What is the function of muscle fibers?

• A. Contract or pull
• B. Transmit nerve impulses
• C. Store calcium
• D. Absorb nutrients

Answer: (A)

Muscle fibers are built to shorten and pull on tendons, converting chemical energy into mechanical work to move bones, maintain posture, and generate heat. When a nerve signal reaches a muscle, calcium is released inside the fiber, enabling actin and myosin filaments to slide past each other and shorten the fiber. This contraction is the essence of the fiber’s function. Note that transmitting nerve impulses is done by nerves, not by the muscle fibers themselves, and while calcium is essential for contraction and is stored in the muscle’s sarcoplasmic reticulum, storage isn’t the primary function of the fibers. Similarly, absorbing nutrients is not a role of muscle fibers.