Muscle System BSlide 2Slide 3SarcolemmaSarcoplasmPeripheral NucleiTransverse TubuleInvagination of SarcolemmaCommunicates with Sarcoplasmic ReticulumSarcoplasmic ReticulumSlide 11Terminal CisternaeTriadMyofibril StructureMyofilamentActin Strands with Motor ProteinsMyosin StrandsMysosin HeadsSlide 19Myofilament OrganizationParallelOverlappingSlide 23SarcomereSlide 25Sarcomere StructureI bandA BandZ LineH BandM LineZone of OverlapSlide 33StriationSlide 35Muscle ContractionsSlide 37ResponseSlide 39ConductsContractionContraction of Sarcomere“Sliding”Active SiteSlide 45Cross Bridge FormationSlide 47Myotonia CongenitaSlide 49Muscle ContractionSlide 51Slide 52Slide 53Slide 54MuscleTitinSlide 57Muscle StrengthMotor UnitSlide 60Slide 61Slide 62Contraction CharacteristicsSpecific Motor Units ActivatedMuscle ToneMuscle HypertrophyMuscle AtrophyProlonged AtrophyContraction typesMuscle Fiber PropertiesWhite fibersSlide 72Red fibersRed FibersIntermediate fibersLeversSlide 77Slide 78Slide 79First Class LeverSlide 81Second Class LeverSlide 83Slide 84Third Class LeverSlide 86Slide 87Muscle System BCh 9Sarcolemma•Cell membrane of the muscle fiber•Responds to motor neurons•Conducts contraction signalsSarcoplasm•Muscle cytoplasm•Contains organelles–Mitochondria•High concentration–Nuclei•Multiple•Peripheral•Transverse tubules•Sarcoplasmic reticulum•MyofibrilsPeripheral NucleiTransverse Tubule•Invagination of sarcolemma into the cell•Communicate with all myofibrils•Conducts action potential to cell interior•Distributes contraction signals throughout cell–Communication efficiency–Coordination of muscle contraction•Fluid filled•Specialized interaction with endoplasmic reticulum–Sarcoplasmic reticulumInvagination of SarcolemmaCommunicates with Sarcoplasmic ReticulumSarcoplasmic Reticulum•Specialized Endoplasmic Reticulum•Stores & releases calcium•Terminal Cisternae–Enlarged region of SR–Stores & releases the majority of Ca+•Connects with T-tubule to form Triad–Arrangement of SR & T-tubuleSarcoplasmic ReticulumTerminal CisternaeTriadMyofibril Structure•Protein filaments & motor proteins used in muscle contraction–Myofilament •bundles of protein filaments•Highly organized microfilaments•Work in conjunction with motor proteins–100-1000+ of myofilaments per myofibril•Change orientation to produce muscle contraction–Active unit•Use ATPMyofilament•2 types fibers–Actin- thin filaments•Primarily actin protein•Contain active site –Myosin- thick filaments•Primarily myosin protein•Contain myosin heads–Motor proteins- active site•Tropomyosin•TroponinActin Strands with Motor ProteinsMyosin StrandsMysosin HeadsMyofilament Organization•Parallel overlapping arrangement•Organization produces striation pattern•Arranged in sarcomeresParallelOverlapping3 DimensionalSarcomere•Unit of myofilaments–Comprised of thick & thin fibers•Functional contractile unit•Sarcomere changes length–Protein fibers that make up sarcomere do not change length•1000s+ make up myofibril•Each contract in coordination with other sarcomeres to create muscle contraction•Distinct organization patternsSarcomereSarcomere Structure•Overlapping fibers with thick filaments in the center & thin filaments on either side•Z line–Protein ends mark boundary of sacromere–Thin filaments attach here•M line–Connect thick filaments•A band–Thick & thin filaments •I band–Thin filaments only•H band–Gap between thin filamentsI band•Isotropic•Thick light outer band•Comprised of only thin filaments•Gets smaller during contractionA Band•Anisotropic•An= not•Thick dark central band•Comprised of both thick & thin filaments•Remains the same during contractionZ Line•Aka Z Disc, Zwischen Scheibe•Zwischen= disc Scheibe= inside•Dark, outer boundary of sarcomere•Region of interlocking thin filaments•Move closer together during contractionH Band•Aka H Zone•Thin, light, middle band•“middle of sarcomere”•Comprised of thick filaments only•Gets smaller during contractionM Line•Thin, dark, middle line•Region of interlocking thick filaments•Does not change during contractionZone of Overlap•Area where thick and thin filaments overlap•Increases during muscle contractionStriationhttp://www.youtube.com/watch?v=EdHzKYDxrKc&feature=player_embeddedMuscle Contractions•Cumulative shortening of each sarcomere•Actions of myofilaments & motor proteins cause filaments to move against each other in a sliding fashion–Sliding Filament Theory•Coordinated movements•Occur in unique sequence of events triggered by electrical signal•Response•Conduction•ContractionResponse•Responds to motor neurons•Neuromuscular junction•Site of communication with motor nerves•motor end plates•Motor end plates•High density of receptors•Respond to nerve signal•Neurotransmitters–Ex Ach: Acetylcholinehttp://www.youtube.com/watch?v=ZscXOvDgCmQ&feature=relatedConducts•Conducts contraction signals to myofibrils in sarcoplasm•Signal is an electrical current–Action potential•Region of specialization to maximize communication efficiency–Transverse tubule (T Tubule)•Communicates signal to myofibrilsContraction•Sliding Filament Theory•Contraction a result of coordinated sarcomere shortening–Sarcomere, not filaments change in length•Thin filaments slide inward across thick filaments–Slide over thick filaments–Increase zone of overlap–Produce shortening of sarcomereContraction of Sarcomerehttp://www.youtube.com/watch?v=Ds6f5qeLA8c&feature=related“Sliding”•Interaction between thin & thick filaments•Active site –Found on thin fibers–Tropomyosin & Troponin–Will interact with myosin heads to create contraction–Connection with myosin forms cross bridgeActive SiteCross Bridge FormationMuscle Contraction Produces ForceMyotonia Congenita•Lack of muscle relaxation after contraction•http://www.youtube.com/watch?v=f_3Utmj4RPU&feature=fvwMuscle Contraction•Uses both chemical & electrical signal•Signal received at sarcolemma and travels to the interior of the cell via T tubules•T Tubules interact with sarcoplasmic reticulum at the cisternae •Trigger release of stored calcium from triad region•Calcium binds with troponin & causes exposure of active site•Myosin cross bridge formed when myosin heads attach to exposed active site–Movement (contraction)•ATP molecule