physiology of muscle

80
Physiology of Muscle Physiology of Muscle Humaryanto Humaryanto

Upload: tave

Post on 13-Jan-2016

55 views

Category:

Documents


9 download

DESCRIPTION

Physiology of Muscle. Humaryanto. TIPE OTOT. Otot Skeletal (lurik/striata) Otot Jantung (lurik/striata) Otot Polos (polos) (GI, VU, Vascular). Extrafusal Muscle Fibers. Striate muscle Force for limb movements flexion - closes joint extension - opens joint Contract or relax ~. - PowerPoint PPT Presentation

TRANSCRIPT

Page 1: Physiology of  Muscle

Physiology of MusclePhysiology of Muscle

HumaryantoHumaryanto

Page 2: Physiology of  Muscle

TIPE OTOTTIPE OTOT

Otot SkeletalOtot Skeletal (lurik/striata)(lurik/striata)

Otot JantungOtot Jantung (lurik/striata)(lurik/striata)

Otot Polos (polos)Otot Polos (polos)

(GI, VU, Vascular)(GI, VU, Vascular)

Page 3: Physiology of  Muscle

Extrafusal Muscle FibersExtrafusal Muscle Fibers

Striate muscleStriate muscle

Force for limb Force for limb movements movements – flexion - closes jointflexion - closes joint– extension - opens jointextension - opens joint

Contract or relax ~Contract or relax ~

Page 4: Physiology of  Muscle

OTOT SKELETALOTOT SKELETAL

40%40% BB tubuh BB tubuh

FungsiFungsi : mengatur posisi : mengatur posisi dan gerak rangkadan gerak rangka

Melekat ke tulang melalui Melekat ke tulang melalui tendotendo

OrigoOrigo : perlekatan pada : perlekatan pada bag. proksimal, bersifat bag. proksimal, bersifat stasionerstasioner

InsersioInsersio : perlekatan pada : perlekatan pada bag. distal, bersifat mobilbag. distal, bersifat mobil

Page 5: Physiology of  Muscle
Page 6: Physiology of  Muscle

TIPE OTOT SKELETALTIPE OTOT SKELETAL

Berdasarkan kecepatan kontraksi dan daya Berdasarkan kecepatan kontraksi dan daya tahan terhadap fatigue.tahan terhadap fatigue.

Fast-twitch glycolitic fibers (putih)Fast-twitch glycolitic fibers (putih)Fast-twitch oxidative fibers (merah)Fast-twitch oxidative fibers (merah)Slow twitch oxidative fibers (merah)Slow twitch oxidative fibers (merah)

Setiap orang punya 3 tipe otot, tapi berbeda Setiap orang punya 3 tipe otot, tapi berbeda pada komposisi dominanpada komposisi dominan

(Jauhari Johan vs John Murray/ Ben Johnson)(Jauhari Johan vs John Murray/ Ben Johnson)

Page 7: Physiology of  Muscle

Type 1 FibersType 1 FibersSlow fibersSlow fibers

dark reddark red

– slow, sustained contraction slow, sustained contraction – slow to fatigue slow to fatigue

Aerobic metabolism Aerobic metabolism – many capillaries & mitochondriamany capillaries & mitochondria– oxygen required for ATP synthesis oxygen required for ATP synthesis – myoglobin myoglobin

gives dark red appearance ~gives dark red appearance ~

Page 8: Physiology of  Muscle

Type 2b FibersType 2b FibersFast fatigable fibersFast fatigable fibers

white fiberswhite fibers

– rapid, brief contraction rapid, brief contraction – fast to fatiguefast to fatigue– produce about 10x force of Type 1 produce about 10x force of Type 1

Anaerobic metabolism Anaerobic metabolism – fewer capillaries & mitochondriafewer capillaries & mitochondria– ATP generated by glycolysisATP generated by glycolysis– lactic acid buildup ~lactic acid buildup ~

Page 9: Physiology of  Muscle

Type 2a FibersType 2a Fibers

Fast fatigue-resistant fibersFast fatigue-resistant fiberspale redpale red

– properties intermediate to types 1 & 2bproperties intermediate to types 1 & 2b– rapid, brief contraction rapid, brief contraction – slow to fatigueslow to fatigue– produce least force produce least force

Aerobic & Anaerobic metabolism Aerobic & Anaerobic metabolism – many capillaries & mitochondria ~many capillaries & mitochondria ~

Page 10: Physiology of  Muscle
Page 11: Physiology of  Muscle
Page 12: Physiology of  Muscle

Neuromuscular JunctionNeuromuscular Junction

Synapse between neuron & effectorSynapse between neuron & effector

Cholinergic (ACh)Cholinergic (ACh)– nicotinic receptorsnicotinic receptors

Motor end-plateMotor end-plate– postsynaptic membranepostsynaptic membrane– folds packed with receptorsfolds packed with receptors

increased surface area ~increased surface area ~

Page 13: Physiology of  Muscle

Global view of a Global view of a neuromuscular neuromuscular junction:junction:1. 1. Axon2. Motor end-plate2. Motor end-plate3. 3. Muscle fiber4. 4. Myofibril

