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Chapter 10 Muscle System muscles representsnearly half ofbody's mass help us move using bonesas levers transform chemicalenergy ATP into directed mechanicalenergy which is capable of exertingforce function produce movement skeletalmuscles produce body movement bloodmoves...

Chapter 10 Muscle System muscles representsnearly half ofbody's mass help us move using bonesas levers transform chemicalenergy ATP into directed mechanicalenergy which is capable of exertingforce function produce movement skeletalmuscles produce body movement bloodmoves through the body via cardiac muscles smoothmusclemay alter bloodflow at capillary beds supportssome of the vessel walls smoothmuscles in organs of the digestive reproduitive urinary tract maintain posture bodyposition stabilize joints skeletal muscle support soft tissues guard body entrances exits maintain bodytempature typesofmuscles a Skeletal b smooth cardiac grossanatomy ofskeletalmuscle musclefibermusclecell origin attachmentto immovable orless movable bone insertion attachment tomovable bone musclefiber skeletal muscle cell muscule fascicle bundleofmusclefibers connective tissues of skeletalmuscle epimysium outside the muscle surrounds entire skeletalmusile continuous w tendons dense irregular connectivetissue perimysium aroundmuscle separates adjacent musclefascilesvessels nervestravelthrough fibrous connective tissue endomysium within the muscle surrounds single muscle fiber areolar connective tissue cell musclefiber anatomy sarcolemma cellmembrane ofmusclefiber Sarcoplasma cytoplasmof muscle fiber multinucleate lotsof mitochondria glycosomes carry stored glycogen myoglobin storesoxygen myofibrils containcontractileelements sarcoplasmicreticulum T tubules stimulate coordinate muscle contractions tubules sacroplasmic reticulum tubules enhance cellularcommunication during musclecontraction tubular extension of sacro lemma that extend deep into sacroplasm action potential off tubules lauserelease of calciumby the Sacroplasmicreticulum Sacroplasmicreticulum elaborate smoothendoplasmicreticulum ERI tubular network aroundeachmyofibril regulates levels ofcalcium storagesite of calcium myofibrils myofilaments myofibril organized collectionofmyofilaments myofilaments fineproteinfilaments asinglemuscle fiber contains100s 10005 ofmyofibrils myofibrils account for80 ofcellular volume Abandsdark thick thinfilaments Ibands light thinfilaments Mylofilaments Hzone myosine I zone actine Aband allofmyosine zone ofoverlap botha M thickfilaments bundleof myosin clunshaped head headpinas to activebindingsiteon actin thinfilaments twisted Strand Ofa Hin active site on actin tropomyosinbindsto active site of actin at rest troponin binds to tropomyosin calcium  functional unit of both sacromere skeletal smooth functionunit of SkeletalMuscle Either Jin filament other components elasticfilamentcomposedof protein titin holds thick filaments inplace helpsrecollafter stretch resists excessive stretching dystrophin linksthin filaments to proteins of sacro lemma nebulm myomesin proteinsbindfilaments or sacromeres together maintain alignment ofsacromere elasticfilament muscle contractions neurons stimulate the sacrolemma t tubules via neurotransmitter the neuromuscular junction each muscle fiber iontrolled by amotor neuron motor unit motor neuron all the musclefiber it innervates the big picture fourstepsmustoccur forskeletalmuscle to contract 1 events the neuromuscular junction 21muscle fiber excitement 3 excitation contraction coupling 41Crossbridge cyclying neuromuscularjunction 1 AP in presynapticneuron 21fat voltage gatedchannels opencausing Acetylcholine if there'snoATP the IACHto be released actinstayswhere it is 31 AChdiffusesacrossthecleft 41Afnbinds tothe receptors themusclestaycontracted you'redead happenswhen musclecontractionceaseswhen Ash is degraded ordiffusesaway rigormortis 51binding ofAChcausesEPSP 61excitatorygradedpotential travelsalong thesacrolemma 71AP is stimulated in