题干

已知图中神经元a、b与痛觉传入有关,神经元c能释放脑啡肽(具有镇痛作用)。下列判断不合理的是  (     )

A:痛觉感受器产生的兴奋会引发神经元a释放乙酰胆碱

B:神经元c兴奋会释放脑啡肽从而引起乙酰胆碱释放量减少

C:a与脑啡肽结合的受体和b与乙酰胆碱结合的受体不同

D:两种递质均引起图中突触后膜电位由内正外负变为内负外正

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D

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