19Muscle OverviewMuscle SimilaritiesSkeletal Muscle TissueCardiac Muscle TissueSmooth Muscle TissueFunctional Characteristics of Muscle TissueMuscle FunctionSkeletal MuscleSlide 11Skeletal Muscle: Nerve and Blood SupplySkeletal Muscle: AttachmentsMicroscopic Anatomy of a Skeletal Muscle FiberMyofibrilsSlide 16SarcomeresSlide 18Myofilaments: Banding PatternSlide 20Slide 21Ultrastructure of Myofilaments: Thick FilamentsSlide 23Ultrastructure of Myofilaments: Thin FilamentsSlide 25Arrangement of the Filaments in a SarcomereSarcoplasmic Reticulum (SR)Slide 28T TubulesTriad RelationshipsSliding Filament Model of ContractionSlide 32Skeletal Muscle ContractionNerve Stimulus of Skeletal MuscleNeuromuscular JunctionSlide 36Slide 37Slide 38Destruction of AcetylcholineAction PotentialRole of Acetylcholine (Ach)Slide 42DepolarizationAction Potential: Electrical Conditions of a Polarized SarcolemmaSlide 45Action Potential: Depolarization and Generation of the Action PotentialSlide 47Action Potential: Propagation of the Action PotentialSlide 49Action Potential: RepolarizationSlide 51Excitation-Contraction CouplingSlide 53Slide 54Role of Ionic Calcium (Ca2+) in the Contraction MechanismSlide 56Slide 57Slide 58Sequential Events of ContractionSlide 60Contraction of Skeletal Muscle FibersContraction of Skeletal Muscle (Organ Level)Motor Unit: The Nerve-Muscle Functional UnitSlide 64Slide 65Muscle TwitchSlide 67Graded Muscle ResponsesMuscle Response to Varying StimuliSlide 70Muscle Response: Stimulation StrengthStimulus Intensity and Muscle TensionTreppe: The Staircase EffectSlide 74Slide 75Muscle ToneIsotonic ContractionsSlide 78Isometric ContractionsSlide 80Muscle Metabolism: Energy for ContractionSlide 82Muscle Metabolism: Anaerobic GlycolysisSlide 84Muscle FatigueSlide 86Oxygen DebtHeat Production During Muscle ActivityForce of Muscle ContractionSlide 90Muscle Fiber Type: Functional CharacteristicsMuscle Fiber Type: Speed of ContractionSmooth MuscleSlide 94PeristalsisInnervation of Smooth MuscleSlide 97Microscopic Anatomy of Smooth MuscleProportion and Organization of Myofilaments in Smooth MuscleSlide 100Contraction of Smooth MuscleContraction MechanismRole of Calcium IonSpecial Features of Smooth Muscle ContractionResponse to StretchHyperplasiaTypes of Smooth Muscle: Single UnitTypes of Smooth Muscle: MultiunitSlide 109Muscular DystrophySlide 111Slide 112Developmental AspectsDevelopmental Aspects: RegenerationDevelopmental Aspects: After BirthDevelopmental Aspects: Male and FemaleSlide 117Developmental Aspects: Age Related11Rat Dissectiongsdfg29Muscles and Muscle TissuePart A3Muscle OverviewThe three types of muscle tissue are skeletal, cardiac, and smoothThese types differ in structure, location, function, and means of activation4Muscle SimilaritiesSkeletal and smooth muscle cells are elongated and are called muscle fibersMuscle contraction depends on two kinds of myofilaments – actin and myosinMuscle terminology is similarSarcolemma – muscle plasma membraneSarcoplasm – cytoplasm of a muscle cellPrefixes – myo, mys, and sarco all refer to muscle5Skeletal Muscle TissuePackaged in skeletal muscles that attach to and cover the bony skeletonHas obvious stripes called striationsIs controlled voluntarily (i.e., by conscious control)Contracts rapidly but tires easilyIs responsible for overall body motilityIs extremely adaptable and can exert forces ranging from a fraction of an ounce to over 70 pounds6Cardiac Muscle TissueOccurs only in the heart Is striated like skeletal muscle but is not voluntaryContracts at a fairly steady rate set by the heart’s pacemakerNeural controls allow the heart to respond to changes in bodily needs7Smooth Muscle TissueFound in the walls of hollow visceral organs, such as the stomach, urinary bladder, and respiratory passagesForces food and other substances through internal body channelsIt is not striated and is involuntary8Functional Characteristics of Muscle TissueExcitability, or irritability – the ability to receive and respond to stimuliContractility – the ability to shorten forciblyExtensibility – the ability to be stretched or extendedElasticity – the ability to recoil and resume the original resting length9Muscle FunctionSkeletal muscles are responsible for all locomotionCardiac muscle is responsible for coursing the blood through the bodySmooth muscle helps maintain blood pressure, and squeezes or propels substances (i.e., food, feces) through organsMuscles also maintain posture, stabilize joints, and generate heat10Skeletal MuscleEach muscle is a discrete organ composed of muscle tissue, blood vessels, nerve fibers, and connective tissueThe three connective tissue sheaths are:Endomysium – fine sheath of connective tissue composed of reticular fibers surrounding each muscle fiberPerimysium – fibrous connective tissue that surrounds groups of muscle fibers called fasciclesEpimysium – an overcoat of dense regular connective tissue that surrounds the entire muscle11Skeletal MuscleFigure 9.2 (a)12Skeletal Muscle: Nerve and Blood SupplyEach muscle is served by one nerve, an artery, and one or more veinsEach skeletal muscle fiber is supplied with a nerve ending that controls contractionContracting fibers require continuous delivery of oxygen and nutrients via arteriesWastes must be removed via veins13Skeletal Muscle: AttachmentsMost skeletal muscles span joints and are attached to bone in at least two placesWhen muscles contract the movable bone, the muscle’s insertion moves toward the immovable bone, the muscle’s originMuscles attach:Directly – epimysium of the muscle is fused to the periosteum of a boneIndirectly – connective tissue wrappings extend beyond the muscle as a tendon or aponeurosis14Microscopic Anatomy of a Skeletal Muscle FiberEach fiber is a long, cylindrical cell with multiple nuclei just beneath the sarcolemmaFibers are 10 to 100 m in diameter, and up to hundreds of centimeters longEach cell is a syncytium produced by fusion of embryonic cellsSarcoplasm has numerous glycosomes and a unique oxygen-binding protein called myoglobinreserve supply of oxygen in muscle cellsFibers contain the usual organelles, myofibrils, sarcoplasmic reticulum, and T tubules15MyofibrilsMyofibrils are densely packed, rodlike contractile elements They make up most of the muscle volume