the sacrolamma 81APtravels along sacrolemma tothe t tubules excitation contractioncoupling 11APin t tubules cause shape change in voltage sensitivetubule protein 2 calcium is released in to the sacroplasm 3 calcium binds to troponin 41tropomyosinmovesaway from actin activebinding sites 5 myosin can nowbind toactin form a crossbridge in the presence of ATP theactionofan crossbridge cycle electricalsignalvia attheactivesite on actin is thereleaseofcalcium exposed as calciumto fromthesacroplasmic reticulum troponin b themyosinheadisattracted to actin r myosin binds actin its actinbindingsite forming acrossbridge results musclecontraction c duringthepowerstrokethe via sliding filament phosphategenerated inthe model previouscontraptioncycle is releasedresults inthe myosin head to pivottoward the center of thesacromere afterwhich the attachedADP phosphate group arereleased It anewmolecule of ATP attaches to the myosinhead causing the cross bridge to detach e themyosinhead hydrolyzes ATP to ADP phosphate which returns the  I 1motorneuronaction potential 2 neurotransmitterrelease 3Musclecellactionpotential 4 releaseofcalciumionsfrom SR 5 ATPdrivenpowerstroke 6 Slidingofmyofilaments 7 Callum issequesteredinto sacroplasmicreticulum simplified version I actionpotential in presynapticneuron 2 acetylcholine binds to sacro lemma 31 action potential in sacro lemma t tubules 41 calcium is released from sacroplasmic reticulum 5 calcium binds to troponin 61tropomyosin moves away from activebinding site 71myosin headattaches to actin 81myosin head pivots at actinfilamentsmovetoward m line 10 myosinhead detaches sliding filamentmodel Mmitosintefdsinsasfonaetiveasitesincieiner.irossiidgets myosinhead pivotstoward mime thin filament slidetowardcenter crossbridgedetaches What it looks like when a sacromere contracts sacromere gets shorter Hband gets shorter fully contracted H band disappears 1 band gets shorter zone of overlap gets longer length of actin myosin stay the same width of band remains constant contracts same principles apply to contraction of bothsingle fibers whole muscle pactin contractionproduces muscle tension the force exerted on load or object to be moved Contraction may may not shorten muscle force duration of contraction vary in responseI A I  m a each muscle is servedby least one motor nerve motor nerve hundred of motor neuron axon axons branch into terminals each terminal forms NMS single muscle fiber w motor unit nerve muscle functional unit the motor neuron all muscle fibers it supplies each motor neuron can serve four to several hundred fiber smaller the fiber number the greater the fine control muscle fibers form a motor unit are spread throughout the whole muscle Stimulation of a single motor unit causes a weak contraction of entire muscle muscle twitch the motor unit muscle twitch simplestcontraction resulting from a musclefiber'sresponse to asingle actionpotentialfrom motor neuron musclefiber contractsquickly then relaxes twitch can be observed recorded as a myogram tracing linevelouding Iontraction activity latentimmediatelyfollowing thearrivalotfhestimulus musclecell askeletal there three phases of muscle twich isashort periodof t ime latent periodeventsofexcitation contraction duringwhichtheneurotrans mitterisreleasedbyexocytosis coupling thesynaptic diffusesacross cleft bindstoreceptors nomuscletensionseen period of contraction crossbridge formation pites's En cart reentry into the sacro plasmic reticulum tension declines to zero musclecontracts faster than it relaxes Single Stimulus single twitches musclecontraction responses areinfluenced by Changing frequency of stimulation Changing Strength Of stimulation wavesummation increase muscle tension temporalsummationmuscle fibers do not have the time to completely relax between stimuli twitches increase in force w each stimulus additional cart that is released w second stimulus stimulates more shortening It stimullfrequency increases muscletension reachesnearmaximum or maximum unfused incompletetetanus