SISTEM MUSKULOSKELETAL (2)
Dwi RetnoningrumSISTEM MUSKULOSKELETAL (2)
3 Tipe jaringan ototOtot polosmemiliki 1 inti yg berada di tengah, dipersarafi oleh saraf otonom (involunter), serat otot polos (tidak berserat), terdapat di organ dalam tubuh (viseral), sumber Ca2+ dari CES, sumber energi terutama dari metabolisme aerobik, awal kontraksi lambat, kadang mengalami tetani, tahan terhadap kelelahanOtot rangkamemiliki banyak inti, dipersarafi oleh saraf motorik somatik (volunter), melekat pada tulang, sumber Ca2+ dari retikulum sarkoplasma (RS), sumber energi dari metabolisme aerobik & anaerobik, awal kontraksi cepat, mengalami tetani, & cepat lelahOtot jantungmemiliki 1 inti yang berada di tengah, dipersarafi oleh saraf otonom (involunter), serat otot berserat, hanya ada di jantung, sumber Ca2+ dari CES & RS, sumber energi dari metabolisme aerobik, awal kontraksi lambat, tidak mengalami tetani, & tahan terhadap kelelahan
3 Tipe Jaringan Otot
Otot polosOtot rangkaOtot jantung
Perbedaan 3 tipe otot
SIFAT-SIFAT OTOTKONTRAKTILITAS kemampuan otot untuk mengadakan respon (memendek) bila dirangsang (otot polos 1/6 kali; otot rangka 1/10 kali)
EKSTENSIBILITAS = DISTENSIBILITAS kemampuan otot untuk memanjang bila otot ditarik atau ada gaya yang bekerja pada otot tersebut bila otot rangka diberi beban; uterus berisi fetus
ELASTISITAS kemampuan otot untuk kembali ke bentuk & ukuran semula setelah mengalami ekstensibilitas/distensibilitas (memanjang) atau kontraktilitas (memendek)
IRRITABILITAS = EKSITABILITAS kemampuan otot untuk mengadakan respon bila di rangsang
Cardiac MuscleBranching cellsOne/two nuclei per cellStriatedInvoluntaryMedium speed contractions
6Cardiac muscle tissue is only found in the heart. *Cardiac cells are arranged in a branching pattern. * Only one or two nuclei are present each cardiac cell. *Like skeletal muscle, cardiac muscle is striated. *Cardiac muscle is involuntary. *Its speed of contraction is not as fast as skeletal, but faster than that of smooth muscle.
OTOT JANTUNG
BENTUK: terdiri beberapa serabut otot yang bercabang & bersatu dengan serabut di sebelahnya anastomosa atau sinsitium; mempunyai garis gelap dan terang (tidak sejelas otot rangka); intinya di tengah (center); pada interval tertentu terdapat keping-keping interkalar (intercalar disc), pada intercalar disc terdapat jaringan Purkinye yang berfungsi mempercepat penghantaran impuls (kecepatan 4 m/detik)LOKASI: hanya ada di jantungINNERVASI: sistem syaraf otonomAKSI: kontraksi otomatis & ritmis
OTOT JANTUNGOtonom, bisa simpatis, bisa parasimpatis
Untuk otot jantung: peningkatan denyut jatung sangat dipengaruhi oleh syaraf simpatis, sedangkan pengurangan denyut jantung sangat dipengaruhi oleh syaraf parasimpatis
Kerja syaraf otonom, baik simpatis maupun parasimpatis kebalikan dari kerja otot polos
SIFAT-SIFAT OTOT JANTUNG1. KONTRAKTILITAS sistol (kontraksi), diastol (relaksasi) dan selalu ada platau (dataran yang menyebabkan fase diastol lebih panjang dari sistol = memberi kesempatan darah tertampung lebih banyak di jantung)2. KONDUKTIVITAS perambatan impuls sinoatrial nodus atrium atrioventrikular nodus ventrikel berkas HIS jaringan Purkinye 4 m/detik3. OTOMATIS & RITMIS secara otomotis dan ritmis selalu berdenyut kecuali ada gangguan4. IRRITABILITAS = EKSITABILITAS mengadakan respons bila di rangsang5. PERIODE REFRAKTER YANG LAMA Absolut pada saat sistol tidak akan terjadi perubahan apa-apa (grafik tetap berjalan tanpa gangguan) Relatif pada saat diastol akan terjadi perubahan tergantung rangsangan terjadi pada awal diastol, pertengahan diastol, atau hampir akhir diastol
Smooth MuscleFusiform cellsOne nucleus per cellNonstriatedInvoluntarySlow, wave-like contractions
10Smooth muscle is found in the walls of hollow organs. *Their muscle cells are fusiform in shape. *Smooth muscle cells have just on nucleus per cell. *Smooth muscle is nonstriated. *Smooth muscle is involuntary. *The contractions of smooth muscle are slow and wave-like.
