Chapter 2 Quiz - Electrophysiology

The PR segment is a flat line located between the QRS complex and the T wave.

False - PR segment = flat line between the P wave and the QRS complex

Cardiac cell stimulus during the absolute refractory period often results in very fast, dangerous rhythms.

False -During the absolute refractory period, the cell cannot accept another impulse because it's still dealing with last one. Absolutely no stimulus, no matter how strong, will result in another depolarization.

The ST segment is a flat line from which the waves and complexes take off.

False -PR segment: -ST segment:

The normal pacemaker of the heart is the AV node

False -The normal pacemaker of the heart is the Sinus Node

The cardiac cell, at rest, has a transmembrane potential of +20 mV.

False -the Transmembrane potential (the electrical charge at the cell membrane) is -90 millivolts -Essentially, nothing is happening in phase 4 (phase 4 is a flat line. Flat line indicates electrical silence)

During the absolute refractory period, only a strong stimulus can result in depolarizaiton.

False Refractory Periods: 1) Absolute: The cell cannot accept another impulse because its still dealing with the last one. Absolute no stimulus, no matter how strong, will result in another depolarization. 2) Relative: A strong stimulus will result in depolarization. 3) Supernormal period: Even a weak stimulus will cause depolarization.

The polarized cardiac cell is electrically negative.

True

If the PR interval is 0.10 secs, the time it takes for the impulse to travel from the atrium down to the ventricle is abnormal.

True -Normal PR interval is 0.12 to 0.20 seconds. It's measured from the beginning of the P wave to the beginning of the QRS and includes the P wave and the PR segment. The P wave itself should measure no more than 0.10 seconds wide and 2.5 mm high

The P wave represents atrial depolarization.

True -P wave - atrial depolarization *Ta wave - Atrial repolarization *QRS complex = ventricular depolarization *T wave = ventricular repolarization * U wave = Late ventricular repolarization and is usually not seen

The PR interval measures the time it takes for the impulse to travel from the atrium down to the ventricle.

True -PR interval measures the time it takes for the impulse to get from the atria to the ventricles. Normal PR interval is 0.12 to 0.20 seconds. It's measured from the beginning of the P wave to the beginning of the qRS and includes the P wave and the PR segment.

The normal rate of the sinus node is 60 to 100 beats per minute.

True -Sinus node: 60 to 100 beats per minute -AV junction: 40 to 60 beats per minute -Ventricle: 20 to 40 beats per minute

The baseline is a flat line from which the waves and complexes take off.

True -The baseline or Isoelectric line is the flat line between the T wave of one beat and the P wave of the next beat