Anonymous
Anonymous asked in Science & MathematicsBiology · 9 years ago

Acetylcholine (ACh) is an excitatory neurotransmitter at the neuromuscular junction (NMJ),?

Acetylcholine (ACh) is an excitatory neurotransmitter at the neuromuscular junction (NMJ), but an inhibitory neurotransmitter of many target organs of the parasympathetic nervous system (PSNS). This seemingly dichotomous role for ACh is because:

a. ACh activates ligand-gated Na+ channels at the NMJ, but activates ligand-gated Cl- channels in the PSNS.

b. at the NMJ, ACh activates ligand-gated ion channels, which flux Na+ to depolarize the muscle; whereas ACh activates G-protein coupled receptors at many PSNS synapses, which in turn activate voltage-gated K+ channels, which hyperpolarize the target cells.

c. ACh activates ligand-gated Na+ channels at the NMJ, but activated ligand-gated K+ channels in the PSNS.

d. at the NMJ, ACh works through G-protein coupled receptors to open Na+ channels to depolarize the muscle; whereas at PSNS synapses, ACh activates G-protein coupled receptors to activate voltage-gated K+ channels to hyperpolarize the target cells.

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  • 9 years ago
    Best Answer

    that would be b.

    at the NMJ, acetylcholine acts on ionotropic receptors - ones that have the channel built in

    in PSNS, ACh acts on metabotropic receptors - ones that trigger G-proteins

    Source(s): many years of studying electrophysiology
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