Final answer:
Electrical signals in cardiomyocytes pass through gap junctions, which are part of the intercalated discs, enabling synchronized heart contractions.
Step-by-step explanation:
Electrical signals pass between cardiomyocytes through the gap junctions. Gap junctions form channels between adjacent cardiac muscle fibers, allowing for the depolarizing current produced by cations to flow from one cardiac muscle cell to the next. This process is known as electric coupling, and in cardiac muscle, it enables the fast transmission of action potentials and the coordinated contraction of the heart. The entire heart contracts in a synchronized manner, acting as a functional unit of contraction termed a syncytium.
The intercalated discs are critical structures found at the junction of adjacent cardiac muscle cells and are responsible for supporting the synchronized contraction of the muscle. Aside from gap junctions, intercalated discs also consist of desmosomes which act like strong welds anchoring the cells together during the stress of contractions. However, it is the gap junctions that are particularly significant for the passage of electrical signals, and not the desmosomes, tight junctions, or hemidesmosomes.