Final answer:
The arrangement of organelles in cardiac muscle cells includes fewer T tubules that are located only at Z discs, a sarcoplasmic reticulum storing less calcium, and abundant mitochondria due to the heart's energy needs. Cardiac muscle cells usually have one central nucleus but may contain more, contrasting with skeletal muscle characteristics.
Step-by-step explanation:
Differences in Organelle Arrangement in Cardiac Muscle vs. VSM
The organelle arrangement in cardiac (cardiomyocytes) and skeletal muscle (VSM) cells exhibits both similarities and differences. Both muscle types are striated, demonstrating a pattern of dark A bands and light I bands. However, the arrangement is due to the organized sarcomeres, which is distinct between these muscles. An important distinction concerns the presence and distribution of T (transverse) tubules; in cardiac muscle cells, T tubules are found only at the Z discs, whereas in skeletal muscle cells, they occur at the A-I junctions. This leads to fewer T tubules in cardiac muscle. Additionally, the sarcoplasmic reticulum in cardiac muscle stores less calcium, requiring the cells to depend more on external calcium, resulting in a slower contraction onset. Lastly, cardiomyocytes tend to have a single central nucleus, although some may have multiple nuclei, and they contain more mitochondria due to the high energy demands of the heart.