A THIN FILAMENT oun Troponin complex to troponin IT Tnc Tnl Actin Tropomyosin Myosin binding site B MYOSIN MOLECULE Heads of myosin heavy chain(S,) light chain Alkali light chain ge region of heavy chains Tail region of heavy chains C INTERACTION OF THIN AND THICK FILAMENTS tin(thin Structure of thin and thick filaments Myosin( thick Myosin head boun filament) to actin filament at myosin binding site
Structure of thin and thick filaments
Ttin肌联蛋白 Muscle sarcomere an A-band N Z-disk ig domains ePEK● ● fniii don
Titin肌联蛋白
Sarcotubular system (1) Transverse Tubule横管 (2) Longitudina| Tubule纵管 Sarcoplasmic reticulum肌浆网 Structure of a muscle Fiber Nucleus a band z disc Mitochondria into Sarcoplasmic transverse reticulum tubules Triad Terminal cisternae Transverse tubule Sarcolemma Sarcoplasm Myofibrils
Sarcotubular system (1) Transverse Tubule横管 (2) Longitudinal Tubule纵管 Sarcoplasmic reticulum肌浆网
Copyright o The McGraw-Hill Companies, Inc. Permission required for reproduction or display a) Relaxed H zone Contraction A band (shortening) myosin binds to actin, and slides it, pulling the Z-lines closer a band i I band I H zone unchanged reduced .i reduced together, and (b) Shortened reducing the width of the -bands Note that filament lengths have not Z line changed Z line Z line
Contraction (shortening): myosin binds to actin, and slides it, pulling the Z-lines closer together, and reducing the width of the I-bands. Note that filament lengths have not changed
Copyright o The McGraw-Hill Companies, Inc. Permission required for reproduction or display Z line Cross-bridge Z line movement Thin filament Thick filament Contraction myosIn' s cross- bridges(横桥) bind to actin; the crossbridges then flex to slide actin
Contraction: myosin’s cross-bridges（横桥） bind to actin; the crossbridges then flex to slide actin