Final answer:
Neurotransmitters act primarily on neural circuitry by binding to receptors on postsynaptic cell membranes, influencing various responses including excitatory, inhibitory, or modulatory effects. Dopamine is a neurotransmitter that can cause an increase in cAMP when it binds to its receptor.
Step-by-step explanation:
Neurotransmitters primarily act on neural circuitry. These chemical messengers are released from neurons into the small gaps (synapses) between cells, where they can bind to receptors on the postsynaptic cell membranes. An example of a neurotransmitter is dopamine, which is involved in numerous neurological processes and binds to G-protein-linked receptors, causing various effects depending on the receptors they bind to. Neurotransmitters can influence the postsynaptic cell in multiple ways, including initiating excitatory or inhibitory responses or even modulating the signal in more complex manners.
When a neurotransmitter like dopamine binds its receptor, we might expect to see an increase in secondary messenger molecules such as cAMP. It is important to note that neurotransmitter molecules differ from hormones in that they are released across synapses, while hormones are released into the bloodstream.