Final answer:
When your head is still, there is a basal release of neurotransmitters, with acetylcholine being the key neurotransmitter involved 'at the neuromuscular junction. Certain drugs can modulate this process by affecting neurotransmitter receptors.
Step-by-step explanation:
When your head isn't moving, there is a basal neurotransmitter release. This steady, ongoing release helps maintain a balance in signal transmission in the nervous system.
Specifically, at the neuromuscular junction, the neurotransmitter involved is acetylcholine (ACh). ACh is released from the presynaptic neuron and binds to ACh receptors on the postsynaptic membrane, which can either facilitate an action potential if the signal is strong enough, or keep the postsynaptic neuron at its resting potential if the signal is not strong enough for depolarization.
A drug that affects both divisions of the autonomic system would likely bind to or block the receptors for neurotransmitters that are common to both divisions, such as ACh at cholinergic synapses.
In the central nervous system, an abnormally low level of certain neurotransmitters can affect brain regions controlling movement, leading to disorders like Parkinson's disease. For instance, dopamine is a critical neurotransmitter in movement control.