Final answer:
The substance secreted from neuron type A that acts on neuron B is dopamine, a neurotransmitter that plays a crucial role in numerous neurological functions. Dopamine binds to G-protein-linked receptors, resulting in increased levels of the secondary messenger cAMP.
Step-by-step explanation:
The substance found in neuron type A that can act on neuron B could be one of several neurotransmitters. These neurotransmitters are chemicals that neurons release to communicate with other neurons, muscles, or glands. In the context provided, the neuron type A would be secreting dopamine, which is a neurotransmitter involved in numerous neurological processes, such as the regulation of mood, motivation, and the reward system.
Dopamine operates by binding to its receptors on neighboring neurons and can cause long-term changes in the functioning of these neurons. When dopamine binds to a G-protein-linked receptor, one would expect an increase in the concentration of cAMP, which is a secondary messenger that amplifies the signal of dopamine.