muscle draft

Muscle is the body’s motor because it converts chemical energy into mechanical energy. This means that the ATP that is synthesized through reactions in the body are used as energy to drive mechanical force of muscles and movement. Within skeletal muscle, there are muscle fascicles containing muscle fibers that generate movement. The muscle fibers are cells that have their own plasma membrane as well as multiple nuclei. The muscle fibers are separated by the endomysium while the muscle fascicles are separated by the perimysium tissue. It is important to know that the skeletal muscle is connected to bone by collagen fibers in the epimysium, endomysium and perimysium interwoven with collagen fibers in the periosteum and bone tissue. These connections are usually made are the origin of the muscle. Muscles contract and generate movement by cross bridge cycles of the thick and thin filaments. The thick filament has motor proteins called myosin that grab onto the thin filament and drag them closer together. This shortening is the muscle contraction. The thin filaments are composed of mostly actin and regulatory proteins: tropomyosin and troponin. Although these names sound similar, they perform very different functions which will be summarized in another class period. The signal for the contraction of the muscle is the calcium ion.