51) The QRS complex an ECG tracing represents
A) atrial depolarization.
B) : 1200318.
51) The QRS complex on an ECG tracing represents
A) atrial depolarization.
B) atrial repolarization.
C) ventricular depolarization.
D) ventricular repolarization.
E) ventricular contraction.
52) The T wave of an ECG corresponds to
A) atrial depolarization.
B) atrial diastole.
C) ventricular systole.
D) ventricular repolarization.
E) atrial repolarization
53) The property of heart muscle in which it contracts in the absence of neural or hormonal stimulation is called ________.
A) tamponade
B) thrombosis
C) autorhythmicity
D) arrhythmias
E) tetanus
54) A faster-than-normal heart rate is called ________.
A) bradycardia
B) tachycardia
C) tetanus
D) myocardial infarctions
E) arrhythmias
55) Abnormal patterns of cardiac activity are known as ________.
A) automaticity
B) ischemias
C) defibrillations
D) arrhythmias
E) contractility
56) The maximum rate of contraction in normal cardiac muscle fibers is ________ per minute.
A) 80
B) 140
C) 200
D) 250
E) 300+
57) If the AV node does not receive action potentials generated by the SA node,
A) the ventricles will beat faster.
B) the ventricular rate of contraction will not be affected.
C) the stroke volume will increase.
D) tachycardia will occur.
E) it will establish a heart rate of 40-60 bpm.
58) During rapid depolarization of a ventricular contractile cell, the voltage-gated sodium channels close when the transmembrane potential reaches ________.
A) -90 mV
B) -30 mV
C) 0 mV
D) +30 mV
E) +90 mV
59) During repolarization, ________ ions rush out of the ventricular contractile cell.
A) sodium
B) calcium
C) magnesium
D) selenium
E) potassium
60) Specialized ________ convey the impulses to the contractile cells of the ventricular myocardium.
A) Purkinje fibers
B) nodal cells
C) AV bundles
D) bundle branches
E) ectopic cells
51) The QRS complex an ECG tracing represents
A) atrial depolarization.
B) : 1200318
