When there is no measurable activity in the brain and the brainstem, this is called brain death. In a person who has been declared brain dead, removal of breathing devices will result in cessation of breathing and eventual heart failure. Brain death is considered irreversible.
The functional unit of a skeletal muscle is called a sarcomere. Hole's Anatomy 12th edition, pg 287 states: Muscle fibers, and in a way muscles themselves, are basically collections of sarcomeres, discussed later in this chapter as the functional units of muscle contraction.. sarcomere. Tina Wright.
Myofibrils are assembled of repeated structures called sarcomeres â the smallest functional unit of muscle fiber. Each sarcomere is formed of actin (called thin) and myosin (called thick) filaments arranged in a precise order and of protein complexes which support the filament structures.