Interkalaterade

Interkalaterade, or intercalated discs, are specialized cell junctions that connect neighboring cardiomyocytes in cardiac muscle. They appear as distinct dark lines that run through the tissue and help bind heart cells into a functional syncytium, enabling coordinated contraction.

Structure and components: Intercalated discs comprise a network of junctional complexes. Desmosomes (macula adherens) and fascia adherens provide mechanical adhesion, while gap junctions form low-resistance pathways for ions and small signaling molecules. The gap junctions are largely built from connexin proteins, with connexin-43 being especially prominent in the human heart. The arrangement places these junctions at the ends of cardiomyocytes, facilitating rapid coupling between cells.

Function: The intercalated discs serve dual roles. Mechanically, they anchor cells together so the tissue can withstand the forces of repeated contraction. Electrically, they enable swift propagation of action potentials from cell to cell, ensuring synchronized, rhythmic heartbeats.

Clinical relevance: Alterations in intercalated discs or their components are linked to cardiac diseases. Changes in gap junction density or distribution, particularly involving connexin-43, can disrupt electrical conduction and contribute to arrhythmias. Remodeling of adherens junctions and desmosomes is also observed in certain cardiomyopathies, affecting both mechanical stability and electrical coupling.

Notes: The term reflects histological features of cardiac tissue and is primarily used in studying heart muscle structure and function. Intercalated discs exemplify the close interplay between mechanical and electrical connectivity in the heart.