Muscular System Muscle Tissue The Muscular System

Muscular SystemMuscular System

Muscle TissueMuscle Tissue The Muscular SystemThe Muscular System

Muscle TissueMuscle Tissue

IntroductionIntroductionSkeletal Muscle Tissue & Skeletal Muscle Tissue &

The Muscular SystemThe Muscular SystemAnatomy of Skeletal Anatomy of Skeletal

MuscleMuscleContraction of Skeletal Contraction of Skeletal

MuscleMuscleMuscle MechanicsMuscle Mechanics


Aging & the Muscular Aging & the Muscular SystemSystem

Integration With Other Integration With Other SystemsSystems

Cardiac Muscle TissueCardiac Muscle TissueSmooth Muscle TissueSmooth Muscle Tissue

IntroductionIntroduction

• Importance to body functionImportance to body function

• Importance to human activityImportance to human activity

• Active & passive forcesActive & passive forces

Learning ObjectivesLearning Objectives

• ImportanceImportance:: Discuss the central role of muscle Discuss the central role of muscle

tissue in a variety of human activities tissue in a variety of human activities and necessary body functionsand necessary body functions

• ActiveActive ForcesForces:: Compare & contrast Compare & contrast tensiontension,,

compressioncompression, & , & resistanceresistance

Importance:Importance:Function & ActivityFunction & Activity

• Human activityHuman activity gross movements of the bodygross movements of the body communicationcommunication

speakingspeakingfacial expression & gesturesfacial expression & gestures

• Body functionBody function circulationcirculation respirationrespiration digestiondigestion reproductionreproduction

Body MovementBody Movement

CommunicationCommunication

Bodily FunctionsBodily Functions

Active & Passive Active & Passive ForcesForces

• ResistanceResistance passivepassive force force opposing movementopposing movement dependent on weight, shape, friction, etcdependent on weight, shape, friction, etc

• TensionTension activeactive force force applied to an object to produce applied to an object to produce

movementmovement when applied tension > resistance, object is when applied tension > resistance, object is pulled pulled

towardtoward source of tension source of tension

• CompressionCompression (not assoc. w/ muscle movement)(not assoc. w/ muscle movement) activeactive force force applied to an object to produce applied to an object to produce

movementmovement when applied compression > resistance, object is when applied compression > resistance, object is

pushed awaypushed away from source of compression from source of compression

Muscle Contraction Muscle Contraction Produces TensionProduces Tension

TENSIONTENSION

RESISTANCERESISTANCE

Skeletal Muscle Tissue & Skeletal Muscle Tissue & The Muscular SystemThe Muscular System

• Tissue characteristicsTissue characteristics

• Functions of muscle tissueFunctions of muscle tissue


• CharacteristicsCharacteristics && FunctionsFunctions:: Describe the characteristics & Describe the characteristics &

functions of muscle tissuefunctions of muscle tissue


• One of 4 primary tissue types of the One of 4 primary tissue types of the bodybody

• Types of muscle tissueTypes of muscle tissue skeletalskeletal cardiaccardiac smoothsmooth

• Body muscles are Body muscles are organsorgans that contain that contain skeletal muscleskeletal muscle tissuetissue, , connective tissuesconnective tissues, , nervesnerves, , epithelial epithelial tissuetissue & & smooth muscle smooth muscle tissuetissue (in blood (in blood vessels)vessels)

Muscle Tissue TypesMuscle Tissue Types

skeletal muscleskeletal muscle

cardiac musclecardiac muscle

smooth musclesmooth muscle

Functions ofFunctions ofSkeletal Muscle TissueSkeletal Muscle Tissue

• ProduceProduce skeletal skeletal movementmovement• MaintainMaintain postureposture & body position & body position• SupportSupport soft tissues soft tissues• GuardGuard entrances into & exists out entrances into & exists out

of the bodyof the body• MaintainMaintain body temperaturebody temperature

Mr. GMr. GBefore he got marriedBefore he got married

Anatomy of Anatomy of Skeletal MuscleSkeletal Muscle

• Connective tissue organizationConnective tissue organization

• Blood vessels & nervesBlood vessels & nerves

• Microanatomy of skeletal muscle Microanatomy of skeletal muscle fibersfibers


• TissueTissue StructureStructure:: Describe the organization of muscle at Describe the organization of muscle at

the tissue levelthe tissue level

• CellularCellular StructureStructure:: Explain the unique characteristics of Explain the unique characteristics of

skeletal muscle fibersskeletal muscle fibers

• OrganelleOrganelle StructureStructure:: Identify the structural components of Identify the structural components of

a sarcomerea sarcomere

Connective TissueConnective TissueOrganizationOrganization

• Surrounding SheathsSurrounding Sheaths– EpimysiumEpimysium

– PerimysiumPerimysium

– EndomysiumEndomysium

• TendonsTendons

Connective Tissue Connective Tissue OrganizationOrganization

• EpimysiumEpimysium outerouter connective tissueconnective tissue layer layer

dense layer of collagen fibersdense layer of collagen fibersdeep fasciadeep fascia

surrounds entire musclesurrounds entire muscle• PerimysiumPerimysium

middlemiddle connective tissueconnective tissue layer layercollagen & elastic fiberscollagen & elastic fiberscontains blood vessels & nervescontains blood vessels & nerves

surroundssurrounds fasciclesfascicles: dividing muscle : dividing muscle into compartmentsinto compartments


• EndomysiumEndomysium innerinner connective tissueconnective tissue layer layer

delicate c.t.delicate c.t.

surrounds muscle fibers & satellite surrounds muscle fibers & satellite cellscellssatellite cellssatellite cells (stem cells)(stem cells)


EpimysiumEpimysium, , perimysiumperimysium, & , & endomysiumendomysium unite at muscle ends to unite at muscle ends to form:form:

• TendonsTendons – –

linear bundlelinear bundle attaching muscle to boneattaching muscle to bone• AponeurosesAponeuroses – –

broad sheetbroad sheet attaching muscle to boneattaching muscle to bone [same function as “tendon”][same function as “tendon”]


