The heartbeat is initiated by an electrical impulse that originates at the ____________.

Question

Quizplus · Accepted Answer

Just like skeletal and smooth muscle, cardiac muscle must have an electrical signal, or action potential, in order to contract. However, unlike smooth and skeletal muscle, which receive these signals from the brain, the heart possesses the property of autorhythmicity. This means that the heart can contract on its own without the brain telling it to contract. This is possible due to the sinoatrial (SA) node, which can spontaneously initiate an action potential. This action potential is initiated in the right atrium where the SA node is located, and disperse throughout the heart allowing muscle contraction to occur. Interestingly, if the SA node is unable to function properly, a secondary location of pacemaker cells, the atrioventricular (AV) node may take over.
It should be mentioned that although the brain is not required to initiate an electrical impulse, it is involved in modifying heart activity, primarily through the vagus nerve.
Purkinje fibers are involved in relaying the electrical signal however the impulse does not originate there.
You may use the diagram below as a visual reference for the structure of the heart.
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The Heartbeat Is Initiated by an Electrical Impulse That Originates