Explain the structure of striated muscle tissue
Answers
Explanation:
Histologically noticeable are the spindle shaped nuclei located peripherally. The eosinophilic sarcoplasm (=cytoplasm) comprises almost completely of myofibrils. Along the myofibrils runs the longitudinal (L-) system (=sarcoplasmic reticulum). The sarcolemma (=cell membrane) is surrounded by a basal lamina and deeply invaginates into the sarcoplasm forming the transverse (T-) tubules. The bright bands are referred to as isotropic (I-) bands, the dark bands as anisotropic (A-) bands. In the center of the A-bands runs the M-line where the myosin filaments are anchored. The actin filaments are attached to the Z-line which is found in the middle of the I-bands. The area between two Z-lines makes up a functional unit, the sarcomere. The myosin filaments bind to the actin filaments through cross bridges. The contraction of the muscle results from the ATP-dependent rowing motion of the myosin heads causing a shift of the actin filaments.