OTOT POLOS
Bentuk: seperti gelendong, panjang, ramping, pipih dan langsingSetiap otot memiliki 1 inti (nukleus) di tengah (center)Sitoplasmanya terdiri dari sarkoplasma yang mengandung miofibril (elemen yang mampu berkontraksi sehingga dapat bergerak)Panjang otot polos bervariasi antara 15-500 mikron, tergantung lokasi: paling pendek pembuluh darah; paling panjang uterus (rahim)
OTOT POLOSLOKASI: saluran pencernaan makanan (batang kerongkongan, esophagus, lambung, usus halus, usus kasar); batang tenggorokan, bronkus, pulmo, uterus (rahim), kantung urine, kantung empedu, pembuluh darah
INNERVASI (PERSYARAFAN): sangat dipengaruhi oleh sistem syaraf otonom (bisa simpatis, bisa parasimpatis)Untuk otot polos peningkatan kerja otot polos seperti gerak peristaltik dilakukan oleh syaraf parasimpatis, sedangkan penghambatan kerja otot polos dilakukan oleh syaraf simpatis
AKSI: kontraksi lambat, berlangsung lama, kadang-kadang ritmis
Skeletal MuscleLong cylindrical cellsMany nuclei per cellStriatedVoluntaryRapid contractions
13Skeletal muscle attaches to our skeleton. *The muscle cells a long and cylindrical. *Each muscle cell has many nuclei. *Skeletal muscle tissue is striated. It has tiny bands that run across the muscle cells. *Skeletal muscle is voluntary. We can move them when we want to. *Skeletal muscle is capable of rapid contractions. It is the most rapid of the muscle types.
OTOT RANGKA = OTOT SADAR = OTOT LURIK = OTOT SERAN LINTANG
BENTUK: Terdiri banyak serabutIntinya terletak di tepi (pinggir), terdapat garis gelap dan terang (sangat jelas)Panjang bervariasi 1-40 mm, tebalnya 10-100 mikronSetiap serabut dilapisi sarkolema (dalam sarkolema terdapat miofibril = elemen yang dapat berkontraksi)Serabut otot yang masing-masing dilapisi sarkolema berkelopok membentuk 15-30 serabut otot dan dilapisi fasiculus. Masing-masing fasikulus dilapisi oleh jaringan ikat perimisium. Jaringan ikat yang meliputi serabut otot rangka disebut endomisium. Masing-masing endomisium dilapisi lagi oleh epimisium. Dalam otot rangka terdapat mioglobin
LOKASI : semua otot yang melekat pada tulang, otot lidah, langit-langi (palatinum), pharing, ujung esophagus
INNERVASI : sistem syaraf kraniospinal bekerja menurut kehendak individu
AKSI: kontraksi cepat, berlangsung sebentarOTOT RANGKA = OTOT SADAR = OTOT LURIK = OTOT SERAN LINTANG
Fungsi Sistem Otot RangkaMenghasilkan gerakan rangka.Mempertahankan sikap & posisi tubuh.Menyokong jaringan lunak.Menunjukkan pintu masuk & keluar saluran dalam sistem tubuh.Mempertahankan suhu tubuh; kontraksi otot:energi panas
Struktur Otot Rangka Tendon/TendoHampir semua otot rangka menempel pada tulang. Tendon: jaringan ikat fibrosa yang tebal dan berwarna putih yang menghubungkan otot rangka dengan tulang.
