[Campbell Biology P.1180] Based on the "Other Types of Muscle" section, which of the followin... | Practice Question

Based on the "Other Types of Muscle" section, which of the following statements accurately describes a distinguishing characteristic of vertebrate cardiac muscle?

  • A: Cardiac muscle cells lack striations and have actin and myosin filaments scattered throughout the cytoplasm.
  • B: Unlike skeletal muscle, some cardiac muscle cells can initiate rhythmic depolarization and contraction without nervous system input.
  • C: Cardiac muscle action potentials last up to 20 times shorter than those of skeletal muscle fibers, preventing summation.
  • D: Cardiac muscle is primarily found in the walls of hollow organs like blood vessels and the digestive tract.

Explanation

The text states: 'Unlike the cells of skeletal muscle fibers, some cardiac muscle cells can initiate rhythmic depolarization and contraction without nervous system input.' This highlights the autorhythmicity of cardiac muscle, distinguishing it from skeletal muscle which requires nervous input.