3. Mekanisme Kontraksi Otot Rangka

Nani Cahyani Sudarsono Ahmad Aulia JusufSKELETAL MUSCLE CONTRACTION

Skeletal muscle contraction Modul Muskuloskeletal FKUI - December 2007*Muscle Characteristics4 major functional characteristicsContractilityCapacity of muscle to contract forcefullyExcitabilityResponds to stimulation by nerves or hormonesExtensibilityMuscles can be stretched to normal resting length and beyond to a limited degreeElasticityIf muscles are stretched, they can recoil to their original resting length

Skeletal muscle contraction Modul Muskuloskeletal FKUI - December 2007

muscles move the bodythrough skeletal muscle contraction that produce muscle tension

Primal Pictures: Interactive Functional Anatomy

Muscle structure

http://home.earthlink.net/~dayvdanls/biology1_2/physiolect8.htmMuscle structure

Longitudinal Section of MyofibrilI

Muscloskeletal module Faculty of Medicine Universitas Indonesia December 2007*molecular basis of muscle contraction:repeated sliding of myofilaments at sufficient ATP and Ca

Neuromuscular JunctionLECTURE 18

NMJ and Motor End PlateExcitation of the MuscleCa++ Voltage-gatedChannelsLECTURE 18

Skeletal Muscle InnervationFigure 10.10cAndrei R. Manolescu M.D. Department of Physiology, Faculty of Medicine University of Alberta - Sept 27 2005

The Contraction CycleFigure 10.12Andrei R. Manolescu M.D. Department of Physiology, Faculty of Medicine University of Alberta - Sept 27 2005

Based in part on Color Atlas of Physiology, Agamemnon Despopoulos, Stefan Silbernagl Thieme Medical Publishers, Inc. , 1991, New York http://www.sci.sdsu.edu/movies/actin_myosin.htmlActin Myosin Crossbridge 3D Animation San Diego State University College of Sciences

Andrei R. Manolescu M.D. Department of Physiology, Faculty of Medicine University of Alberta Sept 27th , 2005Changes in the appearance of a Sarcomere during the Contraction of a Skeletal Muscle Fiber

muscle contraction produces tension


Isotonic ContractionsFigure 9.17 (a)Elaine N. Marieb Human Anatomy & Physiology, Sixth Edition


Isometric ContractionsFigure 9.17 (b)Elaine N. Marieb Human Anatomy & Physiology, Sixth Edition

Silverthorn; Human Physiology An Integrated approach

Muscloskeletal module Faculty of Medicine Universitas Indonesia December 2007*Metabolism for muscle contraction

Energy for ContractionVander, Sherman, Luciano's Human Physiology: The Mechanisms of Body Function, 9/e

Nelson, D. L., and M. M. Cox. 2000. Lehninger principles of biochemistry, 3rd ed., p. 604. Worth Publishers, New York.Metabolic Pathways

Muscloskeletal module Faculty of Medicine Universitas Indonesia December 2007*Kind of exercisefor weight control?

Muscloskeletal module Faculty of Medicine Universitas Indonesia December 2007*Kind of exercisefor building muscle?

Copyright 2001-2004, E.C. Niederhoffer. All Rights Reserved.

Molecular Model of Sarcomere

(http://cellbio.annualreviews.org/cgi/content/full/18/1/637)Molecular model of the I-band, A-band, and M-line regions of the sarcomere. Polar thin filaments, containing actin, tropomyosin, troponins C, I, and T, and single molecules of skeletal muscle nebulin, span the I-band and interdigitate with the myosin (thick) filaments in the A-band, where they are capped at their pointed ends by tropomodulin. The myosin heads extend from the core of the thick filaments in the C-zone of the A-band, and are anchored and aligned in the middle of the sarcomere, the M-line. Myosin-binding proteins, including MyBP-C, are associated with the thick filaments and likely play multiple roles in the sarcomere. Single molecules of the giant protein titin extend an entire half sarcomere and are proposed to function as a template for sarcomere assembly. Titin's I-band region contains elastic elements that contribute to the passive force of myofibrils. The M-line proteins myomesin and M-protein, as well as MyBP-C, likely contribute to the linkage of thick filaments with titin, whereas MURF-1 and p94 may function in titin M-line region protein turn-over. Also shown here is Novex-3, a novel mini-titin, that binds to another giant protein, obscurin. Other novel titin isoforms have been found that are not shown here. Components whose binding sites are unknown are shown with question marks.


