(a)While studying the structure of a striated muscle, you come actoss following terms:
(i) Membrane of Krause (Z band), (ii) Henson's line (H Zone), (iii) Sarcomere. Explain these terms.
(b) Name the proteins that comprise primary myofilaments and secondary myofilaments.

Explanation

(a)(i) Membrane of Krause (Z band). Each I-band is crossed through its centre by a dark membrane, the membrane of Krause of Z-band.
(ii) Henson's line (H Zone). Each A band has at its middle a light zone termed Henson's line or H zone.
(iii) Sarcomere. The part of the myofibril between two successive Z lines functions as a contractile unit termed the sarcomere.
(b) Primary myofilaments are composed of myosin and bear cross-bridges of meromyosin. Secondary myofilaments are composed of actin, tropomyosin and troponin.