MUSCLE PHYSIOLOGY

Detailed explanation-1: -Myofibrils are composed of long proteins including actin, myosin, and titin, and other proteins that hold them together. These proteins are organized into thick, thin, and elastic myofilaments, which repeat along the length of the myofibril in sections or units of contraction called sarcomeres.

Detailed explanation-2: -A sarcomere is the basic functional unit of any muscle. A group of sarcomere comprises a myofibril within a muscle. The thick filaments in the A band and thin filaments in the I band interact and bond together in order to cause contraction and shortening of the muscle fiber.

Detailed explanation-3: -For an average myofibril comprised of 10 serially aligned sarcomeres at optimal length (10 × 2.4 µm for the rabbit psoas muscle), the total length before activation would be about 24 µm or 24, 000 nm.