BILD2_Lecture_3_1_12 - Figure 40.5ca Figure 50.UN01 Sarcomere Muscle Tissue Skeletal muscle Relaxed muscle Nuclei Muscle fiber Sarcomere 100 m

Figure 40.5ca Muscle Tissue Skeletal muscle Nuclei Muscle fiber Sarcomere 100 μ m Smooth muscle Cardiac muscle Nucleus Muscle fibers 25 μ m Nucleus Intercalated disk 50 μ m Figure 50.UN01 Relaxed muscle Contracting muscle Fully contracted muscle Sarcomere Contracted sarcomere Thin filament Thick filament Figure 50.28a-5 Thin filament Myosin head (low- energy configuration) ATP Thick filament Myosin- binding sites Actin High-energy configuration ATP ADP P i ADP Cross-bridge Low-energy configuration Thin filament moves toward center of sarcomere. P i 3 4 2 1 5 P i ADP Figure 50.26 Muscle Bundle of muscle fibers Nuclei Single muscle fiber (cell) Plasma membrane Myofibril Z lines Sarcomere TEM 0.5 μ m Z line M line Sarcomere Z line Thick filaments (myosin) Thin filaments (actin)

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Figure 50.27 Sarcomere 0.5 μ m Z Z M Relaxed muscle Contracting muscle Fully contracted muscle Contracted sarcomere Figure 50.29 Tropomyosin Actin Troponin complex Ca 2 + -binding sites (a) Myosin-binding sites blocked Ca 2 + Myosin- binding site