Rapid depolarization (phase 0) of the action potential of ventricular muscle results from opening of ()
A. voltage-gated Ca2+ channels
B. voltage-gated Na+ channels
C. acetylcholine-activated K+ channels
D. inward rectifying K+ channels
E. ATP-sensitive K+ channels
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What is most responsible for phase 0 of a cardiac nodal cell? ()
A. Voltage-gated Na+ channels
B. Acetylcholine-activated K+ channels
C. Inward rectifying K+ channels
D. Voltage-gated Ca2+ channels
E. Pacemaker channels
Atrial repolarization normally occurs during the ()
A. P wave
B. QRS complex
C. ST segment
D. T wave
E. isoelectric period
The pressure measured in either the arterial or the venous circulation when the heart has stopped long enough to allow the pressures to equalize is called the ()
A. hemodynamic pressure
B. mean arterial pressure
C. transmural pressure
D. mean circulatory filling pressure
E. hydrostatic pressure
Resistance of blood flow through a tube is proportional to the ()
A. square of the radius
B. square root of the length
C. fourth power of the radius
D. square of the length
E. square root of the radius
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