Which statement about autonomic nervous system control of a mammalian heartbeat is false? A) Acetylcholine is a parasympathetic neurotransmitter that influences ion channels of pacemaker cells. B) The heart slows down in response to acetylcholine. C) Acetylcholine increases permeability of Ca²⁺ channels. D) Norepinephrine is a sympathetic neurotransmitter that influences ion channels of pacemaker cells. E) Acetylcholine increases the permeability of K⁺channels.

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Quizplus · Accepted Answer

Acetylcholine decreases permeability of Ca2+ channels, rather than increasing it. This allows less calcium to enter the pacemaker cells, which decreases their depolarization rate and results in a slower heart rate.

Which Statement About Autonomic Nervous System Control of a Mammalian