Phase 3 of the action potential in the cardiac working cells is formed by ___. ()
A. deactivation of Na+ channel
B. Na+ influx
C. K+ efflux
D. Ca2+ influx
E. Cl- influx
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QRS complex signifies ___. ()
A. depolarization of the atria
B. depolarization of the ventricles
C. systole of ventricles
D. systole of atria
E. diastole of ventricles
Which of the following normally serves as the pacemaker of the heart? ()
A. SA node
B. the atria
C. A-V node
D. the Purkinje fiber
E. the ventricle
The characteristic of ventricular muscle cells includes ()
A. conductivity and contractility
B. excitability, autorhythmicity, conductivity and contractility
C. autorhythmicity, conductivity and contractility
D. excitability, conductivity and contractility
E. excitability, autorhythmicity and contractility
The relative stabilization of physical and chemical properties of internal environment is called ()
A. excitability
B. reflex
C. hemostasis
D. homeostasis
E. hematocrit
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