Animation

Blood Vessels Blood Vessels & Nerves& Nerves

blood vesselsblood vessels

nervenerve

MicroanatomyMicroanatomy

• Organelles of Skeletal Muscle Organelles of Skeletal Muscle FibersFibers

• Sarcomere OrganizationSarcomere Organization

• Microfilament StructureMicrofilament Structure

Microanatomy of Skeletal Microanatomy of Skeletal Muscle FibersMuscle Fibers

• Muscle fiberMuscle fiber:: muscle cellmuscle cell long, thin long, thin (among largest cells in body)(among largest cells in body)

multinucleatemultinucleate – peripheral, oval nuclei – peripheral, oval nuclei

• SarcolemmaSarcolemma:: cellcell membranemembrane openings for penetrating tubulesopenings for penetrating tubules established membrane potential due established membrane potential due

to Na-K ion exchange pumpsto Na-K ion exchange pumps


• SarcoplasmSarcoplasm:: cytoplasmcytoplasm contains contains contractile proteinscontractile proteins contains numerous contains numerous mitochondriamitochondria

• Sarcoplasmic reticulum Sarcoplasmic reticulum ((SRSR)):: endoplasmic reticulumendoplasmic reticulum terminal cisternae – terminal cisternae – fused SR tubules fused SR tubules triadstriads – regions where T tubules & SR – regions where T tubules & SR

cisternae contactcisternae contact


• Transverse tubulesTransverse tubules: : T tubulesT tubules continuous w/ continuous w/ sarcolemmasarcolemma networknetwork throughout cell throughout cell close contact w/ close contact w/ SRSR

• MyofibrilsMyofibrils 100s-1000s of bundles of100s-1000s of bundles of

myofilamentsmyofilamentsthin filamentsthin filamentsthick filamentsthick filaments


• SarcomereSarcomere repeating units in myofibrilsrepeating units in myofibrils linked end-to-endlinked end-to-end functionalfunctional unitunit of a muscle fiber of a muscle fiber componentscomponents

thickthick protein filamentsprotein filamentsthinthin protein filamentsprotein filamentsproteins stabilizing thick & thin filamentsproteins stabilizing thick & thin filamentsproteins regulating interaction btw/ thin & proteins regulating interaction btw/ thin &

thick filamentsthick filaments

Sarcomere Sarcomere OrganizationOrganization

• Banded appearance due to overlap Banded appearance due to overlap of thick & thin filamentsof thick & thin filaments A bands – appear A bands – appear ddaarkrk I bands – appear I bands – appear lliightght

• A bandA band – – contains thick & thin contains thick & thin filamentsfilaments M lineM line

center of sarcomerecenter of sarcomerethick filaments onlythick filaments only - connected by - connected by

stabilizing proteinstabilizing protein


• A bandA band (cont) (cont)

H zonesH zoneslateral to M linelateral to M linethick filaments onlythick filaments only

Zones of overlapZones of overlaplateral to H zoneslateral to H zonesthick & thin filaments overlapthick & thin filaments overlap


• I bandsI bands – – contain thin filaments onlycontain thin filaments only edges of sarcomereedges of sarcomere

• Z linesZ lines boundaries btw/ adjacent sarcomeresboundaries btw/ adjacent sarcomeres protein complexes attached to thin protein complexes attached to thin

filamentsfilaments

Sarcomere OrganizationSarcomere OrganizationNote A & I bands & Note A & I bands & peripheral nucleiperipheral nuclei

AAII

Functional OrganizationFunctional Organization

Thin FilamentsThin Filaments

• Composition (proteins)Composition (proteins) F actinF actin

twisted filamenttwisted filament of G actin globular proteins of G actin globular proteinscontains contains active sitesactive sites that can bind to thick that can bind to thick

filamentsfilaments

tropomyosintropomyosinprotein coverprotein cover over over active sites active sites ofof F actin F actin

troponintroponinbinds tropomyosinbinds tropomyosin to active site to active sitecontains Cacontains Ca2+2+ receptor receptor

Thin FilamentsThin Filaments

• Troponin-tropomyosin complexTroponin-tropomyosin complex reacts to bound Careacts to bound Ca2+2+ by uncovering by uncovering

active sites on F actin of thin filamentactive sites on F actin of thin filament necessary for contractionnecessary for contraction

Thick FilamentsThick Filaments

• Composition (protein)Composition (protein) myosinmyosin

subunits – tail & headsubunits – tail & head tailtail – – binds to other myosin moleculesbinds to other myosin molecules headhead – – projects outward toward thin filamentprojects outward toward thin filament

called called cross-bridgescross-bridges

Thick & Thin Thick & Thin Filament StructureFilament Structure

ContractionContractionOf Skeletal MuscleOf Skeletal Muscle

• The control of skeletal muscle The control of skeletal muscle activityactivity

• RelaxationRelaxation

• The contraction cycleThe contraction cycle

• Length-tension relationshipsLength-tension relationships


• NeuromuscularNeuromuscular JunctionJunction:: Identify the components of the Identify the components of the

neuromuscular junction & summarize neuromuscular junction & summarize the events involved in the neural the events involved in the neural control of skeletal muscle functioncontrol of skeletal muscle function

• MuscleMuscle CellCell ContractionContraction:: Explain the key steps involved in the Explain the key steps involved in the

contraction of a skeletal muscle fibercontraction of a skeletal muscle fiber

Control of Skeletal Muscle Control of Skeletal Muscle ActivityActivity

• Neuromuscular junctionNeuromuscular junction neural neural axonaxon branch terminates w/ branch terminates w/

synaptic terminal at synaptic terminal at everyevery muscle muscle fiberfiber

synapticsynaptic terminalterminal – contains – contains neurotransmitter neurotransmitter acetylcholineacetylcholine ( (AChACh))

synapticsynaptic cleftcleft – separates terminal – separates terminal from muscle fiber sarcolemmafrom muscle fiber sarcolemma

Control of Skeletal Muscle Control of Skeletal Muscle ActivityActivity

• Neuromuscular junctionNeuromuscular junction motor end platemotor end plate – sarcolemma surface – sarcolemma surface

w/ ACh receptorsw/ ACh receptors acetylcholinesteraseacetylcholinesterase ( (AChEAChE) – in cleft; ) – in cleft;

breaks down AChbreaks down ACh• ACh receptors of motor end plate bind to ACh receptors of motor end plate bind to

ACh released from synaptic terminal and ACh released from synaptic terminal and respond by opening respond by opening gated ion channelsgated ion channels in sarcolemmain sarcolemma

Membrane Potential:Membrane Potential:Electrochemical GradientElectrochemical Gradient

positive charge due to positive charge due to [Na+] [Na+]

negative charge due to negative charge due to

[protein] [protein] [a.a.] [a.a.] [F.A.] [F.A.]