TENDON
Struktur Otot RangkaFascia adalah jaringan yang membungkus dan mengikat jaringan lunakFungsi: mengelilingi otot, menyedikan tempat tambahan otot, memungkinkan struktur bergerak satu sama lain dan menyediakan tempat pembuluh darah dan saraf - Otot rangka kumpulan fasciculus (berkas sel otot berbentuk silindris yang diikat oleh jaringan ikat).- Seluruh serat otot dihimpun menjadi satu oleh jaringan ikat epimysium (fascia).- Setiap fasciculus dipisahkan oleh jar.ikat perimysium- Dalam fascicle, endomysium mengelilingi 1 berkas sel otot.- Di antara endomysium & berkas serat otot tersebar sel satelit yg berfungsi dlm perbaikan jaringan otot yang rusak.
Sel otot serat otot (endomysium) fascicle fasciculus (perimysium) fascia (epimysium) otot rangka (organ)
Struktur Otot RangkaSarcolemma (membran sel/serat otot) & Sarcoplasma
Unit struktural jaringan otot ialah serat otot (diameter 0,01-0,1 mm;panjang 1-40 mm). Besar dan jumlah jaringan, terutama jaringan elastik, akan meningkat sejalan dengan penambahan usia. Setiap 1 serat otot dilapisi oleh jaringan elastik tipis yg disebut sarcolemma. Protoplasma serat otot yg berisi materi semicair disebut sarkoplasma. Di dalam matriks serat otot terbenam unit fungsional otot berdiameter 0,001 mm yang disebut miofibril.
Struktur Otot RangkaMiofibril (diameter 1-2m)Di bawah mikroskop, miofibril akan tampak seperti pita gelap & terang yang bersilangan. Pita gelap (thick filament) dibentuk oleh miosinPita terang (thin filament) dibentuk oleh aktin, troponin & tropomiosin)
Struktur Otot RangkaSarkomer1 sarkomer terdiri dari:- filamen tebal, - filamen tipis, - protein yg menstabilkan posisi filamen tebal & tipis,- protein yg mengatur interaksi antara filamen tebal & tipis.Pita gelap (pita/ bands Aanisotropic); pita terang (pita/bands I isotropic)Filamen tebal tdp di tengah sarkomer Pita A, tdd 3 bgn:- garis M; zona H; dan zona overlapFilamen tebal tdp pd pita I; garis Z mrp batas antara 2 sarkomer yg berdekatan & mengandung protein Connectins yg menghubungkan filamen tiois pd sarkomer yg berdekatan.
Struktur Otot RangkaRetikulum sarkoplasmaJejaring kantung dan tubulus yang terorganisir pada jaringan otot retikulum endoplasma di sel lain.Tdd tubulus-tubulus yg sejajar dg miofibril, yg pd garis Z dan zona H bergabung membentuk kantung (lateral sac) yang dekat dengan sistem tubulus transversal (Tubulus T). Tempat penyimpanan ion Ca2+. Tubulus T saluran untuk berpindahnya cairan yang mengandung ion.Tubulus T dan retikulum sarkoplasma berperan dlm metabolisme, eksitasi, dan kontraksi otot.
