Which of the following processes does not involved in the signal propagation at a chemical synapse?<br/>16. (Part 06, medium) 105-Mid A: synaptic vesicles release neurotransmitters in the presynaptic terminal. B: neurotransmitters diffuse across the synaptic clef. C: Postsynaptic receptors are activated by the neurotransmitters. D: Vesicles transport neurotransmitters from the synaptic terminals to the soma in the postsynaptic side.

___ has "all or none" phenomenon. () A: The postsynaptic potential B: The end-plate potential C: The receptor potential D: The spike potential E: The generator potential

Phentolamine<br/>may increase heart rate by targeting____. A: presynapticα2-adrenoceptors B: postsynapticα2-adrenoceptors C: cardiacβ-adrenoceptors D: cardiacα1-adrenoceptors E: vascularα1-adrenoceptors

Tachycardia is more common observed in phentolamine than prazosin because the former A: has some M-agonist action B: has some β1-agonist action C: blocks postsynaptic α₂-receptors D: blocks presynaptic α₂-receptors E: stimulates heart directly