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CONDUCTING SYSTEM OF HEART.pptx
- 1. CONDUCTING SYSTEM OFHEART Prepared by Mr . RAJEEV THIRUMAL .,M . Pharm. Assistant Professor, Dept of Pharamacology , Kasthooribha Gandhi Pharmacy College, Namakkal ,Tamil nadu .
- 2. LAYERS OF HEART •ENDOCARDIUM i. Endothelium ii. Sub-endocardial connective tissue • MYOCARDIUM • PERICARDIUM i. Serous a) Visceral serous pericardium (EPICARDIUM) b) Parietal serous pericardium ii. fibrous
- 3. TYPES OF MYOCARDIALFIBERS 1) Contractile fibers a) Atrial muscle fibers b) Ventricular muscle fibers 2) Non – contractile fibers (modified cardiac muscle fibers) a) Specialized excitatory structure : SA node b) Specialized conductive structure: AV node, Bundle of HIS and Purkinje fibers.
- 4. SINO ATRIAL /SA NODE Pacemaker of mammalian heart • Small strip (1.5 cm length & 0.5 cm wide) of modified cardiac muscle. • Location: superior part of lateral wall of right atrium • Contains Pacemaker or P cells –generate impulse (70-80 impulses / min) • Continuous with atrial muscle fibers and intermodal fibers • Velocity of conduction of impulse is very slow (0.05 meter/sec)
- 5. ATRIOVENTRICULAR /AV NODE •Small diameter & multiple sub-branches fiber(2.2cm length,1cm width & 0.3 cm thickness) • Location: inferior part of medial wall of right atrium • Generate impulse (40-60 impulses / min) • Continuous with atrioventricular fibers • Velocity of conduction of impulse is very slow (0.05 meter/sec)
- 6. INTERNODAL FIBERS • ConnectSA node and AV node 1) Anterior internodal fibers / tract of Bachman 2) Middle internodal fibers / tract of Wenckebach 3) Posterior internodal fibers / tract of Thorel • Location: wall of right atrium • Velocity of conduction of impulse is fast (1 meter/sec)
- 7. BUNDLE OF HIS •Small bundle of fibers (1cm length) • Location: middle part of atrioventricular septum (below the AV node) • At the level of interventricular septum divides into right and left bundle branch. • RBB longer & thinner, innervates right ventricle • LBB bifurcates into anterior &posterior , innervates left ventricle • Generate impulse • Continuous with purkinje fibers • Velocity of conduction of impulse is slow (0.12meter/sec)
- 8. PURKINJE FIBERS • Networkof very small bundle of fibers • Purkinje cell - larger diameter & numerous gap junction (low impedance electrical synapse) • Location: sub-endocardial regions of right and left ventricles • Generate impulse (35-40 impulses / min) • Velocity of conduction of impulse is very fast ( 4 meters/sec)