Biology 2010 Student Edition

Published by Prentice Hall
ISBN 10: 9780133669510
ISBN 13: 978-0-13366-951-0

Chapter 33, Circulatory and Respiratory Systems - Standardized Test Prep - Page 975: 3



Work Step by Step

Option A is incorrect. The heartbeat is generated in the heart tissue itself. Option C is incorrect. The atrioventricular node picks up the impulse from the sinoatrial node and initiates contractions in the ventricles following a short pause. Option D is incorrect. The aorta is the largest artery in the body and does not have anything to do with a heartbeat. Option B is correct. The sinoatrial or SA node is known as the pacemaker. It is a collective of cardiac muscle fibers that initiate the impulse that spreads throughout the atria, causing the atria to contract simultaneously.
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