Page 14: Physiology of  Muscle

Detailed view of a Detailed view of a neuromuscular junction:neuromuscular junction:1. 1. Presynaptic terminal terminal2. 2. Sarcolemma3. Synaptic vesicle3. Synaptic vesicle4. Nicotinic acetylcholine 4. Nicotinic acetylcholine receptorreceptor5. Mitochondrion 5. Mitochondrion

Page 15: Physiology of  Muscle

Mechanism of action Mechanism of action

Upon the arrival of an action potential at the axon Upon the arrival of an action potential at the axon terminal, voltage-dependent calcium channels open and terminal, voltage-dependent calcium channels open and Ca2+ ions flow from the extracellular fluid into the motor Ca2+ ions flow from the extracellular fluid into the motor neuron's cytosol. This influx of Ca2+ triggers neuron's cytosol. This influx of Ca2+ triggers excitation-excitation-contraction couplingcontraction coupling, a biochemical cascade that , a biochemical cascade that causes neurotransmitter-containing vesicles to fuse to causes neurotransmitter-containing vesicles to fuse to the motor neuron's cell membrane and release the motor neuron's cell membrane and release acetylcholine into the synaptic cleft.acetylcholine into the synaptic cleft.Acetylcholine diffuses across the synaptic cleft and binds Acetylcholine diffuses across the synaptic cleft and binds to the nicotinic acetylcholine receptors that dot the motor to the nicotinic acetylcholine receptors that dot the motor end plate.end plate.The receptors are ligand-gated ion channels, and when The receptors are ligand-gated ion channels, and when bound by acetylcholine, they open, allowing sodium and bound by acetylcholine, they open, allowing sodium and potassium ions to flow in and out of the muscle's cytosol, potassium ions to flow in and out of the muscle's cytosol, respectively.respectively.

Page 16: Physiology of  Muscle

Mechanism of action Mechanism of action

Because of the differences in electrochemical gradients Because of the differences in electrochemical gradients across the plasma membrane, more sodium moves in across the plasma membrane, more sodium moves in than potassium out, producing a local depolarization of than potassium out, producing a local depolarization of the motor end plate known as an end-plate potential the motor end plate known as an end-plate potential (EPP).(EPP).This depolarization spreads across the surface of the This depolarization spreads across the surface of the muscle fiber into transverse tubules, eliciting the release muscle fiber into transverse tubules, eliciting the release of calcium from the sarcoplasmic reticulum, thus of calcium from the sarcoplasmic reticulum, thus initiating muscle contraction.initiating muscle contraction.The action of acetylcholine is terminated when the The action of acetylcholine is terminated when the enzyme acetylcholinesterase degrades the enzyme acetylcholinesterase degrades the neurotransmitter and the unhydrolysed neurotransmitter neurotransmitter and the unhydrolysed neurotransmitter diffuses awaydiffuses away

Page 17: Physiology of  Muscle

Neurotransmitters and Neurotransmitters and NeuromodulatorsNeuromodulators

Neuromodulators modify the postsynaptic cell's response to Neuromodulators modify the postsynaptic cell's response to neurotransmitters or change the presynaptic cell's synthesis, release or neurotransmitters or change the presynaptic cell's synthesis, release or metabolism of the neurotransmitter. metabolism of the neurotransmitter.

Acetylcholine (Ach)Acetylcholine (Ach)Major neurotransmitter. Fibers that release ACh are called cholinergic Major neurotransmitter. Fibers that release ACh are called cholinergic fibers. Acetylcholine is degraded by the enzyme, acetylcholinesterase. fibers. Acetylcholine is degraded by the enzyme, acetylcholinesterase.

Biogenic Amines Biogenic Amines Biogenic amines are neurotransmitters containing an amino group. Biogenic amines are neurotransmitters containing an amino group. Catecholamines such as dopamine, norepinephrine and epinephrine, Catecholamines such as dopamine, norepinephrine and epinephrine, serotonin. Nerve fibers that release epinephrine and norepinephrine are serotonin. Nerve fibers that release epinephrine and norepinephrine are called adrenergic and noradrenergic fibers respectively. called adrenergic and noradrenergic fibers respectively.

Page 18: Physiology of  Muscle

Neurotransmitters and Neurotransmitters and NeuromodulatorsNeuromodulators

Amino Acid Neurotransmitters Amino Acid Neurotransmitters Amino acid neurotransmitters are the most prevalent Amino acid neurotransmitters are the most prevalent neurotransmitters in CNS. Glutamate, aspartate GABA (gamma neurotransmitters in CNS. Glutamate, aspartate GABA (gamma aminobutyric acid), glycine, aminobutyric acid), glycine,

Neuropeptides Neuropeptides Neuropeptides are composed of two or more amino acids. Neurons Neuropeptides are composed of two or more amino acids. Neurons releasing neuropeptides are called releasing neuropeptides are called peptidergicpeptidergic. Beta-endorphin, . Beta-endorphin, dynorphin, enkephalins. dynorphin, enkephalins. Nitric oxide, ATP, adenine also act as neurotransmitters. Nitric oxide, ATP, adenine also act as neurotransmitters.