Neural Stimulation of Neural Stimulation of Muscle FibersMuscle Fibers

Step 1Step 1. . Arrival of action potentialArrival of action potential..action potentialaction potential – – electric impulseelectric impulse

travels down axon of neurontravels down axon of neuronenters enters synaptic terminalsynaptic terminal of neuron of neuron

Step 2Step 2. . Release of AChRelease of ACh..exocytosisexocytosis – – synaptic vesiclessynaptic vesicles

containing ACh fuse w/ neurolemmacontaining ACh fuse w/ neurolemmaAChACh enters enters synaptic cleftsynaptic cleft


Step 3Step 3. . ACh binds at motor end ACh binds at motor end plateplate..ACh ACh diffusesdiffuses across cleft & binds to across cleft & binds to

ACh receptorsACh receptors of sarcolemma of sarcolemmagated Na-channel proteins open & gated Na-channel proteins open &

sarcolemma becomes sarcolemma becomes permeablepermeable to to NaNa++

NaNa++ floods into sarcoplasm floods into sarcoplasm


Step 4Step 4. . Appearance of action Appearance of action potential in sarcolemmapotential in sarcolemma..NaNa++ influx results in influx results in actionaction potentialpotential at at

motor end platemotor end plateaction potential spreads across the action potential spreads across the

“excitable” sarcolemma & down “excitable” sarcolemma & down T T tubulestubules

action potential affects action potential affects SRSR


Step 5Step 5. . Return to initial stateReturn to initial state..AChEAChE in cleft breaks down ACh in cleft breaks down ACh ACh ACh unbindsunbinds from receptors from receptorsgated Na-channels gated Na-channels closeclose & Na+ is & Na+ is

pumped back out of sarcoplasm by pumped back out of sarcoplasm by Na-K ion pumpsNa-K ion pumps

Steps 1 – 5 Steps 1 – 5

Contraction & RelaxationContraction & Relaxation

• Excitation-Contraction CouplingExcitation-Contraction Coupling action potential impulses cause action potential impulses cause

release of Carelease of Ca2+2+ from SR from SR CaCa2+2+ binds to F actin of myofibrils to binds to F actin of myofibrils to

initiate sarcomere contractioninitiate sarcomere contraction continued reception of impulses continued reception of impulses

causes continued contractioncauses continued contraction• RelaxationRelaxation

CaCa2+2+ is reabsorbed by SR is reabsorbed by SR sarcomeres cease contractionsarcomeres cease contraction

Sarcomere Sarcomere Contraction CycleContraction Cycle

Step 1Step 1. . Active site exposureActive site exposure..CaCa2+2+ released from SR released from SR bindsbinds to to

troponintroponintroponin pulls troponin pulls tropomyosin away from tropomyosin away from

active siteactive site on F actin on F actin

Step 2Step 2. . Cross-bridge attachmentCross-bridge attachment..myosin headsmyosin heads (cross-bridges) (cross-bridges) bindbind to to

exposed exposed active sitesactive sites of F actin of F actin


Step 3Step 3. . Pivoting of myosin headPivoting of myosin head.. ““cocked” myosin headscocked” myosin heads are bent away from are bent away from

M line due to stored energy from breakdown M line due to stored energy from breakdown of ATP to ADP + Pof ATP to ADP + Pii

ADP & PADP & Pi i remain bound to heads in resting remain bound to heads in resting sarcomeresarcomere

attachment of myosin head to active site of attachment of myosin head to active site of F actin F actin releases stored energyreleases stored energy to create a to create a power strokepower stroke of head toward M line of head toward M line

ADP & PADP & Pi i are released as stroke occursare released as stroke occurs


Step 4Step 4. . Cross-bridge detachmentCross-bridge detachment..ATPATP bindsbinds to myosin head following to myosin head following

strokestrokeheadhead unbindsunbinds from from active siteactive siteexposed active site available for exposed active site available for

binding to next myosin head along binding to next myosin head along length of myosin filamentlength of myosin filament


Step 5Step 5. . Myosin reactivationMyosin reactivation..ATP ATP ADP + P ADP + Pii released energy “released energy “recockesrecockes” myosin ” myosin

headhead

Cycle can now be repeated underCycle can now be repeated underconditions:conditions: [Ca[Ca2+2+] maintained] maintained [ATP] maintained[ATP] maintained

Observations of Sarcomere Observations of Sarcomere During Muscle ContractionDuring Muscle Contraction

sliding filament theorysliding filament theory

Sarcomere Contraction

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Additional Animation

Muscle MechanicsMuscle Mechanics

• Tension productionTension production

• Energetics of muscular activityEnergetics of muscular activity

• Muscle performanceMuscle performance


• MuscleMuscle ContractionContraction:: Explain the all-or-nothing principle of Explain the all-or-nothing principle of

muscle contractionmuscle contraction Discuss the structure & function of a Discuss the structure & function of a

motor unitmotor unit Distinguish between isotonic & Distinguish between isotonic &

isometric contractionisometric contraction• EnergeticsEnergetics::

Describe the mechanisms by which Describe the mechanisms by which muscle fibers obtain the energy to muscle fibers obtain the energy to power contractionspower contractions

Muscle Contraction:Muscle Contraction:Tension ProductionTension Production

• All-or-None PrincipleAll-or-None Principle muscle fibers are either stimulated to muscle fibers are either stimulated to

the point of contraction or notthe point of contraction or not once stimulated, the entire muscle once stimulated, the entire muscle

fiber contractsfiber contracts • Tension produced by Tension produced by wholewhole

skeletal muscle due to:skeletal muscle due to:1)1) frequency of stimulationfrequency of stimulation2)2) # of fibers stimulated w/in muscle# of fibers stimulated w/in muscle

Muscle Contraction:Muscle Contraction:Motor Unit Motor Unit

• Motor unitMotor unit A single motor neuron & all the A single motor neuron & all the

muscle fibers controlled by itmuscle fibers controlled by it• Motor unit sizeMotor unit size

4-6 fibers in eye muscles – provide 4-6 fibers in eye muscles – provide preciseprecise control of movement control of movement

