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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 .
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 ...
[6] Cardiac muscle cells form the cardiac muscle in the walls of the heart chambers, and have a single central nucleus. [7] Cardiac muscle cells are joined to neighboring cells by intercalated discs, and when joined in a visible unit they are described as a cardiac muscle fiber. [8]
In the histology of skeletal muscle, a triad is the structure formed by a T tubule with a sarcoplasmic reticulum (SR) known as the terminal cisterna on either side. [1] Each skeletal muscle fiber has many thousands of triads, visible in muscle fibers that have been sectioned longitudinally. (This property holds because T tubules run ...
The heart is a muscular organ situated in the mediastinum.It consists of four chambers, four valves, two main arteries (the coronary arteries), and the conduction system. The left and right sides of the heart have different functions: the right side receives de-oxygenated blood through the superior and inferior venae cavae and pumps blood to the lungs through the pulmonary artery, and the left ...
T-tubules (transverse tubules) are extensions of the cell membrane that penetrate into the center 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.
Dissection in right anterior oblique view of the right atrium shows the borders of the triangle of Koch. In this view, the putative fast and slow pathways toward the AV node (dotted shape in yellow) are depicted.
As with skeletal muscles the heart can increase in size and efficiency with exercise. [1] Thus endurance athletes such as marathon runners may have a heart that has hypertrophied by up to 40%. [ 3 ] : 1063–64 The difference between maximum and minimum cardiac outputs is known as the cardiac reserve and this measures the residual capacity to ...