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| Control of the Heart Function |
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| The control of the heart function is by a set of muscles and is, therefore, called myogenic. |
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| If the heart is removed from a living mammal and placed in a well oxygenated salt solution maintained at 37oC, the heart continues to function though at a slower rate. |
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| Position of the Sino-atrial and Atrio-ventricular Nodes |
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| There are certain points in the walls of the heart called the nodes. A node is a collection of muscles. There are two major nodes called the sinoatrial node (Sino-atrial ventricular node) and atrioventricular node (atrio ventricular node). Sino-atrial ventricular node is present at the junction of the vena cavae and the right auricle. It is the initiator of the contraction of heart by making the auricles contract. This is the auricular systole. This impulse is generated and spread by the presence of electrochemical gradient. The impulse is carried to atrio ventricular node that is situated almost at the junction of the auricles and the ventricles. It then transmits it to the other nerves of the heart. The atrio ventricular node is connected to a set of modified cardiac fibres called the 'bundle of His'. From the 'bundle of His' arise various other fine fibres that form a network of fibres running all over the ventricles. These fine fibres are called the Purkinje fibres. Thus, the Sino-atrial ventricular node is called the pacemaker. |
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| In case of failure of the pacemaker, it can be replaced by an artificial battery operated pacemaker. |
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