Neuroeffector Communication Neuroeffector Communication Many neurons of peripheral nervous system end at neuroeffector Many neurons of peripheral nervous system end at neuroeffector junctions on muscle and gland cells. Neurotransmitters released by junctions on muscle and gland cells. Neurotransmitters released by these efferent neurons then activate the target cell. these efferent neurons then activate the target cell.

Page 19: Physiology of  Muscle

Muscle ContractionMuscle Contraction

AP generated in muscle fiber (cell)AP generated in muscle fiber (cell)

Ca++ released from internal stores Ca++ released from internal stores

Muscle fiber contractsMuscle fiber contracts– continues while Ca++ & ATP availablecontinues while Ca++ & ATP available

RelaxationRelaxation– Ca++ sequestered by active transport ~Ca++ sequestered by active transport ~

Page 20: Physiology of  Muscle

Muscle Fiber StructureMuscle Fiber Structure

MultinucleatedMultinucleated– fusion of multiple precursor cellsfusion of multiple precursor cells

Sarcolemma Excitable membrane Sarcolemma Excitable membrane

Myofibrils: contractile unitsMyofibrils: contractile units

Sarcopasmic reticulum (SR)Sarcopasmic reticulum (SR)– sequesters Ca++ sequesters Ca++

T tubulesT tubules– AP from sarcolemma to SR AP from sarcolemma to SR – like inside-out axons ~like inside-out axons ~

Page 21: Physiology of  Muscle

Miofibril Miofibril struktur kontraksi otot struktur kontraksi otot

1 Serat otot, tdd: ribuan miofibril1 Serat otot, tdd: ribuan miofibril1 miofibril tdd: 1 miofibril tdd: Aktin & miosinAktin & miosin (protein kontraksi) (protein kontraksi)Troponin & tropomiosinTroponin & tropomiosin (protein pengatur) (protein pengatur)Titin & nebulinTitin & nebulin (protein asessoris besar) (protein asessoris besar)MiosinMiosin thick filament, punya kepala thick filament, punya kepala

Motor protein, E kimia Motor protein, E kimia E mekanik, mgd ATP-ase E mekanik, mgd ATP-ase (hidrolisis)(hidrolisis)

AktinAktin thin filament, melekat troponin & tropomiosin thin filament, melekat troponin & tropomiosinTitinTitin molekul elastis (protein terbesar) molekul elastis (protein terbesar)

stabilitas & elastisistas ototstabilitas & elastisistas ototNebulinNebulin penyanggah aktin penyanggah aktin

Page 22: Physiology of  Muscle

SarcolemmaMyofibrils

Sarcoplasmic Reticulum

T tubules

Page 23: Physiology of  Muscle
Page 24: Physiology of  Muscle

Myofibril: structure & Myofibril: structure & functionfunction

SarcomeresSarcomeres– repeating sectionsrepeating sectionsZ linesZ lines

dividers between sarcomeresdividers between sarcomeres

thin filaments anchored to Z linesthin filaments anchored to Z lines– actin & troponinactin & troponinThick filaments between thin filamentsThick filaments between thin filaments– myosinmyosinContraction:filaments slide by each Contraction:filaments slide by each other ~other ~

Page 25: Physiology of  Muscle

Sarcomere

Z line Z lineThin filaments

ThickFilaments

Page 26: Physiology of  Muscle
Page 27: Physiology of  Muscle

KONTRAKSI OTOTKONTRAKSI OTOTMenghasilkan force / gaya Menghasilkan force / gaya muscle tension muscle tensionMelawan beban/ loadMelawan beban/ loadMemerlukan energi (dari ATP)Memerlukan energi (dari ATP)

Pencetus kontraksi ototPencetus kontraksi otot1. Neuromuscular junction : 1. Neuromuscular junction :

Rangsang somatik Rangsang somatik rangsang listrik rangsang listrik2. Excitation-contraction coupling2. Excitation-contraction coupling

Potensial aksi Potensial aksi signal Ca++ signal Ca++ siklus kontr-relaks siklus kontr-relaks

SIKLUS KONTRAKSI DAN RELAKSASI SIKLUS KONTRAKSI DAN RELAKSASI Sliding filaments theorySliding filaments theory

Page 28: Physiology of  Muscle

ContractionContractionExcitation-contraction couplingExcitation-contraction coupling