1000-2000 in leg muscles – provide 1000-2000 in leg muscles – provide less preciseless precise control control

Muscle Contraction:Muscle Contraction:Motor Unit Motor Unit

• RecruitmentRecruitment Smooth, steadySmooth, steady increase in the number of increase in the number of

motor units involved in a muscle contractionmotor units involved in a muscle contraction a.k.a.,a.k.a., multiple motor unit summation multiple motor unit summation

• MuscleMuscle tonetone some motor units w/in a muscle are always some motor units w/in a muscle are always

activeactive switch off w/ resting units regularly to switch off w/ resting units regularly to

distribute activitydistribute activity

Isotonic Muscle Isotonic Muscle ContractionContraction

• Isotonic contractionIsotonic contractionTension plateaus & muscle changes lengthTension plateaus & muscle changes length concentric concentric contraction contraction

– – tension > resistancetension > resistance: muscle shortens: muscle shortens

exex: : liftinglifting weight weight eccentriceccentric contraction contraction

– – peak tension < resistancepeak tension < resistance: muscle : muscle elongates due to contraction of another elongates due to contraction of another muscle or gravitymuscle or gravity

exex: : loweringlowering weight weight

Isometric Muscle Isometric Muscle ContractionContraction

• Isometric contractionIsometric contraction tension varies but does not tension varies but does not

overcome resistanceovercome resistance muscle does not shorten muscle does not shorten NoteNote: individual muscle fibers shorten : individual muscle fibers shorten

until tendons are taught & external until tendons are taught & external tension = internal tension generated tension = internal tension generated by fibersby fibers

exex: : holding a weight stationaryholding a weight stationary; pushing ; pushing against an immovable objectagainst an immovable object

Charles Charles AtlasAtlas

Muscle Relaxation: Return to Muscle Relaxation: Return to Resting LengthResting Length

Causes of muscle relaxation:Causes of muscle relaxation:

• RecoilRecoil of stretched of stretched elastic fiberselastic fibers in in perimyziumperimyzium

• Contractions of Contractions of opposing musclesopposing muscles

• GravityGravity

Energetics Energetics of Muscle Activityof Muscle Activity

• ATPATP is produced by is produced by cellular respirationcellular respiration in in muscle fibersmuscle fibers

• At At restrest, , excess ATPexcess ATP energyenergy stored as stored as creatine phosphatecreatine phosphate ( (CPCP))

ATP + creatine ATP + creatine

ADP + creatine phosphateADP + creatine phosphate

Energetics Energetics of Muscle Activityof Muscle Activity

• During During contractioncontraction myosin cross-bridgesmyosin cross-bridges beak down beak down ATPATP to to ADP + PADP + Pii

• EnergyEnergy stored as stored as creatine phosphatecreatine phosphate ((CPCP) “recharges” ) “recharges” ADPADP

ADP + creatine phosphateADP + creatine phosphate

ATP + creatineATP + creatine

Aerobic Energy Aerobic Energy Metabolism : OMetabolism : O22 Present Present

• GlycolysisGlycolysis in cytosol of cytoplasmin cytosol of cytoplasm CC66HH1212OO66 2 pyruvate 2 pyruvate yields yields 2 ATP2 ATP (net) (net)

• Aerobic cellular respirationAerobic cellular respiration in mitochondriain mitochondria 22 pyruvate + 6Opyruvate + 6O2 2 6CO 6CO22 + 6H + 6H22OO yields yields 25-34 ATP25-34 ATP

Storage CompoundsStorage Compounds

glycogen stores glucoseglycogen stores glucose myoglobin stores Omyoglobin stores O22

O=OO=O

Anaerobic Energy Anaerobic Energy Metabolism: OMetabolism: O22 Absent Absent

• GlycolysisGlycolysis in cytosol of cytoplasmin cytosol of cytoplasm CC66HH1212OO66 2 pyruvate 2 pyruvate yields yields 2 ATP2 ATP (net) (net)

• Lactic acid fermentationLactic acid fermentation in cytosolin cytosol 2 pyruvate 2 pyruvate 2 lactic acid 2 lactic acid yields yields 0 ATP 0 ATP

Muscle Activity:Muscle Activity:Resting Resting Muscle Activity:Muscle Activity:ModerateModerateMuscle Activity:Muscle Activity:StrenuousStrenuous


• FiberFiber TypesTypes:: Relate the types of muscle fibers to Relate the types of muscle fibers to

muscle performancemuscle performance• AerobicAerobic && AnaerobicAnaerobic EnduranceEndurance::

Distinguish between aerobic & Distinguish between aerobic & anaerobic endurance & explain their anaerobic endurance & explain their implications for muscle performanceimplications for muscle performance

Fiber Types: FastFiber Types: Fast

• Fast twitchFast twitch muscle fibers muscle fibers contract w/in 0.01 sec after stimulationcontract w/in 0.01 sec after stimulation large diameterlarge diameter densely packed myofibrilsdensely packed myofibrils reserves: reserves: glycogen; glycogen; ↓ ↓ myoglobinmyoglobin fewfew mitochondria mitochondria

• Powerful contractionPowerful contraction w/ w/ rapidrapid fatigue fatigue deplete ATP reserves rapidlydeplete ATP reserves rapidly activity supported by activity supported by anaerobic metabolismanaerobic metabolism

• Pale reddish colorPale reddish color

Fiber Types: SlowFiber Types: Slow

• Slow twitchSlow twitch muscle fibers muscle fibers contract w/in 0.03 sec after stimulationcontract w/in 0.03 sec after stimulation small diametersmall diameter fewer myofibrilsfewer myofibrils reserves: reserves: myoglobin; myoglobin; lipid; lipid; ↓↓ glycogen glycogen manymany mitochondria mitochondria

• Moderate contractionModerate contraction w/ w/ slowslow fatigue fatigue deplete ATP reserves more slowlydeplete ATP reserves more slowly activity supported by activity supported by aerobic metabolismaerobic metabolism

• Dark reddish colorDark reddish color

Fiber Types: IntermediateFiber Types: Intermediate

• IntermediateIntermediate muscle fibers muscle fibers properties intermediate btw/ fast twitch & properties intermediate btw/ fast twitch &

slow twitchslow twitch

• Pale reddish colorPale reddish color

NoteNote:: Human muscles contain mixtures of 3 Human muscles contain mixtures of 3

typestypes Content varies w/ genetics & useContent varies w/ genetics & use

Muscle SizeMuscle Size

• HypertrophyHypertrophy increase in muscle massincrease in muscle mass # muscle fibers constant# muscle fibers constant diameter of muscle fibers diameter of muscle fibers

