Texas Cosmetology Operator Written ExamAnatomy and PhysiologyMedium
A client complains of chronic muscle stiffness and reduced flexibility. Which component of the muscular system is primarily responsible for the voluntary contraction and relaxation that allows for movement?
- ASkeletal muscle fibers
- BTendons
- CLigaments
- DCartilage
Show answer & explanationAnswer & explanation
Correct answer: A. Skeletal muscle fibers
Skeletal muscle fibers are the individual cells that make up skeletal muscles. They are directly responsible for voluntary contraction and relaxation, enabling movement and contributing to flexibility. Stiffness and reduced flexibility indicate issues with these fibers' proper function.
Why the other options are wrong
- B. Tendons connect muscle to bone, transmitting force, but are not the contractile units.
- C. Ligaments connect bone to bone, providing joint stability, but are not part of the contractile muscular system.
- D. Cartilage is a connective tissue found in joints, providing cushioning, but is not part of the muscular system's contractile mechanism.
Skeletal Muscle Fibers
Skeletal muscle fibers are elongated, multinucleated cells that constitute skeletal muscles, enabling voluntary movement.
- Responsible for voluntary contractions.
- Contain myofibrils, which are composed of actin and myosin filaments.
- Contract in response to nerve impulses.
- Contribute to posture, movement, and heat generation.
Memory trick: Muscle fibers are the 'engines' of movement.