Answered: Your grandfather was told that his SA…

Human Anatomy & Physiology (11th Edition)

11th Edition

ISBN:9780134580999

Author:Elaine N. Marieb, Katja N. Hoehn

Publisher:Elaine N. Marieb, Katja N. Hoehn

Chapter1: The Human Body: An Orientation

Section: Chapter Questions

Problem 1RQ: The correct sequence of levels forming the structural hierarchy is A. (a) organ, organ system,...

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Question

Your grandfather was told that his SA node (pacemaker) had stopped functioning. Explain how his heart is still beating at a rate of 40-50 times per minute. Are the atria still being stimulated to contract, and what area of the heart is stimulating them?

Expert Solution

Step 1

The sinoatrial node is a smaller body of cells present in the right atrium and is composed of pacemaker cells that are principal in generating action potential, a type of electrical impulse which is extremely important in employing contraction across the chambers of the heart. This action is important in setting the sinus rhythm (heart’s rhythm) which plays a crucial role in the functioning of healthy hearts. This is the reason why the sinoatrial node is referred to as the natural pacemaker of the heart.