Notes Ch.6 HSC 211
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This 17 page Class Notes was uploaded by Sara Nieboer on Tuesday October 6, 2015. The Class Notes belongs to HSC 211 at Central Michigan University taught by Jayaraman, Roop in Fall 2015. Since its upload, it has received 43 views. For similar materials see Human Anatomy & Physiology in Nursing and Health Sciences at Central Michigan University.
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Date Created: 10/06/15
Chapter 6 The Muscular Svstem Learning objectives Describe similarities and differences in the structure and function of the three types of muscle tissue and indicate where they are found in the body Define muscular system Define and explain the role of the following endomysium perimysium epimysium tendon and aponeurosis Describe the microscopic structure of skeletal muscle and explain the role of actin and myosin containing myofilaments Describe how an action potential is initiated in a muscle cell Describe the events of muscle cell contraction Define graded response tetanus isotonic and isometric contractions and muscle tone as these terms apply to a skeletal muscle Describe three ways in which ATP is regenerated during muscle activity Define oxygen deficit and muscle fatigue and list possible causes of muscle fatigue Describe the effects of aerobic and resistance exercise on skeletal muscles and other body organs Define origin insertion prime mover antagonist synergist and fixator as they relate to muscles Demonstrate or identify the different types of body movements List some criteria used in naming muscles Name and locate the major muscles of the human body listed on the skeletal muscle identification sheet and state the action of each Explain the importance of a nerve supply and exercise in keeping muscles healthy Describe the changes that occur in aging muscles The Muscular System Muscles are responsible Table 61 Comparison of Skeletal Cardiac and Smooth Muscles Characteristic Skeletal Cardiac Smooth for all types of body Body location Attached to bones or for Walls of the heart Mostly in walls of hollow movement some facial muscles to skin visceral organs other than the heart Three basic muscle types are found in the body l Skeletal muscle Cell shape and Single very long cylindrical Branching chains of cells Single fusiiorm a earance multinucleate cells with very uninucleate striations uninucleate no striations ar 13C IIIUSC 6 pp obvious striations intercalated discs 3 l E a39quot surrounding blood vessels and l I ll rr lrlrrrllwlll i l l H llllmlll llllllllllllllllllul illfll l39llll39 organs Contraction and shortening of muscles is due to the movement of microfilaments microfilaments do not change in size they slide past eachother Table 61 Comparison of Skeletal Cardiac and Smooth Muscles continued Characteristic Skeletal Cardiac Smooth Regulation of contraction controls Speed of Slow to Fast contraction Rhythmic No contraction voluntary via nervous system Involuntary the heart has a pacemaker also nervous system controls hormones Slow Yes Involuntary nervous system controls hormones Chemicals stretch Very slow r esi in some Skeletal Muscle Characteristics I Most are attached by tendons to bones tendons attach muscle to bone Ligaments attach bone to bone I Cells are multinucleated I Striated have visible banding I Voluntary subject to conscious control Connective Tissue Wrappings of Skeletal Muscle I Cells are surrounded and bundled by connective tissue Endomysium encloses a single muscle fiber Perimysium wraps around a fascicle bundle of muscle fibers Epimysium covers the entire skeletal muscle Fascia on the outside of the epimysium Skeletal Muscle Attachments I Epimysium blends into a connective tissue attachmentF Blood weesell Perimysium lEplmyrslunt wraps entire muselej Muscle f ber eellil Feselcle EWFEFIIPE hi perlnwslum Eindomyslum between tubers Tandem E li l Tendons cordlike structures Mostly collagen fibers I Often cross a joint because of their toughness and small size Aponeuroses sheetlike structures Attach muscles indirectly to bones cartilages or connective tissue coverings Skeletal Muscle Functions I Produce movement I Maintain posture I Stabilize joints I Generate heat thermoregulation Skeletal Muscle Attachments I Sites of muscle attachment I Bones lever system I Cartilages I Connective tissue coverings Microscopic Anatomy of Skeletal Muscle