Muscle Types and PhysiologyFunction of MusclesSkeletal Muscle: AttachmentsThe Muscular SystemCharacteristics of MusclesSlide 6Skeletal Muscle CharacteristicsSmooth Muscle CharacteristicsCardiac Muscle CharacteristicsSlide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18How Muscle Contracts: 1) Events at the Neuromuscular JunctionSlide 20How Muscle Contracts: 2) Initiation of an Action PotentialHow Muscle Contracts: 3) How the Sarcolemma ResetsSlide 23How Muscle Contracts: 4) Action Potential Causes Ca++ ReleaseSlide 25How Muscle Contracts: 5) Ca++ Binds to TroponinSlide 27How Muscle Contracts: 6) Troponin Slides Tropomyosin Off Myosin Binding SitesSlide 29Slide 30Slide 31Slide 32Slide 33Slide 34The Power CycleSlide 36Principles of Muscle MechanicsMuscle TwitchSlide 39Graded Muscle ResponsesResponse to Change in Stimulus FrequencySlide 42Slide 43Response to Change in Stimulus StrengthSlide 45Slide 46Slide 47Energy for Muscle ContractionSlide 49Slide 50Isotonic ContractionsIsometric ContractionsSlide 53Slide 54Effects of Exercise on MuscleSlide 56Muscle Fiber TypeSlide 58Slide 59Developmental AspectsDiseases and Medical Conditions (Myopathies) of the Muscular SystemMuscular DystrophySlide 63Muscle Types and PhysiologyTypes and Characteristics of MuscleMuscle Function and TypesMicroscopic Anatomy of MuscleMuscular StimulationMuscular Contraction MechanismMuscular Response Based on StimulusEnergy Sources for Muscular ContractionTypes of Muscular ContractionsEffects of Exercise on MusclesDevelopmental AspectsMuscular DystrophyFunction of MusclesProduce movementMaintain postureStabilize jointsGenerate heatSkeletal Muscle: AttachmentsMuscles attach:•Directly—epimysium of muscle is fused to the periosteum of bone or perichondrium of cartilage•Indirectly—connective tissue wrappings extend beyond the muscle as a ropelike tendon or sheetlike aponeurosisThe Muscular SystemMuscles are responsible for all types of body movementThree basic muscle types are found in the bodyCharacteristics of MusclesMuscle cells are elongated (muscle cell = muscle fiber)Contraction of muscles is due to the movement of microfilaments within fiber cellsAll muscles share some terminology•Prefix myo refers to muscle•Prefix mys refers to muscle•Prefix sarco refers to fleshTable 9.3Skeletal Muscle CharacteristicsMost are attached by tendons to bonesCells are multinucleateStriated – have visible bandingVoluntary – subject to conscious controlCells are cylindricalCells are surrounded and bundled by connective tissuePlasma/cell membrane called a sarcolemmaGlycosomes for glycogen storage, myoglobin for O2 storageAlso contain myofibrils, sarcoplasmic reticulum (modified ER), and T tubulesSmooth Muscle CharacteristicsHas no striationsSpindle-shaped cellsSingle nucleusInvoluntary – no conscious controlFound mainly in the walls of hollow organsCardiac Muscle CharacteristicsHas striationsUsually has a single nucleusJoined to another muscle cell at an intercalated discInvoluntaryFound only in the heartMuscle Types and PhysiologyTypes and Characteristics of MuscleMuscle Function and TypesMicroscopic Anatomy of MuscleMuscular StimulationMuscular Contraction MechanismMuscular Response Based on StimulusEnergy Sources for Muscular ContractionTypes of Muscular ContractionsEffects of Exercise on MusclesDevelopmental AspectsMuscular DystrophyTable 9.1Figure 9.1BonePerimysiumEndomysium(between individualmuscle fibers)Muscle fiberFascicle(wrapped by perimysium)EpimysiumTendonEpimysiumMuscle fiberin middle ofa fascicleBlood vesselPerimysiumEndomysiumFascicle(b)• Each fascicle is composed of muscle fibers (cells), surrounded by a perimysium• Each muscle fiber is surrounded by endomysium ( & then the sarcolemma)• Muscle fibers (cells) contain several myofibrils• Whole muscle is surrounded by an epimysium and is composed of wrapped fasciclesNested Structures in a MuscleFib-Endo-Fas-Per-EpNucleusLight I bandDark A bandSarcolemmaMitochondrion(b) Diagram of part of a muscle fiber showing the myofibrils. Onemyofibril is extended afrom the cut end of the fiber.MyofibrilFigure 9.5MyofibrilMyofibrilsTriad:Tubules ofthe SRSarcolemma (muscle fiber plasma membrane)SarcolemmaMitochondriaI band I bandA bandH zone Z discZ discPart of a skeletalmuscle fiber (cell) • T tubule• Terminalcisternaeof the SR (2) M lineSarcoplasmic Reticulum is Modified Endoplasmic Reticulum(Storage Depot for Calcium Ions)T tubules are continuous with the sarcolemmaThey penetrate the cell’s interior at each A band–I band junctionThey’re associated with the paired terminal cisternae to form triads that encircle each sarcomereT tubules conduct impulses deep into muscle fiber; contains gated channels that regulate Ca2+ releaseFigure 9.2c, dI band I bandA bandSarcomereThick (myosin)filamentM lineZ disc Z discM lineSarcomereThin (actin) filamentThick (myosin) filamentElastic (titin) filamentsH zoneThin (actin)filamentZ disc Z discPatterns Visible in the Sarcomere (Smallest Contractile Unit of a Myofibril) Microscopic Muscle Anatomy (online)Figure 9.3Flexible hinge regionTailTropomyosinTroponin ActinMyosin headATP-bindingsiteHeadsActive sitesfor myosinattachment Actinsubunits Actin-binding sitesThick filamentEach thick filament consists of manymyosin molecules whose heads protrude at opposite ends of the filament.Thin filamentA thin filament consists of two strandsof actin subunits twisted into a helix plus two types of regulatory proteins(troponin and tropomyosin).Thin filamentThick filamentIn the center of the sarcomere, the thickfilaments lack myosin heads. Myosin heads are present only in areas of myosin-actin overlap.Longitudinal section of filamentswithin one sarcomere of a myofibril Portion of a thick filamentPortion of a thin filamentMyosin moleculeActin subunitsTropomyosin and troponin: regulatory proteins bound to actinThin and Thick Filament CompositionFigure 9.6IFully relaxed sarcomere of a muscle fiberFully contracted sarcomere of a muscle fiberIAZ ZHI IAZ Z12Muscle Types and PhysiologyTypes and Characteristics of MuscleMuscle Function and TypesMicroscopic Anatomy of MuscleMuscular StimulationMuscular Contraction MechanismMuscular Response Based on StimulusEnergy Sources for Muscular ContractionTypes of Muscular