sustained quivering contraltion complete fused tetanus contractions fuse intoonesmooth sustainedcontractionplateau prolongedmuscle contractions lead to musclefatigue It stimull Strength changes recruitment multiple motorunit summation stimulus is senttomove musliefibers leadingtomoreprecise control now recruitmentworks whatchangestheforce of lontraction length  isometric something Classifying contractions whenpickingup isotonic contractionmusclechanges in length movesload islight isotonicsomething is caneitherbeconcentric or eccentric tooheavytopickup concentricmuscles shortens doeswork exbicepscontracttopickup abook eccentric muscle lengthens generatesforce ex laying a bookdown causes biceps tolengthen while generating aforce isometriccontraction loadisgreaterthanthemaximumtensionmuscle can generate somuscle neithershortensnovlengthens isotonic concentric contraction isometric contractions muscle hypertrophy exercise increases strength size endurance ofmuscle larger number of mitochondria more myofibrils increased bloodflow enlargement of muscle muscle atrophy when a muscle is notstimulatedby a motor neuronon aregular basis it loses muscle tone mass eventemporary reduction in muscle use canleadto atrophy importance ofphysicaltherapy velocity of lontraction verultment musclefibertype  a musclefibertypes Slowoxidative Fastglycolytic Slowtwitcholdmuscle fasttwitchwhitemuscle contain alotofmyoglobin fewermitochondria mitochondria little tonomyoglobin maximumtension maximumtensiondevelops developsslow fast highlyresistanttofatigue fiberfatiguequickly full resourcesglycogen fat fewif anyfuelreserves longtermaerobicexercise shorttermexercisethat requiresmaximum Strength significance of exercise exercise increases musclestrength endurance anaerobic exercise causesmuscles togetlarger stronger increased mitochondriamyofilamentsglycogen stores areopicactivities increase oxidative capacity dueto increased myoglobinsynthesismitochondria enzymes involved in energy use density ofcapillaries that deliveroxygen ATP availability limits muscle contractions three systems I directphosphorylationusespreformed ATP creatine phosphate 2 anaerobic pathway metabolizes carbohydrates lactate pyruvate 31aerobic pathway metabolizes carbohydrates fats H2O CO2 muscleATDsupply systems directphosphorylationof ADPbycreatinephosphate CP immediatesyste I isImmediately available insmall amounts muscles contain creatinephosphate CP stores energy in aphosphate bond ADP this system is exhausted within seconds of exercise anaerobic pathway glycolyticsystem glycolysis metabolizes carbohydrates tolactate pyruvate low O2 prevents completion of cellular restration produces some ATP but not alot lactic acid accumulates lactic acid diffuses into bloodstream used as fuel by liver kidneys heart converted back into pyruvate acid orglucoseby prides energy for less than one minute aerobicpathway oxidativesystem produces 95 of ATP during rest light to moderate exercises metabolizes carbohydrates or fats to water carbon dioxide oxidative system produces large amounts of ATP in mitochondria ATPmustdiffuse from mitochondria to the myosin rate is slower than other two systems cardiacmuscle striated cardiocytes heartonly largesinglenucleussometime2 Shortfatbranchedmusclefibersthat varyin diameter mitochondria large 25 35 Ofcellularvolume comparedto 2 in Skeletal Striated move via slidingfilamentmechanism intercalated discs cellbridgesconnect  9A 91 19 1 91 e a 1 some cardiaccellsareself exiltable muscle contractions are regular intervals involuntarycontrol smooth muscle ours inor around almosteveryorgan including vessels exceptforcapillaries involved in peristaticmovement spindle shaped i nucleus muchsmallerthan skeletalmuscle cells stillcontractvia actin myosin cells connected through gap junctions neural hormonal mechanicalstimulation involuntary control contraction influx of calcium neurotransmittershormones a stretching callium mediated change is on myosin not actin tropomyosin troponin  Chapter 12 Nervous System Tissue where arewegonna centralnervoussystem CNS aa sii skull enclosed the in vertebralcolumn iiiiiiiiifia.mil thebodybythePNS MMM t.tt ni rirTissiEirtff ani d ttfmmggg.