sarco and myo mean muscle I Sarcolemma specialized plasma membrane I Myofibrils long organelles inside muscle cell Light 1 bands and dark A bands give the muscle its striped appearance Sarcolemma i F g 712 13 9 4391 Ell lja lj ll Darquot 39L th it Nucleus A hand I hand at ragingmi nf a I Thick filaments myosin filaments I Composed of the protein myosin I Contain ATPase enzymes I Possess myosin heads I Heads are known as cross bridges when they link thick and thin filaments during contraction I h f Ie Sreemere I fag refund LlrEFquotII 39 Ml line I i Z dlee I 2 than myefilemenit Ill hiek Imy39eeain my nfilement e segment ef a mye hril I Thin filaments actin filaments Composed of the contractile protein actin Actin is anchored to the Z disc I Banding pattern I band 2 Light band I Contains only thin filaments I Z disc is a midline interruption Z d iee IHI zene Z diee Thin aeIIIII 3 I A myfiillement 39 Thiiek myeein myefiilement I quot III I ll i Ileana Abe mend Mline EI Sareemere gjj if ig j eemplex r genelle eempeeed ef bundles I Banding pattern I A band 2 dark band I Contains the entire length of the thick filaments I H zone is a lighter central area 2 disc H zone 2 disc Thin actin my llament 39ll39lhiiek myosin my fiilament T I m I II I I land Ahand lhand Mline 4 53 rmmera artful 39 EDIT IIIEI organelle arm s 1 m hundmes D my lni I M line is in center of H zone I Sarcomere contractile unit of a muscle fiber I Organization of the sarcomere Myofilaments produce banding striped pattern Thick filaments myosin filaments Thin filaments actin filaments il1 remen p M llline Thin amid myu lamE t Thiinlk mynsiin myu lament a sam mgm Segment of a myo brll I Sarcoplasmic Reticulum SR Specialized smooth endoplasmic reticulum Stores and releases calcium Surrounds the myofibril Stimulation and Contraction of Single Skeletal Muscle Cells I Irritability also called responsiveness ability to receive and respond to a stimulus I Contractility ability to shorten when an adequate stimulus is received I Extensibility ability of muscle cells to be stretched I Elasticity ability to recoil and resume resting length after stretching The Nerve Stimulus and Action Potential I Skeletal muscles must be Assn terminals all st1mulated by a motor neuron neuralquotMESquot lar junmi n nerve cell to contract E39IFm39l ll E r Illllllsr Mstsr R Iuniil ILIInil I Motor Unit one motor neuron E ll and all the skeletal muscle cells stimulated by that neuron Matsr msumm sslll hxsdliss ms tsr msunr sln Mussls Muscle filjsrs I Neuromuscular Junction Association site of axon terminal of the motor neuron and sarcolemma of a muscle I Neurotransmitter Chemical released by nerve upon arrival of nerve impulse in the axon terminal Acetylcholine ACh is the neurotransmitter that stimulates skeletal muscle I Synaptic Cleft Gap between nerve and muscle Nerve and muscle do not make contact Filled with interstitial uid When muscles contract they only pull on the joints and bone Transmission of Nerve Impulse to Muscle I When a nerve impulse reaches the axon terminal of the motor neuron 1 Calcium channels open and calcium ions enter the axon terminal 2 Calcium ion entry causes some synaptic vesicles to release acetylcholine ACh 3 ACh diffuses across the synaptic cleft and attaches to receptors on the sarcolemma of the muscle cellIf enough ACh is released the sarcolemma becomes temporarily more permeable to sodium N8 Sodium rushes into the cell and potassium leaves the cell 4 Depolarization opens more sodium channels that allow sodium ions to enter the cell 5 Once started the action potential cannot be stopped and contraction occurs Acetylcholinesterase AChE breaks down acetylcholine into acetic acid and choline AChE ends muscle contraction Myelinatetl an at meter neurcn ENE impun 39 leach terminal at Nume quot39 newremuacular k junctien r aarceleimma cf the muscle tiihaer Acilcn pete ntial reaches 3 quot laminaquot Bf mamquot mm synaptic yesicle ccntalning acn than terminal at meter neur en Mit h l l lri n if V pain a 3 Earc lenn rna Ealciwm cats channels cpen anti ayenters the aacn tenminal gifi a2 entry ceases senne synaptic 1tesicles te release their cntents acetylcheline a neurctransn39litter l Fusing synaptic lay eacytcsis WEEiGIE acetylchcline diffuses actress the f w synaptic cleit anti hintis te f A L recepters in the sarcalermma 1 F l if E ill39 ll liil39llm h h binds and channels epen that alch simultanecus