Final answer:
The correct option is C. The cytoplasm of the neuromuscular terminal contains vesicles filled with molecules of the neurotransmitter acetylcholine (ACh). The muscle weakness of myasthenia gravis results from the loss of these receptors in the end-plate membrane.
Step-by-step explanation:
The cytoplasm of the neuromuscular terminal contains vesicles filled with molecules of the neurotransmitter acetylcholine (ACh). The muscle weakness of myasthenia gravis results from the loss of these receptors in the end-plate membrane.
When an action potential travels down the motor neuron's axon, it leads to the release of ACh into the synaptic cleft, where it diffuses across to the motor end plate and binds with ACh receptors. This binding triggers depolarization and muscle contraction.