The "M" line.
The striation that consists of overlapping thick filaments with the M line in the center is called the A band. The A band represents the region of the sarcomere where thick filaments (myosin) overlap with thin filaments (actin), and the M line is the midpoint that anchors the thick filaments. This arrangement is crucial for muscle contraction, as it allows for the interaction between the thick and thin filaments.
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.
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.
Flexing of the cross bridge (power stroke)
Yes, myosin filaments are found in the A band of a sarcomere, which is a structural unit of a muscle cell. The A band contains both myosin and actin filaments and is located in the middle of the sarcomere.
Myosin
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.
thick filaments and thin filaments
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.
The area of the sarcomere containing the thick filaments is known as the A band. It appears dark under a microscope due to the overlapping thick filaments. The A band also includes some thin filaments at its edges where they overlap with the thick filaments.
In thick filaments
The three different types of myofilaments are thick filaments, thin filaments, and elastic filaments. Thick filaments are composed of myosin protein, thin filaments are primarily made of actin protein, and elastic filaments (also known as titin) provide elasticity and stability to the sarcomere.