PATHOLOGY MCQ
HEART
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Because the SA node initiates 1 cardiac cycle, it fires at a rate of
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40-60 bpm
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80-90 bpm
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60-80 bpm
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60-100 bpm
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Explanation:
Detailed explanation-1: -The SA node fires at a normal rate of 60–100 beats per minute (bpm), and causes depolarization in atrial muscle tissue and subsequent atrial contraction.
Detailed explanation-2: -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.
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