Stimulation of the parasympathetic nerves to the normal heart can lead to complete inhibition of the SA node for several seconds. During that period:
Correct Answer: There would be fewer P waves than T waves
Description: Ans. C. There would be fewer P waves than T wavesa. When stimulation of the parasympathetic nerves to the normal heart leads to complete inhibition of the SA node for several seconds, nodal escape usually occurs.b. In this situation, pacemaker activity usually is taken over by cells in the AV node or bundle of His.c. QRS complexes are normal because the pacemaker activity is high enough in the conducting system to lead to a normal pattern of ventricular excitation.d. T waves would be normal for the same reason. Because at least one beat begins without atrial excitation, there would be fewer P waves than either QRS complexes or T waves.
Category:
Physiology
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