The reason that the myocardial cell does not produce the complete tetanus is___. ()
A. that it is controlled autorhythmicity
B. that its effective refractory period is very long
C. due to its "all or none" contraction
D. due to its atrioventricular delay
E. due to its little reserve of calcium in its sarcoplasmic reticulum
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The aorta play an important role in maintaining the diastolic pressure because ___. ()
A. its diameter is large
B. the aortic wall is thick
C. its wall has elasticity and distensibility
D. aortic blood flow is rapid
E. its frictional resistance to the blood flow is small
The diastolic pressure reflects mainly ___. ()
A. stroke volume
B. heart rate
C. peripheral resistance
D. elasticity of aorta
E. blood volume
The resistance vessel is ___. ()
A. the large artery
B. the small artery and the arteriole
C. the capillaries
D. the small vein
E. the large vein
The distribution of sympathetic vasoconstrictor fiber is the densest in the ___. ()
A. large artery
B. arteriole
C. precapillary sphincter
D. venule
E. large vein
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