What is the function of gap junctions in cardiac muscle?

What is the function of gap junctions in cardiac muscle?

• A. They mechanically couple cells for structural support.
• B. They electrically connect adjacent cardiac muscle cells, enabling synchronous contractions.
• C. They store calcium for contraction.
• D. They generate action potentials.

Answer: (B)

Gap junctions provide electrical coupling between cardiac muscle cells, creating direct cytoplasmic connections that allow ions to pass quickly from one cell to the next. This low-resistance pathway lets the depolarizing current spread rapidly across the myocardium, so adjacent cells reach threshold almost together and contract in a coordinated, synchronous rhythm. In the heart, this rapid ion flow is essential for the entire chamber to beat as a unit. Other options don’t fit because gap junctions are channels that enable electrical communication, not mechanical linkages; they don’t store calcium—that’s handled by the sarcoplasmic reticulum; and they don’t generate action potentials themselves—pacemaker cells initiate APs while gap junctions propagate the resulting current to neighboring cells.

Gap junctions provide electrical coupling between cardiac muscle cells, creating direct cytoplasmic connections that allow ions to pass quickly from one cell to the next. This low-resistance pathway lets the depolarizing current spread rapidly across the myocardium, so adjacent cells reach threshold almost together and contract in a coordinated, synchronous rhythm. In the heart, this rapid ion flow is essential for the entire chamber to beat as a unit.

Other options don’t fit because gap junctions are channels that enable electrical communication, not mechanical linkages; they don’t store calcium—that’s handled by the sarcoplasmic reticulum; and they don’t generate action potentials themselves—pacemaker cells initiate APs while gap junctions propagate the resulting current to neighboring cells.