Given below is the ECG of a normal human. Which one of its components is human, which one of its components…

Given below is the ECG of a normal human. Which one of its components is human, which one of its components is correctly interpreted below.
  1. complex $Q R S-$ One complete pulse
  2. peak T-Initiation of total cardiac contraction
  3. peak $P$ and peak $R$ together-systolic and diastolic blood pressures
  4. peak $P$-Initiation of left atrial contraction only

Solution

A) The QRS complex represents the electrical impulse as it spreads through the ventricles and indicates ventricular depolarization. The QRS complex starts just before ventricular contraction and is the complete pulse.
B) The T wave represents the repolarization of the ventricles. Cardiac relaxation takes place.
C) The P wave represents the depolarization of the atria This happens right before the atria contract and push blood into the ventricles. R represents the peak of the ventricular contraction. Systole corresponds to contraction while diastole corresponds to relaxation. The P and R peaks only signify a systole.
D) T wave signifies the relaxation of the whole heart (diastole).
So the correct answer is 'QRS complex - one complete pulse'.

Asked in: NEET 2011 (Mains)

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