Plasma membrane of a muscle cell. Surrounds muscle fiber and regulates entry and exit of materials
cytoplasm of a muscle fiber
Smooth endoplasmic reticulum in a muscle fiber. Stores CALCIUM ions needed for muscle contraction
Narrow, tubular extensions of the sarcolemma into the sarcoplasm, contacting the terminal cisternae; wrapped around myofibrils Quickly transports a muscle impulse from the sarcolemma throughout the entire muscle fiber
Organized bundles of myofilaments; cylindrical structures as long as the muscle fiber itself.