Ñg ttttttttt httgmitg.tt fFfff 4pfP i1fff iiI ifIe iii o.fi T.fiiiiiiiiiiii i eiiinFIIIiri iiiiiii.rs in iii i iiii.IE ooioooaiiiii iiiiiiiii i.ee i.am Ii Iatttt Ifmtta iiaittttttttm.lt fftfffg Ftftoa É t t htttdltgdfdfTdtttemg ht ÉÉ É É tttlttt fl Ég tltg É hlthl Éf lll ttt fhÉllftedGl Ég ÉÉÉÉÉ hgtttt gftfhtthttttttttht dhgtdtmfMt cpfffggÉf yyyyyypyygygggg.fi f fgg lht.gg Afdpnf tokickaball thesensation afferentcarries is iitiFiiiii ii i EfII ifE.fi i Eiio a ts rt 114touchitto i iai i o.si sEs cord siios yourspinal IIIiIIttiGfi eeei Ei si is iiiiiidf forintegrating coordinating E t.EE aaii i.atoago.sina.si response 5effectorsaremusclesorglandsthat to nerve respond m otor impulses funationof thenervoussystem coordinate responses toexternal internalstimuli rapid specific usuallycausealmostimmediateresponses brokendown 1 sensoryinput stimulus is detected recognized 2 Integrationsensory input isintegrated responseinstructions are develop elicated 3 motoroutput effector organ is activated muscle or gland  coordinatingthe response 2divisions brain central 99T of nervous system peripheral hus a disgraced iBooks atdona rt neurotransmission PNS organization centystious ara resinsetoa stimulus ye f É motorinformation efferent pathway EEEE isinirs sense.ee t cells tosense stimull carryinformation to thecontrolcenterintegrate coordinate aresponse carry information to the effector communicate via electrical chemicalsignals neurons neurogliaworktogethertoaccomplishtheoverallfunction neurogliasupportcellsofthenervoussystem stabilize the environmentsurroundingneurons angren9891899 speed upsignaltransmissionalong axon thebra clean up cellulardebris attackpathogens create circulatecerebrospinalfluid astrocytes supportsblood brain barrier chemicalenvironment providenutrients to neurons involved inprocessing form function microgliaimmunecellsofthe CNSattacks pathogensremovesneuronaldebri images's m form function ependymalcellslineventricles cavities in brain spinal cord create circulate cerebrospinalfluid Oligodendrocytes myelinates neurons of the CNS myelineatesmultiple neurons peroligodendrocyte satellate cells surroundsneuron provides pts star nutrientscontrolsextracellular astrocytesinCns environment sonwannceus.mn iiesiger Schwanncell EEEEi myelinationdisordersautoimmunedisease that affectsprimarilyyoungadultsmyeline sheaths inCNSare destroyedwhenimmunesystem attacksmyelin turnsmyelin into hardenedlesionscalledscleroses impulseconductionslows eventuallyceases demyelinated axons increase Natchannelscausingcycles of relapse remission symptomsvisualdisturbancesweaknesslossof muscularcontrolspeechdisturbances incontinence treatmentdrugsthatmodifyimmunesystemactivity maynot be able to prevent butmaintaininghighbloodlevelsofvitaminD may reduce risk of development multipolarneuron dendriterecieveinformationincreasesurface area Somacellbodyorganellesrecleveinformation axonsiteofactionpotentialsignalproduced sent alongthe axon apartofafferent efferentpathwayPNS axonterminalsecretesneurotransmitter synapsegapbetweenneuronsspecializedsiteof intercellularcommunication multipolar bipolar unipolar pseudounipolar lotsofdendrites onedendrite associatedw sensory oneaxon oneaxon receptors commoninthebrain noschwanncells cellbodyisinthemiddle integratesmanydata usuallysensory sources oneoutput functional classifications experience recreve stimuli aftere isensory neurons integrate the information interneurons respond to our environment efferent motor neurons afferentpathway interneuron efferent pathway CNS PNS sensesstimull carries processingcoordinates carriesefferent motor info to afferentinformation multipolarneurons effectors mostlyunipolarneurons by axonsmyelinated multipolarneurons axonsmyelinatedby Oligodendrocytes axonsmyelinatedbySchwanncells Schwann  t iii communication electricalimpulsesfromthedendritessoma down