Intercalated disc
(Redirected from
Area composita
)Intercalated disc | |
---|---|
cardiomyocytes in magnified section | |
Details | |
Part of | Cardiac muscle |
Identifiers | |
Latin | discus intercalaris, discus intercalatus |
TH | H2.00.05.2.02006 |
Anatomical terms of microanatomy] |
Intercalated discs or lines of Eberth are microscopic identifying features of
cardiomyocytes) connected by intercalated discs to work as a single functional syncytium. By contrast, skeletal muscle consists of multinucleated muscle fibers and exhibits no intercalated discs. Intercalated discs support synchronized contraction of cardiac tissue in a wave-like pattern so that the heart can work like a pump.[1] They occur at the Z line of the sarcomere
and can be visualized easily when observing a longitudinal section of the tissue.
Structure
Intercalated discs are complex structures that connect adjacent
cardiac muscle cells. The three types of cell junction recognised as making up an intercalated disc are desmosomes, fascia adherens junctions, and gap junctions.[2]
- Fascia adherens are anchoring sites for actin, and connect to the closest sarcomere.[3]
- Desmosomes prevent separation during contraction by binding intermediate filaments, anchoring the cell membrane to the intermediate filament network, joining the cells together. [2][3]
- Gap junctions connect the cytoplasms of neighboring cells electrically allowing cardiac action potentials to spread between cardiac cells by permitting the passage of ions between cells, producing depolarization of the heart muscle.[3][2]
All of these junctions work together as a single unit called the area composita.[2]
Clinical significance
Mutations in the intercalated disc gene are responsible for various
cardiomyopathies that can lead to heart failure.[2]
Ruptured intercalated discs, when seen on histopathology, have two main causes:
- Microtome sectioning, thereby being a visual artifact.[4]
- Forceful myocardial contraction, in turn mainly caused by ventricular fibrillation[5] or electrical injury.[6]
Additional signs indicating forceful myocardial contraction are:[5][6]
- Alternating bundles of hypercontracted myocytes with hyperdistended ones.
- Square-shaped myocardiocyte nuclei.
- Hyperdistended myocardiocytes with detached sarcomeres, and in proximity of hypercontracted myocardiocytes.
-
Square-shaped nuclei, indicating forceful myocardial contraction.
References
- ISBN 978-1-947172-04-3.
- ^ S2CID 52919432.
- ^ ISBN 978-0-12-800883-6, retrieved 2020-12-28
- ISBN 9781498712811.
- ^ ISBN 9781420006438.)
{{cite book}}
: CS1 maint: multiple names: authors list (link - ^ S2CID 24759863.
External links
- Histology image: 22502loa – Histology Learning System at Boston University — "Ultrastructure of the Cell: cardiac muscle, intercalated disk "