Outline the process of neuromuscular transmission at the NMJ and name a disorder associated with NMJ dysfunction.

• A. Action potential triggers ACh release into the synaptic cleft; ACh binds nicotinic receptors; Na+ influx triggers muscle action potential; Myasthenia gravis is an NMJ disorder.
• B. Action potential triggers release of GABA into the synaptic cleft; ACh receptors are not involved; Myasthenia gravis is not an NMJ disorder.
• C. Action potential directly opens calcium channels in the sarcolemma without ACh involvement.
• D. The NMJ is not involved in muscle contraction.

Answer: (B)