theaxon synapticbulb chemical neurotransmittersreleasedfromthepresynapticneurontothepostsynapticneuron voltagemeasureofpotentialenergygeneratedbyseparatedcharge measuredbetweentwo points involts V ormillivolts MV potentialdifferenceor potential chargedifferenceacrossplasmamembraneresultsinpotential greatercharge differencebetweenpoints highervoltage currentflowofelectricalcharge ionsbetweentwopoints work dependenton voltage resistance resistancehindrancetochargeflow insulator substancew highelectricalresistance conductorsubstancew lowelectrical resistance Ohm'slawgivesrelationshipofvoltage currentresistance current I voltagev resistance R currentisdirectlyproportional to voltage greaterthevoltage potentialdifference greaterthecurrent no net currentflow betweenpoints w samepotential currentisinverselyproportional to resistance thegreater the resistance thesmallercurrent typically 70mV range 40mVto 90mV positive outsidethecellmembrane negativeinsidethecellmembrane createcarrierpumpschannelsNat K pump activetransport of ions sets up a concentration gradient whywegetachargedifferential passive leak channels Natleak channels K leakchannels generate  Nat K pump 3Nat ispumpedoutsidethecell 2kt ispumpedinsidethecell highestconcentrationofktinsidethecell highest concentrationofNatoutsidethecell measuringchargeacross amembrane leakagechannels membranepotential passiveleakchannels morektleakchannels thanNatleak channels ktionsdiffuseout Nationsdiffuse in interiorofcell causes bemorenegative membraneto exteriorsurface to be more positive howaltertheeletrochemical gradientacrossthemembrane ionicflowacrossthemembranecanchangethe membranepotential bygatedchannelsregulateionicflow ligandchemically gatedchannels opensinresponseto chemical neurotransmitterbinding voltage gatedchannels opensinresponse tochange inmembranepotential mechanically gatedchannels open in responseto mechanicalpressure gatedchannels openionsdiffusequicklyacrossthemembrane alongtheir electrochemical gradients Chemical gradient higher conc lower conc electrical gradient towardoppositeelectricalcharge Ionflowcreates an electrical current voltage changes acrossthe membrane measuringchanges openagatedNatchannel depolarazion Nationsdiffuseintothecell potentialmore membrane positive thanresting effectsincreasesthe excitatory Botswana of anaction probability producing rememberNat K pumpisalwaysworking potential Nat ktleakchannelsarealways openagated K channel open hyperpolarization Kionsdiffuseoutofthecell membrane negativethan potential more resting inhibitoryeffectsdecreasesprobabilityof producing actionpotential gradedpotentialsincomingsignalsshortdistancesbidirectional mayresultinorinhibit an actionpotential actionpotentials transmissionsignals along anaxonlongdistanceunidirectional all or nothing where alongdendritesorsoma whystimulusrestinginopening a gatedionchannel receptor mediated lighttouchheatetc orneurotransmitter whatleadsto achange inrestingmembranepotential shortdistance canbestimulatedorinhibitory stimulus gatedionchannelopens cause a depolarization lessnegative inside outsidemorenegative depolarizationspreads oppositecharges attract createsalocalcurrent momentarychange depolarization decaysdueto leakymembrane PMMEME.tt 999 Pester heaton characteristics ofan actionpotential occursalong axonstart axonhillock Unidirectionaltransmission change in membranepotential all or nothingresponse must reach a threshold signals overlongdistance nodecay over distance factonptotential mustreachthreshold membranepotential  causeschanges voltage gatedchannels majorplayers gatedchannels opensinresponse voltage depolarization repolarization tochangeinmembranepotential membrane maintainresting 9998 potential 70mV hyperpolarization atrestactivationgateclosed atrestgateclosed Inactivationgateopen depolarizationopens activationdepolarizationopens gate inactivationgateremain gate open afteractivationgaterem ñV slowly aftergatecloses inactivationgatecloses gateisfast gateisslow restingstate Nat ktvoltagegatechannelsclosed