objective: know the components of the skin homework: read p. 138-141 (skin structure) agenda: hand...

44
September 17 th Friday Objective: Know the components of the skin Homework: Read p. 138-141 (Skin Structure) Agenda: Hand out article PPT Sun block lab

Upload: judith-mathews

Post on 14-Jan-2016

219 views

Category:

Documents


2 download

TRANSCRIPT

September 17th Friday

September 17th FridayObjective: Know the components of the skinHomework: Read p. 138-141 (Skin Structure)Agenda:Hand out articlePPTSun block labThe Integumentary SystemChapter 4Overview of the Integumentary SystemGuiding Question:

What are the components of the integumentary system?

Cells and tissues associated with the skin.3Overview of the Integumentary SystemNot just a covering for the bodyLargest organBlood vessels, connective tissue structures, glands, hair, nails, nerves, skinPlays a large role in homeostasis

Has inherent and adaptive characteristicsCallusesDarken in sunElasticitySensitive to moisture

Inherent = characteristics determined by genes BUT adaptive = flexibility designed into the genetics of the cells.4The Integumentary SystemGuiding 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?

4-5 weeks: outermost layer of skin form a simple squamous tissue that becomes stratified as the embryo develops from the ectodermIn some areas forms nervous tissue that later becomes integrated into the skin structure.6-7 weeks: deeper parts of skin begin to form from mesoderm.8-9 wks: mesenchyme begins to mature and fibroblasts form, and dents occur in the upper squamous layerform lanugo.10 weeks: ridges form between the outer and inner layers of skinso dont separate when rubbed11 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 vessels20 weeks: Glandular structures formInward growths of the outermost squamous cell layerWill eventually produce oils and sweat25 weeks: PigmentationAbout 26 weeks: melanoblasts mature into melanocytes, and 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 slideOr have them do a human timeline6Development of the Integumentary SystemEctoderm & mesoderm in originSkin is a complex structureMany things can go wrong in its developmentLets make a timeline!Skin StructureSkin 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)

Skin: Structure 3 layers1. Epidermis: EpithelialSuperficial & thinnestcells are very tightly packedNew cells produced here

2. Dermis: ConnectiveDeep to epidermis & thickPrimarily connective tissueloosely packed cells

3. Subcutaneous/Hypodermis (adipose tissue)Deep to the skin/dermisLayer of insulation

10Diagrammatic vs. Histological view

EpidermisOutermost: Stratum corneumDry, dead, keratin filled (waterproof, tough)Stratum GranulosumWaterproofContains granules of keratinStratum SpinosumPrickly layerContains Langerhans cells (fight infections)

12Statum germinativum / basaleCells undergoing mitosis, move up and horizontallyContains malpighian layer or Pigment layer with melanosomesForms epidermal ridges

14

Stratum corneum: Dead squamous cellsStratum Germanitivum/ Basale: dividing columnar cellsStratum Spinosum: cuboidal cells, desmosomes hold together >> spinyStratum granulosum: Granules with lipids and keratin forms waterproof layerStratum lucidum: (only in thick skin); oils from lysosome disintegration15EpidermisSpecialized cells within epidermis:MelanocytesMelanin: pigment, inc. w/sun (protection)KeratinocytesKeratin: tough, waterproof materialAbrasion resistance for cells Langerhans cellsImmune response against microbes invading the skin16DermisSecond layer of the skin17DermisCollagen, elastin fibers scattered

18Dermal Connective tissueDense, irregular connective tissueLoose, connective tissue = areolar connective tissueBinds blood vessels, membranes, muscles, nerves, and skin to other structuresContains extensive meshwork of protein fibers (fibroblasts)Involved primarily in body growthConnective tissue maintenanceWound healingDermal-epidermal junctionDermal papillae: parallel rows of peg-like projectionsUnique to each individual; akin to fingerprints

20Subcutaneous LayerThird layer of the skin

Subcutaneous layerThird, innermost layer of the skinThickness, 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 vesselsSkin AppendagesGlandsNervesNailsHair

Glands3 Types:CeruminousSebaceousSweatCeruminousProduce cerumen (waxy secretion), an apocrine secretion (ear wax)Found lining ear canal

SebaceousHolocrine glands (secrete whole dead cells)Produce, store abundance of fat, which burst and die, releasing sebum

Specialized Structures of the DermisSebaceous GlandsSecrete oil (sebum) for hair/skinDucts open into hair folliclesAccumulated sebum enlarges ducts>>white headsDarkened sebum>>black head27Specialized Structures of DermisSudoriferous GlandsEccrine GlandsWidespreadWatery FluidApocrine GlandsArmpits/GenitalsThick/milky fluid28SweatAprocrine Odorous, sweat-like material in armpits, navel, groin region, areolaeInactive until pubertyContain phermonesBroken 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

30NervesSensory receptorsCommunicate information from environment to the bodyFound in all skin layersMostly in innermost regions, fasciaFree nerve endingsPain-sensing structuresFound throughout inner part of epidermisDetect chemicals associated with tissue damage and bleeding

32Encapsulated receptorsMerkel cellsSensitive to gentle physical sensationFound in stratum germinativumAbundant in fingertipsMeissners (tactile) corpusclesElongated, club-shaped pile of connective tissueUpper region of dermis (in dermal papilla)Respond to touch

34Pacinian (lamellated) corpuscleLook like onionsDeeper parts of hypodermisHard pressure, vibrations

Ruffini receptorsPressure, constant touch

36Krause end bulbsSensitive touch receptorsFound mostly in mucous membrane of mouth

37NailsMerely a keratin secretionNail rootLies beneath skin-nail foldGrow back as long as nail root and skin-nail fold are not severely damagedGrow 1/8 in per month

DermisSpecialized 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 BVsRoot: part of hair hidden in follicleShaft: visible part of hair

39HairModified stratum corneumGrows from an individual follicle buried in subcutaneous layer

41

42DermisSpecialized Structures (continued)Arrector pili: tiny, smooth muscle attached to base of dermal papillae & side of hair follicleContracts: pulls on both simultaneously>>goosebumps

43

44