passage cf hla intc the muscle tiher and W cut at the muscle ber Mare his lens enter than itquot icns leaye practicing a Ical change in the electrical ccnrlitichs at the naemnhra he cl epelarizatieni This eyenttially leans he an acticn ctential lcn channel in r I sarcclemma c pens ins pass Ian channel clsed d I ins canht pass The enaytne acetylchclinesterase larealrs tlc39wn ace in the synaptic clettr ending the precess 39 Cell returns to its resting state when 1 Potassium ions diffuse out of the cell 2 Sodium potassium pump moves sodium and potassium ions back to their original positions Transmission of Nerve Impulse Across Muscle Originally our neuron sends an action potential that gets converted to a chemical signal at the neuromuscular junction which turns into an electrical current which moves down the motor neuron and causes the muscles to contract Mechanism of Muscle Contraction The Sliding Filament Theory Email twig I Match L flame GE Flamp ignites tihp twig i i Flame spreads rapitilgir airing the twig Nprur pmiusmlar jiiriptipm Muscle e pr filiJer Etriatipins iii 3 diff sips lint the E Em Aciipm pptpntiall spraadp rapidlyr airing the sampleMina ihi I Calcium binds to regulatory proteins on thin filaments and eXposes myosin binding sites allowing the myosin heads on the thick filaments to attach My sin Austin I The attached heads pivot sliding the thin filaments toward the center of the sarcomere and contraction occurs HE 39 ATP provides the energy for the sliding I process which continues as long as ionic calcium is present 7 m w r Muscle contraction does not mean actin and myosin V 739 39 t K 77 1 quot ll they do not change in length instead think about the i it sliding filament theory they move past eachother Fri 331 In Fully cuntra tedl sarcamare Regulatory Protein Troponin tropomyosin covers the binding sites Pretein emplett aetin7 39 mige lament w My sin I a mgetiian39lent Ea quot yesi Jil l ilquotlg site l w ii I r Upper part at thielt Intern ilh i manlyr in In a reiaiteti mnsele sell the regniataryr preteins termng FEET ii thE aetin n39Igefiian39Ients FTEV EI III myesin hintiing see a When an aetien petential A sweeps aieng its sareeiemnta anti a musale seii is teneitea saleinn iens Gait are reieasea frent intraeelliilar sterage areas the sass ef the saraplasn39lie retietiiunti The tleati ef ealeiiin39i eats as the nai trigger fer eentraetien heeause as aaleiuint hntis te the reguiatry prateins n the aetin laments the prateins nntierg a change in nth their shape anti their pesitien en the thin tilan1ents This aetien espeses myesinmhintiing sites an the aetin ta which the mgesin heath sen attaah see in anti the nipesin heads intmetiiatelg haegin seelting ut hinaing sites The tree mgesin hearts are peeked mush lilte a set intensetrap Mgesin attaehntent t aetin springs the trap sensing the nwesin heetis te snap pittat tewarti the eenter ef the seremere When this happens the thin laments are slightlgir ptiileti twarti the eenter ef the sarentere see we are prairies the energyr neetieti te release and resale eeeh mpesin heati se that it is ready ta attaeh te a hintiing site farther aieng the thin tilantent When the an enris anti eeleinnt iens are rettirneti ta EH sterage areas the regulataryr prteins resume their rignai shape anti psitin anti again latest myesin Iaintiing tn the thin l lll39 E lIE as a result the nutsale eell rlases anti setties hash t its eriginal length Cross bridge formation requires the release of calcium which is released from the SR Cross bridge detachment requires ATP Contraction of Skeletal Muscle I Muscle fiber contraction is all or none I Within a skeletal muscle not all fibers may be stimulated during the same interval I Different combinations of muscle fiber contractions may give differing responses I Graded responses different degrees of skeletal muscle shortening I Graded responses can be produced by changing The frequency of muscle stimulation small changes in force production The number of muscle cells being stimulated at one time large changes in force production Types of Graded Responses I Twitch 0 Single brief contraction 0 Not a normal muscle function I Summing of contractions I One contraction is immediately followed by another I Because stimulations are more frequent the muscle does not completely return to a resting state I The effects are summed added I Unfused incomplete tenanus I Some relaxation occurs between