In an ECG, the P wave is representative of:
A. Conduction through the AV node.
B. Atrial contraction.
C. Ventricular depolarization.
D. Sinus node discharge.
Answer: B. Atrial contraction.
The P wave is the first waveform of the ECG and represents the depolarization (contraction) if the atria. The QRS complex is the second waveform and corresponds to the depolarization (contraction) of the ventricles and the main contraction of the heart. The T wave is the third waveform and represents the repolarization (relaxation) of the ventricles.
You might also like to view...
In the two-lead method of axis determination, a negative deflection of the QRS in Lead I and a positive QRS deflection in Lead aVF indicate:
A) normal axis B) left axis deviation C) right axis deviation D) extreme right axis deviation
Which laboratory specimens must be treated with standard (universal) precautions?
a. Only those labeled with a biohazard sticker b. Only those from patients known to have human immunodeficiency virus (HIV) or hepatitis c. All human blood and body fluids d. All specimens submitted for bacterial culture