SCIE 22273 Chapter Notes - Chapter 13: Electrical Conduction System Of The Heart, Purkinje Fibers, Interventricular Septum

• School: Sheridan College
• Department: Faculty of Applied Health and Community Studies
• Course: SCIE 22273
• Professor: Tara Hayes

Document Summary

Throughout the myocardium are specialized cardiac muscle tissue that initiate and distribute impulses. A key portion called the sa node (sinoatrial node) is located just beneath the epicardium in the right atrium near the opening of the superior vena cava. Sa node activity is rhythmic with 70-80 bpm in an adult. Sa is also known as the pacemaker because it generates the heart"s rhythmic actions. Av node (atrioventricular node) is located in inferior part of septum that separates atria. The junctional fibers that conduct impulse into av node have small diameters because small fibers conduct impulses slowly. Therefore, impulse gets delayed as it moves towards av node. This allows time for atria to contract completely emptying all the blood intro ventricles before they contract. Once cardiac impulse reaches distal ends of av node, it passes into group of fibers that make up the av bundle. These branches give rise to purkinje fibers. Av bundle and purkinje fibers conduct impulses rapidly.