Myosin “heads” crossbridges w/ actinMyosin “heads” crossbridges w/ actin– Ca++ dependentCa++ dependent– binds to troponin, reveals binding sitebinds to troponin, reveals binding site

Myosin head rotatesMyosin head rotates– ““ratchets” actin inward ~ratchets” actin inward ~

Page 29: Physiology of  Muscle

ContractionContractionATP binds to myosin ---> detachmentATP binds to myosin ---> detachment– cocks myosin ---> binds againcocks myosin ---> binds again– rigor mortis: no ATPrigor mortis: no ATP

fibers remain crosslinkedfibers remain crosslinked

Repeats as long as Ca++ presentRepeats as long as Ca++ present– sequestered via active transport ~sequestered via active transport ~

Page 30: Physiology of  Muscle

SLIDING FILAMENT THEORYSLIDING FILAMENT THEORY

Serat Serat otot memendekotot memendek (overlapping thick & thin filament) (overlapping thick & thin filament)Sliding aktin terhadap miosinSliding aktin terhadap miosinGaya dari crossbridge miosin mendorong aktin Gaya dari crossbridge miosin mendorong aktin ((power strokepower stroke))Crossbridge miosin mendorong aktin Crossbridge miosin mendorong aktin menuju pusatmenuju pusat sarkomersarkomerSetelah Setelah power stroke power stroke kepala miosin melepas aktin untuk kepala miosin melepas aktin untuk mengikat bagian aktin yang lain, demikian seterusnya mengikat bagian aktin yang lain, demikian seterusnya jadi siklus.jadi siklus.

Analogi : Analogi : menarik tambangmenarik tambang..

Page 31: Physiology of  Muscle
Page 32: Physiology of  Muscle

In the absence of calcium ions, tropomyosin In the absence of calcium ions, tropomyosin blocks access to the mysosin binding site of blocks access to the mysosin binding site of actin. actin. When calcium binds to troponin, the positions of When calcium binds to troponin, the positions of troponin and tropomyosin are altered on the the troponin and tropomyosin are altered on the the thin flament and myosin then has access to its thin flament and myosin then has access to its binding site on actin. binding site on actin. Myosin hydolyzes ATP and undergoes a Myosin hydolyzes ATP and undergoes a conformational change into a high-energy state. conformational change into a high-energy state. The head group of myosin binds to actin forming The head group of myosin binds to actin forming a cross-bridge between the thick and thin a cross-bridge between the thick and thin filaments. filaments.

Page 33: Physiology of  Muscle

Role of CaRole of Ca+2+2 in Muscle Contraction in Muscle Contraction

Ca+2

Ca++

Ca++

* Actin-binding sites are exposed as a result of Ca+2 binding to troponin complex that causes a conformational shift of tropomyosin

Page 34: Physiology of  Muscle
Page 35: Physiology of  Muscle

The energy stored by myosin is released, and The energy stored by myosin is released, and ADP and inorganic phosphate dissociate from ADP and inorganic phosphate dissociate from myosin. myosin.

The resulting relaxation of the myosin molecule The resulting relaxation of the myosin molecule entails rotation of the globular head, which entails rotation of the globular head, which induces longitudinal sliding of the filaments. induces longitudinal sliding of the filaments.

When the calcium level decreases, troponin When the calcium level decreases, troponin locks tropomyosin in the blocking position and locks tropomyosin in the blocking position and the thin filament slides back to the resting state. the thin filament slides back to the resting state.

Page 36: Physiology of  Muscle
Page 37: Physiology of  Muscle

Sliding-Filament MechanismSliding-Filament Mechanism

Muscle contraction is produced by cross bridge cycles. Muscle contraction is produced by cross bridge cycles. A cycle has 4 steps: A cycle has 4 steps: (1) Energizing of myosin cross bridge (1) Energizing of myosin cross bridge                         A + M•ATP —> A + M*•ADP•Pi (ATP is energizer here) A + M•ATP —> A + M*•ADP•Pi (ATP is energizer here) (2) Attachment of cross bridge to a thin filament (2) Attachment of cross bridge to a thin filament                         A + M*•ADP•Pi —> A•M*•ADP•Pi A + M*•ADP•Pi —> A•M*•ADP•Pi (3) Movement of cross bridge, producing tension (3) Movement of cross bridge, producing tension                         A•M*•ADP•Pi —> A•M + ADP + Pi A•M*•ADP•Pi —> A•M + ADP + Pi (4) Detachment of cross bridge from thin filament (4) Detachment of cross bridge from thin filament                         A•M + ATP —> A + M•ATP (ATP is modulator here) A•M + ATP —> A + M•ATP (ATP is modulator here)

Movement of the cross bridges make the overlapping Movement of the cross bridges make the overlapping thick and thin filaments slide past each other (they do not thick and thin filaments slide past each other (they do not change in length) to produce a contraction. change in length) to produce a contraction.

