration of tissue, environmental or physical stressGeneticMutationsInfectiousMicroorganisms that damage tissues and organs
69Degenerative Skin Disorders Solar lentigenePeople in their 30s w/ overexposureDermatitisCosmeticsFacial cleansersTonersCan accelerate skin aging
70Degenerative Skin Disorders Skin CancerUnderlying genetic component—precancerous genesIf damaged, genes cause abnormal divisions of cellsSun exposureIrregularly shaped black or brown spots that can develop into open soresInjury deep in the skinDiscolored blisters or sores
72Degenerative Skin Disorders Moles: flat squamous cell tumorsSkin tags: soft knobby tumors that grow out of skinSeborrheic keratosis: Black to brown growth on face or body that creates a greasy, rough appearance to the skinSebaceous hyperplasia: caused by oil glands, small yellow bumps with an opening in the middleSyringomas: sweat-gland duct tumor, small lumps on the cheeks and eyelidsLipomas: fat cell tumor, don’t cause problems normally
74Genetic Skin Disorders Acne: stimulated by hormonal changes that cause and increase in sebum around the hair follicles.Furuncle or boil: a buildup of dead cells and blood components caused by the inflammation of hair follicles.Cysts or nodules: a sack-like structure filled with a fluid or semi-solidBacteria that feed on the acne pimple produce chemicals that aggravate acne
75Genetic Skin Disorders PsoriasisIncreased amt of skin cell productionCauses a build up of thick scales on skin.Unsightly, inflamed, painful, swollenBirthmarksPort wine: begins at birth and grows, can bleedSpider veins: central blood vessel with smaller vessels branching from itStrawberry hemangiomas: enlarged blood vessels
76Genetic Skin Disorders VitiligoMichael JacksonWhite spots—hypopigmentationReduced melanocytesAlbinismNo melanin production in the eyes, hair or skinMelasmaBrown patches on both sides of the faceSymmetricalDoes not completely disappear
77Infectious Skin Disorders Staphylococcus aureus (bacteria)destructive secretions that erodes and inflame the skinImpetigo, SSSS, folliculitisCandida albicans (fungus)Yeast in digestive system and female reproductive tract infect skin when immune system is compromisedDegrade tissue and cause inflammation
78Infectious Skin Disorders More fungal infections = dermatophytesEat keratin-rich materials: hair, nails, and outer layers of epidermisItching, hair loss, deformation of nailsRingworm (aka tinea)Contracted from furry petsSpread from one person to another through contact via clothes and skinRelated to athlete’s foot or jock itch
79Infectious Skin Disorders Warts (virus)60 typesHPV (human papilloma virus)IncurableRemoval procedureProtistsExotic tropical diseases that are spread by insect bites.Can cause severe bodily damage if spread to internal organs
80Infectious Skin Disorders ArthropodsInsects with exoskeletons, segmented bodies, jointed limbsFollicle mite—undetected until inflammation of eyelash follicle occursLice—blood sucking insects that irritate skin and spread infection as they feed
81Aging of the Integumentary System Guiding QuestionsWhat are “intrinsic” factors? How can they affect the skin’s aging?What kinds of extrinsic factors can affect skin aging?How does lifestyle accelerate skin aging?
82Aging Extrinsic Intrinsic Also external aging Environmental factors: disease, pollution, sunIntrinsicNatural maturationAlso internal agingAccelerated by stress—pathology of other organ systems or environmental interactions
83Aging Characteristics of skin aging Loss of head hair Graying and whitening of hairExcessive growth of body and facial hairWrinklingDrying of the skin due to diminished oil secretionSkin sagging due to muscle atrophyRegular irritation due to microbial population changes on the skin
84Aging Impossible to stop Natural decline of cells Can be slowed by living in a mild environmentElastin is naturally degraded by the dermis and subcutaneous layersMakes the skin less flexible, thinner, more brittleDecrease in blood flow slows cell division in basale & causes thinning of the epidermisMore difficult to repair skin damagePeople with vascular diseases exhibit premature aging
85Aging Decrease in melanocytes, nerves Susceptible to DNA damage More susceptible to environmental damageOlder skin can’t protect from UV and has difficulty registering injury.Susceptible to DNA damageOxidizing chemicals and sunlightCause cancers and tumors
86AgingHow to slow…Diet, reducing exposure to UV, avoiding skin irritation, not smoking, protecting from air pollutantsSmoking reduces blood flow to skinCan’t healDecreases ability to maintain body’s tempSkin needlingPromotes growth and swelling in wrinkled depression areasMakes skin smooth for a whileTake care of skin at a young age…difficult to reverse skin aging once the damage is done