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Cardiac muscle

Cardiac muscles are only found in the heart, where it constitutes the bulk of the heart’s walls. Highly coordinated contractions of cardiac muscle pump blood into the vessels of the circulatory system.

Cardiac muscle cells are striated like skeletal muscle cells, but cardiac muscle is not voluntary.

Diagram has three parts labeled a, b and c. Image A shows a schematic diagram of several cardiac muscle cells, with some in cross-section so the internal structure can also be seen. The cells are cylindrical, branching, and uninucleated. The cardiac muscle cells are joined by intercalated discs which contain gap junctions and desmosomes. Image B is a photomicrograph of the cardiac muscle cells. The cardiac muscle tissue appears striated due to the cardiac muscle cells being long and all aligned in the same direction. Cross-cutting the cardiac muscle cells are intercalated discs. These can be seen as vertical lines that cross perpendicular to the elongated cardiac cells. Image C is a schematic diagram showing a close-up of a cardiac cell with horizontal rows of sarcomeres, separated by mitochondria. At the junction between two cardiac cells, there is a winding white stripe called the intercalated disc. This intercalated disc contains desmosomes and gap junctions.

Figure 1. Cardiac Muscle. (a) Cardiac muscle cells have myofibrils composed of myofilaments arranged in sarcomeres, T tubules to transmit the impulse from the sarcolemma to the interior of the cell, numerous mitochondria for energy, and intercalated discs that are found at the junction of different cardiac muscle cells. (b) A photomicrograph of cardiac muscle cells shows the nuclei and intercalated discs. (c) An intercalated disc connects cardiac muscle cells and consists of desmosomes and gap junctions.

Cardiac muscle cells are rectangular shaped cells connected by regions called intercalated discs. Intercalated discs contain gap junctions and desmosomes. The desmosomes prevent adjacent cells from separating during contraction. The gap junctions allow ions to pass from cell to cell, transmitting current across the entire heart.

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References: OpenStax College, Biology. (OpenStax CNX. Mar 13, 2015)

Referred from:

Article
Types of Animal Cells
Article
Autonomic nervous system