Page 38: Physiology of  Muscle

Actin MyofilamentActin Myofilament

During contraction, calcium binds to troponin

Covers actin-bindingsites at rest

Page 39: Physiology of  Muscle

Cross-Bridge FormationCross-Bridge Formation

Page 40: Physiology of  Muscle

Cross-Bridge CycleCross-Bridge Cycle

Page 41: Physiology of  Muscle

Cross-bridge Cycle

This animation by Mike Geeves, Laboratory of Molecular Biology in the UK and the Cambridge Institute for Medical Research

Page 42: Physiology of  Muscle

SIKLUS KONTRAKSISIKLUS KONTRAKSI

1.1. Rigor state: Rigor state: Kepala miosin terikat dg molekul G-aktin.Kepala miosin terikat dg molekul G-aktin.2.2. ATP menempel ke miosin, kepala miosin lepas dari ATP menempel ke miosin, kepala miosin lepas dari

aktin.aktin.3.3. Hidrolisis ATP: Hidrolisis ATP: jadi ADP + Pi (masih menempel) jadi ADP + Pi (masih menempel) 4.4. Miosin melekat ke G-aktin yang baruMiosin melekat ke G-aktin yang baru, energi dari , energi dari

pecahnya ATP, saat ada potensial energi di kepala pecahnya ATP, saat ada potensial energi di kepala miosin untuk power stroke.miosin untuk power stroke.

5.5. Pi lepas & power strokePi lepas & power stroke: Kepala miosin berotasi : Kepala miosin berotasi mendorong aktin mendekati pusat sarkomer mendorong aktin mendekati pusat sarkomer (crossbridge tilting)(crossbridge tilting)

6.6. ADP lepasADP lepas: kepala miosin tetap melekat ke aktin, siap : kepala miosin tetap melekat ke aktin, siap untuk siklus berikut bila ada ATP yang baruuntuk siklus berikut bila ada ATP yang baru

Page 43: Physiology of  Muscle

Excitation-Contraction CouplingExcitation-Contraction Coupling

Page 44: Physiology of  Muscle

Excitation-Contraction CouplingExcitation-Contraction Coupling

Excitation-Contraction (EC) Coupling:1. An AP travels down a motor (somatic neuron).2. The AP causes the release of the neurotransmitter

acetylcholine into the synapse at the neuromuscular junction.

3. The acetylcholine binds to the acetylcholine receptors on the muscle fiber and cause an EPSP.

4. If the EPSP reaches threshold, an AP is produced on the sarcolemma of the muscle fiber. Meanwhile, the acetylcholine attached to the receptor is destroyed.

5. The AP travels rapidly along the sarcolemma and enters the fiber at every t-tubule.

Page 45: Physiology of  Muscle

Excitation-Contraction CouplingExcitation-Contraction Coupling

6. As the AP travels through the t-tubule, it causes the Ca++ gates to open and Ca++ flows from the SR into the sarcoplasm. The Ca++ gates close when the AP ends.

7. The increased [Ca++] in the sarcoplasm results in Ca++ binding to troponin. This induces an allosteric change, the tropomyosin is pulled out of the way and steric inhibition is removed. The result is crossbridges begin to form, rotate and break (provided there is plenty of ATP).

8. Cross-bridge cycling continues as long as sarcoplasmic [Ca++] remains high.

9. However, if the Ca++ gates close, the action of the Ca++ ATPase (pump) begins to predominate and sarcoplasmic [Ca++]] drops. When it drops low enough, the troponin loses its Ca++ and changes shape the next time a crossbridge is not in the way. Steric inhibition is quickly re-established and the muscle contraction is over.

Page 46: Physiology of  Muscle
Page 47: Physiology of  Muscle

Exitation-Contraction CouplingExitation-Contraction Coupling

Dirangsang oleh asetilkolin/achetylcholineDirangsang oleh asetilkolin/achetylcholine

TahapTahap::

Asetilkolin (Ach) lepas dari motor neuron Asetilkolin (Ach) lepas dari motor neuron somatiksomatik

Ach merangsang potensial aksi serat ototAch merangsang potensial aksi serat otot

PA, m’rsg Ca++ lepas dr Ret.SarkoplasmaPA, m’rsg Ca++ lepas dr Ret.Sarkoplasma

Ca++ me’ikat troponin dan m’rsg kontraksiCa++ me’ikat troponin dan m’rsg kontraksi

Page 48: Physiology of  Muscle

DHP:

Dihydropiridine

Saat PA:

Ca 100x

Relaksasi:

Ca masuk RS krn enzim

Ca-ATP-ase

Page 49: Physiology of  Muscle

PERIODE KONTRAKSI/ TWITCHPERIODE KONTRAKSI/ TWITCH

1.1. Periode LatenPeriode Laten

(Antara potensial aksi-kontraksi)(Antara potensial aksi-kontraksi)

2. Periode kontraksi2. Periode kontraksi

3. Periode relaksasi3. Periode relaksasi

Lama periode kontraksi tergantung tipe ototLama periode kontraksi tergantung tipe otot

