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Cardiac muscle (also called heart muscle or myocardium) is one of three types of vertebrate muscle tissues, the others being skeletal muscle and smooth muscle. It is an involuntary, striated muscle that constitutes the main tissue of the wall of the heart .
Intercalated discs or lines of Eberth 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 syncytium. By contrast, skeletal muscle consists of multinucleated muscle
However, cardiac muscle cells contain a diad, which is a linking of only one sarcoplasmic reticulum with its respective t-tubule. Another notable distinction between all muscle cells and cardiac muscle cells is the presence of intercalated discs. These tight connections between the cardiomyocytes allows for the accelerated sending of action ...
Striated muscle tissue is a muscle tissue that features repeating functional units called sarcomeres. Under the microscope, sarcomeres are visible along muscle fibers, giving a striated appearance to the tissue. The two types of striated muscle are skeletal muscle, and cardiac muscle.
It requires cutting out a piece of cardiac muscle to look at the sarcomeres under a microscope. It is currently not possible to directly measure preload in the beating heart of a living animal. Preload is estimated from end-diastolic ventricular pressure and is measured in millimeters of mercury (mmHg).
This protein is found as a pentamer and is a major substrate for the cAMP-dependent protein kinase in cardiac muscle. In the unphosphorylated state, phospholamban is an inhibitor of cardiac muscle sarcoplasmic reticulum Ca 2+ -ATPase ( SERCA2 ) [ 7 ] which transports calcium from cytosol into the sarcoplasmic reticulum .
Although earlier changes can be discerned using electron microscopy, one of the earliest changes under a normal microscope are so-called wavy fibers. [23] Subsequently, the myocyte cytoplasm becomes more eosinophilic (pink) and the cells lose their transversal striations, with typical changes and eventually loss of the cell nucleus . [ 24 ]
The name of the histopathologic finding comes from the appearance under the microscope; contraction bands are thick intensely eosinophilic staining bands (typically 4-5 micrometres wide) that span the short axis of the myocyte. They can be thought of extra thick striae, typical of cardiac muscle and striated muscle.