1) microstructure of skeletal muscle fiber O long cylindrical 10-100um in diameter, 1-40mm long 2 multinucleate, nuclei are ovoid distributed under sarcolemma 8 filled with long itudinal parallel-arranged myofibrils
1) microstructure of skeletal muscle fiber ① long cylindrical 10-100um in diameter,1-40mm long ② multinucleate, nuclei are ovoid, distributed under sarcolemma ③ filled with longitudinal parallel-arranged myofibrils
myofibril 1-2um in diameter e cross striation: light band -l(isotropic) band dark band-A(anisotropic)band a band: M-line. H-band i band: Z-line
myofibril: 1-2um in diameter cross striation: light band -I(isotropic) band, dark band- A(anisotropic) band --A band: M-line, H-band --I band: Z-line
教额 sacromere: a/ segment of myfibri extending from one Z line to next Z line, which is composed of 1/2 I band, A band and 1/2 band. is the smallest structural and functional unit of myofibril
* sacromere: a segment of myfibril extending from one Z line to next Z line, which is composed of 1/2 I band, A band and 1/2 I band ,is the smallest structural and functional unit of myofibril
2 Ultrastructure of myofiber ∵··· ① myofibril: composed of thick myofilament: 1.5 um long, 15nm in diameter ● composed of myosin: rob: in bundles 肌动蛋白单体原肌球蛋白 肌原蛋白 In T -head 细肌丝 cross bridge binding (3 site(ATPase activity) 肌球蛋白杆 (横桥)
2) Ultrastructure of myofiber ① myofibril: composed of ---thick myofilament: 1.5 um long, 15nm in diameter composed of myosin: -rob: in bundles -head: cross bridge- binding site(ATPase activity)