The H-zone in a contracted sarcomere differ from that of a relaxed sarcomere because H-Zone is narrower in contracted sarcomere. In a striated muscle sarcomere is small unit of myofibril. Between two Z line sarcomere is the repeated unit . Sarcomere is the very basic unit that makes up our skeletal muscle.
Answer:
H-zone is shortened in contracted sarcomere and regains its length in relaxed sarcomere
Explanation:
Sarcomere is the unit of striated muscle tissue. Its contraction and relaxation makes the muscle contract or relax. It is present between two Z-lines. Actin filaments anchor on Z-lines. Next to Z-line is the I-band which is a region of only actin filaments. Next to I-band is A-band region where both actin and myosin filaments are present. Within A-band, H-zone is present. H-zone does not have actin filaments and only consists of myosin filaments.
When a sarcomere contracts, the I-band and H-zone shorten which brings the Z-lines closer. Myosin binding sites are also uncovered on actin filaments and cross bridges are formed between them.
