Textbook Question
An experimental toxin makes the refractory period of cardiac muscle cells equal in length to that of skeletal muscle fibers. Predict the consequences of this toxin.
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18. The Heart
Cardiac Action Potentials
Multiple Choice
Which part of the heart's electrical conduction system is responsible for initiating the heartbeat?
A
Bundle of His
B
Purkinje fibers
C
Sinoatrial (SA) node
D
Atrioventricular (AV) node
Verified step by step guidance1
Understand the heart's electrical conduction system, which is responsible for coordinating the heartbeat.
Identify the key components of the conduction system: Sinoatrial (SA) node, Atrioventricular (AV) node, Bundle of His, and Purkinje fibers.
Recognize that the Sinoatrial (SA) node is known as the heart's natural pacemaker.
Learn that the SA node initiates the electrical impulse that starts the heartbeat, causing the atria to contract.
Note that the impulse then travels to the Atrioventricular (AV) node, Bundle of His, and Purkinje fibers to coordinate the contraction of the ventricles.
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