leakchannelsopen NatK pumpworking depolarization gradedpotential threshold someNatvoltagegatedchannelsopen kt voltage gatedchannels closed leakchannelsopen NatK pumpworking depolarizationthreshold actionpotential alllocalNatvoltage gatedchannelsopen kt voltagegatedchannelsclosed leakchannelsopen Nat K pumpworking repolarization alllocalNatvoltage gatedchannelsinactivated eventuallyresetting ktvoltagegatedchannelsopen leakchannelsopen NatK pumpworking hyperpolarization alllocalNatvoltage gatedchannelsarereset ktvoltagegatedchannels closeslowly Natmakesitmorepositivetomovingoutofthecell somearestill opened backtorestingstate Nota ktvoltage gatedchannels closed leakchannelsopen NatK pumpworking restoreresting membrane potential allornoneeitherhappenscompletely ordoesnothappenat all for an axonto five depolaraztionreachthreshold membrane is depolarizedby15 20mV Natpermeabilityincreases Nat influxexceedsK efflux positivefeedbackcyclebegins propagationaptransmittedfromorgin downentireaxonlengthtoterminals Natinfluxthroughvoltagegates one membraneregion local currents openingof Natvoltagegatesinadjacentregions leads to depolarization of thatregion depolarizationinnextregion absoluterefactory depolarization causedinactivation ofvoltage gatedNatchannel inactivationgateisclosed resultcannotfireanewapuntilvoltage gatedNatchannelsarereset relative refactory caused hyperpolarization slowclosingofvoltagegatedK channel result hyperpolarizationcausesmembranepotentialtobemorenegative muchstrongerstimulusisnecessaryforanaptooccur Notvoltagegatedchannelsareresethere dendrite nomyelination novoltagegatedchannels axonvoltagegatedchannels nomyelination axonvoltage gatedchannelsmyelination groupA group b groupc smallest diameter largest intermediate myelination myelinated myelinated unmyelinated lightly transgression f9ts8mpn interseth QEmon 1111 faimmutes ansvisceralmotor sensory 98they whate thatservevisceralorgans  gradedpotential action potential whereontheneuron dendrites Soma axons directionluni orbi 1 bidirectional unidirectional relativedistance the signal impulse can short long travel short or long type ofchannels chemically gated stimulatedcausingthe mechanically gated voltage gated event opened resultof thechangein depolarizationorhyper actionpotential membranepotential dependingonthe depolarization repolarization depolarizationrepolarization channel hyper hyperpolarization other channelspresent Natleakchannelsktleak NatleakchannelsK in the membrane near channels Nat ktpump leakchannels Nat kt the events pump is there myelininvolved no yesmostof thetime inpropagatingthe stimulus neuronscommunicatew otherneuronsortargetcells synapses chemicalsynapse chemicalsfrom a presynapticcell inducechanges in apost synapticcell electricalsynapse action potentialspreadsdirectly to the postsyapticcell 1 APinpresynapticneuron I 2 voltagegatedCa channelsopencast ions diffuseintoterminal 2 3 neurotransmittervesiclesfusew terminal membrane exocytoseneurotransmitter 4 neurotransmitterdiffusesacrossthe 3 synaptic cleft bindsto receptors delay 3 5ms 5 binding oftheneurotransmittercauses achange 4 inthepostsynapticmembranepotential 5 aleffectsofneurotransmitterstopwhen it isnolonger bound 6 action presynapticcell potential voltage gold Caychannelsopen Ca ᵗ causessynapticvescileto release exocytosis neurotransmitter neurotransmitterdiffusesacross thesynapticcleft bindstoreceptor neurotransmitter onchemicallygatedionchannel meditationchance open gradedpotentialisgeneratedin postsynapticcell neurotransmitterreuptake or enzymaticdegradation EEE on Einton potential main E.tk aio EPSP chemmically gatedchannels thatopen IPSP.YIE.ca spatialsummation temporalsummation neurotransmitters Chemicalstructure byfunction 50 havebeenidentified mostneuronsmak2ormore Etyfgh stimulationtreauenciesvary inhibitory tatory pharmaceuticalsdrugabuse neurotransmitters drugsinteract w neurotransmitters ortheirreceptors makeNTmorepotent massiveamount release ofNT preventNTinactivation preventNTbindingtoreceptors MIMICNT