Which statement best describes differences between cardiac and skeletal myocytes?

Which statement best describes differences between cardiac and skeletal myocytes?

• A. Skeletal muscles are multinucleated; cardiac are single-nucleated.
• B. Cardiac myocytes do not connect to neighboring cells; skeletal muscles do.
• C. Cardiac myocytes are typically single-nucleated and connected via intercalated discs; skeletal muscles are multinucleated.
• D. Cardiac and skeletal myocytes have identical nuclei counts and connections.

Answer: (C)

The key difference here is how heart muscle cells are organized and connected compared with skeletal muscle fibers. Cardiac myocytes are typically single-nucleated and are physically linked to their neighbors by intercalated discs. Those discs contain gap junctions for electrical coupling and desmosomes for strong mechanical adhesion, which allows the heart to contract as a synchronized unit. Skeletal muscle fibers, on the other hand, are formed by the fusion of many precursor cells, resulting in multinucleated fibers that function more independently and do not form intercalated discs between fibers. This combination—single nucleus with intercellular connections in cardiac tissue versus multinucleated, individually innervated fibers in skeletal tissue—best describes the differences. The other statements either omit the crucial connection aspect or misstate the presence of intercellular connections in the heart, or claim both nuclei counts and connections are identical, which is not accurate.

The key difference here is how heart muscle cells are organized and connected compared with skeletal muscle fibers. Cardiac myocytes are typically single-nucleated and are physically linked to their neighbors by intercalated discs. Those discs contain gap junctions for electrical coupling and desmosomes for strong mechanical adhesion, which allows the heart to contract as a synchronized unit. Skeletal muscle fibers, on the other hand, are formed by the fusion of many precursor cells, resulting in multinucleated fibers that function more independently and do not form intercalated discs between fibers. This combination—single nucleus with intercellular connections in cardiac tissue versus multinucleated, individually innervated fibers in skeletal tissue—best describes the differences.

The other statements either omit the crucial connection aspect or misstate the presence of intercellular connections in the heart, or claim both nuclei counts and connections are identical, which is not accurate.