Three typesSkeletalCardiacSmoothFunctionExcitability- respond to stimulusContractibility- shorten and exert tensionExtensibility- can contract even when stretchedElasticity- rebound lengthSkeletal MuscleProduces movementMaintains posture and positionSupports soft tissuesGuards orficesMaintain body temperatureOrganizationThe organGroups of fibers within a muscle- fasiclesInside the fascles are the muscle fibers (or cells)Organ fascicle fiber myofibrils myofilamentsConnective Tissue layersEpimysium- outer layer covers the whole muscle organPerimysium- covers the fascicle find blood vessels and nervesEndomysium- surrounds the muscle fibers/cellsContain the muscle and have the nerves and arteries within themConverge to form tendons (muscle to bone attachment)Flattened is an aponeurosesInterwoven into periosteum and boneFeatures of skeletal musclesLarge cylindrical muscle fibersMultinucleatedStriatedVoluntarySatellite cells help in repair- limited but possibleSacrolemma is the membraneSacroplasm is the cytoplasmA muscle fiberMyofibrils in sacroplasm (all red dots)Blue nuclei (multi)An abundance of mitochondriaMembrane= sacrolemmaInvagination of sacrolemma is transverse tubules which carry electrical impulses (nerve impulses)Inside myofibrils are myofilamentsMyofibrils surrounded by sacroplasmic reticulumInternal membrane systemone myofibril is as long as fiber and is attached to sacrolemmacisterna- swollen parts of reticulum near t-tubulesMyofilamentsSacromere- one unit in a myofilamentGoes from z line to z lineThin filament- actin (red lines)Have active site on themThick filament- myosin (purple lines)Has a tail and headMoveable headA band- band where thick filaments reach (only thick)Bumps on a band- heads of myosinM line- the middle where actin and myosin meet in the sacromereI band= thin filamentsZ line- boundaries of the sacromereCross bridges= head of myosinSliding filament theoryRequires presence of calcium and ATPExplains how a muscle fiber exerts tensionActive sites of actin filamentsAnd head of myosin filamentCross bridge- head of myosin to active site of actinAttach, pivot, detach, returnAttach when calcium and atp is presentDetach when calcium and atp is not presentElasticity make muscle go back to original shapeHappens to all sacromere in one cell at a timeSkeletal mucle fascicle fibermyofibrilmyofilament sacromereSkeletal muscle innervationStimulated by a nerve fiber at a neuromuscular junctionMotor nerve from a cell bodySends it down axon to neuromuscular synapseSynaptic terminals- have small vesicles that release Ach (a neurotransmitter)Stimulate motor end paltes causing an action potential (impulse)a.a (acetylcholinesterase) breaks down Achunderstand summary of eventscontractionAch is released, binding to receptorsAction potential reaches t-tubulesSacroplasmic reticulum releases Ca2+Active-site exposure, cross-bridge bindingContraction beginsEnd contractionAch removed by AChESacroplasmic Reticulum recaptures Ca2+Active sites covered, no cross-bridge interactionContraction endsRelaxation occurs, passive return to resting lengthMove towards m line when contracting and a band shortensMotor unitsOne axon to one group of muscle cellsContraction- all motor unit are activeMuscle tone- restingSome motor units are active causing muscles to be tense but no movementsMaintain body positionMuscle hypertrophy- muscle becomes enlargesMuscle repeated stimulatedIncrease in number of myofibrilsIncrease amount of mitochondriaTension increasesMuscle atrophy-Muscle is not stimulatedMuscle becomes smallerMuscle tone is decreased- flaccid (low muscle tone)Cause by lack of nerve input or disuseShapes of MusclesParallel muscle- fascicles are lined up parallel to one another and a tendon at each endConvergent- base of muscles (wide) and converge down to a single tendonLots of movementspennate- fibers are at an angleMultiple or single tendons (uni-, bi-, or multi-The angle of the tendons cause for different types of movementCircular muscle- around an orificeContract- smaller and smaller radiusRelaxed- largerTerminology- pg 253Terms indicating actionTerms indicating directionTerm indicating specific regionSpecificBuccinator- trumpeterRisorious- laughterOriginBicep (two head) etcShapeDeltoid (triangle) etcAxial musculatureArises and inserts onto the axial skeletonPoisitions head and vertebral columnMoves rib cage- thus assits in brething60% of musclesAppendicular musculatureStabilizes components of the appendicular skeletonAxial Skeletal muscles- know name, origin, insertion, action, and innervationRefer to ch 12Muscles of the head and neckStrap muscles just know names and origin and insertionCranial nerves!Veretebral columnAbdominalPelvic floorCh 9. Skeletal Muscular System 09/02/2010 19:16:00← Three types- Skeletal- Cardiac- SmoothFunction- Excitability- respond to stimulus- Contractibility- shorten and exert tension- Extensibility- can contract even when stretched- Elasticity- rebound length← Skeletal Muscle- Produces movement- Maintains posture and position- Supports soft tissues- Guards orfices- Maintain body temperature← Organization- The organ- Groups of fibers within a muscle- fasicles- Inside the fascles are the muscle fibers (or cells)- Organ fascicle fiber myofibrils myofilamentsConnective Tissue layers- Epimysium- outer layer covers the whole muscle organ- Perimysium- covers the fascicle find blood vessels and nerves- Endomysium- surrounds the muscle fibers/cells- Contain the muscle and have the nerves and arteries within them- Converge to form tendons (muscle to bone attachment)oFlattened is an aponeurosesoInterwoven into periosteum and bone← Features of skeletal muscles- Large cylindrical muscle fibers- Multinucleated- Striated- Voluntary- Satellite cells help in repair- limited but possible- Sacrolemma is the membrane- Sacroplasm is the cytoplasm← A muscle fiber- Myofibrils in sacroplasm (all red dots)- Blue nuclei (multi)- An abundance of mitochondria- Membrane= sacrolemma- Invagination of sacrolemma is transverse tubules which carry electrical impulses (nerve impulses)- Inside myofibrils are myofilaments- Myofibrils surrounded by sacroplasmic reticulumoInternal membrane system- one myofibril is as long as fiber and is attached to sacrolemma- cisterna- swollen parts of reticulum near t-tubules← Myofilaments- Sacromere- one unit in a myofilamentoGoes