What term is used to describe the elongated rod-shaped cells in muscles?

The term "fibres" is used to describe elongated rod-shaped cells in muscles, specifically referring to muscle fibers. Muscle fibers are the basic structural and functional units of muscle tissue, and they have a unique elongated shape that enables them to contract and produce movement. These fibers are primarily composed of proteins such as actin and myosin, which play crucial roles in muscle contraction.

Muscle fibers can be classified into different types, such as slow-twitch and fast-twitch, depending on their characteristics and functions. The elongated shape of these fibers allows for efficient force generation and makes them well-suited to facilitate the pulling action necessary for movement.

Other terms in the choices do not accurately represent the specific structure of elongated muscle cells. "Cells" is a more general term that could apply to any cell type, while "tissues" refers to a group of similar cells working together and does not specifically describe the individual muscle fibers. "Mitochondria" are organelles within cells responsible for energy production and are not a descriptor of muscle structure. Thus, "fibres" is the most accurate term to describe these elongated rod-shaped cells in the context of muscle anatomy.