sarcolemma肌浆膜

《sarcolemma肌浆膜》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、1MUSCLESANDHOWTHEYMOVEchapterLearningObjectiveswLearnthebasiccomponentsofskeletalmuscle,themusclefiber,andthemyofibril.wNotethecellulareventsleadingtoabasicmuscleaction.wDiscoverhowmusclefunctionsduringexercise.wConsiderthedifferencesinfibertypesandtheirimpactonphysicalperformance.wLea

2、rnhowmusclesgenerateforceandmovementbypullingonbones.SkeletalwVoluntarymuscle;controlledconsciouslyOver600throughoutthebodyCardiacwControlsitselfwithassistancefromthenervousandendocrinesystemswOnlyintheheartSmoothwInvoluntarymuscle;controlledunconsciouslyInthewallsofbloodvesselsandintern

3、alorgansTypesofMusclesSKELETALMUSCLESTRUCTURESINGLEMUSCLEFIBERKeyPointswAnindividualmusclecelliscalledamusclefiber.wAmusclefiberisenclosedbyaplasmamembranecalledthesarcolemma肌漿膜.MuscleFiberwThecytoplasmofamusclefiberiscalledthesarcoplasm.wWithinthesarcoplasm,theTtubulesallowtransportofsu

4、bstancesthroughoutthemusclefiber.wThesarcoplasmicreticulumstorescalcium.MICROGRAPHOFMYOFIBRILSARRANGEMENTOFFILAMENTSARRANGEMENTOFFILAMENTSINASARCOMEREACTINFILAMENTMOTORUNITKeyPointswMyofibrilsarethecontractileelementsofskeletalmuscle,withseveralhundredtoseveralthousandcomposingasinglemus

5、cle.wAsarcomereiscomposedoffilamentsoftwoproteins,myosinandactin,whichareresponsibleformusclecontraction.MyofibrilswMyosinisathickfilamentwithaglobularheadatoneend.wAnactinfilament—composedofactin,tropomyosin,andtroponin—isattachedtoaZdisk.wMyofibrilsaremadeupofsarcomeres,thesmallestfunct

6、ionalunitsofamuscle.1.Amotorneuron,withsignalsfromthebrainorspinalcord,releasestheneurotransmitteracetylcholine(Ach)attheneuromuscularjunction.2.AChcrossesthejunctionandbindstoreceptorsonthesarcolemma.3.Thisinitiatesanactionpotential,providingsufficientACh.Excitation/ContractionCoupling4.

7、TheactionpotentialtravelsalongthesarcolemmaandthroughtheTtubulestotheSRreleasingCa2+.5.TheCa2+bindstotroponinontheactinfilament,andthetroponinpullstropomyosinofftheactivesites,allowingmyosinheadstoattachtotheactinfilament.(continued)6.Onceastrongbindingstateisextabl