1Muscular Tissue201404152 Overview1) components:-cell:musclefiber-myofiberelongatedthread-likedSarcolemma（肌膜）Sarcoplasm（肌质）Sarcoplasmicreticulum（肌质网）:SER-extracellularG.S:CTwithBV,LVandN3 2) classificationAccordingtothestructureandfunctionskeletalmuscle(骨骼肌):striated,voluntarycardiacmuscle(心肌):striated,involuntarysmoothmuscle(平滑肌):unstriated,involuntary4Skeletal muscle5 Epimysium（肌外膜）:DCTPerimysium（肌束膜）Endomysium（肌内膜）6 LM: llongcylindrical10-100umindiameter,1-40mmlonglmultinucleate, nuclei are ovoid, distributed undersarcolemmalfilledwithlongitudinalparallel-arrangedmyofibrils7Skeletal MuscleCells are long multinucleate “cylinders”89Identify:Endomysium,Perimysium,myofiberandfascicleEndomysiumPerimysiumMyofiberFascicle10Endomysium:connectivetissue,nutrientcapillaries,nerveendingsandaroundeachmyofiberabasalorexternallamina11Myofiber12 Myofibril:1-2umindiametercrossstriation:lightband-Ibanddarkband-Aband-Aband:M-line,H-band-Iband:Z-line13DefinitionsIsotropic (各向同性各向同性)Anisotropic (各向异性各向异性)14Aband:Anisotropic(各向异性各向异性)Iband:Isotropic(各向同性各向同性)15HBandislightandinthecenteroftheABand16 Sacromere（肌节）（肌节）:1/2I+A+1/2Ithe smallest structural and functional unit ofmyofibril171.Transverse tubule (T tubule):横小管横小管udefinition: sarcolemma invaginate intosarcoplasmtoformatransversedistributedtubularsystemulocation:A-Ijunctionalpartufunction: transfer the information intocytoplasmEM:182.Sarcoplasmic reticulum:肌质网肌质网usmoothendoplasmicreticulumulongitudinaltubule(Ltubule)uterminalcisternae(终池)uTriad(三 联 体 ): one T-tubule +twoterminalcisternaeucalciumpumpproteinsustoreandreleasecalciumions1920 3.Myofibril (肌原纤维肌原纤维)uthickmyofilamentuthinmyofilament 21Skeletal MuscleOrganizational HierarchyMuscleiscomposedoffasciclesFascicle(smallest)iscomposedofmyofibersMyofiberiscomposedofmyofibrilsMyofibriliscomposedofmyofilaments22Thick myofilamentThick myofilament uu1.5umlong,15nmindiameter1.5umlong,15nmindiameteruucomposedofcomposedofmyosinmyosin( (肌球蛋白肌球蛋白) )-rob:inbundles-rob:inbundles-head:crossbridge-bindingsite(ATPaseactivity)-head:crossbridge-bindingsite(ATPaseactivity)23Thin myofilament u1umlong,u5nmindiameterA.Actin(肌动蛋白)-bindingsiteB.Tropomyosin(原肌球蛋白)C.Troponin(肌原/钙蛋白)-TnT:bindtotropomyosin-TnC:bindstocalciumions-TnI:inhibitactin-myosininteraction 24Is cross banding evident at the level of the myofibril?Define a sarcomere.A sarcomere is that portion of the contractile apparatus between and attaching to two Z lines.Myofibril25MyofibrilThesarcomereisthesmallestcontractileunit.Itconsistsofapreciselyorganizedarrayofmyofilaments.Thickmyofilamentsconsistofmyosin.MyosinisONLYfoundintheABand26MyofibrilThinmyofilamentsconsistofActin,tropomyosinandtroponin.ThinmyofilamentsarefoundinBOTHtheABandandIBand27MyofibrilMLine,inthecenteroftheHBand,consistsofproteinsthatholdmyosinfilamentstogether.28MyofibrilZLine.29MicrographProvidedbyErnestWhitterElectron Micrograph of Human Skeletal MuscleDark granules are glycogenMyofibril30MicrographProvidedbyErnestWhitterElectron Micrograph of Human Skeletal MuscleSarcomere31MicrographProvidedbyErnestWhitterElectron Micrograph of Human Skeletal MuscleA Band32MicrographProvidedbyErnestWhitterElectron Micrograph of Human Skeletal MuscleI BandZ LineM Line in H Band33Sliding filament hypothesis(肌丝滑动学说肌丝滑动学说)34Cardiac muscle 35 LMshort column in shaped, 100um long,15um indiameter,withbranches1-2ovoidnuclei,centrally-locatedstriated,butnoveryclearintercalateddisc36EMl T tubule at Z-line levellless terminal cisternael diad(二联体二联体): one T-tubule + one terminal cisternaelNumerous mitochondria 37intercalated discs 3839 Smooth muscle 40 LMlelongated,spindle-shapedcells,8umindiameter,200(20-500)umlonglrob-likedorovoidnucleuslnostriation,nomyofibril41Smooth MuscleLongitudinal SectionCross Section42EMlcaveola:sarcolemmeinvaginateintocytoplasmldensepatch(密斑):undersarcolemmadensebody(密体):insarcoplasmlintermediatefilament:/composedofdesmin(结蛋白)/10nmindiameter/connectbetweendensebody43l thickfilament:myosin,15nmthinfilament:actin,5nm-fixedondensepatchorbodycontractile unit(肌 丝 收 缩 单 位 ): several thickfilamentandthinfilamentaggregate4445