HUMAN PHYSIOLOGY
BODY FLUIDS AND CIRCULATION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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rate of breathing
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cardiac output
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heart beat rate
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stroke volume
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Detailed explanation-1: -Thus, the correct answer is ‘By counting the number of QRS complexes one can determine the pulse rate.
Detailed explanation-2: -By counting the number of QRS complexes and multiplying by six, the number per minute can be calculated-because 10 seconds times six equals 60 seconds, or 1 minute. This is a better method when the QRS complexes are irregular, as during atrial fibrillation, in which case the RR intervals may vary from beat to beat.
Detailed explanation-3: -A simple, quick technique is to find a QRS complex that falls on a major vertical grid-line (1), then count the number of large squares to the next QRS complex (2). Dividing this number into 300 gives you the heart rate.
Detailed explanation-4: -QRS complex corresponds to the ventricular systole of cardiac cycle. Heart rate is the number of cardiac cycles per minute. Counting the number of QRS complexes appearing on the ECG recording corresponding to the duration of one minute, one can easily ascertain the number of heart beats.
Detailed explanation-5: -The heart rate is equal to the number of QRS complexes in the ECG in one minute. The normal duration (interval) of the QRS complex is between 0.08 and 0.10 seconds.