Title: Cardiac muscle - Wikipedia
Headings: Cardiac muscle
Cardiac muscle
From Wikipedia, the free encyclopedia
Contents
Structure
Gross anatomy
Microanatomy
Cardiac muscle cells
T-tubules
Intercalated discs
Fibroblasts
Extracellular matrix
Physiology
Regeneration
Differences between atria and ventricles
Clinical significance
See also
References
External links

Content: The functions of T-tubules include rapidly transmitting electrical impulses known as action potentials from the cell surface to the cell's core, and helping to regulate the concentration of calcium within the cell in a process known as excitation-contraction coupling. Intercalated discs
Main article: Intercalated disc
Intercalated discs are part of the cardiac muscle sarcolemma and they contain gap junctions and desmosomes. The cardiac syncytium is a network of cardiomyocytes connected by intercalated discs that enable the rapid transmission of electrical impulses through the network, enabling the syncytium to act in a coordinated contraction of the myocardium. There is an atrial syncytium and a ventricular syncytium that are connected by cardiac connection fibres. Electrical resistance through intercalated discs is very low, thus allowing free diffusion of ions. The ease of ion movement along cardiac muscle fibers axes is such that action potentials are able to travel from one cardiac muscle cell to the next, facing only slight resistance. Each syncytium obeys the all or none law. Intercalated discs are complex adhering structures that connect the single cardiomyocytes to an electrochemical syncytium (in contrast to the skeletal muscle, which becomes a multicellular syncytium during mammalian embryonic development). The discs are responsible mainly for force transmission during muscle contraction.