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Similar to skeletal in terms of striations, contractions. However the following differences apply:

1. Contains more mitochondria.

2. Intercalated disks occur at Z line & provide a strong union between fibers, maintaining cell-to-cell cohesion so that one pull is transmitted along to the next.

3. Gap junctions allow easy spread of excitation.

4. Transverse tubule system is located at the Z lines rather than at the A-I junction.

5. Transverse tubules (T-tubules) are extensions of the cell membrane that penetrate into the centre of skeletal and cardiac muscle cells. With membranes that contain large concentrations of ion channels, transporters, and pumps, T-tubules permit rapid transmission of the action potential into the cell, and also play an important role in regulating cellular calcium concentration.

6. Cardiac contraction is initiated due to influx of Ca rather than release of stored Ca from sarcoplasmic reticulum.


1. Mcminn. (2003). Last's Anatomy. Elsevier Australia. ISBN:0729537528. Read it at Google Books - Find it at Amazon
2. Netter, F. H. (2019). Atlas of human anatomy. Philadelphia, PA: Elsevier.
3. Image: Blausen.com staff (2014). "Medical gallery of Blausen Medical 2014". WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.010. ISSN 2002-4436 [Accessed 17 Nov. 2018].

Ⓒ A. Manickam 2018

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