Histological structure of the heart:
The heart is composed of three concentric layers: endocardium, myocardium and Epicardium. Endocardium consists of a basal endothelium located in a membrane that is continuous with the endothelial layer, composed of collagen fibers, reticulin fibers, elastic fibers, rare cells conjuctive and many sensitive nerve endings.
Myocardium consists of cardiac muscle bundles,circular oriented atria wall, and oblique fiber-coil in ventricles,in the heart wall. In addition to myocardial cells, there are specialized cells in the generation and conduction of the impulses.
Epicardium is a thin membrane covering the cardiac surface and is the visceral foil ofthe pericardial sac. Between pericardial foils,it is found pericardial cavity, with a thin blade of fluid, which promotes slipping during heart activity.
Properties of heart muscle
Myocardium which is structurally a striated muscle has common property as striated muscles , but also a number of characteristic properties.
-Heart-rhythm is property to contract sequentially as a result of contractions generated by pulse of sinoatrial node. These pulses are the result of metabolic changes that occur in excito conductor system.
-Conductivity is the property of Myocardium, in particular of node tissue, to drive shrinkage waves generated by the sinoatrial node in the whole heart.
-Excitability is the property of myocardium to respond by a contraction to appropriate stimulus.
-Myocardial contractility is property-to contract when stimulated appropriately. Cardiac contractions are called systolics and reliefs, diastole.
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