Chapter 19.4, Problem 4AYLO

Summary Introduction

To discuss:

The excitation of atria, AV node, AV bundle and bundle branches, and sub-endocardial conducting network; changing conduction speeds at different points along this path and why these changes are important; and the correlation of atrial and ventricular systole with the travelling wave of excitation.

Introduction:

The sinoatrial node is termed as the pacemaker of the heart because it initiates the heartbeat. It is the prime nodal center of the heartbeat that triggers firing. Such firing mechanism is done by the specialized cells in the SA node and its membrane potential. In case of the SA node suppression, an alternate heartbeat firing mechanism could be carried by the atrio ventricular (AV) node.