M line
The thin filaments at either end of the sarcomere are attached to interconnecting filaments called Z-lines or Z-discs. These structures help anchor and align the thin filaments during muscle contraction.
Structures that help to anchor the thick and thin filaments in place include the Z-discs (also called Z-lines or Z-bands) in skeletal muscle and the dense bodies in smooth muscle. These structures provide attachment points for the filaments and help maintain the organization and alignment of the muscle proteins during contraction.
Interactions between actin and myosin filaments of the sarcomere are responsible for muscle contractions. The I bands contain only thin (actin) filaments, whereas the A bands contain thick (myosin) filaments.
This area is the A band of a sarcomere, which contains both thick myosin filaments and thin actin filaments. The overlapping of these filaments is essential for muscle contraction to occur through the sliding filament mechanism.
The H band is located at the center of the A band in the sarcomere and is where only thick filaments (myosin) are present, with no overlap with thin filaments (actin). It appears lighter under a microscope due to the organization of filaments. This region shortens during muscle contraction as the myosin filaments slide past the actin filaments towards the M line.
No active force can be generated.
There more thin filaments than thick filaments in smooth muscle. The ratio is of the thin to thick filaments in the smooth muscle is approximately 15:1.
I believe the Z-lines anchor the Thin filaments
thick filaments and thin filaments
The thin filaments are actin, and the thick filaments are myosin. The filaments run parrel to one another along the length of the sarcomere.The dark bands that occur in the middle of the sarcomere are regions where the thick filaments and thin filaments overlap.
The thin filaments at either end of the sarcomere are attached to interconnecting filaments called Z-lines or Z-discs. These structures help anchor and align the thin filaments during muscle contraction.
Structures that help to anchor the thick and thin filaments in place include the Z-discs (also called Z-lines or Z-bands) in skeletal muscle and the dense bodies in smooth muscle. These structures provide attachment points for the filaments and help maintain the organization and alignment of the muscle proteins during contraction.
Interactions between actin and myosin filaments of the sarcomere are responsible for muscle contractions. The I bands contain only thin (actin) filaments, whereas the A bands contain thick (myosin) filaments.
Myosin
Thin filaments
The end of a sarcomere is marked by Z-lines, which serve as attachment points for actin filaments. The Z-lines help to define the boundaries of a sarcomere and play a role in muscle contraction by anchoring the thin filaments.
when the Thick filaments pull the thin filaments toward the center of the sarcomere