Page 50: Physiology of  Muscle
Page 51: Physiology of  Muscle

SUMBER ENERGI KONTRAKSISUMBER ENERGI KONTRAKSI

ATP (Adenosine Tri Phosphate)ATP (Adenosine Tri Phosphate)1.1. Kontraksi: gerakan crossbridgeKontraksi: gerakan crossbridge2.2. Relaksasi: Ca++ masuk lagi ke RSRelaksasi: Ca++ masuk lagi ke RS3.3. Relaksasi: melepas ikatan aktin dan miosinRelaksasi: melepas ikatan aktin dan miosin4.4. Diluar periode kontraksi : restore Na-KDiluar periode kontraksi : restore Na-K

SUMBER ATPSUMBER ATP1.1. Konversi posfo-kreatin (8 twitch)Konversi posfo-kreatin (8 twitch)2.2. An-aerobik glikolisisAn-aerobik glikolisis3.3. Posforilasi-oksidatifPosforilasi-oksidatif

Page 52: Physiology of  Muscle
Page 53: Physiology of  Muscle

KELELAHAN OTOTKELELAHAN OTOT

Fatigue:Fatigue:

Kondisi dimana otot tidak mampu lagi Kondisi dimana otot tidak mampu lagi melakukan / mempertahankan kontraksimelakukan / mempertahankan kontraksi

Jenis FatigueJenis Fatigue::Sentral: SSPSentral: SSPPerifer: NM-Junction – elemen kontraksiPerifer: NM-Junction – elemen kontraksi

E/ >> E/ >> elemen kontraksi elemen kontraksi

Page 54: Physiology of  Muscle

Lelah Sentral SSP Psikologis

Refleks Proteksi

Asidosis

(as. Laktat)

NM-Junction Pelepasan Neurotransmitter dan sensitivitas reseptor

Ggn.

Neuromuskuler

(Ach )

Kelelahan

Perifer

Excitation-contraction coupling

Perubahan membran potensial

Gangguan elektrolit (Hipokalemia)

Ca++ signal Pelepasan Ca & interaksi dg troponin

Pi

Kontraksi-relaksasi

PCr, ATP, glikogen

H+, Pi, laktat

Pi

Page 55: Physiology of  Muscle

Daya kontraksi (tension) maksimal tjd pada Daya kontraksi (tension) maksimal tjd pada panjang sarokomere yang optimalpanjang sarokomere yang optimal

Page 56: Physiology of  Muscle

Tension juga meningkat bila stimulus dilakukan Tension juga meningkat bila stimulus dilakukan berulang kali sebelum mencapai relaksasi berulang kali sebelum mencapai relaksasi maksimum (Stimulus Summation)maksimum (Stimulus Summation)

Akan tetapi, bila stimulus (potensial aksi) berlangsung terus menerus dg cepat (frekuensi tinggi), tanpa fase relaksasi terjadi Tetanus

Tetanus

-Komplet/ fused

-Inkomplet / unfused

Page 57: Physiology of  Muscle

Muscle Adaptation to ExerciseMuscle Adaptation to Exercise

Increased amount of contractile activity Increased amount of contractile activity (exercise) increases size (hypertrophy) of (exercise) increases size (hypertrophy) of muscle fibers and capacity for ATP production. muscle fibers and capacity for ATP production. Low intensity exercise affects oxidative fibers, Low intensity exercise affects oxidative fibers, increasing the number of mitochondria and increasing the number of mitochondria and capillaries. capillaries. High intensity exercise affects glycolytic fibers, High intensity exercise affects glycolytic fibers, increasing their diameter by an increased increasing their diameter by an increased synthesis of actin and myosin filaments, and an synthesis of actin and myosin filaments, and an increased synthesis of glycolytic enzymes. increased synthesis of glycolytic enzymes.

Page 58: Physiology of  Muscle

Speed of Muscle Contraction Varies by Fiber Type

Page 59: Physiology of  Muscle

MOTOR UNITMOTOR UNIT

Unit dasar kontraksiUnit dasar kontraksi, tdd: bbrp serat otot + motor , tdd: bbrp serat otot + motor neuron somatikneuron somatikMotor neuron mencetuskan potensial aksi Motor neuron mencetuskan potensial aksi kontraksi 1 motor unit.kontraksi 1 motor unit.1 motor neuron 1 motor neuron bbrp otot; 1 serat otot bbrp otot; 1 serat otot dipersyarafi 1 neurondipersyarafi 1 neuronOtot kecil (gerak halus; tangan, wajah) Otot kecil (gerak halus; tangan, wajah) 1 motor unit = 3-5 serat otot1 motor unit = 3-5 serat ototOtot besar (gerak kasar; tungkai, trunkus) Otot besar (gerak kasar; tungkai, trunkus) 1 motor unit = 100an- 1000an serat otot1 motor unit = 100an- 1000an serat otot

