Intercalated disc

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An intercalated disc is an undulating double membrane separating adjacent cells in cardiac muscle fibers. Intercalated discs support synchronized contraction of cardiac tissue. They can easily be visualized by a longitudinal section of the tissue.

Three types of membrane junctions exist within an intercalated disc—fascia adherens, macula adherens (aka desmosomes), and gap junctions.

• Fascia adherens are anchoring sites for actin, and connects to the closest sarcomere.

• Macula adherens stop separation during contraction by binding intermediate filaments joining the cells together also called a desmosome.

• Gap junctions allow action potentials to spread between cardiac cells by permitting the passage of ions between cells, producing depolarization of the heart muscle.

When observing cardiac tissue through a microscope, intercalated discs are an identifying feature of cardiac muscle.

[edit] See also

• Gap junction
• Cardiac muscle

[edit] External links

• Intercalated+disc at eMedicine Dictionary
• Histology at BU 22502loa - "Ultrastructure of the Cell: cardiac muscle, intercalated disk "

v • d • e Histology: muscle tissue skeletal muscle/general epimysium, fascicle, perimysium, endomysium, muscle fiber (intrafusal, extrafusal), myofibril sarcomere (a, i, and h bands; z and m lines), myofilaments (thin filament/actin, thick filament/myosin, elastic filament/titin, nebulin), tropomyosin, troponin (T, C, I) costamere (dystrophin, α,β-dystrobrevin, syncoilin, synemin/desmuslin, dysbindin, sarcoglycan, dystroglycan, sarcospan), desmin neuromuscular junction, motor unit, muscle spindle, excitation-contraction coupling, sliding filament mechanism myoblast, satellite cell, sarcoplasm, sarcolemma, sarcoplasmic reticulum, T-tubule cardiac muscle myocardium, intercalated disc, nebulette smooth muscle calmodulin, vascular smooth muscle