Molecular Model of Sarcomere

(http://cellbio.annualreviews.org/cgi/content/full/18/1/637)Molecular model of sarcomeric Z-disk components, which form the borders of individual sarcomeres. Opposing thin filaments and individual titin molecules interdigitate at the Z-line and are cross-linked by {alpha}-actinin dimers. The diagram depicts one {alpha}-actinin dimer simultaneously cross-linking two actin filaments and two titin molecules; other configurations are possible. Myopodin and filamin can also bind actin filaments, but it is not clear if they actually cross-link opposing thin filaments, as indicated here. Z-line-associated proteins are shown individually or with known binding partners; the two-dimensional nature of the drawing prevents a full appreciation of how the proteins are arranged with respect to each other. Proteins whose binding sites are unknown are indicated with question marks. It is possible that some Z-line components may be preferentially localized to the Z-line/I-band boundary (e.g., filamin, MLP) or more prominent in the Z-lines of peripheral myofibrils.


Sarcolemma

(http://cellbio.annualreviews.org/cgi/content/full/18/1/637)A schematic model of the cytoskeletal filament linkages at the sarcolemma of striated muscle. Four major cytoskeletal/membrane junctions are depicted: (a) cadherin-based linkages to actin and intermediate filaments (desmin); (b) integrin-based focal adhesions; (c) dystroglycan complex (DGC); and (d) spectrin-based membrane cytoskeleton. The cadherin-based fascia adheren at the intercalated disc couples neighboring cardiomyocytes (through homotypic interactions) and tethers the contractile apparatus to the muscle termini. Desmosomes are a second cadherin-based junction that anchor desmin filaments at the intercalated disc. Connections between intermediate filament proteins and the membrane may occur through a plectin/{alpha}-crystallin complex or via an association with DGC via dystrobrevin. Integrin-based focal adhesions and the DGC act as transmembrane receptors for ECM components (e.g., laminin) and link the extracellular surface with the actin cytoskeleton. Integrins associate with talin, {alpha}-actinin, vinculin and N-RAP to form a strong mechanical link to actin filaments. Integrins could directly interact with {alpha}-actinin and/or other components not depicted here to mediate a connection with actin. The DGC consists of the transmembrane complex {alpha}/-dystroglycan, dystrophin, the sarcoglycans, and other components not depicted here. Spectrin is enriched at costameres, and is an important component of the membrane cytoskeleton. It is linked to the membrane through ankyrin and probably the Na,K-ATPase transmembrane protein. Spectrin may have an additional role in anchoring the contractile apparatus to the membrane though an interaction with MLP. Importantly, all of these linkage complexes can bind to the submembraneous actin ({gamma}-actin) and are probably interlinked through this association as well as other unknown interactions.

Role of calciumMuscle contractiontroponin CGlycogen breakdowncalmodulin (activates phosphorylase b kinase)Citric acid cycle activationpyruvate dehydrogenase complexisocitrate dehydrogenase-ketoglutarate dehydrogenase

Muscloskeletal module Faculty of Medicine Universitas Indonesia December 2007*Muscle fiber type and its role in movement

Glycogen?Myoglobin?Capillary?Diameter?>>>

Glycogen?Myoglobin?Capillary?Diameter?>>

Metabolism? Myosin ATPase activity? Time to develop max tension?Ca++-ATPase activity in SR? Contraction duration?Endurance?Use?WHITE muscle fiber

Muscloskeletal module Faculty of Medicine Universitas Indonesia December 2007*Muscle contraction incontrol of movement

Bear, Connors, Paradiso; Neuroscience. Exploring the Brain Spinal Reflex

Graded Muscle ResponsesGraded muscle responses are:Variations in the degree of muscle contractionRequired for proper control of skeletal movementResponses are graded by:Changing the strength of the stimulus Changing the frequency of stimulation

Copyright 2004 Pearson Education, Inc., publishing as Benjamin CummingsElaine N. Marieb Human Anatomy & Physiology, Sixth Edition

Motor unit stimulationSubthreshold stimulusThreshold stimulusSubmaximal stimulusMaximal stimulusSupramaximal stimulus0MECHANOMYOGRAMNumber of motor unit recruitedtwitch

Skeletal muscle contraction Modul Muskuloskeletal FKUI - December 2007*

Skeletal muscle contraction Modul Muskuloskeletal FKUI - December 2007

ncs & aaj

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