Acetylcholine is excitatory at the neuromuscular junction, but inhibitory at the SA node. Explain why this is true.
What will be an ideal response?
Acetylcholine receptors in heart muscle are muscarinic, whereas they are nicotinic in skeletal muscle. These receptors are linked to different types of ion channels. At the nicotinic receptor, the response is excitatory due to a sodium influx. At the muscarinic receptor, the response is inhibitory due to a potassium efflux.
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