Skeletal Muscle Structure
24Organization of Connective TissuesMuscle attachmentsEndomysium, perimysium, and epimysium come together at ends of muscles to form connective tissue attachment to bone matrix i.e., tendon (bundle) or aponeurosis (sheet)NervesSkeletal muscles are voluntary muscles, controlled by nerves of the central nervous system (brain and spinal cord)Blood VesselsMuscles have extensive vascular systems that1) Supply large amounts of oxygen2) Supply nutrients3) Carry away wastesSkeletal Muscle fibers are:Are very long Develop through fusion of mesodermal cells (myoblasts)Become very large Contain hundreds of nuclei
Skeletal Muscle Fiber
Internal Organization of Muscle FibersThe sarcolemmaThe cell membrane of a muscle fiber (cell) Surrounds the sarcoplasm (cytoplasm of muscle fiber)A change in transmembrane potential begins contractionsTransverse tubules (T tubules)Transmit action potential through cellAllow entire muscle fiber to contract simultaneouslyHave same properties as sarcolemmaMyofibrilsLengthwise subdivisions within muscle fiberMade up of bundles of protein filaments (myofilaments)Myofilaments are responsible for muscle contraction Types of myofilaments:thin filaments: made of the protein actinthick filaments: made of the protein myosinSarcoplasmic reticulum (SR)A membranous structure surrounding each myofibril Helps transmit action potential to myofibrilSimilar in structure to smooth endoplasmic reticulumForms chambers (terminal cisternae) attached to T tubulesTriadIs formed by one T tubule and two terminal cisternaeCisternae:concentrate Ca2+ (via ion pumps) release Ca2+ into sarcomeres to begin muscle contraction
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Sarcomere
Internal Organization of Muscle FibersSarcomeresThe contractile units of muscleStructural units of myofibrils Form visible patterns within myofibrilsMuscle striationsA striped or striated pattern within myofibrils:alternating dark, thick filaments (A bands) and light, thin filaments (I bands) M Lines and Z Lines:M line:the center of the A bandat midline of sarcomereZ lines:the centers of the I bandsat two ends of sarcomereZone of overlap:the densest, darkest area on a light micrograph where thick and thin filaments overlapThe H Band:the area around the M line has thick filaments but no thin filaments Titin:Strands of protein reach from tips of thick filaments to the Z linestabilize the filaments
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Initiating ContractionCa2+ binds to receptor on troponin moleculeTroponintropomyosin complex changesExposes active site of F-actinThick FilamentsContain twisted myosin subunits Contain titin strands that recoil after stretchingThe mysosin moleculeTail:binds to other myosin molecules Head:made of two globular protein subunitsreaches the nearest thin filamentMyosin ActionDuring contraction, myosin headsInteract with actin filaments, forming cross-bridges Pivot, producing motion Skeletal Muscle ContractionSliding filament theoryThin filaments of sarcomere slide toward M line, alongside thick filamentsThe width of A zone stays the sameZ lines move closer together
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30Which filament has moved as the sarcomere contracted? Note the thick myosin filaments have not changed, but the thin actin filaments have moved closer together.
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32The Ca ions bind to the troponinThis binding weakens troponin-tropomoysin complex and actinTroponin moiecule changes position, rolling the tropomyosin away from the active sites on actinThus allowing them to interact with energized myosin heads
With the active sites on the actin exposed, the myosin heads bind to the, forming cross-bridges 33
After cross-bridge formation, the ATP present in the myosin is used to cock (the opposite direction from its resting state). As the ATP is used and the ADP + P is released, the power stroke occurs as the myosin pivots toward the M line.34
When another ATP molecule attaches to the myosin head, the cross-bridge between the active site of the actin molecule and myosin head is broken. Thus freeing up the head to make another bridge and complete the contraction.35
Myosin splits the ATP into ADP + P and uses the released energy to re-cock the myosin head (reaching forward). Cycle can be repeated endlessly as along as calcium ion concentration remain high and sufficient ATP is present.