contractions but nerve stimuli arrive at an even faster rate than during summing of contractions I Unless the muscle contraction is smooth and sustained it is said to be in unfused tetanus E E El 5 E w 39 Etimiiiii a Twitch E 2 m E F isiimiiiii Tan iniii i9 iatiimuii I m Bi Un usveii i i i l t t39Et minis I Fused complete tetanus I No evidence of relaxation before the following contractions I Frequency of stimulations does not Tension 9 allow for relaxation between contractions I The result is a smooth and sustained Stimmi I I I I I I I I I I I I muscle contraction FHEE complete Muscle Response to Strong Stimuli tatanus I Muscle force depends upon the number of fibers stimulated I Contraction of more fibers results in greater muscle tension I Muscles can continue to contract unless they run out of energy Energy for Muscle Contraction ATP I Immediate source of energy for muscle contraction I Stored in muscle fibers in small amounts that are quickly used up I After this initial time other pathways must be utilized to produce ATP Three ways to generate ATP 1 Direct phosphorylation of ADP by creatine phosphate 2 Aerobic respiration required Oxygen occurs in the mitochondria 3 Anaerobic glycolysis no 02 amp using breakdown of sugars and lactic acid formation Occurs in the Cytoplasm a lre t hsphurylatln Gunmen rean nn of creatine ph s hate GP and ADF Energy sauna GP ki hgm Eailing EHFEIEH NEE Home PmdME ts 1 ATP per EP creatine Dmatiun f energy prunisinn 3915 EEGDHHIE Direct phosphorylation of ADP by creatine phosphate CB fastest Muscle cells store CP a high energy molecule After ATP is depleted ADP remains Anaerobic glycolysis and lactic acid formation I Reaction that breaks down glucose without oxygen I Glucose is broken down to pyruVic acid to produce about 2 ATP I PyruVic acid is converted to lactic acid This reaction is not as efficient but is fast I Huge amounts of glucose are needed I Lactic acid produces muscle fatigue rL if t L Gillynmliy ilis I l Iantilln El f llf ali liili ll Enemy Enurne gimme 1 quot1F 94quot 7L 7 A armc i F grif n F 39 u mam Elyc r s 1 n cytnnll i39fijjifquot J4 i net gain Rulesed l x In land Hquot Lam mm F Ryan use Hana Ff l t i E ATP per gimme lactic acid wratlun all energy pf i lisl a 44E sEmandsv nr Ealihtly llITI EITE I Aerobic respiration Glucose is broken down to carbon dioxide and water releasing energy about 32 ATP A series of metabolic pathways occurs in the mitochondria This is a slower reaction that requires continuous oxygen Carbon dioxide and water are produced Muscle Fatigue and Oxygen Deficit Earning Ellllllill FEEIJII EI39HEHI39I Energy aaurne glumaa pyiruala acid furea Matty aai a fraann a lpa 5a tisaua amnina aaiczla raim ratalrzi aaialaaliana tam is W j i i If 54 ing a militia 5 nail gain ar glumaa IfIEII39I use taqulra F m untaa aa ATP PERT glumaa GEE HEB Dura n n Lair Energy pamilisan Haara I If muscle activity is strenuous and prolonged muscle fatigue occurs because I Ionic imbalances occur I Lactic acid accumulates in the muscle I Energy ATP supply decreases I After exercise the oxygen deficit is repaid by rapid deep breathing Types of Muscle Contractions I Isotonic contractions I Myofilaments are able to slide past each other during contractions I The muscle shortens and movement occurs I Example bending the knee rotating the arm I Isometric iso same metric distance contractions I Tension in the muscles increases I The muscle is unable to shorten or produce movement I Example pushing against a wall with bent elbows Muscle Tone I Muscle tone keeps muscles healthy and ready to react Result of a staggered series of nerve impulses delivered to different cells within the muscle If the nerve supply is destroyed the muscle loses tone becomes paralyzed and atrophies Effect of Exercise on Muscles I Exercise increases muscle size strength and endurance Table The Five Gellden Rules ell Aembic endurance CXCrCiSe biking Skeletal Muscle Activity jogging results in stronger more 1 With a few excelptl hs all skeletal muscles eXIble mUSCICS Wlth greater cross at least ehe je int resistance to fatigue Typically the bulk ef a skeletal muscle lies proximal te the jeint messed all skeletal messes have at least twe attachments the ring end the insertion Skeletal muscles can enl y pull they neeear plush During centreetlen a skeletal muscle lnsertieh metres tewetd the etlgin Resistance isometric exercise weight lifting increases