Intercalated disc

Intercalated disc
Cardiac muscle, an intercalated disc can be seen joining cardiomyocytes in magnified section
Details
Latin	Discus intercalaris, discus intercalatus
Identifiers
Code	TH H2.00.05.2.02006
TA
TH	{{#property:P1694}}
TE	{{#property:P1693}}
FMA	{{#property:P1402}}
Anatomical terminology [[[d:|edit on Wikidata]]]

Intercalated discs are microscopic identifying features of cardiac muscle. Cardiac muscle consists of individual heart muscle cells (cardiomyocytes) connected by intercalated discs to work as a single functional organ or syncytium. By contrast, skeletal muscle consists of multinucleated muscle fibers and exhibit no intercalated discs. Intercalated discs support synchronised contraction of cardiac tissue. They occur at the Z line of the sarcomere and can be visualized easily when observing a longitudinal section of the tissue.

Three types of cell junction make up an intercalated disc — fascia adherens, desmosomes and gap junctions.

• Fascia adherens are anchoring sites for actin, and connect to the closest sarcomere.
• Desmosomes stop separation during contraction by binding intermediate filaments, joining the cells together. Desmosomes are also known as macula adherens.
• Gap junctions allow action potentials to spread between cardiac cells by permitting the passage of ions between cells, producing depolarization of the heart muscle.

Molecular, biological, and comprehensive studies have shown that intercalated discs consist for the most part of mixed type adherens junctions, termed composite junctions or areae compositae (singular area composita). These represent an amalgamation of typical desmosomal and fascia adherens proteins (in contrast to various epithelia). Thus cardiomyocyte adherens junctions differ from epithelial adherens junctions and desmosomes.

External links

• Histology image: 22502loa – Histology Learning System at Boston University — "Ultrastructure of the Cell: cardiac muscle, intercalated disk "