MEDICAL
HEART AND PERICARDIUM
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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AV node
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Premature Atrial Contractions
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Either A or B
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None of the above
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Detailed explanation-1: -Myocardial conduction cells initiate and propagate the action potential (the electrical impulse) that travels throughout the heart and triggers the contractions that propel the blood.
Detailed explanation-2: -While it is the norm for nerve cells that they require a stimulus to fire, the SA node can be considered to be “self-firing". It repetitively goes through a depolarizing discharge and then repolarizes to fire again. This action is analogous to a relaxation oscillator in electronics.
Detailed explanation-3: -The SA node starts the sequence by causing the atrial muscles to contract. That’s why doctors sometimes call it the anatomical pacemaker. Next, the signal travels to the AV node, through the bundle of HIS, down the bundle branches, and through the Purkinje fibers, causing the ventricles to contract.