What do muscles do?

What do muscles do?

• A. Elongate and relax
• B. Contract and shorten
• C. Absorb shock
• D. Store minerals

Answer: (B)

Muscles generate movement by actively shortening. When a muscle contracts, its fibers slide past each other and pull on the attached tendon, which in turn pulls on a bone to create a joint motion. This shortening is the essential action that produces movement, and muscles can’t push—only pull. After contracting, a muscle relaxes and returns to its resting length, either by the opposing muscle pulling in the opposite direction or by being stretched passively. Other functions you might think of aren’t the primary job of muscles. Absorbing shock is mainly handled by joint structures, cartilage, and connective tissues, while storing minerals is a duty of bone, not muscle. Muscles do use energy and can generate heat when contracting, but the defining action is contraction and shortening to produce movement.

Muscles generate movement by actively shortening. When a muscle contracts, its fibers slide past each other and pull on the attached tendon, which in turn pulls on a bone to create a joint motion. This shortening is the essential action that produces movement, and muscles can’t push—only pull. After contracting, a muscle relaxes and returns to its resting length, either by the opposing muscle pulling in the opposite direction or by being stretched passively.

Other functions you might think of aren’t the primary job of muscles. Absorbing shock is mainly handled by joint structures, cartilage, and connective tissues, while storing minerals is a duty of bone, not muscle. Muscles do use energy and can generate heat when contracting, but the defining action is contraction and shortening to produce movement.