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The Purkinje fibers transmit the signals more rapidly to stimulate contraction of the ventricles. [2] The conduction system consists of specialized heart muscle cells, situated within the myocardium. [3] There is a skeleton of fibrous tissue that surrounds the conduction system which can be seen on an ECG.
The lateral semicircular duct is about a 30-degree angle from the horizontal plane. The orientations of the ducts cause a different duct to be stimulated by movement of the head in different planes, and more than one duct is stimulated at once if the movement is off those planes. The lateral semicircular duct detects angular acceleration of the ...
In a healthy heart all activities and rests during each individual cardiac cycle, or heartbeat, are initiated and orchestrated by signals of the heart's electrical conduction system, which is the "wiring" of the heart that carries electrical impulses throughout the body of cardiomyocytes, the specialized muscle cells of the heart.
Cardiac excitation-contraction coupling (Cardiac EC coupling) describes the series of events, from the production of an electrical impulse (action potential) to the contraction of muscles in the heart. [1] This process is of vital importance as it allows for the heart to beat in a
Cardiac muscle tissue has autorhythmicity, the unique ability to initiate a cardiac action potential at a fixed rate – spreading the impulse rapidly from cell to cell to trigger the contraction of the entire heart. This autorhythmicity is still modulated by the endocrine and nervous systems. [1]
Within the muscle tissue of animals and humans, contraction and relaxation of the muscle cells is a highly regulated and rhythmic process.In cardiomyocytes, or cardiac muscle cells, muscular contraction takes place due to movement at a structure referred to as the diad, sometimes spelled "dyad."
An increase in sympathetic stimulation to the heart increases contractility and heart rate. An increase in contractility tends to increase stroke volume and thus a secondary increase in preload. An increase in preload results in an increased force of contraction by Starling's law of the heart; this does not require a change in contractility.
Illustration depicting the layers of the heart wall including the innermost endocardium. The endocardium (pl.: endocardia) is the innermost layer of tissue that lines the chambers of the heart. Its cells are embryologically and biologically similar to the endothelial cells that line blood vessels. The endocardium also provides protection to the ...