ATP produced in cells aerobic vs. anaerobicCa controlled by what?36
Neuromuscular Junction
Is the location of neural stimulationAction potential (electrical signal)Travels along nerve axonEnds at synaptic terminal Synaptic terminal:releases neurotransmitter (acetylcholine or ACh)into the synaptic cleft (gap between synaptic terminal and motor end plate)
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The NeurotransmitterAcetylcholine or AChTravels across the synaptic cleft Binds to membrane receptors on sarcolemma (motor end plate)Causes sodiumion rush into sarcoplasmIs quickly broken down by enzyme (acetylcholinesterase or AChE)
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40The influx of sodium will create an action potential in the sarcolemma. Note: This is the same mechanism for generating action potentials for the nerve impulse. The action potential travels down a T tubule. As the action potential passes through the sarcoplamic reticulum it stimulates the release of calcium ions. Calcium binds with troponin to move tropomyosin and expose the binding sites. Myosin heads attach to the binding sites of the actin filament and create a power stroke. ATP detaches the myosin heads and energizes them for another contraction. The process will continue until the action potentials cease. Without action potentials the calcium ions will return to the sarcoplasmic reticulum.Five Steps of the Contraction CycleExposure of active sitesFormation of cross-bridgesPivoting of myosin headsDetachment of cross-bridgesReactivation of myosin
RelaxationCa2+ concentrations fallCa2+ detaches from troponinActive sites are re-covered by tropomyosinSarcomeres remain contracted Skeletal muscle fibers shorten as thin filaments slide between thick filamentsFree Ca2+ in the sarcoplasm triggers contractionSR releases Ca2+ when a motor neuron stimulates the muscle fiber Contraction is an active processRelaxation and return to resting length are passive
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Muscle Contraction TypesIsotonic contraction
Isometric contraction
Two Types of Skeletal Muscle TensionIsotonic ContractionSkeletal muscle changes length:resulting in motionIf muscle tension > load (resistance):muscle shortens (concentric contraction)If muscle tension < load (resistance):muscle lengthens (eccentric contraction)
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Muscle Contraction TypesIsotonic contraction
Isometric contraction
Two Types of Skeletal Muscle TensionIsometric contractionSkeletal muscle develops tension, but is prevented from changing lengthNote: iso- = same, metric = measureProduces no movementUsed inStandingSittingPosture43
MetabolismAerobic metabolism95% of cell demandKrebs cycle1 pyruvic acid molecule 17 ATPAnaerobic metabolismGlycolysis 2 pyruvic acids + 2 ATPProvides substrates for aerobic metabolismAs pyruvic acid builds converted to lactic acid
44Muscle fatigue is often due to a lack of oxygen that causes ATP deficit. Lactic acid builds up from anaerobic respiration in the absence of oxygen. Lactic acid fatigues the muscle.
BEBERAPA ISTILAHTreppe Rangsang yang berulang dengan intensitas (kuat) rangsang yang sama sehingga lambat laun kuat kontraksi meningkat
Hipertropi Bila otot melakukan kerja secara terus menerus maka otot akan membesar setiap diameter serabut syaraf juga akan membesar, tetapi jumlah serabut serabut di dalamnya tetap atau tidak bertambah
Atropi Bila otot tidak digunakan (misalnya sakit shg tidak berjalan karena sakit) maka otot akan mengecil
Hiperplasia Membesarnya otot, karena jumlah serabut yang bertambah
Muscle HypertrophyMuscle growth from heavy trainingIncreases diameter of muscle fibersIncreases number of myofibrilsIncreases mitochondria, glycogen reserves
46Hypertrophy is the enlargement of a muscle. Hypertrophied muscles have more capillaries and more mitochondria to help them generate more energy. Strenuous exercise and steroid hormones can induce muscle hypertrophy. Since men produce more steroid hormones than women, they usually have more hypertrophied muscles.
Muscle AtrophyLack of muscle activityReduces muscle size, tone, and power