• AtrophyAtrophy decrease in muscle massdecrease in muscle mass # muscle fibers constant# muscle fibers constant diameter of muscle fibers diameter of muscle fibers

Anaerobic EnduranceAnaerobic Endurance

• Length of time muscular Length of time muscular contraction can continue supported contraction can continue supported byby glycolysisglycolysis & existing reserves of & existing reserves of ATPATP & & CPCP

• Limited byLimited by Amount of Amount of ATPATP & & CPCP on hand on hand Amount of available Amount of available glycogenglycogen ability of muscle to tolerate lactic acidability of muscle to tolerate lactic acid

Anaerobic EnduranceAnaerobic Endurance

• Training regimenTraining regimen Frequent, short-Frequent, short-

duration exercise duration exercise w/ intensive levels w/ intensive levels of muscular of muscular activityactivity

ExEx: sprinting; : sprinting; speed swimming; speed swimming; weight lifting; weight lifting; basketballbasketball

Aerobic EnduranceAerobic Endurance

• Length of time muscular Length of time muscular contraction can continue supported contraction can continue supported byby mitochondrialmitochondrial activityactivity

• Limited byLimited by Amount of substrates from breakdown Amount of substrates from breakdown

of of carbohydratescarbohydrates, fatty acids, &/or , fatty acids, &/or amino acidsamino acids

Amount of available Amount of available oxygenoxygen

Aerobic EnduranceAerobic Endurance

• Training regimenTraining regimen Sustained, long Sustained, long

duration exercise duration exercise w/ low levels of w/ low levels of muscular activitymuscular activity

ExEx: jogging; cross : jogging; cross country running; country running; distance distance swimming; dance swimming; dance movementsmovements

Aging & Aging & The Muscular SystemThe Muscular System

• Effects of aging on the body’s Effects of aging on the body’s skeletal musclesskeletal muscles

• Effect of life style on aging of Effect of life style on aging of musclesmuscles


• AgingAging:: Specify 4 effects of aging on Specify 4 effects of aging on

musclesmuscles Discuss how regular exercise early Discuss how regular exercise early

in life can counter the effects of in life can counter the effects of aging on the muscular systemaging on the muscular system

Effects of AgingEffects of Aging

• Skeletal muscle fibers Skeletal muscle fibers decreasedecrease in diameter in diameter in myofibrilsin myofibrils

• Skeletal muscles Skeletal muscles loselose elasticity elasticity– fibrosis fibrosis collagen contentcollagen content

• Tolerance for exercise Tolerance for exercise decreasesdecreases thermoregulatory abilitythermoregulatory ability rate of fatiguerate of fatigue

• Ability to recover from muscular injuries Ability to recover from muscular injuries decreasesdecreases– # satellite cells # satellite cells collagen contentcollagen content

Life Style & AgingLife Style & Aging

• Rate of declineRate of decline in muscle performance is in muscle performance is samesame for all individuals for all individuals regardless of regardless of exerciseexercise patterns or lifestyle patterns or lifestyle

• To be in To be in goodgood shape late in life …… you shape late in life …… you must be in must be in veryvery good shape early in life good shape early in life

• Regular, moderate exerciseRegular, moderate exercise is more is more important than extremely demanding important than extremely demanding exerciseexercise

Integration With Other Integration With Other SystemsSystems

• Dependence on other body Dependence on other body systemssystems

• Responses of body systems to Responses of body systems to muscular activitymuscular activity


• IntegrationIntegration:: Discuss the interaction & Discuss the interaction &

responses of 5 specific body responses of 5 specific body systems to muscular activitysystems to muscular activity

Integration: Support From Integration: Support From Other Body SystemsOther Body Systems

• CardiovascularCardiovascular System System heartheart rate & dilation of rate & dilation of blood vesselsblood vessels cause cause

OO22 delivery & CO delivery & CO22 removal removaltransports heat to skin for radiation to transports heat to skin for radiation to

environmentenvironment

• RespiratoryRespiratory System System respiratory raterespiratory rate & depth of respiration & depth of respiration

OO22 delivery & CO delivery & CO22 removal removal

• IntegumentaryIntegumentary System System dilation of dilation of blood vesselsblood vessels & & sweatingsweating

removes excess heat that would interfere w/ removes excess heat that would interfere w/ muscle protein activitymuscle protein activity

Integration: Support From Integration: Support From Other Body SystemsOther Body Systems

• NervousNervous System System controls voluntary muscle contractioncontrols voluntary muscle contraction regulates/coordinatesregulates/coordinates cardiovascular, cardiovascular,

respiratory, & integumentary system respiratory, & integumentary system activitiesactivities

• EndocrineEndocrine System System regulates/coordinatesregulates/coordinates cardiovascular, cardiovascular,

respiratory, & integumentary system respiratory, & integumentary system activitiesactivities

maintains [Camaintains [Ca2+2+] & [-PO] & [-PO443-3-] in blood & other ] in blood & other

body fluids via body fluids via skeletalskeletal, , digestivedigestive, & , & urinaryurinary systemssystems

Integration: Bones, Joints, & Muscles


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presentationpresentation

Cardiac Cardiac Muscle TissueMuscle Tissue

• Structural differences between Structural differences between cardiac & skeletal muscle tissuescardiac & skeletal muscle tissues

• Functional differences between Functional differences between cardiac & skeletal muscle tissuescardiac & skeletal muscle tissues

• The role of cardiac muscle in the The role of cardiac muscle in the bodybody


• StructureStructure && FunctionFunction:: Identify the structural & functional Identify the structural & functional

differences between cardiac differences between cardiac muscle tissue & the other types of muscle tissue & the other types of muscle tissuemuscle tissue

Discuss the role that cardiac Discuss the role that cardiac muscle plays in the cardiovascular muscle plays in the cardiovascular systemsystem

