What kinds of channels open during the phase 2 of the ventricular action potential（）
A. Ca2+ channel and K+ channel
B. Na+ channel and K+ channel
C. Na+ channel and Cl- channel
D. Na+ channel and Ca2+ channel
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Internal respiration is（）
A. gas exchange between the cells and the blood in the capillary
B. gas exchange between alveoli and blood in the capillary surrounding the alveoli
C. gas exchange between mitochondria and intracellular fluid
D. gas change between the cells in the tissue
E. gas exchange between alveoli and skeletal muscle cells
The major factor that cause the alveoli to collapse is（）
A. alveolar surface tension
B. contraction of smooth muscle in the bronchia
C. pleural pressure
D. atmosphere pressure
E. pulmonary pressure
The elasticity of the Windkessel vessel mainly influence（）
A. pulse pressure
B. Systolic pressure （Ps）
C. Diastole pressure （Pd）
D. peripheral venous pressure
Which of the following is most likely to cause the heart to go into spastic contraction（）
A. Excess extracellular fluid calcium ions
B. Increased sympathetic activity
C. Increased body temperature
Decreased extracellular fluid potassium ions
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