Which intercellular junctions are present at cardiac intercalated discs to provide mechanical and electrical coupling?

• A. Desmosomes and gap junctions
• B. Tight junctions
• C. Hemidesmosomes
• D. Adherens junctions

Answer: (A)

Cardiac intercalated discs coordinate heart muscle cells by two complementary junctions: desmosomes and gap junctions. Desmosomes provide mechanical strength by linking intermediate filaments of adjacent cells, so the tissue can withstand the strong forces of contraction. Gap junctions create direct cytoplasmic channels between neighboring cells, allowing ions and small molecules to pass and enabling the rapid spread of action potentials for synchronized beating. While adherens junctions exist in these regions and tight junctions are not a feature of cardiac intercalated discs, the combination of mechanical attachment (desmosomes) and electrical communication (gap junctions) best explains how cardiomyocytes stay connected and beat in unison.