Cardiocytes:Cardiocytes:Structural OrganizationStructural Organization

• Single nucleusSingle nucleus• BranchedBranched cellular structure cellular structure• StriatedStriated – myofibrils & sarcomeres – myofibrils & sarcomeres• TT tubulestubules – short & broad; no triads – short & broad; no triads• SRSR – no terminal cisternae – no terminal cisternae• MitochondriaMitochondria – – # # • IntercalatedIntercalated discsdiscs – btw/ adjacent cells; – btw/ adjacent cells;

transfer contractions from one cell to transfer contractions from one cell to several others instantaneously several others instantaneously

Cardiocytes:Cardiocytes:Functional FeaturesFunctional Features

• AutomaticityAutomaticity – contraction w/out neural – contraction w/out neural stimulationstimulation– “ “pacemaker” cellspacemaker” cells

• InnervationInnervation – alters pace of contraction – alters pace of contraction• DurationDuration of contraction – 10 X longer of contraction – 10 X longer• SarcolemmaSarcolemma characteristicscharacteristics – prevent – prevent

summation & tetanysummation & tetany• Dependent on Dependent on aerobic metabolismaerobic metabolism – – # #

mitochondria & mitochondria & [myoglobin] [myoglobin]

SmoothSmoothMuscle TissueMuscle Tissue

• Structural differences between Structural differences between smooth & skeletal muscle tissuessmooth & skeletal muscle tissues

• Functional differences between Functional differences between smooth & skeletal muscle tissuessmooth & skeletal muscle tissues

• The role of smooth muscle in body The role of smooth muscle in body systemssystems


• StructureStructure && FunctionFunction:: Identify the structural & functional Identify the structural & functional

differences between smooth muscle differences between smooth muscle tissue & the other types of muscle tissue & the other types of muscle tissuetissue

Discuss the role that smooth muscle Discuss the role that smooth muscle plays in various body systemsplays in various body systems

Smooth Muscle Cells:Smooth Muscle Cells:Structural OrganizationStructural Organization

• Single nucleusSingle nucleus• Spindle-shaped Spindle-shaped cellular structurecellular structure• Non-striatedNon-striated – no myofibrils or – no myofibrils or

sarcomeres; thick & thin filaments sarcomeres; thick & thin filaments scattered through cytoplasmscattered through cytoplasm

• Dense body networkDense body network – attach to thin – attach to thin filaments & to sarcolemmafilaments & to sarcolemma

• No No T tubulesT tubules • SRSR – loose network – loose network • Connective tissue sheathsConnective tissue sheaths – do – do notnot unite unite

to form tendons or aponeurosesto form tendons or aponeuroses

Smooth Muscle Cell:Smooth Muscle Cell:Functional FeaturesFunctional Features

• Excitation-Contraction couplingExcitation-Contraction coupling – Ca – Ca2+2+ enter cell from extracellular fluid & bind enter cell from extracellular fluid & bind to to calmodulincalmodulin which activates which activates myosin myosin light chain kinaselight chain kinase to break down ATP & to break down ATP & initiate contractioninitiate contraction

• PlasticityPlasticity – length-tension relationship – length-tension relationship allows for allows for variable contraction lengthvariable contraction length

Smooth Muscle Cell:Smooth Muscle Cell:Functional FeaturesFunctional Features

• Control of contractionControl of contraction – – involuntaryinvoluntary; ; many cells not innervated; respond to many cells not innervated; respond to nearby smooth muscle cellsnearby smooth muscle cells multiunit smooth musclemultiunit smooth muscle cellscells – –

connected to 1 or more motor neurons; connected to 1 or more motor neurons; leisurely contractionleisurely contractionloci – iris of eye; loci – iris of eye; ♂♂ reproductive tract; large reproductive tract; large

arteries; arrector pili muscles arteries; arrector pili muscles

visceral smooth muscle cellsvisceral smooth muscle cells – many – many lack direct neural contactlack direct neural contactloci – digestive tract; urinary & gall bladders; loci – digestive tract; urinary & gall bladders;

many internal organs many internal organs

smooth muscle sheetsmooth muscle sheet

The Muscular SystemThe Muscular System

IntroductionIntroductionBiomechanics & Muscle Biomechanics & Muscle

AnatomyAnatomyMuscle TerminologyMuscle TerminologyThe Axial MusclesThe Axial MusclesThe Appendicular MusclesThe Appendicular Muscles

IntroductionIntroduction

• Voluntary controlVoluntary control

• Form & functionForm & function

• Factors determining the effects of Factors determining the effects of contractioncontraction

Muscles


• ASX Video plays about 5 minASX Video plays about 5 min


• MuscleMuscle ControlControl:: Relate the muscular system to nervous Relate the muscular system to nervous

controlcontrol

• MuscleMuscle ShapeShape:: Discuss how the structure of a muscle Discuss how the structure of a muscle

provides clues to its primary functionprovides clues to its primary function

• EffectsEffects ofof MuscleMuscle ContractionContraction:: Discuss 2 factors that interact to determine Discuss 2 factors that interact to determine

the effect of a muscle’s contractionthe effect of a muscle’s contraction

Voluntary MusclesVoluntary Muscles

• Muscular SystemMuscular System All muscles controlled All muscles controlled voluntarilyvoluntarily 700700 identified identified

20% studied in book20% studied in book ~ ~ 3030 studied for course studied for course

• Form & functionForm & function locomotor muscles - locomotor muscles - stretch across jointsstretch across joints soft tissue support muscles - soft tissue support muscles - form sheets or form sheets or

slingsslings muscles guarding body entrances - muscles guarding body entrances - form form

ringsrings

Voluntary MusclesVoluntary Muscles

• Effects of contraction determined byEffects of contraction determined by anatomical anatomical arrangement of muscle fibersarrangement of muscle fibers attachmentattachment points of muscle points of muscle toto bonesbones

Biomechanics & Biomechanics & Muscle AnatomyMuscle Anatomy

• Organization of skeletal muscle Organization of skeletal muscle fibersfibers

• Skeletal muscle length-tension Skeletal muscle length-tension relationshipsrelationships

• LeversLevers


• FasciclesFascicles:: Describe the arrangement of fascicles Describe the arrangement of fascicles

in the various types of muscles & in the various types of muscles & explain the resulting functional explain the resulting functional differencesdifferences

• LeversLevers:: Describe the different classes of Describe the different classes of

levers & how they make muscles levers & how they make muscles more efficient more efficient

Organization of Skeletal Organization of Skeletal Muscle FibersMuscle Fibers

• FasciclesFascicles bundles of muscle fibers w/in a musclebundles of muscle fibers w/in a muscle

