This simple sentence comprised Section 1 of the Equal Rights Amendment (ERA), which was first proposed in Congress by the National Women's Party in 1923.
Muscle fibers are in turn composed of myofibrils. The myofibrils are composed of actin and myosin filaments, repeated in units called sarcomeres, which are the basic functional units of the muscle fiber.
Skeletal muscles are composed of striated subunits called sarcomeres, which are composed of the myofilaments actin and myosin. Illustrate the structure of a skeletal muscle fiber. 1  Muscles are composed of long bundles of myocytes or muscle fibers.  Myocytes contain thousands of myofibrils.