Page 60: Physiology of  Muscle

Motor Pool Motor Pool all a motor neurons that innervate a single all a motor neurons that innervate a single muscle muscle

An a motor neuron and An a motor neuron and all the muscle fibers that it innervates all the muscle fibers that it innervates

1:3 to 1:1001:3 to 1:100

fewer muscle fibers ---> finer controlfewer muscle fibers ---> finer control– 3 types3 types based on speed of contraction & fatigue based on speed of contraction & fatigue

~~

Motor Pools & Motor UnitsMotor Pools & Motor Units

Page 61: Physiology of  Muscle

Types of Motor UnitsTypes of Motor UnitsMost muscle contain both slow- & fast-Most muscle contain both slow- & fast-twitch fibers twitch fibers – ratio depends on functionratio depends on function

e.g. ankle extensorse.g. ankle extensors– Soleus active during standing Soleus active during standing

hi ratio of slow fibers hi ratio of slow fibers – Medial Gastrocnemius: active during running Medial Gastrocnemius: active during running

& jumping& jumping

hi ratio of fast fibers ~hi ratio of fast fibers ~

Page 62: Physiology of  Muscle
Page 63: Physiology of  Muscle

Variasi gradasi, gaya & durasi kontrksi Variasi gradasi, gaya & durasi kontrksi ditentukan oleh : ditentukan oleh :

Jumlah & jenis motor unit yang aktif Jumlah & jenis motor unit yang aktif (‘Recruitment’ dikontrol oleh SSP)(‘Recruitment’ dikontrol oleh SSP) Kontraksi lemah Kontraksi lemah SSP m’rsg sedikit motor unit SSP m’rsg sedikit motor unit Motor unit yang t’rsg Ix nilai ambang rendah Motor unit yang t’rsg Ix nilai ambang rendah slow- slow-

twitchtwitch Stimulus Stimulus m’rsg motor neuron dg nilai ambang tinggi m’rsg motor neuron dg nilai ambang tinggi

fast-twitch fast-twitch Jumlah motor unit Jumlah motor unit daya kontraksi daya kontraksi Asynchronous RecruitmentAsynchronous Recruitment

Pada kontraksi lama, SSP m’rsg bbrp motor unit scr Pada kontraksi lama, SSP m’rsg bbrp motor unit scr bergantian bergantian 1 serat kontraksi, serat lain istirahat 1 serat kontraksi, serat lain istirahatHanya terjadi pada kontraksi sub-maksimal, why ?Hanya terjadi pada kontraksi sub-maksimal, why ?

Page 64: Physiology of  Muscle

BIOMEKANIKA GERAK BIOMEKANIKA GERAK TUBUHTUBUH

Fs otot: menggerakkan rangkaFs otot: menggerakkan rangka

KONTRAKSI ISOTONIK (Iso;=, teinein; stretch)KONTRAKSI ISOTONIK (Iso;=, teinein; stretch)Kontraksi Kontraksi gaya + menggerakkan beban gaya + menggerakkan beban Sarkomer menarik beban dan serat elastisSarkomer menarik beban dan serat elastisKonsentrikKonsentrik arah gerak = pemendekan otot arah gerak = pemendekan ototEksentrikEksentrik arah gerak = pemanjangan otot arah gerak = pemanjangan otot

>> m’rusak otot (DOMS)>> m’rusak otot (DOMS)KONTRAKSI ISOMETRIK (Iso;=, metric;ukuran)KONTRAKSI ISOMETRIK (Iso;=, metric;ukuran)Kontraksi Kontraksi gaya + tanpa menggerakkan beban gaya + tanpa menggerakkan beban Sarkomer otot hanya menarik serat elastisSarkomer otot hanya menarik serat elastis

Page 65: Physiology of  Muscle
Page 66: Physiology of  Muscle
Page 67: Physiology of  Muscle
Page 68: Physiology of  Muscle

USAHA OTOTUSAHA OTOTLever/ lengan Lever/ lengan dibentuk oleh rangkadibentuk oleh rangkaFulcrum/ sumbu Fulcrum/ sumbu dibentuk sendidibentuk sendi

W = F x dW = F x d WW (otot) = W (otot) = W (beban) (beban)

Insersi bisep 5 cm dari sikuInsersi bisep 5 cm dari sikuPanjang lengan 20 cmPanjang lengan 20 cmBerat beban 5 kgBerat beban 5 kg

Berapa usaha otot bisep Berapa usaha otot bisep mengangkat beban ?mengangkat beban ?

