MICROANATOMY

Detailed explanation-1: -The distance between Z-lines (i.e., sarcomere length) ranges from about 1.6 to 2.2 in human hearts. The sarcomere is composed of thick and thin filaments – myosin and actin, respectively, along with a titin that anchors the myosin to the Z-lines.

Detailed explanation-2: -A sarcomere is defined as the distance between the Z-lines. The Z-lines are pulled closer together during contraction and move further apart during relaxation. The Z-lines are closer during contraction because actin and myosin interaction generates cross-bridges, which slide the myofilaments over each other.

Detailed explanation-3: -The resting sarcomere is about 2.2 mm long.

Detailed explanation-4: -A sarcomere is defined as the segment between two neighbouring Z-lines (or Z-discs). In electron micrographs of cross-striated muscle, the Z-line (from the German “zwischen” meaning between) appears in between the I-bands as a dark line that anchors the actin myofilaments.