What is a muscle fiber? the myosin that makes up the contractile unit of a muscle cell the connective tissue outer covering of a muscle a group of muscle cells that make up the same muscle group a single cell of a muscle?
The release of calcium ions initiates muscle contractions. ... The contraction of a striated muscle fiber occurs as the sarcomeres, linearly arranged within myofibrils, shorten as myosin heads pull on the actin filaments.