Semakin dekat insersi ke fulcrum Semakin dekat insersi ke fulcrum Gerak semakin luasGerak semakin luas

Page 69: Physiology of  Muscle

Refleks Otot SkeletalRefleks Otot Skeletal

Berfungsi utkBerfungsi utk::1.1. Mengatur keseimbanganMengatur keseimbangan2.2. Gerak spesifik (keselamatan)Gerak spesifik (keselamatan)3.3. Optimalisasi gerakOptimalisasi gerakKomponen RefleksKomponen Refleks1.Reseptor sensoris (proprioceptors)1.Reseptor sensoris (proprioceptors)

Spindle otot, organ tendo Golgi & reseptor sendiSpindle otot, organ tendo Golgi & reseptor sendi2. Neuron sensoris (transfer input)2. Neuron sensoris (transfer input)3. SSP3. SSP4. Motor neuron somatik (alfa motor neuron)4. Motor neuron somatik (alfa motor neuron)5. Serat otot (serat ekstrafusal5. Serat otot (serat ekstrafusal) )

Page 70: Physiology of  Muscle
Page 71: Physiology of  Muscle

Reseptor SendiReseptor Sendi

Terdapat di kapsul sendi dan ligamenTerdapat di kapsul sendi dan ligamen

Distimulasi oleh distorsi mekanik krn Distimulasi oleh distorsi mekanik krn perubahan sudut, beban dan posisi sendi perubahan sudut, beban dan posisi sendi & tulang& tulang

Pusat pengaturan di cerebellumPusat pengaturan di cerebellum

Page 72: Physiology of  Muscle

Spindle OtotSpindle Otot

Reseptor regangan ototReseptor regangan ototMengirim impuls ke Med. Spinalis & otakMengirim impuls ke Med. Spinalis & otakResponsif thd perubahan panjang ototResponsif thd perubahan panjang otot1 otot memiliki bbrp spindle otot, kec, 1 otot memiliki bbrp spindle otot, kec, rahangrahangTerletak di sisi dalam otot ekstrafusal, Terletak di sisi dalam otot ekstrafusal, mengelilingi otot intrafusalmengelilingi otot intrafusalAkibat dari rangsangan menghasilkan Akibat dari rangsangan menghasilkan refleks kontraksirefleks kontraksi

Page 73: Physiology of  Muscle

Organ Tendo GolgiOrgan Tendo Golgi

Terletak di sambungan tendo dan ototTerletak di sambungan tendo dan otot

Responsif terhadap tegangan ototResponsif terhadap tegangan otot

Menghasilkan refleks relaksasiMenghasilkan refleks relaksasi

Terdiri dari ujung syaraf bebasTerdiri dari ujung syaraf bebas

Refleks menghambat interneuron di MS, Refleks menghambat interneuron di MS, interneuron menghambat alfa motor interneuron menghambat alfa motor neuron sehingga kontraksi berkurang.neuron sehingga kontraksi berkurang.

Page 74: Physiology of  Muscle
Page 75: Physiology of  Muscle

Knee Jerk reflexes; Knee Jerk reflexes;

merangsang spindle ototmerangsang spindle otot

Flexion reflexes;Flexion reflexes;

menghindari bahayamenghindari bahaya

Page 76: Physiology of  Muscle

Movement Disorders of Movement Disorders of MuscleMuscle

Page 77: Physiology of  Muscle

Duchenne’s Muscular Duchenne’s Muscular DystrophyDystrophy

Muscular DystrophiesMuscular Dystrophies– wasting away of muscleswasting away of muscles– metabolic / structural abnormalitiesmetabolic / structural abnormalities

Duchenne’sDuchenne’s– best understoodbest understood– young boys ~young boys ~

Page 78: Physiology of  Muscle

Duchenne’s Muscular Duchenne’s Muscular DystrophyDystrophy

CauseCause– hereditary - maternal X chromosome hereditary - maternal X chromosome – single gene ---> proteinsingle gene ---> protein

dystrophindystrophin– maybe involved in Ca++ regulationmaybe involved in Ca++ regulation

TreatmentTreatment– Inject dystrophin or mRNAInject dystrophin or mRNA– Gene therapy promising for muscles ~Gene therapy promising for muscles ~

Page 79: Physiology of  Muscle

Myasthenia GravisMyasthenia Gravis

Severe muscle weaknessSevere muscle weakness– rapid fatigue following exerciserapid fatigue following exercise

Develops in people of all agesDevelops in people of all ages– Most common: women in 30sMost common: women in 30s– Risk of respiratory paralysisRisk of respiratory paralysis

Autoimmune disorderAutoimmune disorder– body develops antibodies for ACh-Rbody develops antibodies for ACh-R– reduces synaptic transmission ~reduces synaptic transmission ~

Page 80: Physiology of  Muscle

Myasthenia Gravis: Myasthenia Gravis: Treatment Treatment

AChE inhibitors AChE inhibitors – ¯ degradation of ACh¯ degradation of ACh– narrow therapeutic windownarrow therapeutic window– too much ACh ---> paralysistoo much ACh ---> paralysis

Reduce immune responseReduce immune response– remove thymusremove thymus– filtering antibodies from blood filtering antibodies from blood

temporary ~temporary ~