Final answer:
Gap junctions and desmosomes function in the coordination and structural integrity of cardiac muscle cells.
Step-by-step explanation:
Gap junctions and desmosomes play important roles in cardiac muscle cells. Gap junctions are channels that allow the flow of depolarizing current from one cardiac muscle cell to the next, facilitating the quick transmission of action potentials and the coordinated contraction of the entire heart. This network of electrically connected cells creates a functional unit of contraction called a syncytium. On the other hand, desmosomes anchor the ends of cardiac muscle fibers together, preventing the cells from pulling apart during contraction.