• Patterns of fascicle organizationPatterns of fascicle organization parallelparallel muscles – fascicles parallel to muscles – fascicles parallel to

long axislong axis of muscle of musclecentral central bodybody or belly w/ tendons at ends or belly w/ tendons at ends

(most muscles)(most muscles)some w/ broad attachments – some w/ broad attachments –

aponeurosesaponeuroses

ExEx: : biceps brachiibiceps brachii


• Patterns of fasciclePatterns of fascicle organization organization convergentconvergent muscles – fascicles begin muscles – fascicles begin

over a over a broadbroad area & area & narrownarrow to a single to a single tendon or tendinous sheettendon or tendinous sheet rapheraphe – some attach to band of collagen – some attach to band of collagen

fibersfibers

ExEx: : pectoralis majorpectoralis major


• Patterns of fasciclePatterns of fascicle organization organization pennatepennate muscles – fascicles form muscles – fascicles form

common common angleangle w/ tendon w/ tendonfeather-shapedfeather-shaped

unipennateunipennate – all fascicles on same side – all fascicles on same side of tendon; of tendon; ExEx: : tensor digitorumtensor digitorum

bipennatebipennate – fascicles on both sides of – fascicles on both sides of tendon; tendon; ExEx: : rectus femorisrectus femoris

multipennatemultipennate – tendon & fascicles – tendon & fascicles branch; branch; ExEx: : deltoiddeltoid


• Patterns of fasciclePatterns of fascicle organization organization circularcircular muscles – fascicles muscles – fascicles concentricallyconcentrically

arranged around arranged around openingopening or recess or recess contraction contraction decrease in diameter decrease in diameter

ExEx: : orbicularis orisorbicularis oris

Fascicle ArrangementsFascicle Arrangements

Length-TensionLength-TensionRelationshipsRelationships

• Muscles develop maximum tension over Muscles develop maximum tension over a narrow range of a narrow range of sarcomeresarcomere length length stretched musclestretched muscle – less overlap of thick & – less overlap of thick &

thin filaments in sarcomerethin filaments in sarcomere contracted musclecontracted muscle – normal thick-thin – normal thick-thin

filament relationship is disruptedfilament relationship is disruptedExEx: when : when curling weightscurling weights flexion is harder to achieve flexion is harder to achieve

when arm muscles are stretched in extended arm, when arm muscles are stretched in extended arm, becomes easier as muscles contract, then harder becomes easier as muscles contract, then harder after full flexion is achievedafter full flexion is achieved

Length-TensionLength-TensionRelationshipsRelationships

• During complex movement – During complex movement – muscles muscles work in groupswork in groups smaller muscles aid larger muscles to smaller muscles aid larger muscles to

reach length where maximum tension reach length where maximum tension can be achievedcan be achieved

LeversLevers

• LeverLever – – rigid structure that moves on a rigid structure that moves on a fixed point called the fixed point called the fulcrumfulcrum

In body, each In body, each bonebone is a lever; each is a lever; each jointjoint is is a fulcruma fulcrum

• Lever actionLever action1)1) change change directiondirection of an applied force of an applied force

2)2) change change distancedistance & & speedspeed of movement of movement produced by applied forceproduced by applied force

3)3) change the effective change the effective strengthstrength of an applied of an applied forceforce

Classes of LeversClasses of Levers

• First-classFirst-class - - fulcrum btw/ AF & Rfulcrum btw/ AF & R like see-sawlike see-saw

ExEx: muscles that : muscles that extendextend neck neck

• Second-classSecond-class - - R btw/ AF & fulcrumR btw/ AF & fulcrum like loaded wheelbarrowlike loaded wheelbarrow

ExEx: calf muscles during : calf muscles during plantar flexionplantar flexion

• Third-classThird-class - - AF btw/ R & fulcrumAF btw/ R & fulcrum opposite of 2opposite of 2ndnd-class-class most most commoncommon lever action of body lever action of body

ExEx: : biceps brachiibiceps brachii during during flexionflexion

Muscle TerminologyMuscle Terminology

• Origins & insertionsOrigins & insertions

• ActionsActions

• Names of skeletal musclesNames of skeletal muscles

• Divisions of the muscular systemDivisions of the muscular system


• OriginsOrigins && InsertionsInsertions:: Predict the actions of a muscle on the basis Predict the actions of a muscle on the basis

of the relative positions of its origin & of the relative positions of its origin & insertioninsertion

• MovementsMovements:: Explain how muscles interact to produce or Explain how muscles interact to produce or

oppose movementsoppose movements

• MuscleMuscle NamesNames:: Explain how the name of a muscle can help Explain how the name of a muscle can help

identify its location, appearance, and/or identify its location, appearance, and/or functionfunction

Origins & InsertionsOrigins & Insertions

• OriginOrigin beginningbeginning pointpoint of muscle attachment of muscle attachment usually remains usually remains stationarystationary – bone that – bone that

moves little or not at allmoves little or not at all usually usually proximalproximal on limb on limb

• InsertionInsertion endend pointpoint of muscle attachment of muscle attachment usually usually movesmoves – bone that moves – bone that moves usually usually distaldistal on limb on limb

ActionsActions

• Actions include Actions include flexionflexion, , extensionextension, , adductionadduction, etc , etc

• In terms of In terms of bone affectedbone affected textbook ex: “flexion of the forearm”textbook ex: “flexion of the forearm”

• In terms of In terms of joint affectedjoint affected professional ex: “flexion of the elbow”professional ex: “flexion of the elbow”

Primary ActionsPrimary Actions

• AgonistAgonist

– – prime moverprime mover muscle chiefly muscle chiefly responsible for a responsible for a movementmovementExEx: : biceps brachiibiceps brachii flexes elbow flexes elbow

• AntagonistAntagonist

– – prime moverprime mover muscle chiefly muscle chiefly responsible for the responsible for the oppositeopposite actionaction of the agonistof the agonistExEx: : triceps brachiitriceps brachii extends elbow extends elbow

Primary ActionsPrimary Actions

• SynergistSynergist

– – assistsassists action of prime mover action of prime mover agonistagonist or or antagonistantagonist aid in actionaid in action of prime mover of prime mover fixatorfixator - - stabilizesstabilizes origin of prime origin of prime

mover by preventing competing mover by preventing competing movement at a jointmovement at a joint

Naming Skeletal MusclesNaming Skeletal Muscles

• Fascicle organizationFascicle organization rectusrectus = straight: fascicles parallel to = straight: fascicles parallel to

long axis of bodylong axis of body transversustransversus = across: fascicles = across: fascicles

perpendicular to long axis of bodyperpendicular to long axis of body obliquusobliquus = oblique: fascicles angled to = oblique: fascicles angled to

long axis of bodylong axis of body• LocationLocation

brachiibrachii = arm = arm femorisfemoris = thigh = thigh


• Relative positionRelative position externusexternus,, extrinsicextrinsic, , superficialissuperficialis = outer = outer

body surfacebody surface internusinternus,, intrinsicintrinsic, , profundusprofundus = beneath the = beneath the

body surfacebody surface

• StructureStructure bicepsbiceps = 2 tendons of origin = 2 tendons of origin quadricepsquadriceps = 4 tendons of origin = 4 tendons of origin

• ShapeShape deltoiddeltoid = triangular = triangular orbicularisorbicularis = circular = circular


• Size & lengthSize & length longuslongus & & longissimuslongissimus = long & longest = long & longest

(respectively)(respectively) vastusvastus = large = large teresteres = long & round = long & round brevisbrevis = short = short magnusmagnus, , majormajor, & , & maximusmaximus = big, = big,

bigger, & biggest (respectively)bigger, & biggest (respectively) minorminor & & minimusminimus = smaller & smallest = smaller & smallest

(respectively)(respectively)


• Position relative to body axisPosition relative to body axis anterioranterior = front = front posteriorposterior = back = back lateralislateralis = toward side = toward side medialismedialis = toward midline = toward midline

• Origin & insertionOrigin & insertion sternohyoidsternohyoid = origin on sternum, = origin on sternum,

insertion on hyoid boneinsertion on hyoid bone


• ActionAction flexorflexor = causes flexion = causes flexion extensorextensor, , tensortensor = causes extension = causes extension depressordepressor = causes lowering of body part = causes lowering of body part buccinatorbuccinator = trumpeter (muscle that purses = trumpeter (muscle that purses

lips)lips) sartoriussartorius = tailor-like (muscle that allows = tailor-like (muscle that allows

crossing of legs)crossing of legs)

Muscular SystemMuscular System

• Divisions of the Muscular SystemDivisions of the Muscular System axial musculatureaxial musculature

positions head & spinal columnpositions head & spinal columnmoves rib cagemoves rib cage60% of all muscles60% of all muscles

appendicular musculatureappendicular musculaturestabilizes & moves the arms & legsstabilizes & moves the arms & legs40% of all muscles40% of all muscles

Axial MusclesAxial Muscles

• Muscles of the head & neckMuscles of the head & neck

• Muscles of the spineMuscles of the spine

• Oblique & rectus musclesOblique & rectus muscles

• Muscles of the pelvic floorMuscles of the pelvic floor


• AxialAxial MusclesMuscles:: Identify the principal axial muscles of Identify the principal axial muscles of

the body together with their origins, the body together with their origins, insertions, actions, & innervation insertions, actions, & innervation

Muscles of theMuscles of theHead & NeckHead & Neck

• orbicularis orisorbicularis oris• orbicularis oculiorbicularis oculi• oculomotor musclesoculomotor muscles• zygomaticus major & minorzygomaticus major & minor• buccinatorbuccinator• massetermasseter• sternocleidomastoidsternocleidomastoid• platysmaplatysma

Muscles of the Muscles of the FaceFace

Oculomotor MusclesOculomotor Muscles

Muscles of the Muscles of the TorsoTorso

• scalenes scalenes • external intercostalsexternal intercostals• internal intercostalsinternal intercostals• external obliqueexternal oblique• rectus abdominisrectus abdominis• diaphragmdiaphragm

Appendicular MusclesAppendicular Muscles

• Muscles of the shoulders & upper Muscles of the shoulders & upper limbslimbs

• Muscles of the lower limbsMuscles of the lower limbs

• Musculoskeletal compartmentsMusculoskeletal compartments


• AppendicularAppendicular MusclesMuscles:: Identify the principal appendicular Identify the principal appendicular

muscles of the body together with muscles of the body together with their origins, insertions, actions, & their origins, insertions, actions, & innervation innervation

Compare the major muscle groups of Compare the major muscle groups of the upper & lower limbs & relate their the upper & lower limbs & relate their differences to their functional rolesdifferences to their functional roles

Muscles of the Muscles of the ShoulderShoulder

• trapezius trapezius • serratus anteriorserratus anterior• pectoralis minorpectoralis minor• pectoralis majorpectoralis major• latissimus dorsilatissimus dorsi• deltoiddeltoid

Muscles of the Muscles of the Upper LimbUpper Limb

• triceps brachii triceps brachii • biceps brachiibiceps brachii• brachioradialisbrachioradialis• brachialisbrachialis• extensor muscles (general locus)extensor muscles (general locus)• flexor muscles (general locus)flexor muscles (general locus)

Muscles of the Muscles of the Anterior ThighAnterior Thigh

• rectus femorisrectus femoris• vastus lateralisvastus lateralis• vastus medialisvastus medialis• vastus intermedius vastus intermedius • sartoriussartorius• gracilisgracilis

quadriceps quadriceps femorisfemoris

Muscles of theMuscles of theAnterior ThighAnterior Thigh

Muscles of the Muscles of the Lateral & Posterior ThighLateral & Posterior Thigh

• tensor fasciae lataetensor fasciae latae• gluteus maximusgluteus maximus• semitendinosissemitendinosis• biceps femorisbiceps femoris• semimembranosissemimembranosis

hamstringshamstrings

Muscles of the Muscles of the Lower LegLower Leg

• gastocnemiusgastocnemius– calcaneal tendon (Achilles tendon) calcaneal tendon (Achilles tendon)

• soleussoleus• tibialis anteriortibialis anterior• peroneus longusperoneus longus• peroneus brevisperoneus brevis

Muscles of theMuscles of theAnterior Lower LegAnterior Lower Leg

Musculoskeletal Musculoskeletal CompartmentsCompartments

Muscular SystemMuscular SystemOverviewOverview

Documents

Muscular System Muscle Tissue The Muscular System